大氣化學(xué)和大氣成分
Atmospheric Chemistry and Atmospheric Composition

大氣成分研究進(jìn)展

2012年，大氣成分研究所圓滿完成了承擔(dān)的各項(xiàng)任務(wù)，在分析方法建立、比對(duì)校驗(yàn)、質(zhì)量控制，大氣成分及相關(guān)特性的觀測(cè)、模式發(fā)展應(yīng)用，影響評(píng)估等方面均取得了明顯的進(jìn)展。

1 分析方法、比對(duì)校驗(yàn)和質(zhì)量控制研究

1.1 大氣有機(jī)物熱脫附-全二維氣相色譜-氫火焰離子化分析方法

全二維氣相色譜（GC×GC）是20世紀(jì)90年代發(fā)展起來的具有高分辨率、高靈敏度、高峰容量等優(yōu)勢(shì)的分離技術(shù)，在我國(guó)將其用于大氣揮發(fā)性有機(jī)物（VOCs）的研究才剛剛起步。將GC×GC與氫火焰離子化檢測(cè)器（FID）聯(lián)用，構(gòu)建了用于測(cè)量大氣有機(jī)物的熱脫附-全二維氣相色譜-氫火焰離子化分析系統(tǒng)（TD-GC×GC-FID）。采用HP-5MS和HP-INNOWAX色譜柱，建立了C5～C15大氣有機(jī)物分析方法，實(shí)現(xiàn)了一次分析過程同時(shí)分離非甲烷烴（NMHCs）、含氧揮發(fā)性有機(jī)物（OVOCs）和鹵代烴等多種組分。利用標(biāo)準(zhǔn)物質(zhì)和4級(jí)桿質(zhì)譜（qMS）進(jìn)行定性，外標(biāo)法結(jié)合FID質(zhì)量校正因子定量。目標(biāo)物在GC×GC譜圖中第一和第二維保留時(shí)間變化分別小于0.6 s和0.02 s，峰體積平均相對(duì)標(biāo)準(zhǔn)偏差為14.3%，其中烷烴和芳香烴為4.5%。標(biāo)準(zhǔn)曲線r2均值大于0.99，平均檢出限為6.04 ng，平均回收率為111%。利用該方法檢測(cè)到2010年1月北京市區(qū)大氣中400多種有機(jī)物（信噪比大于50），鑒定了其中的103種物質(zhì)，包括烷烴、烯烴、芳香烴、鹵代烴、醛、酮、酯、醇和醚等。（王瑛）

1.2 大氣氫氟碳化物采樣分析和質(zhì)量控制方法

用自組裝采樣系統(tǒng)沖洗雙口不銹鋼采樣罐，并采集大氣樣品至1.36×105Pa，在實(shí)驗(yàn)室利用自組裝氣相色譜-質(zhì)譜聯(lián)用（GC-MS）系統(tǒng)分析樣品，對(duì)6種主要?dú)浞蓟铮℉FCs）分析的精度為0.24%～ 1.02%?？瞻讓?shí)驗(yàn)表明，采樣-分析過程未引入污染。通過壓力-體積曲線對(duì)進(jìn)樣壓力變化的影響進(jìn)行了校正?；厥章蕦?shí)驗(yàn)及存儲(chǔ)實(shí)驗(yàn)表明，6種HFCs回收率范圍為99.5%～100.4%，存儲(chǔ)112天內(nèi)HFCs濃度沒有顯著變化。在北京上甸子區(qū)域大氣本底站采集80 m梯度塔頂大氣樣品并分析，2個(gè)串聯(lián)采樣罐HFCs濃度差值范圍為0.04×10-12～0.16×10-12。采樣分析與同期該站GC-MS在線觀測(cè)系統(tǒng)獲得的HFCs濃度差值范圍為-0.86×10-12～-0.17×10-12。本研究建立的采樣-分析-質(zhì)量控制方法和流程適用于大氣中HFCs高精度觀測(cè)。（姚波）

1.3 北京上甸子站氣相色譜法大氣CH4和CO在線觀測(cè)方法研究

參照青海瓦里關(guān)全球大氣本底站氣相色譜在線觀測(cè)系統(tǒng)的設(shè)計(jì)，通過系統(tǒng)調(diào)試、測(cè)試和參數(shù)優(yōu)化，于2009年在北京上甸子區(qū)域大氣本底站建立了高精度氣相色譜法大氣CH4和CO在線觀測(cè)系統(tǒng)。該系統(tǒng)對(duì)CH4和CO的測(cè)量精度分別優(yōu)于0.03%和0.45%，達(dá)到世界氣象組織全球大氣觀測(cè)計(jì)劃（ WMO/ GAW） 的質(zhì)量目標(biāo)。研究建立了與該系統(tǒng)配套的標(biāo)氣選取方法及運(yùn)行序列∶選取可基本涵蓋該站大氣CH4和CO濃度范圍的2瓶標(biāo)氣作為工作標(biāo)氣，其中CH4濃度分別為2007.1×10-9和1809.5×10-9（摩爾分?jǐn)?shù)），CO濃度分別為405.6×10-9和123.8×10-9，在高低濃度工作標(biāo)氣之間穿插分析3 次大氣樣品，能夠保證測(cè)量的準(zhǔn)確度（觀測(cè)濃度的標(biāo)準(zhǔn)偏差CH4＜1.7×10-9和CO＜1.0×10-9），同時(shí)可最大程度地節(jié)省工作標(biāo)氣。該方法已應(yīng)用于華北地區(qū)本底大氣CH4和CO的高精度連續(xù)觀測(cè)。（周凌晞）

1.4 水汽對(duì)光腔衰蕩光譜系統(tǒng)（CRDS）法測(cè)定CH4的影響

分析了利用光腔衰蕩光譜系統(tǒng)（CRDS）法測(cè)定CH4濃度與水汽含量的關(guān)系，并建立了水汽含量在0.50%～2.45%（體積比，下同）范圍內(nèi)的有效校正方法。采用CRDS法對(duì)水汽含量為0.93% 的CH4標(biāo)氣進(jìn)行多次測(cè)量，測(cè)量值經(jīng)校正后與理論值的偏差均小于2.0×10-9，最大偏差1.8×10-9，優(yōu)于大氣本底CH4觀測(cè)質(zhì)控標(biāo)準(zhǔn)。校正瓦里關(guān)站CRDS系統(tǒng)試運(yùn)行期間的CH4實(shí)測(cè)數(shù)據(jù)（水汽含量為0.50%～2.45%），與該站氣相色譜-氫火焰離子化檢測(cè)器系統(tǒng)（GC-FID）同期測(cè)量結(jié)果相比，38.48%的數(shù)據(jù)偏差小于2.0×10-9，說明在系統(tǒng)未配備超低溫冷阱除水單元之前，此方法適用于觀測(cè)數(shù)據(jù)的校正。（周凌晞）

1.5 兩種探空儀觀測(cè)濕度垂直分布及其應(yīng)用比較

對(duì)2010年8月在云南騰沖利用芬蘭Vaisala RS80探空儀和低溫霜點(diǎn)儀（CFH）測(cè)量大氣濕度的垂直分布進(jìn)行對(duì)比分析，同時(shí)比較二者白天和夜間測(cè)量誤差的差別。結(jié)果表明，RS80濕度測(cè)值在整個(gè)對(duì)流層比CFH 測(cè)值偏干（23.7±18.5）%；因太陽(yáng)輻射白天RS80偏干較夜間更明顯，比夜間偏干（13.5±14.8）%。而在對(duì)流層上層向平流層過渡區(qū)域內(nèi)RS80濕度數(shù)據(jù)基本無(wú)效。CFH 在低溫、低濕環(huán)境下對(duì)濕度能有效測(cè)量，但在濕度較高的對(duì)流層低層測(cè)值偏高，導(dǎo)致CFH水汽總量平均比GPS遙測(cè)的水汽總量偏高（4.3±2.0）mm（樣本數(shù)為11），而RS80、GTS1與GPS的水汽總量差別分別是（0.2±1.4）mm（樣本數(shù)為12）和（-0.2±2.2）mm（樣本數(shù)為43）。地基GPS遙測(cè)的水汽總量對(duì)對(duì)流層上層至平流層的水汽變化不敏感。由于RS80測(cè)量相對(duì)濕度在高空偏低，通過RS80相對(duì)濕度測(cè)值來確定中、高云結(jié)果是偏低的，特別是對(duì)6000 m 以上的高云判別，RS80相對(duì)濕度的探測(cè)幾乎很難甄別到云的存在。（鄭向東）

1.6 塔克拉瑪干沙漠地區(qū)氣溶膠光學(xué)厚度衛(wèi)星遙感產(chǎn)品驗(yàn)證

基于塔克拉瑪干沙漠地區(qū)地基太陽(yáng)光度計(jì)數(shù)據(jù)，系統(tǒng)驗(yàn)證了2007—2008年星載多角度成像光譜儀（MISR）、中分辨率成像光譜儀（MODIS）和臭氧監(jiān)測(cè)儀（OMI）氣溶膠反演產(chǎn)品，旨在定量評(píng)估這些產(chǎn)品在我國(guó)沙漠地區(qū)的氣溶膠光學(xué)厚度（AOD）反演精度。結(jié)果表明：MODIS/AOD的相關(guān)系數(shù)在4種產(chǎn)品中最高（0.91），OMI/AOD次之（0.87），其次為MISR/AOD（0.84）， OMI/UVAI相關(guān)系數(shù)偏低（0.51）；MISR/AOD均方根誤差（0.14）和平均偏差（-0.06）在4種反演產(chǎn)品中最低；與地基觀測(cè)相比，MISR/ AOD、MODIS/AOD系統(tǒng)偏低，OMI/AOD、OMI/UVAI系統(tǒng)偏高；塔克拉瑪干沙漠春夏季AOD較大，秋冬季AOD相對(duì)較小。Angstrom波長(zhǎng)指數(shù)春季（3—5月）最?。ň禐?.11），夏季（6—8月）次之，秋季（9—11月）和冬季（12月至次年2月）較大（均值達(dá)到0.61），這表明在春夏季氣溶膠粒子偏大，秋冬季氣溶膠粒子偏小。研究2000—2010年AOD年際變化表明，由于塔克拉瑪干沙漠地區(qū)屬于沙塵源區(qū)，氣溶膠類型較為單一，總體來說，變化趨勢(shì)不明顯。從反演結(jié)果來看，2003年的氣溶膠含量為此10年中最高，年均值達(dá)到0.32；2005年的氣溶膠含量在這10年中最低，年均值為0.28。（車慧正）

1.7 中國(guó)東部地區(qū)顆粒物（PM）遙感定量反演神經(jīng)網(wǎng)絡(luò)算法研究

近年來中國(guó)區(qū)域的大氣污染情況日趨嚴(yán)重，大氣污染監(jiān)測(cè)與治理已刻不容緩。由于衛(wèi)星遙感具有空間覆蓋廣和成本低等優(yōu)點(diǎn)，衛(wèi)星遙感反演氣溶膠光學(xué)厚度（AOD）產(chǎn)品被普遍認(rèn)為是地面PM2.5濃度的重要指標(biāo)，且已被廣泛地應(yīng)用于地面PM2.5遙感監(jiān)測(cè)。本研究利用2007—2008年的MODIS/Terra氣溶膠光學(xué)厚度產(chǎn)品，考慮中國(guó)東部地區(qū)5個(gè)大氣成分站點(diǎn)的風(fēng)速、風(fēng)向、溫度、濕度和邊界層高度等氣象數(shù)據(jù)，構(gòu)建后向（BP）神經(jīng)網(wǎng)絡(luò)，提出了基于MODIS AOD產(chǎn)品估算PM2.5的模型。利用5個(gè)大氣成分站點(diǎn)PM2.5觀測(cè)數(shù)據(jù)對(duì)模型進(jìn)行散點(diǎn)擬合和時(shí)間序列擬合驗(yàn)證。結(jié)果表明：（1）從PM2.5觀測(cè)值與估算值的散點(diǎn)回歸分析來看，PM2.5估算值與觀測(cè)值相關(guān)系數(shù)最好的為廬山站（R=0.6），其他4個(gè)站次之，但其相關(guān)系數(shù)均在0.4（中強(qiáng)相關(guān)）以上；（2）從PM2.5觀測(cè)值與估算值的時(shí)間序列對(duì)比分析來看，PM2.5估算值和觀測(cè)值差值隨時(shí)間變化而變化，且存在明顯的日際振蕩現(xiàn)象，但經(jīng)相鄰5天滑動(dòng)平均處理，5個(gè)站點(diǎn)的PM2.5估算值與觀測(cè)值相關(guān)系數(shù)得到普遍提升，滑動(dòng)后的相關(guān)系數(shù)（RMA）均在0.7以上（除鄭州外），廬山站RMA達(dá)到0.83。表明在BP網(wǎng)絡(luò)框架下，本研究提出的基于MODIS AOD產(chǎn)品估算PM2.5的模型能較好地應(yīng)用于PM2.5的監(jiān)測(cè)。（郭建平）

1.8 大氣本底站反應(yīng)性氣體觀測(cè)數(shù)據(jù)處理系統(tǒng)功能設(shè)計(jì)及實(shí)現(xiàn)

基于反應(yīng)性氣體多年觀測(cè)的較為成熟的數(shù)據(jù)處理和質(zhì)量控制方法，采用模塊化功能結(jié)構(gòu)設(shè)計(jì)，通過應(yīng)用Visual Studio開發(fā)平臺(tái)并結(jié)合MAP WinGIS等空間和時(shí)間顯示控件，設(shè)計(jì)和開發(fā)了反應(yīng)性氣體觀測(cè)數(shù)據(jù)處理系統(tǒng)。系統(tǒng)實(shí)現(xiàn)了觀測(cè)數(shù)據(jù)在空間和時(shí)間上的可視化，業(yè)務(wù)應(yīng)用表明，具有良好的人機(jī)交互和數(shù)據(jù)處理能力，具備一定的數(shù)據(jù)統(tǒng)計(jì)分析功能。系統(tǒng)實(shí)現(xiàn)了對(duì)大氣本底站反應(yīng)性氣體觀測(cè)數(shù)據(jù)的統(tǒng)一管理和綜合處理，已成為大氣成分觀測(cè)數(shù)據(jù)質(zhì)量控制業(yè)務(wù)系統(tǒng)的一個(gè)重要組成部分。（徐曉斌）

2 大氣成分及相關(guān)特性變化的觀測(cè)研究

2.1 中國(guó)大氣氣溶膠的組成：時(shí)空分布、化學(xué)特征、區(qū)域霾分布

通過野外觀測(cè)和實(shí)驗(yàn)室分析研究，得到了中國(guó)各主要區(qū)域氣溶膠的化學(xué)組成特征。由于各區(qū)域所處地理環(huán)境、人口密度及工業(yè)發(fā)展程度的不同，氣溶膠的排放來源也不同，最終導(dǎo)致了各區(qū)域氣溶膠化學(xué)組分的差異。對(duì)各區(qū)域綜合分析結(jié)果表明，我國(guó)氣溶膠中沙塵氣溶膠占有較高比例（約35%），硫酸鹽、有機(jī)碳、黑碳、硝酸鹽和銨鹽所占比例分別為16%、15%、3.5%、7%和5%。礦物氣溶膠（包括沙塵、城市逸散性粉塵和煤煙塵等）是中國(guó)大氣中含量最大的組分，其主體的變化受到天氣氣候自然變率的控制。與黑碳同源的有機(jī)碳中55%～60%是二次轉(zhuǎn)化的有機(jī)碳?xì)馊苣z（SOC）。SOC的測(cè)定、估算和在數(shù)值模式中的準(zhǔn)確描述不確定性很大，是影響當(dāng)今國(guó)際上準(zhǔn)確估算氣溶膠冷卻效應(yīng)的一個(gè)重要因素。中國(guó)的大氣中硝酸鹽約占7%，銨鹽約占5%，此兩類氣溶膠的氣候冷卻效應(yīng)也不容忽視。綜合分析得到了中國(guó)氣溶膠散射性強(qiáng)、冷卻效應(yīng)大的重要結(jié)論。近50年的地面能見度資料顯示，我國(guó)霾已經(jīng)呈現(xiàn)出區(qū)域分布的特征。其中4個(gè)比較嚴(yán)重的區(qū)域是：（1）華北平原，包括京津快速發(fā)展的經(jīng)濟(jì)區(qū)以及河北、山東、河南，關(guān)中平原因能見度變化類似也歸在此區(qū)；（2）華東區(qū)域，以長(zhǎng)三角快速發(fā)展的經(jīng)濟(jì)區(qū)為主體，涵蓋湖北、安徽、江蘇、上海和浙江；（3）華南區(qū)域，以珠三角快速發(fā)展的經(jīng)濟(jì)區(qū)為主體，包括廣東和廣西；（4）西南區(qū)域，主要是四川盆地。這些區(qū)域能見度的惡化與大氣污染物的排放量變化和高濃度的氣溶膠濃度密切相關(guān)。（張小曳）

2.2 北京亞微米氣溶膠粒徑分布季節(jié)變化特征

利用氣溶膠質(zhì)譜儀（Q-AMS）對(duì)北京2008年不同月份（1、4、6 和10 月）亞微米氣溶膠（PM1）特性進(jìn)行觀測(cè)試驗(yàn)。獲得了PM1 及其主要化學(xué)組分硫酸鹽、硝酸鹽、銨鹽、有機(jī)物的質(zhì)量濃度和粒徑分布數(shù)據(jù)， 總結(jié)了亞微米氣溶膠化學(xué)組分和粒徑分布的季節(jié)變化特征。研究表明， 亞微米氣溶膠質(zhì)量濃度夏季最高， 秋季最低。有機(jī)物濃度在四季中占PM1的比例（36%～58%）高于其他物種， 在冬季濃度最高。硫酸鹽、硝酸鹽和銨鹽平均濃度次之， 3種物種在夏季濃度最高， 其次為春季， 秋冬季最低。利用主因子分析方法將有機(jī)氣溶膠解析為碳?xì)漕愑袡C(jī)氣溶膠（HOA）和氧化性有機(jī)氣溶膠（OOA）兩類。HOA濃度在冬季最高， 占有機(jī)氣溶膠總量的70%左右。OOA 濃度在夏季最高， 秋冬季較低。四季中主要化學(xué)組分質(zhì)量濃度的日變化規(guī)律表現(xiàn)為夜間高， 日間低的特點(diǎn)。HOA 傍晚到夜間濃度變化幅度明顯大于其他物種，其濃度在中午出現(xiàn)峰值，可能與北京餐館排放有直接關(guān)系。OOA 以及硫酸鹽、硝酸鹽、銨鹽和氯化物的日變化特點(diǎn)接近， 09∶00 —13∶00 之間濃度出現(xiàn)上升趨勢(shì)， 午后有所下降。亞微米氣溶膠主要化學(xué)組分粒徑分布峰值均出現(xiàn)在500～600 nm之間。有機(jī)物質(zhì)量譜分布范圍較其他物種寬， 尤其是秋冬季質(zhì)量譜分布更寬。硫酸鹽、硝酸鹽和銨鹽在春、夏、秋3季的平均粒徑分布特點(diǎn)相似， 而冬季譜分布較其他季節(jié)要寬， 峰值粒徑偏小。在粒徑＜200 nm的范圍內(nèi)， 有機(jī)物占亞微米氣溶膠總量60%以上， 粒子越細(xì)， 有機(jī)物占的比例越大， 冬季有機(jī)物在觀測(cè)粒徑范圍內(nèi)占PM1 的50%以上。 春、夏、秋3季HOA 在＜200 nm粒徑范圍內(nèi)占優(yōu)勢(shì)， 而OOA 則在＞300 nm粒徑范圍內(nèi)占有相對(duì)優(yōu)勢(shì)。（張養(yǎng)梅）

2.3 天津武清地區(qū)云凝結(jié)核變化特征

利用2009年11—12月在天津武清氣象局測(cè)量的云凝結(jié)核（CCN）濃度資料以及氣溶膠數(shù)譜分布的觀測(cè)資料，分析了武清地區(qū)在不同過飽和度（0.1%～1.0%）下云凝結(jié)核濃度及活化率的變化特征。結(jié)果表明：武清地區(qū)冬季CCN數(shù)濃度變化范圍很大，過飽和度為1%時(shí)，濃度變化范圍為4000～32000cm-3，且濃度受風(fēng)速影響明顯，風(fēng)速2級(jí)以下CCN數(shù)濃度很高，過飽和度為1%時(shí)，其平均濃度可達(dá)16000 cm-3，但對(duì)于4級(jí)風(fēng)速以上CCN平均濃度為4000 cm-3左右；在過飽和度0.1%～0.4%間CCN濃度變化較大，過飽和度每增加0.1%，CCN濃度增加值平均約為過飽和度0.4%～1.0%間濃度增量的5倍。低過飽和度（0.1%、0.2%）下，活化率受風(fēng)速影響明顯，1級(jí)風(fēng)速下的CCN活化率約為4級(jí)風(fēng)速下的3倍，但在過飽和度1%時(shí)活化率則相差不大。CCN濃度的日變化呈雙峰型，峰值時(shí)刻為北京時(shí)間08∶00和18∶00左右，活化率的日變化則呈雙谷型，主要是受局地排放影響的結(jié)果。利用指數(shù)函數(shù)擬合各風(fēng)速下CCN濃度過飽和度譜，表明該地譜型為典型的大陸型。（孫俊英）

2.4 上甸子區(qū)域大氣本底站鹵代溫室氣體源區(qū)特征分析

利用美國(guó)NOAA研制的拉格朗日粒子擴(kuò)散模型HYSPLIT和聚類分析方法，對(duì)上甸子站2008—2010年逐日4個(gè)時(shí)次5天的后向軌跡按季節(jié)分類，結(jié)合上甸子站鹵代溫室氣體CFC-11、CFC-12、HCFC-22、SF6等的在線濃度觀測(cè)數(shù)據(jù)，分析了不同季節(jié)不同輸送軌跡對(duì)該地區(qū)鹵代溫室氣體濃度的影響。利用上甸子站風(fēng)場(chǎng)資料結(jié)合同期濃度觀測(cè)數(shù)據(jù)，計(jì)算分析了CFC-11、CFC-12、HCFC-22、SF6等的濃度載荷。軌跡聚類分析結(jié)果表明，占有較高比例、移動(dòng)緩慢、垂直高度低的偏南氣團(tuán)組，一直在邊界層下部緩慢移動(dòng)，有利于污染物在邊界層內(nèi)的累積，其對(duì)應(yīng)的上述鹵代溫室氣體平均濃度在各組中一致最高，而移動(dòng)快速、垂直高度高的西北氣團(tuán)組對(duì)應(yīng)的鹵代污染物平均濃度都一致較低。濃度載荷結(jié)果表明，西西南和西南是各鹵代物種的最高濃度載荷方位，北東北和北是最低濃度載荷方位，偏西南-南-東南是高濃度載荷扇區(qū)，偏西北-北-東北是低濃度載荷扇區(qū)。軌跡聚類分析和濃度載荷結(jié)果都表明，上甸子測(cè)站的東南、偏南及西南區(qū)域是上述鹵代物種的高污染源區(qū)，反映了這些高排放地區(qū)的人類源在區(qū)域尺度上對(duì)上甸子測(cè)站的輸送影響，而西北、偏北和東北區(qū)域是測(cè)站的相對(duì)清潔區(qū)。（安興琴）

2.5 上甸子區(qū)域本底站大氣氫氟碳化物和全氟化碳在線觀測(cè)

2010年5月至2011年5月，在上甸子區(qū)域本底站對(duì)大氣中的氫氟碳化物（HFCs）和全氟化碳（PFCs）進(jìn)行了在線觀測(cè)。 5種HFCs和3種PFCs的時(shí)間序列都出現(xiàn)高濃度污染事件，本底數(shù)據(jù)百分比36%（HFC-32）至83%（PFC-218）。觀測(cè)期間各物種平均濃度分別為24.5×10-12（HFC-23）、5.86×10-12（HFC-32）、 9.97×10-12（HFC-125）、 66.0×10-12（HFC-134a）、 9.77×10-12（HFC-152a）、79.1×10-12（CF4）、4.22×10-12（PFC-116）和0.56×10-12（PFC-218）。上甸子站濃度水平同北半球中高緯度其他站點(diǎn)一致。東北來向大氣對(duì)HFCs/PFCs載荷貢獻(xiàn)為負(fù)，而西南方向（城市扇區(qū)）貢獻(xiàn)為正。采用CO作為示蹤物，利用示蹤物比值相關(guān)法計(jì)算了我國(guó)HFCs/PFCs年排放量分別為：（3.6±3.2） kt（HFC-23）、（4.3±3.6）kt （HFC-32）、（2.7±2.3） kt （HFC-125）、（6.0±5.6） kt （HFC-134a）、（2.0±1.8）kt （HFC-152a）、（2.4±2.1） kt （CF4）、（0.27±0.26） kt （PFC-116）和（0.061±0.095） kt （PFC-218）。同早期的研究結(jié)果相比，HFC-23排放量降低，原因是自2005年開始，HFC-23通過清潔發(fā)展機(jī)制（CDM）項(xiàng)目開始減排。（姚波）

2.6 我國(guó)4個(gè)WMO/GAW 本底站大氣CH4濃度及變化特征

利用基于光腔衰蕩光譜（ CRDS） 技術(shù)自組裝的大氣CH4在線觀測(cè)系統(tǒng)，2009—2010年在青海瓦里關(guān)、浙江臨安、北京上甸子和黑龍江龍鳳山4個(gè)世界氣象組織全球大氣觀測(cè)網(wǎng)（ WMO/GAW） 大氣本底站對(duì)大氣CH4進(jìn)行了在線觀測(cè)。臨安站在所有季節(jié)中CH4濃度都表現(xiàn)出類似的日變化趨勢(shì)，即濃度在每日05∶00（北京時(shí)間）達(dá)到最高值，在14∶00最低。夏季龍鳳山站CH4濃度表現(xiàn)出類似的規(guī)律，但其日變化振幅較大，達(dá)到216.8×10-9（摩爾分?jǐn)?shù)）。上甸子站春、秋、冬季CH4濃度呈現(xiàn)類似變化趨勢(shì)，但夏季日平均值較高，在晚間20∶00達(dá)到最高值，瓦里關(guān)站四季CH4濃度日變化均不明顯。3個(gè)區(qū)域本底站（臨安、上甸子和龍鳳山）全年CH4本底濃度存在明顯的變化，臨安站CH4本底濃度在7月達(dá)到全年最低水平。龍鳳山站則表現(xiàn)出相反的趨勢(shì)，在8月達(dá)到全年最高值，其全年濃度表現(xiàn)出“W”型變化。冬季龍鳳山和上甸子站CH4濃度高于春季和秋季。瓦里關(guān)站全年濃度變化較小，月平均濃度振幅僅為11.5×10-9。臨安、上甸子和龍鳳山3個(gè)區(qū)域本底站夏季CH4非本底數(shù)據(jù)占總數(shù)據(jù)的比例＞70%。為分析氣團(tuán)傳輸?shù)挠绊?，?duì)4個(gè)站夏季高濃度時(shí)刻（瓦里關(guān)CH4＞1870×10-9，龍鳳山CH4＞2100×10-9，臨安CH4＞2150×10-9，上甸子CH4＞2050×10-9）對(duì)應(yīng)的氣團(tuán)軌跡進(jìn)行聚類分析表明，夏季出現(xiàn)的高濃度CH4觀測(cè)數(shù)據(jù)可能主要由氣團(tuán)傳輸引起。（方雙喜）

2.7 云南香格里拉本底站大氣CH4體積分?jǐn)?shù)及變化特征

利用基于光腔衰蕩光譜（CRDS）技術(shù)自組裝的大氣CH4在線觀測(cè)系統(tǒng)，2010年7月至2011年10月在云南香格里拉大氣本底站對(duì)大氣CH4進(jìn)行了在線觀測(cè)。結(jié)果發(fā)現(xiàn)，該站春、夏、秋和冬季CH4平均本底值分別為（1850.7±6.9）×10-9（體積分?jǐn)?shù)，下同）、（1850.9±13.4）×10-9、（1865.6±16.1）×10-9和（1839.2±6.5）×10-9。全年體積分?jǐn)?shù)在9月最高，12月最低，月均值振幅約39.6×10-9。四季日平均最低值均出現(xiàn)在14∶00—16∶00。日變化振幅在冬季最小，秋季最大，分別為4.4×10-9和10.0×10-9。西南來向的地面風(fēng)會(huì)明顯抬升CH4體積分?jǐn)?shù)，而北偏東來向的地面風(fēng)顯著降低觀測(cè)結(jié)果。通過四季每日整點(diǎn)后向軌跡聚類計(jì)算，結(jié)合觀測(cè)資料分析發(fā)現(xiàn)，該站CH4主要受西南來向氣團(tuán)傳輸影響，尤其在春、夏、秋季。（方雙喜）

2.8 云南香格里拉本底站大氣CO2濃度及變化特征初步研究

利用基于光腔衰蕩光譜（CRDS）技術(shù)自組裝的大氣CO2在線觀測(cè)系統(tǒng)，2010年9月至2011年8月在云南香格里拉大氣本底站對(duì)大氣CO2進(jìn)行了初步觀測(cè)。該站春、夏、秋和冬季CO2平均本底濃度分別為394.78×10-6（物質(zhì)的量之比，下同）、386.82×10-6、386.46×10-6和390.74×10-6。全年濃度在4—5月最高，7月最低，全年月均值振幅約12.22×10-6。四季濃度日平均最高值出現(xiàn)在07∶00左右，最低值出現(xiàn)在14∶00—17∶00之間。日變化振幅在冬季最小，夏季最大，分別為1.51×10-6和21.82×10-6。四季西南來向的地面風(fēng)對(duì)CO2濃度均有明顯的降低作用。通過四季每日整點(diǎn)后向軌跡聚類計(jì)算，結(jié)合濃度資料分析發(fā)現(xiàn)，該站春、夏、秋季來自于西南方向的氣團(tuán)降低了觀測(cè)的CO2濃度，而在冬季未起到明顯的降低作用，主要因該站局地植被生態(tài)系統(tǒng)排放減少所致。（方雙喜）

2.9 華北地區(qū)上空“大氣污染氧化池”

2006年開展的野外觀測(cè)試驗(yàn)結(jié)果表明，華北地區(qū)大城市和工業(yè)污染排放易在該地區(qū)中心上空匯集，有益于大氣OH自由基維持在較高的濃度水平。這些OH自由基使大氣中揮發(fā)性氣體（如SO2，NO2和VOCs）氧化成低揮發(fā)性的無(wú)機(jī)酸或含氧有機(jī)物，加速大氣中的氣-粒轉(zhuǎn)化過程。因此，華北地區(qū)低空不僅污染十分嚴(yán)重，而且還具有“大氣污染氧化池” 的作用。（馬建中）

2.10 我國(guó)華北及長(zhǎng)三角地區(qū)近幾年SO2變化趨勢(shì)

近年來我國(guó)實(shí)施了較嚴(yán)格的燃煤脫硫措施，火電廠SO2排放得到遏制。此外，與2008年北京奧運(yùn)會(huì)相關(guān)的減排措施也使華北區(qū)域的污染排放顯著減少。本研究關(guān)注這些措施在大氣SO2濃度方面帶來的實(shí)際效果，以華北地區(qū)和長(zhǎng)江三角洲為例開展研究。

對(duì)近些年華北地區(qū)不同類型站點(diǎn)SO2濃度的變化特征分析表明，在北京城區(qū)的中國(guó)氣象局站、河北農(nóng)村的固城站以及華北地區(qū)上甸子區(qū)域大氣本底站SO2平均濃度（±標(biāo)準(zhǔn)偏差）分別為 （16.8±13.1） ×10-9、（14.8±9.4） ×10-9和（ 7.5±4.0） ×10-9。冬季取暖期的SO2濃度約為夏季的4～6倍。各站點(diǎn)SO2日均值存在高度顯著的相關(guān)性，表明SO2污染的區(qū)域性特征。所有站點(diǎn)SO2均在白天出現(xiàn)峰值，很可能與華北上空高SO2濃度氣流的向下混合或水平輸送有關(guān)。北京城區(qū)中國(guó)氣象局站和河北農(nóng)村固城站的SO2存在顯著的下降趨勢(shì)，分別為每年-4.4×10-9和-2.4×10-9， 而上甸子本底站只有微小的下降趨勢(shì) （-0.3×10-9），表明華北區(qū)域背景的降幅并不大。各站SO2濃度在2008年北京奧運(yùn)會(huì)污染控制措施之后均有顯著下降，且在2009年未見反彈，表明奧運(yùn)污染控制具有一定的長(zhǎng)期效應(yīng)。奧運(yùn)后SO2濃度在中國(guó)氣象局、固城和上甸子3個(gè)站點(diǎn)分別下降26%、36%和13%， 這些下降與風(fēng)、溫、濕等氣象條件變化基本無(wú)關(guān)。區(qū)分局地和區(qū)域兩種特征的分析表明，奧運(yùn)污染控制帶來的北京局地和區(qū)域?yàn)橹鞯腟O2降幅分別約為40%和20%。

長(zhǎng)江三角洲臨安大氣本底站的SO2長(zhǎng)期觀測(cè)結(jié)果表明，2005—2010年間該站SO2存在顯著的下降趨勢(shì)，年降幅為2.4×10-9（P ＜ 0.0001），尤其是2008年之后降幅更大。2005—2008年SO2平均濃度（±標(biāo)準(zhǔn)偏差）為（14.2±3.1）×10-9，比1999—2000年測(cè)得的（13.5±5.1）×10-9略高。2008—2010年SO2平均濃度（±標(biāo)準(zhǔn)偏差）為（7.1±3.1）×10-9。嚴(yán)格的排放控制，使2008年之后長(zhǎng)三角地區(qū)的SO2下降了50%。這種下降也導(dǎo)致了SO2日變化的改變，從2009年前的夜間出現(xiàn)峰值改變?yōu)?009年后的 10∶00前后出現(xiàn)峰值。這一變化說明，可能垂直交換過程對(duì)SO2的貢獻(xiàn)超過近地層積累。（徐曉斌）

2.11 北京城區(qū)污染物區(qū)域輸送對(duì)下風(fēng)向地區(qū)夏季O3生成效率（OPE）的影響

2008年6月1日至8月31日在北京城區(qū)中國(guó)氣象局站和北京遠(yuǎn)郊區(qū)的上甸子大氣本底站同步測(cè)量了SO2、 O3、 NOx、 NO和CO等氣態(tài)污染物。不同風(fēng)向條件下上甸子的污染物濃度水平差異巨大，西南風(fēng)時(shí)遠(yuǎn)高于東北風(fēng)。西南風(fēng)有利于北京城區(qū)污染物向下游輸送，而東北風(fēng)則更多反映本底狀況。在上甸子，對(duì)應(yīng)城市氣流的O3濃度水平比來自清潔地區(qū)氣流的約高33.4×10-9。對(duì)應(yīng)城市污染影響和本底條件下計(jì)算的OPE分別為4.0和5.3。根據(jù)這些OPE值和NOz（NOy-NOx）值估算了由城市輸送的污染在上甸子局地產(chǎn)生的O3大約為8.6×10-9，僅相當(dāng)于城市污染輸送總影響的25.7%。這一結(jié)果表明，夏季城市O3的直接輸送是上甸子O3高濃度的主要原因。（徐曉斌）

2.12 北京地區(qū)夏季O3及其前體物的觀測(cè):城市煙羽對(duì)下風(fēng)向鄉(xiāng)村地區(qū)O3污染的影響

2007年6月20日至9月16日，在北京主導(dǎo)風(fēng)向上的4個(gè)站點(diǎn)進(jìn)行了地面O3及其前體物的觀測(cè)，包括2個(gè)城市站點(diǎn)（豐臺(tái)和寶蓮）、1個(gè)郊區(qū)站點(diǎn)（順義）和1個(gè)鄉(xiāng)村站點(diǎn)（上甸子）。4個(gè)站點(diǎn)O3的日變化具有典型污染地區(qū)的O3變化特征，特別是沿自西南至東北的主導(dǎo)風(fēng)向，各個(gè)站點(diǎn)的O3峰值出現(xiàn)的時(shí)間逐站滯后。對(duì)微量氣體相關(guān)分析顯示，與寶蓮站相比，到達(dá)上甸子站的污染氣團(tuán)更加老化，O3和Ox的濃度均較高。研究結(jié)果表明，城市煙羽不僅可以輸送O3，而且還輸送其前體物，后者與下風(fēng)向鄉(xiāng)村地區(qū)大氣混合可以導(dǎo)致更多的光化學(xué)O3生成。（馬建中）

2.13 1992—2009年廬山降水酸度和離子成分的變化特征

對(duì)1992—2009年廬山降水pH和電導(dǎo)率資料的分析結(jié)果表明，該地區(qū)降水pH年均值在4.35～5.01之間變化，平均年變率約為0.037/a，降水酸度呈現(xiàn)顯著下降趨勢(shì)；降水電導(dǎo)率呈現(xiàn)逐年增加趨勢(shì)，平均年變率為1.87 μS/（cm a），非氫電導(dǎo)率未呈現(xiàn)顯著變化趨勢(shì)，降水酸度的增加與進(jìn)入降水的酸性物質(zhì)增加密切相關(guān)。這種趨勢(shì)與我國(guó)東部能源消費(fèi)狀況的變化趨勢(shì)一致。廬山降水酸度的季節(jié)變化較明顯，冬季各月的多年平均降水pH值為4.35，酸雨污染嚴(yán)重；夏季降水平均pH值為4.88，高于其他季節(jié)，酸雨污染輕微。對(duì)2007年1月至2009年6月降水樣品的離子成分分析結(jié)果顯示，SO42-和NO3-是降水中主要陰離子，NH4+和Ca2+是主要陽(yáng)離子。SO42-和NO3-的化學(xué)當(dāng)量比值約為2.7，比20世紀(jì)80年代有明顯的降低，但硫酸仍是降水中最主要的致酸物質(zhì)。NH4+與Ca2+的化學(xué)當(dāng)量比值約為1.0，表明這兩種堿性物質(zhì)提供了相近的酸中和能力。Cl-和Na+的化學(xué)當(dāng)量比值約為0.67，低于自然降水平均值。廬山降水離子濃度總水平和主要離子組成特征具有明顯的季節(jié)變化，與降水量及氣團(tuán)輸送有密切關(guān)系。對(duì)降水時(shí)段氣團(tuán)輸送軌跡的簇分析結(jié)果顯示，共有6簇氣團(tuán)輸送影響廬山降水的酸度和離子組成，其影響相對(duì)均勻，來自南海和廬山周邊的氣團(tuán)起到主要影響。（李怡）

2.14 北京市酸雨變化趨勢(shì)及成因分析

1993—2002年中國(guó)氣象局酸雨觀測(cè)站網(wǎng)在北京地區(qū)有2個(gè)觀測(cè)站，2003年增至3個(gè)。根據(jù)北京3個(gè)酸雨觀測(cè)站的有關(guān)資料，研究了北京市酸雨變化的特征及成因。研究結(jié)果表明∶（1）1993—2007年北京地區(qū)降水酸度呈現(xiàn)2個(gè)階段，即1993—2002年降水酸度穩(wěn)定在較弱水平，而2003—2008年呈逐年增強(qiáng)趨勢(shì)；（2）與2003年以前相比，2003年以后硫酸根和硝酸根離子濃度均呈明顯增加趨勢(shì)，二者比值逐步下降并低于3，這表明北京乃至華北地區(qū)的酸雨已由硫酸型轉(zhuǎn)為硫酸與硝酸并重型；（3）北京周邊省、市二氧化硫年排放量的增加及鈣離子和可吸入顆粒物濃度減少是近年來北京地區(qū)酸雨增強(qiáng)的人為原因；（4）氣象條件是酸雨發(fā)生的主要?jiǎng)恿σ蛩亍Ｒ话闱闆r下，在地面風(fēng)速較小的季節(jié)酸雨頻率較高，850 hPa高度為弱的偏南風(fēng)或發(fā)生低層逆溫時(shí)可促進(jìn)酸雨的發(fā)生。此外，降水量的大小也與酸雨有密切關(guān)系， 24 h降水量達(dá)暴雨量級(jí)時(shí)酸雨頻率最高。（侯青）

2.15 北京空氣持續(xù)污染特征

基于2000—2010年北京空氣質(zhì)量監(jiān)測(cè)日?qǐng)?bào)，研究了近10年來北京空氣持續(xù)污染特征。結(jié)果表明，近10年來北京的空氣質(zhì)量得到明顯改善，空氣持續(xù)污染日數(shù)和質(zhì)量超標(biāo)日數(shù)均呈下降趨勢(shì)，但年持續(xù)污染日數(shù)在年超標(biāo)日數(shù)中所占的比例依然較大，持續(xù)污染已成為北京空氣污染的一個(gè)顯著特征。春季是北京持續(xù)污染最多的季節(jié)，平均每年多達(dá)25.4天。夏季是持續(xù)污染最少的季節(jié)，但是6月麥?zhǔn)掌邴溄辗贌?huì)造成空氣持續(xù)污染。北京空氣持續(xù)污染的空間分布形態(tài)主要分為沙塵天氣影響型、污染累積型和麥?zhǔn)掌邴溄辗贌廴拘?。沙塵天氣影響型造成的空氣持續(xù)污染的空間分布特征表現(xiàn)為整個(gè)北京污染都很嚴(yán)重，特別是城區(qū)和西南部的污染最嚴(yán)重；污染累積型的持續(xù)污染在空間分布上呈南高北低型。麥秸焚燒污染型則是人口相對(duì)稀疏、農(nóng)田面積較多的遠(yuǎn)郊區(qū)污染最嚴(yán)重。（王郁）

2.16 2011年春季日本福島核泄漏污染輸送:貴陽(yáng)131I和137Cs觀測(cè)示蹤分析

2011年3月11日，日本本州9.0級(jí)地震引發(fā)了福島核電站核泄漏，以及由此導(dǎo)致的131I和137Cs在全球大氣環(huán)流傳輸已引起了重視。理論上也對(duì)這種輸送路徑進(jìn)行了研究。本研究為2011年3 月17 日至4 月28 日在貴陽(yáng)觀風(fēng)山對(duì)氣溶膠中天然核素（210Pb、7Be）和人為核素 （131I、137Cs）近地面空氣濃度逐周采樣的系統(tǒng)對(duì)比觀測(cè)，并結(jié)合該時(shí)段貴陽(yáng)距地面500 m高度逐周315 h的氣團(tuán)后向軌跡分析。結(jié)果表明，福島核泄漏污染物通過2條顯著的途徑輸送到貴陽(yáng)地區(qū)。第1條是首波核污染通過全球大氣環(huán)流傳輸，由西向東，幾乎環(huán)繞地球一周，歷經(jīng)約 10天至2周，最終在3 月24—31日從我國(guó)的西北地區(qū)入侵抵至貴陽(yáng)。第2條途徑則是福島地區(qū)上空的核污染氣團(tuán)受東北天氣系統(tǒng)的擠壓南移并在低緯度地區(qū)再次先后受到東北和東南氣流的影響，于4 月7—14 日抵達(dá)貴陽(yáng)。核污染的第1條輸送路徑是全球尺度，第2條是東亞區(qū)域尺度。（鄭向東）

2.17 衛(wèi)星觀測(cè)推測(cè)平流層背景氣溶膠的變化

利用1998—2004年SAGE II （The Stratospheric Aerosol and Gas Experiment II ）的氣溶膠產(chǎn)品分析平流層背景氣溶膠性質(zhì)的變化傾向。 氣溶膠消光系數(shù)（E）在南、北半球的中緯度平流層低層（LS）明顯增加，年變率為2%～5%。氣溶膠面密度（S）在中緯度LS的正變化最明顯，年增長(zhǎng)5%～6%。同時(shí)，氣溶膠的有效半徑（R）減少，尤其是在熱帶LS年變化達(dá)到-2.5%。根據(jù)這些趨勢(shì)，可以得出氣溶膠的數(shù)濃度在熱帶LS大約每年增加5%～10% ，在中緯度LS 每年增加4%～8% 。 氣溶膠質(zhì)量濃度在中緯度LS每年增加1%～5%。面密度產(chǎn)品存在大的不確定性會(huì)影響氣溶膠面密度、氣溶膠數(shù)濃度、氣溶膠質(zhì)量的變化趨勢(shì)。我們的全球估計(jì)支持 Hofmann 等的推測(cè)：局地激光雷達(dá)后向散射增加是由于人為排放的SO2增加造成氣溶膠增加的結(jié)果。而且，平流層氣溶膠增加需要在熱帶由對(duì)流層向平流層輸送的凝結(jié)核增加來支持。（劉煜）

2.18 2010年長(zhǎng)江三角洲臨安區(qū)域本底站PM2.5理化特征

2010年在代表長(zhǎng)三角區(qū)域背景地區(qū)的臨安區(qū)域本底站開展了對(duì)大氣細(xì)粒子PM2.5為期1年的地面觀測(cè)。臨安2010年大氣中PM2.5質(zhì)量濃度平均為（58.2±50.8）g/m3，PM2.5濃度季節(jié)變化明顯。利用HYSPLIT4模式計(jì)算了2010年臨安72 h后向軌跡，根據(jù)軌跡計(jì)算與聚類結(jié)果，結(jié)合地面觀測(cè)的PM2.5數(shù)據(jù)進(jìn)行了分析。研究表明，臨安地區(qū)因受到長(zhǎng)三角區(qū)域及偏北氣流引起的污染傳輸影響，呈現(xiàn)出高細(xì)粒子水平特征。PM2.5中總水溶性離子年平均濃度為（28.5±17.7）g/m3，占PM2.5質(zhì)量濃度的47%。其中，氣溶膠組分SO42-、NO3-和NH4+所占比重最大，共占總水溶性離子的69%。PM2.5中OC和EC的年平均濃度分別為（10.1±6.7）g/m3和（2.4±1.8）g/m3。OC和EC質(zhì)量濃度顯著相關(guān)，表明OC和EC主要來自相同的排放源。（孟昭陽(yáng)）

3 大氣成分模式的發(fā)展應(yīng)用及大氣成分的影響研究

3.1 在線氣溶膠數(shù)值模擬系統(tǒng)CUACE/Aero的評(píng)估及改進(jìn)

使用在線氣溶膠數(shù)值模擬系統(tǒng)CUACE/Aero評(píng)估時(shí)發(fā)現(xiàn)，CUACE/Aero系統(tǒng)可以對(duì)黑碳、有機(jī)碳、硫酸鹽、硝酸鹽、海鹽、沙塵和銨鹽進(jìn)行分檔模擬，前10檔這些組分的濃度和即為PM10濃度。日均PM10模式模擬結(jié)果都在觀測(cè)的2倍因子范圍之內(nèi)，相關(guān)系數(shù)達(dá)到0.39。模式在鄉(xiāng)村站的相關(guān)系數(shù)大于城市站，白天的相關(guān)性大于晚上。模式大氣偏低的低氧化性是導(dǎo)致二次氣溶膠偏低的一個(gè)非常重要的原因。模擬的氣溶膠光學(xué)厚度（AOD）比地基CARSNET、空基MODIS反演的AOD都系統(tǒng)性偏高。系統(tǒng)偏高的重要原因是氣溶膠的初始排放粒徑分布數(shù)濃度峰值集中在0.1μm，使得模擬的細(xì)粒子氣溶膠數(shù)濃度偏高，模擬的消光高1～2個(gè)量級(jí)，導(dǎo)致即使模式在白天PM10模擬偏低的情況下，AOD的模擬還是系統(tǒng)偏高。利用多個(gè)觀測(cè)重構(gòu)所有組分的排放譜分布：質(zhì)量濃度峰值集中在0.5μm左右，數(shù)濃度在小粒徑粒子處更加平滑。新模擬的AOD與觀測(cè)接近，均一偏差和均一誤差減少明顯。（周春紅）

3.2 空氣質(zhì)量診斷識(shí)別的參數(shù)化方法及其應(yīng)用

基于2000—2007年P(guān)M10和氣象要素?cái)?shù)據(jù)的診斷與相關(guān)性分析，研究發(fā)展了北京及周邊地區(qū)空氣質(zhì)量診斷的PLAM參數(shù)化方法。給出診斷識(shí)別空氣污染強(qiáng)度變化的關(guān)鍵氣象影響因子，包括水分凝結(jié)函數(shù)，濕相當(dāng)位溫和風(fēng)速等。結(jié)果表明，與同期平均值相比，表現(xiàn)為高PM10的空氣質(zhì)量較差的日期通常與高值PLAM對(duì)應(yīng)，即與高溫、高濕、弱風(fēng)速和具高“靜穩(wěn)”的日期一致。該方法為北京奧運(yùn)會(huì)開幕式和接續(xù)的體育賽事提供了有意義的24 h 和 72 h預(yù)測(cè)服務(wù)。整個(gè)夏季期間，預(yù)測(cè)PLAM指數(shù)與API （空氣污染指數(shù)）和PM10濃度之間的相關(guān)系數(shù)分別為0.82和0.59，均達(dá)到0.001顯著性水平。PLAM指數(shù)中引入權(quán)重適應(yīng)修正系數(shù)，對(duì)觀測(cè)PM10濃度的診斷一年四季均可適用。（王繼志）

3.3 我國(guó)沙塵天氣過程PLAM指數(shù)跟蹤分析及其波動(dòng)變化特征

采用1980—2011年中國(guó)氣象局氣象站地面氣象要素觀測(cè)資料和高空大氣探空資料、時(shí)間和空間加密氣象觀測(cè)站資料，以及中國(guó)氣象檔案館原始天氣圖表等資料，基于沙塵氣溶膠濃度（PM10）路徑追蹤的潛勢(shì)源地貢獻(xiàn)函數(shù)（PSCF）方法，發(fā)展空氣質(zhì)量氣象條件PLAM指數(shù)對(duì)沙塵天氣過程的路徑跟蹤，給出1980—2011年?yáng)|北亞沙塵天氣過程特征分布；采用Spline趨勢(shì)分析方法，討論沙塵天氣系統(tǒng)強(qiáng)度的年度變化。結(jié)果表明，1980—2011年沙塵天氣過程具有歷史持續(xù)性與轉(zhuǎn)折突變性并存的波狀變化趨勢(shì)，出現(xiàn)準(zhǔn)10年的高低頻活動(dòng)特征。（王繼志）

3.4 抗壞血酸和鐵在醌類產(chǎn)生OH自由基過程中的協(xié)同增強(qiáng)作用

醌類物質(zhì)是大氣顆粒物所攜帶的重要有機(jī)成分，其致毒的機(jī)制非常復(fù)雜。醌類是具有高度自身氧化還原的物質(zhì)，進(jìn)入機(jī)體后導(dǎo)致大量活性氧產(chǎn)生。本研究探討了蒽醌、抗壞血酸和鐵之間在產(chǎn)生OH自由基方面的交互反應(yīng)，并探討了醌類濃度與OH產(chǎn)生的劑量關(guān)系響應(yīng)曲線，估算了近穩(wěn)態(tài)濃度，并對(duì)可能的機(jī)制進(jìn)行了深入的分析。（李怡）

3.5 基于GIS和大氣數(shù)值模擬技術(shù)評(píng)估蘭州市PM10的人群暴露水平

利用2001年1月1—31日蘭州市城區(qū)PM10月均觀測(cè)濃度和CMAQ空氣質(zhì)量模式模擬的PM10月均濃度，基于GIS平臺(tái)，將污染物濃度與人口空間分布圖層疊加，采用PM10人口加權(quán)算法，定量評(píng)估了蘭州市居民的顆粒物暴露水平，并對(duì)應(yīng)用這2套數(shù)據(jù)的評(píng)估結(jié)果進(jìn)行了對(duì)比。結(jié)果表明，與使用觀測(cè)數(shù)據(jù)相比，模擬的PM10濃度空間梯度較大，模擬結(jié)果更加細(xì)致地展示了PM10濃度在蘭州城區(qū)的分布，同時(shí)PM10濃度的最小值和最大值跨度也較大。對(duì)比人口加權(quán)前PM10濃度發(fā)現(xiàn)，人口加權(quán)后，從城區(qū)人口的空間分布來看，蘭州市有較多的人口分布在污染較重的地區(qū)，使用PM10數(shù)值模擬結(jié)果對(duì)人體健康影響的評(píng)估要優(yōu)于使用觀測(cè)數(shù)據(jù)的評(píng)估。（安興琴）

3.6 蘭州市春季沙塵天氣對(duì)呼吸系統(tǒng)疾病的影響

采用半?yún)?shù)廣義相加模型（GAM），在排除入院人數(shù)長(zhǎng)期趨勢(shì)、氣象因素、大氣污染因素和日歷效應(yīng)等因素后，分析了蘭州市2001—2005年春季沙塵天氣對(duì)呼吸系統(tǒng)疾病的影響。結(jié)果表明，春季沙塵天氣與呼吸系統(tǒng)疾病日入院人數(shù)的增加有一定聯(lián)系，且表現(xiàn)為滯后效應(yīng)。沙塵天氣對(duì)健康的影響存在性別和年齡差異，性別差異表現(xiàn)為對(duì)男性人群的影響略大于女性人群（男性相對(duì)危險(xiǎn)度為1.148，女性為1.144，且不具有統(tǒng)計(jì)學(xué)意義）；年齡差異表現(xiàn)為對(duì)年齡大于65歲的老年人群的影響明顯大于小于65歲的人群（年齡大于65歲的老年人群相對(duì)危險(xiǎn)度為1.266，小于65歲的人群為1.119）。（安興琴）

3.7 2009年我國(guó)可吸入顆粒物引起的人體健康經(jīng)濟(jì)損失評(píng)估

利用大氣顆粒物的暴露-反應(yīng)關(guān)系對(duì)中國(guó)2009年因可吸入顆粒物（PM10）造成的人體健康經(jīng)濟(jì)損失進(jìn)行了估算。結(jié)果表明，2009年中國(guó)PM10人體健康經(jīng)濟(jì)損失約占當(dāng)年GDP的2.1%。京津冀都市圈、山東、遼寧、長(zhǎng)江三角洲、珠江三角洲、華東沿海和川渝等地的PM10人體健康經(jīng)濟(jì)損失較高；PM10人體健康經(jīng)濟(jì)損失與當(dāng)年GDP比值高于4%的地區(qū)主要位于京津冀、山東、安徽、上海、重慶和新疆的部分地區(qū)。（侯青）

3.8 氣象條件對(duì)大氣污染物健康效應(yīng)的影響

氣象條件對(duì)大氣污染物的擴(kuò)散、稀釋和積累起到重要的作用，直接對(duì)人體的真實(shí)暴露情況產(chǎn)生影響。因此，大氣污染物的健康效應(yīng)可因氣象條件的不同而改變，其影響與氣象條件密切相關(guān)。此外，污染的大氣也會(huì)使人體對(duì)氣象條件的變化或極端天氣現(xiàn)象更加敏感，從而增強(qiáng)氣象因子的效應(yīng)。由此可見，大氣污染和氣象條件密切相關(guān)，對(duì)人體健康的影響具有不可分割的交互作用。（李怡）

3.9 氣候變化背景下上海市氣溫?zé)嵝?yīng)死亡風(fēng)險(xiǎn)預(yù)估

應(yīng)用統(tǒng)計(jì)降尺度技術(shù)，模擬溫室氣體排放情景下上海市未來中期與遠(yuǎn)期逐日日均氣溫，并基于已經(jīng)發(fā)表的“上海市氣溫-死亡暴露-反應(yīng)關(guān)系”，預(yù)估碳排放相對(duì)高速增長(zhǎng)模式（A2）和碳排放相對(duì)低速增長(zhǎng)模式（B2）情景下上海市未來中期與遠(yuǎn)期氣溫?zé)嵝?yīng)人群死亡風(fēng)險(xiǎn)。A2情景下，上海市2030—2059年和2070—2099年熱相關(guān)死亡人數(shù)的年均值分別為516和1191例，分別比基線時(shí)間段（336例）增加53.6%和254.5%。B2情景下，上海市2030—2059年和2070—2099年熱相關(guān)死亡人數(shù)的年均值分別為498和831例，分別比基線時(shí)間段增加48.2%和147.6%?？梢钥闯鰵夂蜃兓尘跋拢磥砩虾Ｊ袣鉁?zé)嵝?yīng)人群死亡風(fēng)險(xiǎn)增加，未來遠(yuǎn)期的死亡風(fēng)險(xiǎn)增加幅度高于未來中期。（程艷麗）

3.10 北京PM1中的化學(xué)組分及其控制對(duì)策思考

通過分析北京城區(qū)2007年夏季和秋季、2008年冬季和春季4個(gè)季節(jié)PM1中硫酸鹽、硝酸鹽、銨鹽、有機(jī)物和黑碳等氣溶膠化學(xué)組分，結(jié)合對(duì)我國(guó)及全球主要區(qū)域PM10中上述氣溶膠組分及礦物氣溶膠組成的評(píng)估，發(fā)現(xiàn)因受干旱區(qū)產(chǎn)生的沙塵和城市逸散性粉塵的共同影響，整個(gè)亞洲大陸，尤其是我國(guó)的礦物氣溶膠濃度與歐美國(guó)家城市區(qū)域氣溶膠總和的平均值相當(dāng)或更高。我國(guó)在重視控制PM2.5等細(xì)粒子污染的同時(shí)，不應(yīng)忽視對(duì)PM2.5～PM10之間粗粒子的控制力度；北京城區(qū)春、夏、秋、冬的PM1平均質(zhì)量濃度分別約為94、74、66、91 g/m3，全年平均約為81 g/m3，其中有機(jī)物氣溶膠約占41%、硫酸鹽占16%、硝酸鹽占13%、銨鹽占8%，黑碳和氯化物分別占11%和3%，細(xì)礦物氣溶膠約貢獻(xiàn)7%。對(duì)于PM2.5污染的控制，關(guān)鍵是消減PM1中主要?dú)馊苣z粒子的排放與轉(zhuǎn)化，其中對(duì)有機(jī)物的控制更為重要，盡管對(duì)于北京而言進(jìn)一步控制污染的難度已經(jīng)很大。從科學(xué)上來說，即使我國(guó)的控制措施能百分之百實(shí)現(xiàn)，也很難穩(wěn)定地達(dá)到歐美國(guó)家的空氣質(zhì)量水平，因?yàn)槲覈?guó)本底礦物氣溶膠的濃度較高。應(yīng)進(jìn)一步評(píng)估各項(xiàng)控制措施的適用性，并制定考慮我國(guó)人群健康狀況的PM2.5空氣質(zhì)量標(biāo)準(zhǔn)。（張小曳）

Progress in Atmospheric Composition Research

In 2012, the Institute of Atmospheric Composition fulflled various tasks satisfactorily and made obvious progress in such fields as analytical method, comparison and verification, quality control, observation of atmospheric composition and related properties, model development and operation, impact of atmospheric composition on climate, weather and human health, and so on.

1 Study on observation method, comparison and verifcation, and quality control

1.1 Analysis of atmospheric organic compounds by thermal desorption and comprehensive twodimensional gas chromatography with fame ionization detection

As a new separation technology developed in the 1990s, comprehensive two-dimensional gas chromatography (GC×GC) has many advantages, such as high resolution, high sensitivity, and large peak capacity. In this work, a GC×GC system coupled with a flame ionization detector (FID) is set up for the measurement of atmospheric organic compounds. Using a thermal desorption (TD) as injector and a cold/ hot jet modulator for the GC×GC modulation, the TD-GC×GC-FID system is able to separate various typesof C5–C15 atmospheric organic compounds within only one chromatographic run, including non-methane hydrocarbons (NMHCs), oxygenated volatile organic compounds (OVOCs), and halogenated hydrocarbons. Qualitative analysis is made using a quadruple mass spectrometer in combination with standard gases, and quantitative analysis is performed using external standards combined with FID mass correction factors. The mean standard deviations of the frst and second dimension retention times of the target compounds are less than 0.6 s and 0.02 s, respectively. The mean relative standard deviations of the peak volumes are 4.5% for NMHC and 14.3% for all compounds. The average r2of the calibration curve exceeds 0.99. The average detection limit is 6.04 ng and the average recovery is around 111%. In the analysis of air samples from an urban site in Beijing in January 2010, more than 400 peaks of organic compounds was detected, of which 103 compounds have been identifed including alkenes, mono- and poly-aromatics, aldehydes, ketones, alcohols, esters, halogenated hydrocarbons, etc. (Wang Ying)

1.2 Sampling-analysis quality control method for atmospheric hydrofuorocarbons (HFCs)

Air samples were fushed and pumped into two-port stainless steel canisters and pressurized to 1.36×105Pa by a custom-made sampler. The samplers were analyzed by a gas chromatography-mass spectrometry (GCMS) system in the laboratory. The precisions of 6 major hydrofuorocarbons (HFCs) analysis were 0.24%-1.02%. The concentrations of 6 HFCs in the blank samples were below detection limits of the GC-MS system. The infuence caused by various inlet pressure fuctuations was corrected. The recoveries for 6 HFCs during the sampling-analysis procedure were 99.5%-100.4% and there were in significant changes of the HFCs concentrations during the 112 days storage. Air samples from the top of an 80 m tower at Shangdianzi regional station were sampled and analyzed. The concentration differences between two parallel samples were 0.04×10-12-0.16×10-12. The concentration differences between canister samples and in-situ measurement were -0.86×10-12--0.17×10-12. The sampling-analysis quality control method was found suitable for high precision atmospheric HFCs observations. (Yao Bo)

1.3 Study on the in-situ measurement of atmospheric CH4and CO by GC-FID method at the Shangdianzi GAW regional station

In-situ GC-FID system for atmospheric CH4and CO mixing ratio measurements at the Shangdianzi (SDZ) GAW regional station in Beijing was designed and optimized in 2009 based on a comparable system at the Waliguan GAW global station in Qinghai. The results from this study indicate that the system’s precisions for CH4and CO are higher than 0.03% and 0.45%, respectively,which have met the quality target on background greenhouse gas observations by the World Meteorological Organization's Global Atmosphere Watch (WMO/ GAW) program. The selection method of working standards for this system was established and two working standards (WH for high concentration and WL for low concentration) were selected. The concentrations of CH4and CO in these two standards can cover the ambient mixing ratios of CH4(2007.1×10-9and 1809.5×10-9) and CO ( 405.6×10-9and 123.8×10-9) . An injection sequence was programmed so that the two standards were analyzed alternatively for every three runs. The measurement accuracies are high, as shown by the standard deviations of less than 1.7×10-9and 1.0×10-9for CH4and CO respectively. This method has been applied to insitu measurement of atmospheric CH4and CO in North China. (Zhou Lingxi)

1.4 The infuence of water wapor on the measurement of CH4by the CRDS system

The Cavity Ring-Down Spectroscopy (CRDS) system has been introduced to measure methane (CH4) in the background area. It has been proved that the concentration of CH4measured by the CRDS system was affected by water vapor distinctly. In order to ensure the reliability of the observed data, the relationship between CH4and water vapor measured by the CRDS system is studied, and an effective correction method for water vapor in the range of 0.50%-2.45% (V/V) is established. The method validation results show that the deviations between the correction results and the theoretical values are less than 1.8 ×10-9, which is better than the goal of background atmospheric measurement. Finally, the correction method is used to deal with the CH4data measured by the CRDS system at Waliguan station (where water vapor ranges from 0.50% to 2.45%, V/ V), and compared with the data measured by the GC-FID system at the same time. The correction results show reduced deviations of smaller than 2.0×10-9for 38.48% measured data. (Zhou Lingxi)

1.5 Intercomparison and application of atmospheric humidity profles measured by CFH and Vaisala RS80 radisondes

Vertical profiles of atmospheric humidity simultaneously measured by balloon-borne Cryogenic Frost point Hygrometer (CFH) and Vaisala RS80 radiosonde in Tengchong, Yunnan in August 2010 are analyzed. Currently, CFH is the reference instrument in the measurement of atmosphere water vapor profile. RS80 radiosonde is ever extensively used in the world before the mid 1990s. The humidity data measured by CFH are used to assess the quality of RS80 radiosonde humidity data. The difference of RS80 radiosonde humidity data during daytime and nighttime respectively compared to CFH data is also given in individual intercomparison. The results reveal that there is a large dry bias produced by the RS80 humidity sensor with an average value of (23.7±18.5)%, and the daytime dry bias is (13.5±14.8)% larger than that in the nighttime owing to solar radiative heating on the humidity sensor. In addition, RS80 radiosonde is almost incapable of measuring the valuable humidity data in the transition region from the upper troposphere to the lower stratosphere. For the integrated precipitable water (PW) amounts from the profles GTS1, RS80, and CFH, and their comparisons with GPS measurements, CFH integrated PW is (4.3±2.0) mm (number of samples is 11) higher than that of GPS because CFH tends to saturate under moist conditions, especially when passing through cloud in the lower troposphere, while the PW differences of RS80 and GTS1 from the GPS measurements are (0.2±1.4) mm (number of samples is 12) and (-0.2±2.2) mm (number of samples is 43), respectively. The value of GPS PW is not sensitive to the humidity variations with altitude above the upper troposphere. CFH is demonstrated as an effective instrument measuring water vapor concentration in the circumstance with lower temperature as well as lower humidity, such as in the upper troposphere and lower stratosphere. Owing to dry bias, RS80 radiosonde detects less middle or high clouds than CFH does, especially in the detection of high clouds above 6000 m where the low humidity value from RS80 radiosonde almost can not indicate the occurrence of cloud. Therefore, the occurrence frequency and altitude of high clouds are much underestimated if RS80 radiosonde water profles are used. (Zheng Xiangdong)

1.6 Verifcation of the satellite remote sensing products of aerosol optical depth in the Taklimakan Desert area

Using ground-based Aerosol Optical Depth (AOD) data at Tazhong, Taklimakan Desert area, four sets of satellite aerosol data, from the Multi-angle Imaging Spectrometer (MISR), the Moderate Resolution Imaging Spectrometer (MODIS), and the Ozone Monitoring Instrument (OMI) from 2007 to 2008 were validated. The results show that satellite aerosol retrievals are signifcantly correlated with the ground-based ones. The correlation coeffcient for MODIS/AOD is the largest (0.91), followed by OMI/AOD (0.87), MISR/AOD (0.84), and OMI/UVAI (0.51). The MISR/AOD root-mean-square error (0.14) and the average deviation (-0.06) are the lowest in the four products. The MISR/AOD and MODIS/AOD are relatively less than the ground-based AOD; however, OMI/AOD and OMI/UVAI exceed the ground-based ones. Seasonal variations of aerosols are captured by satellite data. AOS is relatively large in spring and summer and is relatively low in autumn and winter. The results of Angstrom wavelength exponent show that spring has the minimum (0.11), followed by summer and autumn, and winter has the maximum (0.61), which shows that the aerosol particle is larger in spring and summer while smaller in autumn and winter. Besides, the Taklimakan Desert area belongs to the sand source with single aerosol type. In summary, the annual variability of AOD from 2000 to 2010 is not obvious. The results of the retrieval show that the maximal aerosol content appears in 2003 during the past decade and the annual average is up to 0.32, while the minimal aerosol content occurs in 2005 and the annual average is 0.28. (Che Huizheng)

1.7 Synergy of satellite and ground based observations in estimation of particulate matter in eastern China

Estimating particulate matter (PM) from space is not straightforward and is mainly achieved using the aerosol optical depth (AOD) retrieved from satellite sensors. However, AOD is a columnar measure, whereas PM is a ground observation. Linking AOD and PM remains a challenge for air pollution monitoring. In this study, a back-propagation artifcial neural network (BP ANN) algorithm trained with Bayesian regularization benefited from the synergy of satellite- and ground-based observations was developed to estimate PM in eastern China. Correlations between observed and estimated PM (denoted by R) during the period 2007—2008 over seven individual sites were investigated comprehensively in terms of site scale, seasonal scale, particle size, and spatio-temporal scale. With respect to site differences, the Nanning site had the best results with 80.3% of cases having a moderate or strong correlation value. Lushan and Zhengzhou followed with results of 75% and 73.8%, respectively. Furthermore, R exhibited a signifcant seasonal variation characterized by a maximum (80.2%) during the autumn period, whereas no obvious differences in R for various spatial scales (spatial averaging schemes of MODIS AOD) were observed. Likewise, the ratio value for daily averaging (64.7%) was found to be better than those for the two hourly temporal averaging schemes (i.e., 61.1% for HA1 and 58.3% for HA2). In addition, PM1 estimated from the ANN algorithm developed in this study had slightly higher R values than PM10 and PM2.5. The planetary boundary layer (PBL) effect on PM estimation was decreasing R with increasing height of the PBL, which is consistent with previous studies. Comparisons of observed versus estimated PM10 mass time series implied that the ANN algorithm basically reproduced the observed PM concentration. However, PM mass at certain sites may be underestimated under the condition of high observed PM concentrations. (Guo Jianping)

1.8 Design and implementation of reactive gas data processing system for atmospheric background monitoring stations

Based on many year practice of reactive gas observation and its sophisticated quality control and data processing methods, the comprehensive and rational functional design and orientation have been assigned to the data processing system, which is developed by using the Visual Studio development platform combined with MAP WinGIS and other display control by means of the modular functional design and development method. The system has realized easily the visualization of the observation data in space and time, the good capabilities of human-computer interaction, certain data statistic analysis, etc. The system is an effcient tool for managing and processing reactive gas observation data, and has become an important component of the operational reactive gas observation data quality control and processing system. (Xu Xiaobin)

2 Observational study on variations of different atmospheric compositions and related properties

2.1 Atmospheric aerosol compositions in China: Spatial/temporal variability, chemical signature, regional haze distribution, and comparisons with global aerosols

From 2006 to 2007, the daily concentrations of major inorganic water-soluble constituents, mineral aerosol, organic carbon (OC), and elemental carbon (EC) in ambient PM10 samples were investigated from 16 urban, rural, and remote sites in various regions of China, and were compared with global aerosol measurements. A large difference between urban and rural chemical species was found, normally with 1.5 to 2.5 factors higher in urban than in rural sites. Optically-scattering aerosols, such as sulfate (16%), OC (15%), nitrate (7%), ammonium (5%), and mineral aerosol (35%) in most circumstances, are majorities of the total aerosols, indicating a dominant scattering feature of aerosols in China. Of the total OC, 55%–60% can be attributed to the formation of the secondary organic carbon (SOC). The absorbing aerosol EC only accountsfor 3.5% of the total PM10. Seasonally, maximum concentrations of most aerosol species were found in winter while mineral aerosol peaks in spring. In addition to the regular seasonal maximum, secondary peaks were found for sulfate and ammonium in summer and for OC and EC in May and June. This can be considered as a typical seasonal pattern in various aerosol components in China. Aerosol acidity was normally neutral in most of urban areas, but became some acidic in rural areas. Based on the surface visibility observations from 681 meteorological stations in China between 1957 and 2005, four major haze areas are identifed with similar visibility changes, namely, (1) the Huabei Plain in North China and the Guanzhong Plain; (2) East China with the main body in the Yangtze River Delta area; (3) South China with most areas of Guangdong and the Pearl River Delta area; and (4) the Sichuan Basin in Southwest China. The degradation of visibility in these areas is linked with the emission changes and high PM concentrations. Such quantitative chemical characterization of aerosols is essential in assessing their role in atmospheric chemistry and weather-climate effects, and in validating atmospheric models. (Zhang Xiaoye)

2.2 Seasonal characteristics of components and size distributions for submicron aerosols in Beijing

Submicron aerosols (PM1) in Beijing were studied using an Aerodyne aerosol mass spectrometer (AMS) from January to October 2008. This study presents seasonal variations of different chemical components (sulfate, nitrate, ammonium, chlorid, and organics) and size distributions of PM1. The results show that mass concentration of PM1 was highest in summer, and lowest in autumn. Organics represented the dominant species in all seasons, accounting for 36%–58% of PM1, and their concentrations were highest in winter. Concentrations of inorganic components, sulfate, nitrate, and ammonium were highest in summer. Based on principal component analysis, organics were deconvolved and quantifed as hydrocarbon-like and oxygenated organic aerosol (HOA and OOA, respectively). HOA was highest in winter, accounting for about 70% of organics. However, OOA was highest in summer, and had lower values in autumn and winter. A similar diurnal pattern of various components was observed, with higher values at nighttime and lower ones during daytime. HOA increased more dramatically than other species between 17∶00 and 21∶00 and peaked at noon, which could be related to cooking emissions. OOA, sulfate, nitrate, ammonium and chloride varied with the same trend. Their concentrations increased with solar radiation from 09∶00 to 13∶00, and declined with weakening solar radiation. Size distributions of all species showed apparent peaks in the range 500–600 nm. Size distributions of organics were much broader than other species, particularly in autumn and winter. Distributions of sulfate, nitrate, and ammonium had similar patterns, broadening in winter. Contributions of different species were size-dependent; the fner the particle, the greater the contribution of organics. Organics represented more than 60% of particles smaller than 200 nm, contributing 50% to PM1 in winter. In spring and summer, HOA was the dominant organic fraction for particles smaller than 200 nm, while OOA contributed more to particles larger than 300 nm. In winter, HOA contributed more than OOA to all PM1 particles. (Zhang Yangmei)

2.3 Characteristics of cloud condensation nuclei at Wuqing

Based on the cloud condensation nuclei (CCN) concentration and aerosol size distribution measured at Wuqing Meteorological Bureau of Tianjin from November to December of 2009, the characteristics of CCN concentration and activation between 0.1% and 1.0% supersaturation were analyzed. The results show that the CCN concentration varies in the range of 4000-32000 cm-3in the supersaturateion of 1% and is affected by wind speed signifcantly at Wuqing in winter. Under the wind speed of 1.5-3.3 m/s, the CCN concentration is very high, and can reach 16000 cm-3at 1% supersaturation, but the CCN concentration is just one fourth of this value with the wind speed of 3.5-5.5 m/s. The CCN concentration varies largely in the range of 0.1% and 0.4% supersaturation. The increase of CCN concentration for every 0.1% supersaturation in the range of 0.1%-0.4% is about 5 times of those in the range of 0.4% and 1.0% supersaturation. The activation rate is affected signifcantly by wind speed in the low supersaturation ( 0.1%, 0.2%), and the value under the wind speed smaller than 1.5 m/s is about three times of that under the wind speed larger than 5.5 m/s, but in the supersaturation of 1%, the activation rate difference with wind speed is little. The diurnal variation of CCNconcentration shows two peaks at 08∶00 and 18∶00 of Beijing time, whereas there are two valleys of the activation rate, which suggests the effects from local emissions. The power law ft for the relationship of CCN concentration and supersaturation under different wind speeds shows that the supersaturation spectrum of CCN at Wuqing belongs to continental style. (Sun Junying)

2.4 Analysis on source features of halogenated gases at Shangdianzi regional atmospheric background station

In this study, fve-day back-trajectories collected at Shangdianzi station were categorized by season and calculated four times a day during the period of 2008—2010, based on the Lagrangian particle integrated trajectory model HYSPLIT, and using the back-trajectory cluster analysis method. Efforts were made to understand the impacts of different trajectories on the concentration of halogenated gases over the site of Shangdianzi (SDZ) in different seasons, in line with the in-situ concentration measurements of halogenated gases, including the 8 species of CFC-11, CFC-12, CCL4, CHCL3, CH3Br, SF6, H-1301, and HCFC-22. Meanwhile, the wind data collected at the same station and the concentration observed during the same period were employed to calculate the loadings of CFC-11, CFC-12, CCL4, CHCL3, CH3Br, SF6, H-1301, and HCFC-22, respectively. The result of back-trajectory cluster analysis suggests that air masses from southeast and southwest accounting for a large proportion of local air masses at SDZ always move slowly within the bottom boundary layer, which is beneficial for the accumulation of pollutants within the boundary layer and leads to the highest mean concentrations of halocarbons among all the clusters. Conversely, the mean concentration of halocarbons corresponding to the fast-moving northwest air masses at high altitude is found to have unanimously low values. The analysis of the concentration loadings proves that WSW and SW are the directions for the maximum concentration loading of all halogenated species, whereas NNW, NNE, NE, and ENE are the directions for the minimum concentration loading. We also fnd that the sector in SW-S-SE is the high concentration loading part, while the sector in NW-N-NE is the low concentration part. The trajectory cluster analysis and concentration loading results indicate that the SE-S-SW towards SDZ is the high pollution source direction for the halogenated species mentioned above, which refects the infuence of human activities on the air pollutant transportation at SDZ on regional scale, while NW-N-NE represents the clean direction of the station. (An Xingqin)

2.5 In-situ measurements of atmospheric hydrofuorocarbons (HFCs) and perfuorocarbons (PFCs) at the Shangdianzi regional background station

Atmospheric hydrofuorocarbons (HFCs) and perfuorocarbons (PFCs) were measured in-situ at the Shangdianzi (SDZ) Global Atmosphere Watch (GAW) regional background station, China, from May 2010 to May 2011. The time series for fve HFCs and three PFCs showed occasionally high-concentration events while background conditions occurred for 36% (HFC-32) to 83% (PFC-218) of all measurements. The mean mixing ratios during background conditions were 24.5×10-12for HFC-23, 5.86×10-12for HFC-32, 9.97×10-12for HFC-125, 66.0×10-12for HFC-134a, 9.77×10-12for HFC-152a, 79.1×10-12for CF4, 4.22×10-12for PFC-116, and 0.56×10-12for PFC-218. The background mixing ratios for the compounds at SDZ were consistent with those obtained at mid to high latitude sites in the Northern Hemisphere. Northeasterly winds were associated with negative contributions to the atmospheric HFC and PFC loadings (mixing ratio anomalies weighted by time associated with winds in a given sector), whereas southwesterly advection (urban sector) showed positive loadings. Chinese emissions estimated by a tracer ratio method using carbon monoxide as tracer were (3.6±3.2) kt/yr for HFC-23, (4.3±3.6) kt/yr for HFC-32, (2.7±2.3) kt/yr for HFC-125, (6.0±5.6) kt/yr for HFC-134a, (2.0±1.8) kt/yr for HFC-152a, (2.4±2.1) kt/yr for CF4, (0.27±0.26) kt/yr for PFC-116, and (0.061±0.095) kt/yr for PFC-218. The lower HFC-23 emissions compared to earlier studies may be a result of the HFC-23 abatement measures taken as part of Clean Development Mechanism (CDM) projects that started in 2005. (Yao Bo)

2.6 CH4concentration and variation characteristics at four WMO/GAW background stations in China

Background CH4concentrations were continuously measured at four WMO/GAW stations (Waliguan in Qinghai (WLG), Lin'an in Zhejiang (LAN), Shangdianzi in Beijing (SDZ), and Longfengshan in Heilongjiang (LFS)) by Cavity Ring Down Spectroscopy system. From 2009 to 2010, the diurnal cycle of hourly average CH4concentration at LAN was found to be similar in all four seasons, with the highest level detected at 05∶00 (Beijing Time) and the lowest at about 14∶00. Similar CH4diurnal cycles were observed at LFS in the summer time; however, the daily amplitude was much higher than that at LAN and reached 216.8 ×10-9(molar ratio). For SDZ station, there were similar trends in spring, autumn, and winter, and the daily average concentration in the summer was much higher than those of the other seasons and reached the highest at about 20∶00. No apparent CH4diurnal cycle was observed at the WLG station during the whole year. The seasonal variations were obvious at the three regional stations ( LAN, SDZ, and LFS) . The background concentration was the lowest in July at LAN while it reached the highest level in August at LFS. The yearly background concentration variation at LFS displayed a “W” pattern. At LFS and SDZ, the wintertime CH4concentrations were higher than those in spring and autumn. WLG represented a clean area and its CH4value was the lowest among the four stations with the monthly average amplitude of about 11.5×10-9. At all three regional stations, non-background data accounted for more than 70% of the whole data. Cluster analysis of 3 day backward trajectories corresponding to the high CH4concentration ( WLG∶CH4＞1870 ×10-9; LFS∶CH4＞2100 ×10-9; LAN∶CH4＞2150 ×10-9; SDZ∶CH4＞2050 ×10-9) data points suggested that the high CH4level measured in summer might be associated with air mass transportation. (Fang Shuangxi)

2.7 Variation of CH4concentration at Xianggelila background station in Yunnan Province

Atmospheric CH4concentration was continuously measured at Xianggelila background station by Cavity Ring Down Spectroscopy system from July 2010 to October 2011. The average CH4background concentrations during spring, summer, autumn and winter were (1850.7±6.9)×10-9, (1850.9±13.4)×10-9, (1865.6±16.1)×10-9and (1839.2±6.5)×10-9, respectively. The monthly average variation reached a maximum in September and a minimum in December with the amplitude of about 39.6×10-9. The hourly average CH4concentration exhibited evident diurnal variations with minimal values around 14∶00—16∶00 for all seasons. The daily variation amplitude was the lowest in winter (4.4×10-9) and the highest in autumn (10.0×10-9). Evident elevation of CH4concentration was observed when the surface wind was from the southwest, whereas great decrease was associated with north to northeasterly wind. Combined with the observed CH4concentrations, cluster analysis of 3-day backward trajectories suggested that the observed CH4concentration during the four seasons at the station was mainly affected by the southwest air mass transport, especially in spring, summer, and autumn. (Fang Shuangxi)

2.8 Preliminary study of the atmospheric CO2concentration and its variation at Xianggelila background station

Atmospheric CO2concentration was continuously measured at Xianggelila background station by Cavity Ring Down Spectroscopy System from September 2010 to August 2011. The average background concentrations of CO2during spring, summer, autumn and winter were 394.78×10-6(mole ratio), 386.82×10-6, 386.46×10-6, and 390.74×10-6, respectively. The monthly average variation reached a maximum in the April—May period and a minimum in July with the amplitude of about 12.22×10-6. The hourly average CO2concentration exhibited evident diurnal variations with maximal values around 07∶00 and minimal around 14∶00—17∶00 during all seasons. The daily variation amplitude was the lowest in winter (1.51×10-6) and the highest in summer (21.82×10-6). Evident elevation of CO2concentration was usually observed when the surface wind came from the west to south. Combined with the observed CO2concentrations, cluster analysis of 3-day backward trajectories ending at full hour suggested that air mass from the southwest obviously reduced the observed CO2concentration during spring, summer, and autumn. However, in winter, the decrease was notapparent because of the lower emissions from the local vegetation than in the other seasons. (Fang Shuangxi)

2.9 A pollution and oxidization pool over North China

A feld measurement campaign performed during spring 2006 revealed that strong pollution emissions from urban and industrial centers tend to accumulate in the lower atmosphere over the central area of Huabei. High pollution concentrations were found to be associated with enhanced levels of OH radicals. The high OH levels tend to promote the formation of semi and low-volatile species, such as inorganic and organic acids, through the oxidation of SO2, NO2, and VOCs, and thus accelerate the gas-particle conversion processes in the atmosphere. Our results indicate that the lower atmosphere over Huabei not only is strongly polluted but also acts as an oxidation pool, with pollutants undergoing very active photochemistry over this part of China. (Ma Jianzhong)

2.10 Recent trends of sulfur dioxide at different sites in North China and the Yangtze River Delta

In recent years, China has implemented stricter measures of coal desulfurization, which have suppressed the emission of SO2from the coal-fred power plants. In addition, emission control measures were implemented in the North China region for the Beijing 2008 Olympic Games. This work focuses on evaluating the real effects of these control measures on the levels of atmospheric SO2in North China and Yangtze River Delta regions.

SO2measurements made in recent years at sites in Beijing and its surrounding areas are performed to study the variations and trends of surface SO2at different types of sites in northern China. The overall average concentrations of SO2are (16.8 ± 13.1) ×10-9, (14.8 ± 9.4) ×10-9, and (7.5 ± 4.0) ×10-9at China Meteorological Administration (CMA, Beijing urban area), Gucheng (GCH, relatively polluted rural area, 110 km to the southwest of Beijing urban area), and Shangdianzi (SDZ, clean background area, 100 km to the northeast of Beijing urban area), respectively. The SO2levels in winter (heating season) are 4–6 folds higher than those in summer. There are highly signifcant correlations among the daily means of SO2at different sites, indicating regional characteristics of SO2pollution. Diurnal patterns of surface SO2at all sites have a common feature with a daytime peak, which is probably caused by the downward mixing and/or the advection transport of SO2-richer air over the North China Plain. The concentrations of SO2at CMA and GCH show signifcant downward trends (–4.4 ×10-9/yr for CMA and –2.4 ×10-9/yr for GCH), while a less significant trend (–0.3×10-9/yr) is identifed in the data from SDZ, refecting the character of SDZ as a regional atmospheric background site in North China. The SO2concentrations at all the three sites show a signifcant decrease from period before to after the control measures for the 2008 Olympic Games, suggesting that the SO2pollution control has longterm effectiveness and benefts. In the post-Olympics period, the mean concentrations of SO2at CMA, GCH, and SDZ are (14.3 ± 11.0) ×10-9, (12.1 ± 7.7) ×10-9, and (7.5 ± 4.0) ×10-9, respectively, with reductions of 26%, 36%, and 13%, respectively, compared to the levels before. Detailed analysis shows that the differences of temperature, relative humidity, wind speed, and wind direction are not the dominant factors for the signifcant differences of SO2between the pre-Olympics and post-Olympics periods. By extracting the data being more representative of local or regional characteristics, a reduction of up to 40% for SO2in polluted areas and a reduction of 20% for regional SO2are obtained for the effect of control measures implemented for the Olympic Games.

SO2has been observed from July 2005 to June 2010 at Lin'an WMO GAW regional station (30.3 °N, 119.73 °E, 138 m a.s.l.) located in the Yangtze River Delta region in eastern China. The observation data are analyzed to understand the trend of regional SO2background concentration. Strict quality controls are conducted to ensure the temporal comparability of the data. Significant downward trend with 2.4×10-9/yr (P＜0.0001) of surface SO2is observed from 2005 to 2010, especially after 2008. The average concentration of SO2from July 2005 to June 2008 is (14.2±3.1) ×10-9, which is slightly higher than the mean values of (13.5±5.1) ×10-9during 1999—2000 and is two folds of the average value (7.1±3.1)×10-9from July 2008 to June 2010. More than 50% of the SO2has been cut down after 2008 in the Yangtze River Delta regiondue to the implementation of stricter emission control measures. The peak SO2concentration appears around 10∶00 in the morning after 2009 while it appears at night before 2009. These diurnal variations of SO2might indicate that after 2009, more SO2is from the vertical exchange process than from the local accumulation. (Xu Xiaobin)

2.11 Impact of the regional transport of urban Beijing pollutants on downwind areas in summer: Ozone production effciency analysis

Ambient measurements of SO2, O3, NOx, NOy, and CO were made at Shangdianzi (SDZ), a rural site in the northeast (NE) of Beijing, and urban Beijing (China Meteorological Administration) from 1 June to 31 August 2008. The pollutants at SDZ showed very different concentration levels under different wind conditions, with the levels under the southwest (SW) wind being much higher than those under the NE wind. The SW wind facilitates the transport of urban plume to SDZ, whereas the NE wind provides a background condition. At SDZ, the ozone (O3) concentration in air masses from urban Beijing was found to be 33.4×10-9higher than that from clean regions in summer. The ozone production effciency (OPEx) for the urban plume and background condition was 4.0 and 5.3, respectively. Based on these OPEx values and the NOz values for the respective conditions, the contribution of in-situ production in the urban plume to the level of O3at SDZ is estimated to be 8.6 ×10-9, corresponding to only 25.7% of the total impact of urban plume transport. This suggests that direct transport of O3rather than in-situ photochemistry contributes mainly to the summer elevation of the level of O3at SDZ. (Xu Xiaobin)

2.12 Measurements of ozone and its precursors in Beijing during summertime: Impact of urban plumes on ozone pollution in downwind rural areas

Sea-land and mountain-valley circulations are the dominant mesoscale synoptic systems affecting the Beijing area during summertime. Under the influence of these two circulations, the prevailing wind is southwesterly from afternoon to midnight, and then changes to northeasterly till forenoon. In this study, surface ozone (O3), carbon monoxide (CO), nitric oxide (NO), nitrogen dioxide (NO2), nitrogen oxide (NOx), and non-methane hydrocarbons (NMHCs) were measured at four sites located along the route of prevailing wind, including two upwind urban sites (Fengtai “FT” and Baolian “BL”), an upwind suburban site (Shunyi “SY”) and a downwind rural site (Shangdianzi ”SDZ”) during 20 June and 16 September 2007. The purpose is to improve our understanding of ozone photochemistry in urban and rural areas of Beijing and the infuence of urban plumes on ozone pollution in downwind rural areas. It is found that ozone pollution was synchronism in the urban and rural areas of Beijing, coinciding with the regional-scale synoptic processes. Due to the high traffic density and local emissions, the average levels of reactive gases NOxand NMHCs at the non-rural sites were much higher than those at SDZ. The level of long-lived gas CO at SDZ was comparable to, though slightly lower than, that at the urban sites. We estimate the photochemical reactivity, represented by OH loss rate coeffcient (LOH), and the ozone formation potential (OFP) in the urban (BL) and rural (SDZ) areas using measured CO and NMHCs. LOHby total NMHCs at the BL and SDZ sites is estimated to be 50.7 s-1and 15.8 s-1, respectively. While alkenes make a major contribution to the LOH, aromatics dominate OFP at both urban and rural sites. With respect to the individual species, CO has the largest ozone formation potential at the rural site, and at the urban site aromatic species are the leading contributors. While the O3diurnal variations at the four sites are typical for polluted areas, the ozone peak values are found to lag behind one site after another along the route of prevailing wind from SW to NE. Intersection analyses of trace gases reveal that polluted air masses arriving at SDZ were more aged with both higher O3and Ox concentrations than those at BL. The results indicate that urban plume can transport not only O3but its precursors, the latter leading to more photochemical O3production when being mixed with background atmosphere in the downwind rural area. (Ma Jianzhong)

2.13 Characteristics of precipitation chemistry at Lushan Mountain

Trends in precipitation pH and conductivity during 1992—2009, and in ionic compositions from January 2007to June 2009, are reported from Lushan Mountain, one of the highest mountains in Central-East China. Annual mean pH was in the range of 4.35-5.01 and showed a statistically significant (P＜0.01) decreasing trend with time. Annual mean conductivity showed a statistically significant (P0.05) increasing trend, although this was not the case for non-H conductivity. Increasing rainwater acidity was mainly caused by increasing amounts of acid substances entering the rain. The trends in precipitation pH and conductivity were directly associated with energy consumption. Over the period of study, Lushan Mountain received more rainfall in spring and summer. The pH values varied seasonally with winter minima. The winter multiyear seasonal mean pH was 4.35. The corresponding summer value was 4.88. SO42-and NO3-were the main anions, and NH4+and Ca2+were the main cations. The anion to cation ratio was 0.8-1.0, and that of [SO42-] to [NO3-] was 2.4-3.0, much lower than that of the 1980s. However, sulfuric acid was still the main acid present. The ratio of [NH4+] to [Ca2+] was about 1.0, suggesting that these two alkaline substances provided close acid neutralizing capacity. The ratio of [Cl-] to [Na+] was about 0.67, somewhat lower than that of natural precipitation. Ionic composition varied seasonally and was closely related to the amounts of rainfall and pollution. Trajectory analyses showed that the trajectories to Lushan Mountain could be classifed in six clusters and trajectories originating from the South Sea and the areas surrounding Lushan Mountain had the greatest impacts on precipitation chemistry. (Li Yi)

2.14 Variation trend and cause analysis of acid rain in the Beijing municipality

The acid rain observation network operated by the China Meteorological Administration (CMA) contained 2 stations in 1993 through 2002 in the Beijing area, and the number of stations was increased to 3 in 2003. According to the monitoring data from the three observation stations, the characteristics and causes of acid rain variation trend in Beijing was studied. The following conclusions are drawn from the study. First, the precipitation acidity between 1993 and 2008 in the Beijing area has two different stages∶ 1993—2002 when precipitation acidity remained at a low level and 2003—2008 when precipitation acidity gradually increased. Second, compared to the period before 2003 in Beijing and even in North China, the annual mean concentration of sulfate ion and nitrate ion obviously increased after 2003, and the ratio of the two gradually decreased until less than 3, which indicates that the acid rain components had changed from sulfate to sulfate combined with nitric acid. Third, the increase of sulfur dioxide (SO2) emission and the decrease of the calcium ion and concentration of PM10 around Beijing are caused by human activities and are the reasons for the aggravation of the acid rain in Beijing in recent years. Fourth, climatic condition is the main driver to the occurrence of acid rain. Generally, lower speed of ground wind, weak south wind at 850 hPa, and temperature inversion at low levels facilitate the occurrence of acid rain. In addition, acid rain is closely related to precipitation, e.g., its frequency reaches the peak when the 24-h precipitation accumulates to the rainstorm level. (Hou Qing)

2.15 Characteristics of persistent air pollution in Beijing

Using the air quality daily reports in Beijing from June 2000 to December 2010, the characteristics of persistent air pollution in Beijing are analyzed. The air quality has been signifcantly improved in Beijing in recent 10 years. The persistent air pollution days are reducing, so are the low air quality days, but persistent pollution days still account for a large proportion of the total pollution days, and persistent pollution has become a distinctive feature of air pollution in Beijing. Spring is the season with most persistent air pollution days, average 25.4 days. Summer is the season with minimum days of persistent air pollution, but the persistent pollution caused by wheat-straw burning often occurs in June. Distribution of persistent air pollution in Beijing can be divided into three types∶ dust storm type, pollution accumulation, and pollution caused by wheat-straw burning. Distribution characteristic of the persistent air pollution affected by dust storms is high air pollution index (API) in the whole city of Beijing, especially in the urban area and its southwest. The persistent air pollution due to pollution accumulation has a pattern of higher in the south than north. The persistent air pollution caused by wheat-straw burning often exhibits high API in the suburbs. (Wang Yu)

2.16 Transport of the radioactivity leakage from the Japan Fukushima Nuclear Power Plant in spring 2011:131I and137Cs tracers observed in Guiyang, China

The 9.0 Ritcher scale earthquake that happened on 11 March, 2011 in the Honshu Island, Japan had caused the radioactivity leakage from the Fukushima Nuclear Power Plant. The leaked artificial nuclides,131I and137Cs, and their transport processes in the global atmosphere had drawn great public attention. In this study, the concentrations of radioactive isotopes7Be,210Pb,131I, and137Cs at the surface level in weekly aerosol samples obtained at the Guanfenshan Moutain, Guiyang, China from 17 March to 28 April 2011 were reported. The variations of the nuclide concentrations associated with their transport paths were analyzed with 315 h backward trajectories initialized at 500 m from the surface level at Guiyang. The results revealed that there were two evident transport paths for131I and137Cs from Fukushima to Guiyang. The frst path, along which the radioactive pollution tracers reached Guiyang faster, was through the northwestern China. These tracers were transported eastward and it took them 10 days to 2 weeks to arrive the northwestern China before they were detected during 24—31 March in Guiyang. The second path extended southeastward from Japan, with transport by the northeast Asian synoptic system at the beginning, then southwestward and northwestward before their arrivals during 7—14 April in Guiyang. The frst transport path of radioactive pollution tracer from the Fukushima Nuclear Power Plant to Guiyang was on the global scale while the second was on the East Asian regional scale. (Zheng Xiangdong)

2.17 Background stratospheric aerosol variations deduced from satellite observations

The Stratospheric Aerosol and Gas Experiment II (SAGE II) aerosol products from 1998 to 2004 have been analyzed to reveal the tendency of changes in background stratospheric aerosol properties. The aerosol extinction coeffcient E has apparently increased in the midlatitude lower stratosphere (LS) in both hemispheres, at an annual rate as great as 2%–5%. Positive changes in the aerosol surface area density S in the midlatitude LS are most distinct, with a rate of increase as high as 5%–6% annually. At the same time, there has been a secular decrease in aerosol effective radius R, especially in the tropical LS, at a rate of up to –2.5% per year. Corresponding to these trends, the aerosol number concentration is inferred to have increased by 5%–10% per year in the tropical LS and by 4%–8% per year in the midlatitude LS. Changes in aerosol mass are also deduced, with rates of increase in the midlatitude LS in the range of 1%–5% per year. The large uncertainty in operational S product is the major factor infuencing the trend in S, aerosol number concentrations, and mass. The authors’ global assessment supports the speculation of Hofmann et al. on the basis of local observations that the cause of an increase in lidar backscatter over a similar period was a consequence of aerosol particle growth due to enhanced anthropogenic sulfur dioxide emissions. Moreover, it is found that an increase in the injection rate of condensation nuclei from the troposphere to the stratosphere at tropical latitudes is required to sustain the increase in stratospheric aerosol concentration identifed in this analysis. (Liu Yu)

2.18 Characteristics of fne particles (PM2.5) at Lin an regional background station in the Yangtze River Delta region

Ground-base observation of fine particles (PM2.5) was conducted in 2010 at Linan regional background station in the Yangtze River Delta region. The annual average concentration of PM2.5 was (58.2 ± 50.8) μg/m3, and its seasonal variation was signifcant. Air mass backward trajectories were performed and analyzed in combination with corresponding pollutants concentrations using the HYSPLIT4 model. Higher PM2.5 levels were found at Linan, indicating that the site was under signifcant regional-scale infuence of the long-range transport from the Yangtze River Delta region and northern China. The annual concentration of total water-soluble inorganic ions was (28.5±17.7) g/m3, contributed an average of 47% of PM2.5 mass concentration. Three major ions SO42-, NO3-, and NH4+counted for 69% of the total water-soluble inorganic ions. The annual mean concentrations of OC and EC were (10.1±6.7) μg/m3and (2.4±1.8) μg/m3, respectively. OC and EC showed a signifcant correlation, indicating that OC and EC were mainly from the common sources. (Meng Zhaoyang)

3 The model development and the impact of atmospheric compositions on climate, weather, and human health

3.1 Improvements in simulating the chemical and optical properties of Chinese aerosols using an online coupled model CUACE/Aero

CUACE/Aero, the China Meteorological Administration (CMA) Unified Atmospheric Chemistry Environment for aerosols, is a comprehensive numerical aerosol module incorporating emissions, gaseous chemistry, and size-segregated multi-component aerosol algorithm. Online coupled into a mesoscale weather forecast model MM5, its performance and improvements for aerosol chemical and optical simulations have been evaluated using the intensive observational data of aerosols/gases from the CMA Atmosphere Watch network, plus aerosol optical depth (AOD) data from the CMA Aerosol Remote Sensing network (CARSNET), and from the Moderate Resolution Imaging Spectroradiometer (MODIS). Targeting Beijing and the North China region from 13 to 31 July 2008, when a heavy hazy weather system occurred, the model captured the general variations of PM10 with most of the data within a factor of 2 from the observations and a combined correlation coeffcient (r) of 0.38 (signifcance level of 0.05). The correlation coeffcients are better at rural than at urban sites, and better at daytime than at nighttime. Chemically, the correlation coeffcients between the daily-averaged modeled and observed concentrations range from 0.34 for black carbon (BC) to 0.09 for nitrates with sulfate, with ammonium and organic carbon (OC) in between. Like PM10, the values of chemical species are higher during daytime than those during nighttime. On average, the sulfate, ammonium, nitrate, and OC are underestimated by about 60%, 70%, 96.0%, and 10.8%, respectively. Black carbon is overestimated by about 120%. A new size distribution for the primary particle emissions was constructed for most of the anthropogenic aerosols such as BC, OC, sulfate, nitrate, and ammonium from the observed size distribution of atmospheric aerosols in Beijing. This not only improves the correlation between the modeled and observed AOD, but also reduces the overestimation of AOD simulated by the original model size distributions of primary aerosols. The normalized mean error has been reduced to 62% with the CARSNET observations and 76% with MODIS, from the original 111% and 143%, respectively. The factors resulting in the underestimation of aerosol concentrations and other discrepancies in the model are explored, and improvements in enhancing the model performance are proposed from the analysis. It is found that the accuracy in meteorological predictions plays a critical role in the simulation of the occurrence and accumulation of heavy pollution episodes, especially the winds and the treatment of the Planetary Boundary Layer (PBL). (Zhou Chunhong)

3.2 A parameterized method for air-quality diagnosis and its applications

A parameterized method is developed to diagnose air quality in Beijing and other cities with an index termed PLAM (parameters linking air-quality to meteorological elements), which is derived from a correlation between PM10 and relevant weather elements based on the data between 2000 and 2007. Key weather factors for diagnosing the air pollution intensity are identified and included in PLAM that include atmospheric condensation of water vapour, wet potential equivalent temperature, and wind velocity. It is found that the poor air quality days with elevated PM10 are usually associated with higher PLAM values, featuring higher temperature, humidity, lower wind velocity, and higher stability compared to the averaged values in the same period. Both 24-h and 72-h forecasts provided useful information and service for the day of the opening ceremony of the Beijing 2008 Olympic Games and the subsequent sport events. A correlation coeffcient of 0.82 was achieved between the forecasts and the air pollution index (API) and 0.59 between the forecasts and observed PM10, all reaching the signifcance level of 0.001, for the summer period. A correction factor was also introduced to enable the PLAM to diagnose the observed PM10 concentrations all year round. (Wang Jizhi)

3.3 PLAM index tracking for trajectories of the SDS system in China and its wave-like trends

The characteristic distributions of regional sand and dust storms (SDS) from 1980 to 2011 wereinvestigated using meteorological data from surface stations, atmospheric sounding data, high density weather data of the CMA, as well as the archived Chinese original weather maps. Based on the SDS deposited PSCF (potential source contribution function) method, a tracking analysis of sand-dust weather processes was developed by using the index of the PLAM (parameters of air quality and meteorology) in the Northeast Asian region. A spline trend analysis was also used to investigate the variability of the SDS system strength. The results show that during the period of 1980—2011, the SDS processes had a wave-like trend, featuring both a historical persistence and abrupt transitions, with an about 10-yr high-low oscillation. (Wang Jizhi)

3.4 Interactive enhancements of ascorbic acid and iron in hydroxyl radical generation in quinone redox cycling

Quinones are toxicological substances in inhalable particulate matter (PM). The mechanisms by which quinones cause hazardous effects are complex. Quinones are highly active redox molecules that can go through a redox cycle with their semiquinone radicals, leading to formation of reactive oxygen species. Electron spin resonance spectra have been reported for semiquinone radicals in PM, indicating the importance of ascorbic acid and iron in quinone redox cycling. However, these fndings are insuffcient for understanding the toxicity associated with quinone exposure. Herein, we investigated the interactions among anthraquinone (AQ), ascorbic acid, and iron in hydroxyl radical (?OH) generation through the AQ redox cycling process in a physiological buffer. We measured ?OH concentration and analyzed the free radical process. Our results showed that AQ, ascorbic acid, and iron have synergistic effects on ?OH generation in quinone redox cycling; i.e., ascorbyl radical oxidized AQ to semiquinone radical and started the redox cycling, iron accelerated this oxidation and enhanced ?OH generation through Fenton reactions, while ascorbic acid and AQ could help iron to release from quartz surface and enhance its bioavailability. Our findings provide direct evidence for the redox cycling hypothesis about airborne particle surface quinone in lung fuid. (Li Yi)

3.5 Assessment on population exposure levels of PM10 in Lanzhou based on GIS and atmospheric numerical simulation technology

The pollutant concentration and population spatial distribution in January 2001 were overlaid, based on monthly average PM10 concentration values from observations and CMAQ simulations. Then, population exposure levels were calculated by the population-weighted PM10 concentrations. Assessment results from these two different sets of data were comparatively analyzed. The simulated PM10 concentration gradient is larger than the observed. The simulation provides more detailed spatial distribution of PM10 concentration as well as larger intervals between maxima and minima. Taking the factor of population weights into account, it was found that there were more people living in more polluted areas based on simulated PM10 concentrations. (An Xingqin)

3.6 Association between dust weather and number of admissions of patients with respiratory diseases in spring in Lanzhou

Excluding the confounding factors on respiratory hospitalizations such as long-term trend, meteorological factor, atmospheric pollution, and calendar effect, this study investigates the effect of sand-dust weather on respiratory diseases from 2001 to 2005 in Lanzhou City, on the basis of a semi-parametric generalized additive model (GAM). The results indicate that there is a lagged association between sand-dust weather and an increase in respiratory hospitalizations, with gender and age differences. The effect of sand-dust weather on health is severer on male than on female patients (with RR value being 1.148 for male and 1.144 for female without statistical signifcance), and much greater on people aged65 years old than＜65 years old ( with RR value being 1.266 for65 years old, and 1.119 for＜65 years old). (An Xingqin)

3.7 An assessment of Chinas PM10-related health economic losses in 2009

Using GIS software and based on exposure-response functions, this study estimated the health-related economic losses that China suffered in 2009 due to the presence of particulate matter (PM10). The resultsshow that China suffered a health-related economic loss due to PM10 of US$ 106.5 billion, or 2.1% of China s GDP, for the year 2009. Some urban areas, including Beijing, Tianjin, Shanghai, Guangzhou, Chongqing, and Changsha, reported large health-related economic losses due to PM10, with a value of US$ 1.5 million per square kilometer or greater. Some parts of Beijing, Ji nan, and Chongqing reported health-related economic losses due to PM10 as being greater than 4% of the 2009 GDP. (Hou Qing)

3.8 The interactive impacts between air pollutants and meteorological factors on human health

Meteorological conditions decide the diffusing, transport, and accumulation of air pollutants, and thus impact human being’s true exposure to air pollution. Air pollution may make people more vulnerable to the effects of temperature variability; while temperature may modify the associations between air pollution and cardio-respiratory diseases. There is often symmetry in modifcation—air pollution modifes temperature and then temperature modifies air pollution—but the magnitudes are likely to differ. The true magnitude of the association between temperature and health outcomes may be obscured if air pollution is an effective modifer of the relationship. Therefore, there are interactions between meteorological factors and air pollutants in their impacts on human health. (Li Yi)

3.9 Projection of heat-related mortality in Shanghai under the climate change

The statistical downscaling techniques are applied to simulations of daily mean temperature in Shanghai in the near and far future under the changing climate. Based on the published exposure-reaction relationship of temperature and mortality in Shanghai, we project the heat-related mortality in the near and far future under the circumstance of high speed increase of carbon emission (A2) and low speed increase of carbon emission (B2). Under the A2 scenario, annual average heat-related mortality is projected to be 516 and 1191 cases in 2030— 2059 and 2070—2099, respectively, increasing by 53.6% and 254.5% compared with the baseline period (336 cases). Under the B2 scenario, annual average heat-related mortality is projected to be 498 and 832 cases in 2030—2059 and 2070—2099, respectively, increasing by 48.2% and 147.3% compared with the baseline period (336 cases). Under the changing climate, heat-related mortality is projected to increase in the future; and the increase will be more obvious in 2070—2099 than in 2030—2059. (Cheng Yanli)

3.10 Aerosol chemical compositions of Beijing PM1 and its control countermeasures

The mass concentrations of sulfate, nitrate, ammonium products, organic matter, and black carbon are measured at urban Beijing during summer and autumn of 2007 and winter and spring of 2008. In comparison with assessment of major chemical compositions in less than 10 micron particles with at least an entire year data from various rural and urban sites in 16 areas of the world, the concentration level of mineral aerosol in China, which is partially a result of sand and dust transported from desert areas and contributions from urban fugitive dust/fy ash sources, is found to be almost equivalent to or even higher than the sum of all kind of aerosols in urban Europe and North America, suggesting the control countermeasures for aerosol particle in diameter between 2.5 and 10 micron in China should not be neglected, especially when the country pays much attention to controlling the fine PM2.5 particles. In urban Beijing, the averaged concentrations of PM1 are around 94, 74, 66, and 91 μg/m3for spring, summer, autumn, and winter, respectively, with the annual mean of 81 μg/m3. The relative contributions of organics, sulfate, nitrate, and ammonium product are about 41%, 16%, 13%, and 8%, respectively. The black carbon and chloride contribute Beijing PM1 about 11% and 3%, respectively. The fne mineral aerosol contributes about 7%. The key to the control of PM2.5 is the reduction in the main emission species and their chemical transformation of PM1 particles, and an important step is to control the organic matter in Beijing, although this has been very diffcult for a 26-million population living here. Scientifcally speaking, even if China’s control countermeasures are realized one hundred percent, it is still hard to reach the air quality level of the Europe and North America because of the higher background mineral aerosol level. The cost-effective control measures and new PM2.5 standard considering the health of the Chinese need to be further investigated. (Zhang Xiaoye)

2012年3月12日，在中國(guó)氣象局局長(zhǎng)鄭國(guó)光等領(lǐng)導(dǎo)陪同下，江蘇省副省長(zhǎng)徐鳴一行到氣科院考察工作，受到院長(zhǎng)張人禾的熱情接待。徐鳴副省長(zhǎng)與氣科院專家就城市及周邊地區(qū)氣溶膠形成和發(fā)展趨勢(shì)等問題進(jìn)行了討論。On 12 March 2012, Vice Governor of Jiangsu Province, Mr. Xu Ming visited CAMS in the accompany of CMA Administrator, Dr. Zheng Guoguang, and was warmly welcomed by CAMS President, Prof. Zhang Renhe. Mr. Xu Ming exchanged views with CAMS experts on aerosol formation and development in urban and surronding areas.

2012年3月20日，國(guó)家自然科學(xué)基金委員會(huì)主任陳宜瑜一行參觀訪問氣科院。副院長(zhǎng)翟盤茂、張小曳為來賓做了第3次青藏高原試驗(yàn)和大氣成分研究等工作匯報(bào)。陳宜瑜主任與鄭國(guó)光局長(zhǎng)及氣科院專家就上述問題深入交換了意見。On 20 March 2012, the delegation of the National Natural Science Fundation of China led by its head, Mr. Chen Yiyu visited CAMS. CAMS Vice Presidents, Dr. Zhai Panmao and Prof. Zhang Xiaoye reported to the guests on the Third Tibetan Plateau Experiment and Atmospheric Composition Research, respectively. Mr. Chen Yiyu exchanged views on the above issues with Dr. Zheng Guoguang and CAMS experts thought-provokingly.

2012年4月28日，氣科院2008—2011年工作評(píng)估會(huì)議在京舉行。院長(zhǎng)張人禾和6個(gè)重點(diǎn)研究領(lǐng)域?qū)W術(shù)帶頭人匯報(bào)了4年來氣科院在科研業(yè)務(wù)、人才隊(duì)伍建設(shè)等方面取得的豐碩成果。評(píng)估專家組充分肯定了氣科院的成績(jī)，并高度評(píng)價(jià)了氣科院評(píng)估報(bào)告。On 28 April 2012, the CAMS Staff Work Performance Assessment Meeting was held in Beijing. CAMS President, Prof. Zhang Renhe and academic leaders reported on the fruitful outcomes achieved over the four years (2008—2011) in scientific research and capacity-building of personnel, etc. The expert team of assessment presented positive comments on CAMS’ achievement and spoke highly of the assessment report.

2012年4月23日，科技部副部長(zhǎng)張來武一行在鄭國(guó)光局長(zhǎng)陪同下參觀氣科院。院長(zhǎng)張人禾主持接待，副院長(zhǎng)張小曳、周廣勝分別做了大氣化學(xué)研究進(jìn)展、農(nóng)業(yè)氣象和人工影響天氣相關(guān)工作的匯報(bào)。On 23 April 2012, the delegation headed by Vice Minister of Science and Technology of China, Mr. Zhang Laiwu visited CAMS in the accompany of CMA Administrator, Dr. Zheng Guoguang. CAMS President, Prof. Zhang Renhe received the guests and Vice Presidents, Prof. Zhang Xiaoye and Dr. Zhou Guangsheng reported on the progress of atmospheric chemistry research and agrometeorological and weather modifcation work, respectively.

2012年5月24日，在鄭國(guó)光局長(zhǎng)陪同下，中央統(tǒng)戰(zhàn)部副部長(zhǎng)陳喜慶帶領(lǐng)由全國(guó)無(wú)黨派人士組成的“防治細(xì)顆粒物(PM2.5)的對(duì)策研究”考察團(tuán)到氣科院調(diào)研，并就細(xì)顆粒物(PM2.5)、空氣質(zhì)量及控制對(duì)策等問題與氣科院專家進(jìn)行了探討。On 24 May 2012, accompanied by CMA Administrator Zheng Guoguang, the study tour delegation of maverick led by the Deputy Head of United Front Work Department of CPC Central Committee, Mr. Chen Xiqing visited CAMS for studying the response measures to prevent fine articles (PM2.5). The delegates exchanged views with CAMS experts on PM2.5, air quality, and control measures, etc.

2012年6月13日，氣科院召開特聘專家張大林教授入選國(guó)家 “千人計(jì)劃”國(guó)家重點(diǎn)創(chuàng)新項(xiàng)目平臺(tái)宣布大會(huì)。張大林是美國(guó)馬里蘭大學(xué)教授，主要從事暴雨、大暴雨機(jī)理研究工作。On 13 June 2012, the declaration ceremony for Prof. Zhang Dalin’s selection into the National Leading Innovation Project Platform of the “1000 High-Level Foreign Experts Project” was held at CAMS. Prof. Zhang Dalin works at University of Maryland of USA, researching in rainstorm and heavy rainstorm mechanisms.

2012年9月28日，氣科院與河北省氣象局合作簽字儀式暨科學(xué)報(bào)告會(huì)在河北省氣象局舉行。雙方將在試驗(yàn)基地建設(shè)、科學(xué)研究、人才培養(yǎng)、資源共享等方面開展全面合作。在之后舉行的科學(xué)報(bào)告會(huì)上，張人禾、張小曳、王東海研究員做了學(xué)術(shù)報(bào)告，雙方科研業(yè)務(wù)人員展開了深入的交流討論。On 28 September 2012, the Signing Ceremony for Cooperation between CAMS and Hebei Provincial Meteorological Service (HPMS) along with a scientific seminar was held at HPMS. At the seminar, Profs. Zhang Renhe and Zhang Xiaoye, Dr. Wang Donghai made academic presentations, respectively, and research & operational staff from both institutions held heated discussions.

2012年10月16日，氣科院召開干部大會(huì)，宣布由端義宏、王懷剛、李集明、趙平、翟盤茂和周廣勝組成氣科院新一屆領(lǐng)導(dǎo)班子的決定。中國(guó)氣象局局長(zhǎng)鄭國(guó)光等領(lǐng)導(dǎo)出席會(huì)議，人事司司長(zhǎng)胡鵬主持會(huì)議。On 16 October 2012, CAMS held the Employee Plenary to announce its new Board of Presidents composed of Mr. Duan Yihong, Mr. Wang Huaigang, Mr. Li Jiming, Mr. Zhao Ping, Mr. Zhai Panmao and Mr. Zhou Guangsheng. CMA leaders including Administrator Zheng Guoguang attended the meeting, which was presided over by the Director-General of CMA Department of Personnel, Mr. Hu Peng.

2012年11月13日，端義宏院長(zhǎng)組織召開“第3次青藏高原大氣科學(xué)試驗(yàn)”專題會(huì)議，與會(huì)專家針對(duì)青藏高原大氣科學(xué)試驗(yàn)問題進(jìn)行了研討。On 13 November 2012, CAMS President, Dr. Duan Yihong hosted a forum on “The Third Tibetan Plateau Scientific Experiment on Atmosphere”. The participating experts discussed about a number of issues related to the atmospheric experiments to be carried out over the Tibetan Plateau.

2012年，氣科院獲得國(guó)家科技進(jìn)步2等獎(jiǎng)1項(xiàng)、獲得專利5項(xiàng)。In 2012, CAMS won a second prize of National S&T Progress Award and fve items were granted patent.