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1.
运用Fialho等提出的线性统计回归方法对2006年塔克拉玛干沙漠腹地塔中气象站春季大气气溶胶中沙尘和黑碳气溶胶吸收系数的波长指数及其对总吸收系数的贡献进行了估算。气溶胶吸收系数由7波段黑碳仪观测数据计算而得,观测时间为2006年3月1日_月31日。选择背景天气(假设其气溶胶吸收无沙尘的贡献)估算的黑碳气溶胶吸收系数的波长指数a为一0．95±0．002;选择6次强沙尘暴天气影响时段估算的沙尘气溶胶吸收系数的波长指数口为一2．55±0．009。用估算的d和口对春季总吸收系数进行分离,结果表明,春季沙尘吸收系数和黑碳吸收系数平均约占总吸收系数的50．5％和49．5％(520am  相似文献   

2.
利用2006年3～5月北京上甸子本底站气溶胶细粒子(PM2.5)质量浓度、吸收和散射系数的连续观测资料,对2006年春季上甸子本底站清洁、污染输送及典型沙尘天气下气溶胶的消光特性进行了分析.结果显示:①本底站在春季清洁情况下PM2.5质量浓度、吸收和散射系数的日均值水平分别为:10 μg/m3、7 Mm-1和20Mm-1左右,单散射反照率分布在0.71～0.78之间;此次观测到的污染输送过程中PM2.5质量浓度、吸收和散射系数平均值分别为:145 μg/m3、44.5 Mm-1、374.3 Mm-1,单散射反照率分布在0.84～0.94之间;沙尘影响期间,PM2.5质量浓度、吸收和散射系数以及单散射反照率的测量结果分布在248.2～424.1 μg/m3、10.8～44.7Mm-1、225.4～392.5 Mm-1和0.89～0.96之间.②观测得出,沙尘影响集中的时段细粒子质量浓度、气溶胶散射系数和气溶胶吸收系数都成倍地上升,其中质量浓度和散射系数上升的幅度要高于吸收系数.③3种天气条件的对比结果显示.受沙尘天气影响PM2.5质量浓度明显上升,且逐时波动幅度大;吸收系数远高于清洁天气下的观测结果,但比污染输送过程的测量结果偏低;散射系数同样高于清洁天气下的观测结果,与污染输送情况下的测量结果接近.沙尘天气导致颗粒物浓度明显上升,其对气溶胶粒子散射作用的贡献要大于吸收作用.  相似文献   

3.
由气溶胶自动观测网(AERONET)反演的细模态气溶胶的吸收光学厚度(AAOD)通常被认为是黑碳气溶胶的AAOD,并且通过这种方法得到的黑碳AAOD已经被用在计算黑碳辐射强迫的研究中。但是这种方法是基于如下假设:直径小于1μm的细模态气溶胶和直径大于1μm的粗模态气溶胶对光的吸收主要分别归功于黑碳和沙尘。为了定量描述细模态沙尘气溶胶对全部细模态气溶胶的AAOD的贡献,我们利用地球系统交互模式(CESM)模拟了中国东部(104–122°E,29–41°N)细模态沙尘气溶胶的AAOD。其中,我们根据9个中国气象局大气观测网(CAWNET)站点观测的细模态沙尘地表浓度调整了模拟的细模态沙尘气溶胶的浓度。结果显示,模拟的中国东部年平均细模态沙尘气溶胶的AAOD的值为3.6×10-3,其中AAOD的最大和最小值分别出现在春季和冬季。细模态沙尘气溶胶对总的细模态气溶胶(细模态沙尘、黑碳和有机碳气溶胶的总和)的AAOD的贡献在春季、夏季、秋季和冬季分别为3.4%、25.2%、12.5%和14.9%,其年平均值为15.1%。这些结果显示当利用AERONET反演得到的细模态气溶胶的AAOD来计算中国东部BC气溶胶的辐射强迫时,去除细模态沙尘粒子的影响显得尤为重要。  相似文献   

4.
北京沙尘质量浓度与气象条件关系研究及其应用   总被引：13，自引：4，他引：9  
运用多元线性回归分析的方法对北京沙尘气溶胶质量浓度观测资料和相关气象资料进行了分析,结果表明北京沙尘气溶胶质量浓度与尘暴、浮尘、降水和大风四种气象要素密切相关。在此基础上给出利用常规气象资料计算沙尘气溶胶质量浓度的计算公式,并进一步计算了１９７１～１９９６年北京春季月平均沙尘气溶胶质量浓度。结果表明,从１９１～１９８９年沙尘气溶胶质量浓度总体呈递减趋势;１９９０年以后,沙尘气溶胶质量浓度有所增加。  相似文献   

5.
北京风沙天气的气溶胶特征   总被引：15，自引：1，他引：15  
利用常规气象观测资料、卫星云图以及1988、1990、1992、1993、1995、2000年等年北京风沙天气期间所采集的气溶胶样品的分析结果,研究了北京的风沙天气分布特征,风沙期间大气污染状况,产生风沙天气的主要原因及沙尘的来源等.初步得出北京的风沙天气主要出现在春季,是造成春季大气污染的重要原因之一;北京春季风沙天气是由沙尘暴、浮尘和扬沙造成,但以扬尘引起的频率为最高,占71.4%;风沙期间大气气溶胶与无风沙时气溶胶的物理化学特征有明显的差异;大气气溶胶的物理化学特征显示出,风沙期间的大气气溶胶主要来源于自然源,以局地尘源为主,人为排放的气溶胶作用相对减弱.  相似文献   

6.
黑碳气溶胶光学厚度的全球分布及分析   总被引：11，自引：2，他引：11  
马井会  郑有飞  张华 《气象科学》2007,27(5):549-556
利用全球气溶胶数据集GADS(Global Aerosol Data Set)计算了冬夏两季黑碳气溶胶质量浓度分布以及在波长0.55μm处的光学厚度、吸收系数和散射系数在全球的分布,并分析了原因。通过分析黑碳气溶胶复折射指数虚部、单次散射反照率、非对称因子、吸收系数、散射系数和消光系数随波长的变化,得出黑碳气溶胶的吸收系数和散射系数在小于0.5μm的短波范围内具有相同的数量级,随着波长的增大,吸收系数比散射系数大几个数量级;黑碳气溶胶对小于1μm的短波有强烈的吸收作用。另外还给出了冬夏两季南北半球及全球黑碳气溶胶平均光学厚度值、7个地区黑碳气溶胶光学厚度及质量浓度最大值,其中冬季黑碳气溶胶光学厚度的最大值为0.027 5,位于东亚地区;而质量浓度最大值为1.555μg/m3,位于西欧地区。  相似文献   

7.
利用激光雷达对2006年6月17日出现浮尘天气进行观测,反演分析浮尘天气气溶胶消光系数特征,并将其消光系数放入LOWTRAN模式中模拟了大气长波冷却率。结果表明:浮尘刚出现时沙尘的消光系数较小,其峰值在地面附近,相应光学厚度也较小。浮尘发展时沙尘的消光系数增大,沙尘粒子慢慢从地面上升至高空,边界层高度达1 500 m左右,边界层内部沙尘气溶胶充分混合,消光系数趋于一致,光学厚度最大达0.41;17日浮尘期间(19:00—23:00),2 200 m以下20:00 h和21:00 h冷却率较其它时刻大,这两个时刻的沙尘浓度也较大;有浮尘时长波冷却率较无浮尘时增加,最大增加值在2 250 m的高度层达到0.04 K/h。   相似文献   

8.
青岛大气气溶胶的浓度分布和干沉降的观测研究   总被引：9，自引：0，他引：9  
根据青岛沙尘天气历史资料和近年来的青岛地面气溶胶观测资料,分析了青岛沙尘日数的长期变化趋势、季节变化特征以及气溶胶质量浓度、谱分布和干沉降的季节变化.分析结果表明,1961～1988年青岛沙尘日数呈波动变化,且幅度较大.1999年以来沙尘日数明显增加,且以浮尘天气为主.青岛在1961～2001年扬沙日数年平均值为1.83天,是北京同期的13%;年浮尘日数为2.93天,是北京同期的75%.青岛沙尘发生日数主要集中在冬春季,春季最高,冬季次高;夏季没有沙尘天气,秋季很低.青岛气溶胶质量浓度有明显的季节变化,春季最高,冬季次之,秋季又次之,夏季最低.大流量观测的总悬浮颗粒物(TSP)年平均浓度为177μgm-3,安德森分级采样器观测的气溶胶质量浓度为123μg m-3,两者的差别与不同的观测时间和观测仪器有关.在3月和4月,粗细粒子的浓度相差很大,粗粒子分别占总浓度的80%和62%.青岛气溶胶沉降通量在0.06～0.2 g m-2d-1之间,平均值为0.13 g m-2d-1,是北京沉降通量的30%.  相似文献   

9.
沙尘辐射效应对天气和沙尘输送影响的数值模拟   总被引：5，自引：1，他引：4  
陈勇  陈德辉  王宏 《大气科学》2009,33(1):38-50
现有的沙尘气溶胶数值预报模式大多是单向模式, 即只考虑气象场对沙尘气溶胶的输送作用, 而忽略沙尘气溶胶的辐射效应对气象场的反馈作用。本文利用一个考虑了沙尘气溶胶短波辐射效应的天气－沙尘双向模式, 对南疆盆地一次冷空气东侵而引起的沙尘天气进行数值模拟。通过比较考虑与不考虑辐射效应的两组试验, 分析了在沙尘暴－强浮尘过程中沙尘辐射效应对气象要素和沙尘输送的影响, 结果表明: 沙尘辐射效应的考虑明显改进后期强浮尘天气过程中海平面气压变化、地面气温日变化和气温垂直变化的预报; 前期沙尘暴过程沙尘辐射效应引起中低层主导风增大, 但同时使起沙量降低及沉降量减少; 沙尘辐射效应与地形的共同作用使沙尘的沉降量比起沙量减少的更显著, 从而使盆地内浮尘天气维持。  相似文献   

10.
杨哲  王宁  段有 《吉林气象》2009,(3):11-15
本文利用2002—2008年近7年吉林省50个气象站的春季沙尘观测资料,分析了春季沙尘天气的特征及其与气象要素的关系。结果表明：时间分布上,区域沙尘天气、区域浮尘天气呈现波动减少的趋势,局地沙尘天气呈现波动起伏状态;空间分布上,区域沙尘天气西北多东南少,区域浮尘天气西南多东北少。影响吉林省产生区域沙尘天气的沙源地、移动路径与区域浮尘天气基本相同,但相同的路径产生的影响却不同。3月区域沙尘天气的出现日数与当月平均降水量呈明显的负相关;与当月平均气温关系不明显。春季沙尘日数与上半年冬季（12、1、2月）平均气温有很大的正相关。  相似文献   

11.
A statistic regression approach was used to estimate the wavelength exponents of black carbon(BC)and dust particles,and further to separate the contributions of the two types of aerosols to the total light absorption coefficient measured in the Beijing urban area in the spring of 2006.The results show that the wavelength exponent(α)of black carbon aerosol at urban site was approximately-0.92.which is in agreement with the value of-0.8±0.2 reported in related studies.The decoupling analysis of the measured light absorption coefficients during the three floating dust periods(March 25,March 27,and April 9)demonstrates that,on average,the light absorption caused by dust particles took up about 32.8% of the total light absorption at 520 nm wavelength,and by black aerosol more than 60%.This indicates that the black carbon was still the major contributor to the total aerosol light absorption in Beijing urban area even during the floating dust periods.  相似文献   

12.
 A statistic regression approach was used to estimate the wavelength exponents of black carbon (BC) and dust particles, and further to separate the contributions of the two types of aerosols to the total light absorption coefficient measured in the Beijing urban area in the spring of 2006. The results show that the wavelength exponent (a) of black carbon aerosol at urban site was approximately -0.92, which is in agreement with the value of -0.8±0.2 reported in related studies. The decoupling analysis of the measured light absorption coefficients during the three floating dust periods ( March 25, March 27, and April 9) demonstrates that, on average, the light absorption caused by dust particles took up about 32.8% of the total light absorption at 520 nm wavelength, and by black aerosol more than 60%. This indicates that the black carbon was still the major contributor to the total aerosol light absorption in Beijing urban area even during the floating dust periods.  相似文献   

13.
This paper reports on the analysis of 24-h aerosol data measured during 2006, at 14 monitoring sites in China. Measurements included seven-wavelength Aethalometers, thermal/optical reflectance analyses of filter samples and determination of dust aerosols. Black (elemental) carbon (BC, EC) is found to be the principal light-absorbing aerosol over many parts of China; however, the fraction of apparent light absorption attributed to dust varied from 14% in winter, to 11% in spring, to 5% in summer to 9% in autumn. Aerosol light absorption in urban areas was larger than in rural areas by factors of 2.4 in winter, 3.1 in spring and 2.5 in both summer and autumn. These differences may lead to contrasts in radiative, thermal and cloud modification effects between urban and rural areas. Absorption 'hotspots' were located in the Sichuan Basin, the provinces south of Beijing, the Pearl Delta River regions and the Guanzhong Plain. The mass absorption coefficient for aerosol BC (σBC) based on Aethalometer data is estimated to be 11.7 m2 g−1 at 880 nm wavelength (λ) with inverse (λ−1) wavelength scaling, whereas the mass absorption coefficient for dust (σdust) is 1.3 m2 g−1 on average without significant wavelength dependence.  相似文献   

14.
北京PM1中的化学组成及其控制对策思考   总被引：5，自引：0，他引：5       下载免费PDF全文
通过分析北京城区2007年夏季和秋季、2008年冬季和春季4个季节PM1中硫酸盐、硝酸盐、铵盐、有机物和黑碳等气溶胶化学组成,结合对我国及全球主要区域PM10中上述气溶胶组分及矿物气溶胶组成的评估,发现因受干旱区产生的沙尘和城市逸散性粉尘的共同影响,整个亚洲大陆,尤其是我国的矿物气溶胶浓度与欧美国家城市区域气溶胶总和的平均值相当或更高。我国在重视控制PM2.5等细粒子污染的同时,不应忽视对PM2.5~PM10之间粗粒子的控制力度;北京城区春、夏、秋、冬的PM1平均质量浓度分别约为94,74,66 μg·m-3和91 μg·m-3,全年平均约为81 μg·m-3,其中有机物气溶胶约占41%,硫酸盐占16%,硝酸盐占13%,铵盐占8%,黑碳和氯化物分别占11%和3%,细矿物气溶胶约贡献7%。对于PM2.5污染的控制,关键是消减PM1中主要气溶胶粒子的排放与转化,其中对有机物的控制更为重要,尽管对于北京而言进一步污染控制的难度已经很大。从科学上来说,即使我国的控制措施能百分之百实现,也很难稳定地达到欧美国家的空气质量水平,因为我国本底矿物气溶胶的浓度较高。应进一步评估各项控制措施的适用性,并制定考虑我国人群健康状况的PM2.5空气质量标准。  相似文献   

15.
Characterization of aerosols is required to reduce uncertainties in satellite retrievals of global aerosols and for modeling the effects of these aerosols on climate.Aerosols in the North China Plain(NCP) are complex,which provides a good opportunity to study key aerosol optical properties for various aerosol types.A cluster analysis of key optical properties obtained from Aerosol Robotic Network(AERONET) data in Beijing and Xianghe during 2001-11 was performed to identify dominant aerosol types and their associated optical properties.Five dominant aerosol types were identified.The results show that the urban/industrial aerosol of moderate absorption was dominant in the region and that this type varied little with season.Urban/industrial aerosol of weak absorption was the next most common type and mainly occurs in summer,followed by that strong aerosols occurring mainly in winter.All were predominantly fine mode particles.Mineral dust(MD) and polluted dust(PD) occurred mainly in spring,followed by winter,and their absorption decreased with wavelength.In addition,aerosol dynamics and optical parameters such as refractive index and asymmetry factor were examined.Results show that the size of coarse mode particles decreased with AOD indicating the domination of external mixing between aerosols.  相似文献   

16.
During the SAMUM-1 experiment, absorption coefficients and imaginary parts of refractive indices of mineral dust particles were investigated in southern Morocco. Main absorbing constituents of airborne samples were identified to be iron oxide and soot. Spectral absorption coefficients were measured using a spectral optical absorption photometer (SOAP) in the wavelength range from 300 to 800 nm with a resolution of 50 nm. A new method that accounts for a loading-dependent correction of fibre filter based absorption photometers, was developed. The imaginary part of the refractive index was determined using Mie calculations from 350 to 800 nm. The spectral absorption coefficient allowed a separation between dust and soot absorption. A correlation analysis showed that the dust absorption coefficient is correlated ( R 2 up to 0.55) with the particle number concentration for particle diameters larger than 0.5 μm, whereas the coefficient of determination R 2 for smaller particles is below 0.1. Refractive indices were derived for both the total aerosol and a dust aerosol that was corrected for soot absorption. Average imaginary parts of refractive indices of the entire aerosol are 7.4 × 10−3, 3.4 × 10−3 and 2.0 × 10−3 at wavelengths of 450, 550 and 650 nm. After a correction for the soot absorption, imaginary parts of refractive indices are 5.1 × 10−3, 1.6 × 10−3 and 4.5 × 10−4.  相似文献   

17.
A comparative study on the vertical distributions of aerosol optical properties during haze and floating dust weather in Shanghai was conducted based on the data obtained from a micro pulse lidar.There was a distinct difference in layer thickness and extinction coefficient under the two types of weather conditions.Aerosols were concentrated below 1 km and the aerosol extinction coefficients ranged from 0.25 to 1.50km-1 on haze days.In contrast,aerosols with smaller extinction coefficients(0.20 0.35 km-1) accumulated mainly from the surface to 2 km on floating dust days.The seasonal variations of extinction and aerosol optical depth（AOD） for both haze and floating dust cases were similar greatest in winter,smaller in spring,and smallest in autumn.More than 85%of the aerosols appeared in the atmosphere below 1 km during severe haze and floating dust weather.The diurnal variation of the extinction coefficient of haze exhibited a bimodal shape with two peaks in the morning or at noon,and at nightfall,respectively.The aerosol extinction coefficient gradually increased throughout the day during floating dust weather.Case studies showed that haze aerosols were generated from the surface and then lifted up,but floating dust aerosols were transported vertically from higher altitude to the surface.The AOD during floating dust weather was higher than that during haze.The boundary layer was more stable during haze than during floating dust weather.  相似文献   

18.
使用NCEP/NCAR再分析资料对2006年4月7~11日北京浮尘天气过程的持续性进行分析,指出此次浮尘天气过程主要受500 hPa西西伯利亚冷涡、鄂霍次克海暖高压以及青藏高原高压脊影响;700 hPa有干冷空气不断向北京地区输送,冷平流和斜压性都很强,大风和沙尘暴发生在强冷平流区域;由于华北南部地区近地面至中低层存在弱的不稳定层结,容易产生弱的上升运动。在近地面低压前部偏东风的作用下将沙尘粒子向北京地区输送,北京地区上空大气在中低层基本处于中性或不稳定层结状态,沙尘粒子不易在北京上空沉降,造成较长时间的浮尘天气。  相似文献   

19.
2008年北京奥运会期间大气气溶胶物理特征分析   总被引：5，自引：0，他引：5  
应用MODIS卫星的气溶胶产品资料和地面的光学粒子计数器的资料,对比分析了北京地区2006、2007、2008年7～9月的气溶胶光学厚度、细粒子光学厚度、Angstrom指数、气溶胶粒子数浓度谱及体积谱,发现2008年北京奥运会期间(7月20日～9月20日)的气溶胶光学厚度比2006、2007年同期明显降低,气溶胶细模态光学厚度占总光学厚度的比上升,Angstrom指数上升,气溶胶细粒子数浓度没有明显相对变化,而粗粒子数浓度则减少约50%.利用大气标高,将MODIS反演的气溶胶柱的质量浓度转化为地面气溶胶质量浓度.用粒子计数器得到的体积谱,在假定气溶胶粒子密度的情况下,计算出其质量浓度.将这两种方法得到的气溶胶质量浓度与国家环境保护部公布的空气质量指数换算得到的可吸入颗粒物(PM10)质量浓度进行比较.结果表明:北京奥运期间空气质量总体达到了国家二级空气质量标准;与2006、2007年同期相比,2008年气溶胶PM10质量浓度明显下降,而这主要是由气溶胶粗粒子的减少引起的.  相似文献   

20.
利用2006年3～5月天空辐射计观测数据反演得到北京地区春季大气气溶胶光学性质参数,包括大气气溶胶光学厚度(0.5μm)、Angstrm指数、单次散射反射比和粒子谱分布特征。结果表明:北京地区春季气溶胶平均光学厚度0.67,Angstrm指数0.54,单次散射比0.88,粒子吸收性质较弱,粒子谱呈双峰形,以粗粒子为主,粗、细模态粒子粒径分别集中在0.17μm和7.7μm左右。相比2004年此次观测期间气溶胶粒径较大,粒子体积浓度较高,散射作用在其消光特性中的比重略有下降。光学厚度日变化呈单峰型,日间单次散射比随时间逐渐递减,Angstrm指数在上午递减趋势明显,午后变得稳定。对同时观测的天空辐射计与CE-318不同波长光学厚度结果进行比较,结果显示两者得到的光学厚度相关性很好,各波长小时平均结果的相对误差小于7%。  相似文献   

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