首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
东亚夏季风环流对气溶胶分布的影响   总被引:2,自引:1,他引:1  
安礼政  江静  周洋 《气象科学》2015,35(1):26-32
用2001—2012年逐月的MODIS-TERRA卫星观测气溶胶光学厚度(AOD)资料和NCEP/NCAR风场资料,分析了5—8月东亚地区AOD的时-空分布特征,研究东亚夏季风环流对气溶胶时-空分布的影响。主要结论如下:5—8月的中国东部及邻近海洋上AOD有着显著的季节演变特征,尤其是32.5 °N附近的AOD高值区,其强度和范围在5—8月逐渐增强然后又减弱。东亚夏季风通过环流输送作用对各地的AOD产生了不同程度的影响,使中国南部AOD减少,而华北和东北地区AOD增加。在强、弱季风年背景下,7月观测的AOD差异与环流输送作用差异的分布特征有着一定的相似性,体现出东亚夏季风年际变化对气溶胶分布的影响。在东亚夏季风演变的不同阶段,季风环流对气溶胶输送大部分情况下,可解释局地气溶胶变化10%~20%的方差。  相似文献   

2.
上海地区大气气溶胶光学特性的初步研究   总被引:4,自引:1,他引:3  
上海是东亚重要的沿海城市之一,其上空大气气溶胶光学特性的研究对了解上海及我国东部沿海地区的环境和气候影响等方面都具有重要性,至今尚无这方面的实际观测分析。本工作利用2000年6月到2002年12月之间测得的上海地区太阳直接辐照度数据,分析之后得出大气气溶胶光学厚度值,并统计分析了大气气溶胶光学厚度的季节变化及其与地面能见度的关系,最后给出了气溶胶消光谱。通过上述工作,发现上海地区大气气溶胶光学厚度具有夏季最大,春季次之,冬季最小的相对稳定的特点。此外,地面能见度及其倒数作为一个相对容易获得的参数,与大气气溶胶的光学厚度具有较好的相关性,可以考虑将其倒数作为一个约束气溶胶光学厚度分布的物理参数,这对今后的观测和研究都具有一定的实际意义。  相似文献   

3.
利用MODIS光学厚度遥感产品研究北京及周边地区的大气污染   总被引:53,自引:2,他引:53  
对2001年在北京地区利用太阳光度计观测的气溶胶光学厚度和NASA发布的MODIS气溶胶产品进行了比较,验证了这一卫星遥感产品的可靠性;比较了2001年MODIS气溶胶光学厚度(AOD)产品和由空气污染指数(API)计算的每日平均可吸入颗粒物(PM10)浓度,得到了比较高的相关系数,证实该气溶胶产品可用于污染分析.将北京地区AOD与气象能见度观测资料进行比较,得到了不同季节的气溶胶"标高".利用统计的不同季节的气溶胶标高,从光学厚度的季节分布得到了能见度(能见距离)的季节分布.气溶胶光学厚度图像的个例分析表明,除局地排放外,周边区域(主要为西南和南向)的输送对北京市区的空气污染贡献份额较大.卫星遥感气溶胶可以比较直观地再现污染物的区域分布和输送,不仅为研究全球气候变化也为研究区域环境的空气质量提供了一种有效手段.  相似文献   

4.
利用Terra和Aqua卫星上的MODIS探测反演气溶胶产品,比较分析了中国中东部和印度次大陆地区的气溶胶物理特性的异同。研究结果表明:中国中东部气溶胶类型以烟尘为主,印度次大陆地区东、西部分别以烟尘和沙尘为主。两地气溶胶光学厚度均有明显的年际变化,冬季低,夏季高。在夏季,两地烟尘所占比例都很大,且光学厚度也大,故两地污染状况都比较严重。总体来说,中国中东部地区污染程度要高于印度次大陆地区。  相似文献   

5.
利用1979-2008年夏季(6—8月)逐日NCEP/NACR再分析资料、MODIS卫星的气溶胶资料等,研究了华东区域夏季行星边界层大气稳定度的气候特征与年际变化,分析了大气稳定度和相应的加热场与气溶胶光学厚度(aerosol optical depth,AOD)的联系。结果表明:华东区域夏季行星边界层大气稳定度在空间上分布不均匀,时间上具有明显的年际变化。边界层中的非绝热加热率、大气稳定度及气溶胶光学厚度三者之间可能存在密切联系。利用经验正交函数分析了华东区域总体理查森数Rib的距平场,得到了边界层稳定度分布的3个主要模态,这3个模态所代表的边界层大气稳定度异常与夏季风环流异常密切相关,特别是P-J型遥相关波列和西太平洋副热带高压在中国东部大气边界层稳定度变化中可能起着非常重要的作用。  相似文献   

6.
利用NCEP/NCAR再分析资料、CMAP降水及Hadley环流中心海温资料等,对东亚季风环流由夏向冬的季节转变与中国前冬气候的关系进行了研究。参考前人定义的亚太热力差指数,计算了1979-2016年亚太热力场由夏向冬的季节转变时间(平均为56. 6候)。结果表明,该季节转变时间点能很好地表征东亚季风环流由夏向冬的季节转变。东亚季风环流由夏向冬的转变特征表现为:低层大陆热低压转为大陆冷高压,阿留申低压形成加强,低空偏南风转为偏北风;中层东亚大槽形成,副高单体减弱成一个副热带高压带;高层南亚高压中心从青藏高原移至菲律宾以东洋面上,高空偏北风转为偏南风。此外由夏向冬的季节转变时间与中国前冬降水和地面气温有着紧密的联系,并且该转变时间的早晚与前期夏季热带太平洋的海温呈现类ENSO异常海温型的相关分布,即表现为前期夏季热带中东太平洋海温偏低(高)时,后期东亚夏季型季风环流向冬季型季风环流转变易偏晚(早),这对东亚季风环流季节转变的预测提供了依据。  相似文献   

7.
近年来华东地区大气气溶胶的时空特征   总被引:4,自引:1,他引:3  
利用2000年2月—2008年12月的AERONET(AErosol RObotic NETwork)地基观测数据对MODIS/TERRA Collection 005气溶胶光学厚度(aerosol optical thickness;AOT)在华东区域的适用性进行了验证,并利用验证后的MODIS气溶胶产品对华东区域气溶胶光学厚度和尺度分布特征进行了分析。结果表明,(1)通过验证比较,MODIS的AOT在华东区域与AERONET站陆基观测到的AOT具有非常好的一致性,满足美国NASA的设计要求。(2)华东区域的气溶胶光学厚度存在明显的时空分布特征。时间上,在春季和夏季达到最大,而在秋季和冬季最小,表现出明显的季节变化规律。空间上,气溶胶光学厚度受地形影响明显。其高值区主要分布在平原地区,而低值区主要在海拔较高的山区。(3)该区域的气溶胶尺度分布也存在显著的变化特征。在冬、春由于沙尘输送的影响,整个华东区域气溶胶粒子的尺度都比较大,主要以自然生成的沙尘粒子为主。而在夏、秋季由于夏季风和降水的影响,气溶胶粒子的尺度都比较小,以工业排放的人为气溶胶粒子为主。  相似文献   

8.
利用2000—2013年MODIS-Terra卫星产品提供的气溶胶光学厚度(aerosol optical depth,AOD)资料及NCEP/NCAR再分析资料集,使用奇异值分解(singular value decomposition,SVD)方法,分析了夏季东亚地区AOD与到达地面太阳辐射(downward solar radiation flux,DSRF)相联系的主要模态,并分析了其与夏季风变化的关系。夏季多年平均的AOD分布显示,在东亚地区存在两个AOD大值区(0.9),分别位于山东、河南、河北交界处附近以及苏中部分地区。而在福建、台湾及其附近洋面上,夏季AOD的值小于0.4。地面太阳辐射总体上呈现出由南往北递增的分布。比较发现,AOD与地面太阳辐射的气候分布较为相似。在保留季节趋势的情况下,运用SVD方法对两者进行分解,结果表明东亚地区AOD与地面太阳辐射表现出较好的正相关关系。由于相对于年际变化而言,季节趋势是更为主要的部分,因而这种同相关系可归因于季风活动的季节性进程。利用SVD1左场时间系数进行相关分析发现:6月(2013年除外),当中国东部气溶胶AOD大而地面太阳辐射亦大时,在中国东南部以及日本岛南部地区,由于气流辐合增强和存在较强的上升运动,降水偏多,而由于副高位置偏南,使得中国中东部偏北地区水汽供应偏弱,降水偏少。由于地面净太阳辐射增强,华北部分地区异常增暖。8月,大陆上空AOD为负(时间系数为负),地面太阳辐射减少,北方降水增多而南方降水减少,华北地区有一小范围的异常降温。上述结果表明北方气溶胶明显偏少时,云量增加,降水将增多,且辐射明显减弱;说明夏季风的季节进程对气溶胶、到达地面的太阳辐射变化等具有重要影响。  相似文献   

9.
气溶胶已是东亚地区最主要的大气污染物之一,其时空分布会受到东亚季风气候的影响.利用2000~2014年MODIS/AOD (Moderate-resolution Imaging Spectroradiometer/Aerosol Optical Depth)和NCEP月平均气象场再分析资料,本研究分析了东亚冬季风长期...  相似文献   

10.
利用2000年3月—2017年3月Terra卫星反演的MODIS气溶胶光学厚度(Aerosol Optical Depth,AOD)资料、NCEP的fnl全球业务分析数据、CMAP降水资料、CERES SYN1deg Ed 4月平均资料以及NCEP/NCAR再分析资料等,依据中国东部冬季区域平均AOD距平具有显著的年际变化特征,将历年冬季AOD划分为5个不同的污染等级,并探讨了不同污染等级的局地成因及其与冬季风环流的联系。结果表明,中国东部冬季AOD区域平均值与气候要素场有很好的相关关系,即AOD异常偏高(低)时,入射到地面的太阳短波辐射通量减小(增加),地面气温降低(增加),地气系统冷却(加热),地面降水呈现华北与江淮内陆少、江淮东南多(华北与江淮西南部多、江淮地区东部少)的分布特征。中国东部AOD值异常偏高与风速异常偏小有关,且这种负相关关系在华北表现最明显:即AOD异常偏高(低)时,华北地面风速偏小(大),江淮地面风速偏大(小)。个例分析表明,纬向风速异常偏小、东风异常及阿留申低压偏弱是2013年AOD异常偏高的主要原因。  相似文献   

11.
冬季赤道西太平洋环流状况与后期亚洲季风   总被引:4,自引:0,他引:4  
武炳义  黄荣辉 《大气科学》2001,25(5):609-626
基于月平均NCEP再分析资料(1958~1997年)以及中国336个台站月降水总量(195l~1994年),通过合成、相关以及统计显著性检验方法,研究了赤道西太平洋区域冬季环流状况与后期春夏季亚洲(东亚和南亚)季风环流变化的关系.研究结果表明,冬季赤道西太平洋环流状况对后期南亚季风和东亚季风以及我国夏季降水均有显著的滞后影响.冬季赤道西太平洋海域海平面气压偏高(低),对应反气旋(气旋)性环流异常,致使后期东亚和南亚夏季风均偏弱(强)以及我国长江流域夏季降水偏多(少),揭示了实施这种滞后影响的一般特征.  相似文献   

12.
The direct and semi-direct radiative effects of anthropogenic aerosols on the radiative transfer and cloud fields in the Western United States (WUS) according to seasonal aerosol optical depth (AOD) and regional climate are examined using a regional climate model (RCM) in conjunction with the aerosol fields from a GEOS-Chem chemical-transport model (CTM) simulation. The two radiative effects cannot be separated within the experimental design in this study, thus the combined direct- and semi-direct effects are called radiative effects hereafter. The CTM shows that the AOD associated with the anthropogenic aerosols is chiefly due to sulfates with minor contributions from black carbon (BC) and that the AOD of the anthropogenic aerosol varies according to local emissions and the seasonal low-level winds. The RCM-simulated anthropogenic aerosol radiative effects vary according to the characteristics of regional climate, in addition to the AOD. The effects on the top of the atmosphere (TOA) outgoing shortwave radiation (OSRT) range from ?0.2?Wm?2 to ?1?Wm?2. In Northwestern US (NWUS), the maximum and minimum impact of anthropogenic aerosols on OSRT occurs in summer and winter, respectively, following the seasonal AOD. In Arizona-New Mexico (AZNM), the effect of anthropogenic sulfates on OSRT shows a bimodal distribution with winter/summer minima and spring/fall maxima, while the effect of anthropogenic BC shows a single peak in summer. The anthropogenic aerosols affect surface insolation range from ?0.6?Wm?2 to ?2.4?Wm?2, with similar variations found for the effects on OSRT except that the radiative effects of anthropogenic BC over AZNM show a bimodal distribution with spring/fall maxima and summer/winter minima. The radiative effects of anthropogenic sulfates on TOA outgoing longwave radiation (OLR) and the surface downward longwave radiation (DLRS) are notable only in summer and are characterized by strong geographical contrasts; the summer OLR in NWUS (AZNM) is reduced (enhanced) by 0.52?Wm?2 (1.14?Wm?2). The anthropogenic sulfates enhance (reduce) summer DLRS by 0.2?Wm?2 (0.65?Wm?2) in NWUS (AZNM). The anthropogenic BC affect DLRS noticeably only in AZNM during summer. The anthropogenic aerosols affect the cloud water path (CWP) and the radiative transfer noticeably only in summer when convective clouds are dominant. Primarily shortwave-reflecting anthropogenic sulfates decrease and increase CWP in AZNM and NWUS, respectively, however, the shortwave-absorbing anthropogenic BC reduces CWP in both regions. Due to strong feedback via convective clouds, the radiative effects of anthropogenic aerosols on the summer radiation field are more closely correlated with the changes in CWP than the AOD. The radiative effect of the total anthropogenic aerosols is dominated by the anthropogenic sulfates that contribute more than 80% of the total AOD associated with the anthropogenic aerosols.  相似文献   

13.
利用NASA发布的MODIS/Terra中Collection6数据集的MOD04_3K气溶胶光学厚度(AOD)产品,进行波段提取、重投影、剪裁等预处理,得到郑州市气溶胶光学厚度资料,对此进行统计分析,研究郑州市气溶胶光学厚度的时空变化特征。结果表明:1)2001-2016年郑州市AOD年均值整体以每年0.0033的速率增加,最大峰值出现在2011年(1.01),以2011年为界,2001-2011年呈显著增长趋势,2012-2016年呈显著下降趋势。AOD季节均值夏季的最大,春季的次之,冬季的最小。2)2001-2016年郑州市AOD夏季均值波动较大,春季均值与年均值趋势基本一致,AOD年均值和季均值与对应时间尺度的降水量有负相关关系。工业产值占GDP比重与AOD年均值呈正相关关系。3)2001-2016年郑州市AOD年均值空间分布呈现北高南低、东高西低的特征,高值区主要分布在新郑市、中牟县、郑州市区、荥阳市及巩义市的西北部。春、夏和秋季的AOD均值空间分布形态基本与年均值的分布一致,冬季的高值区集中在郑州市东南部(新郑市)。  相似文献   

14.
It is well established that aerosols affect the climate in a variety of ways. In order to understand these effects, we require an insight into the properties of aerosols. In this paper we present a study of aerosol properties such as aerosol optical depth (AOD), single scattering albedo (SSA) and aerosol radiative forcing (ARF) over mega city of Lahore (Pakistan). The data from Aerosol Robotic Network (AERONET) have been used for the period December 2009 to October 2011. The seasonal average values of AOD, asymmetry parameter (ASY) and volume size distribution in coarse mode were observed to be highest in summer. On the other hand, the average values of Angstrom exponent (AE) and imaginary part of refractive index (RI) were found to be maximum in winter. The average value of real part of RI was found to be higher in spring than in all other seasons. The SSA exhibited an increasing trend with wavelength in the range 440 nm–1020 nm in spring, summer and fall indicating the dominance of coarse particles (usually dust). However, a decreasing trend was found in winter in the range 675 nm–1020 nm pointing towards the dominance of biomass and urban/industrial aerosols. As far as aerosol radiative forcing (ARF) is concerned, we have found that during the spring season ARF was lowest at the surface of Earth and highest at top of the atmosphere (TOA). This indicates that the atmosphere was warmer in spring than in all the remaining seasons.  相似文献   

15.
利用中分辨率光谱仪(MODIS)获得的气溶胶光学厚度(AOD)、细粒子比例(FMF)和臭氧检测仪(OMI)获得的气溶胶指数(AI)统计分析了2005—2014年我国华东地区气溶胶光学性质的时空分布特征,同时利用潜在源分析(PSCF)模型对我国华东地区AOD和AI的潜在源区进行分析。研究结果表明:华东地区的AOD、FMF和AI时空分布存在较大的差异,2005—2014年AOD和AI的平均值高值主要分布在华东地区北部,FMF的高值区则分布在华东南部地区;10 a间华东地区AOD呈现出先升高后降低的趋势,FMF波动幅度不明显,AI值有所上升;整个华东地区AOD的季节变化较为明显,春夏两季AOD明显高于秋冬两季。华东北部和中部地区夏季由于较高的相对湿度,AOD最大可达0.8以上。而在华东南部地区,夏季受到降水的影响,AOD维持在0.2~0.4之间。FMF季节变化趋势与AOD不同,夏季最大达到0.58,春季最小仅为0.26。AI平均值在冬季最大高达0.63,夏季最小,为0.27。PSCF分析显示华东地区AOD主要源区以局地排放为主,同时也存在由河南、湖北和湖南等周边省市近距离输送影响;AI以局地和北方远距离输送为主,同时也受到河南、湖北等周边省市近距离输送的影响。  相似文献   

16.
Long-term variations and trends of atmospheric aerosols in the East Asian region were analyzed by using aerosol optical depth (AOD or τ), and ångström exponent (AE or α) obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) from 2001 to 2010. The increased emission of anthropogenic fine aerosols in east China resulted in the high AOD in this region during summer. The steady increasing emission of anthropogenic fine aerosols caused an increasing trend of AOD in east China, and the large-scale transport of sandstorms and smoke plume caused by forest fires affected intense inter-annual variations of AOD in the East Asian region. While in the central part of South Korea, located in the lee side of the East Asian continent, AE tended to rise to a level higher than in east China, the ground-based mass concentrations continued to decline. A noticeable decrease of PM10 mass concentration in spring and winter in central Korea is most likely attributable to decreases in sandstorms in the source region of East Asia. However, the ratio of PM2.5 mass concentration to PM10 increases overall with a high level in summer. Aerosol types were classified into dust, smoke plume, and sulphate by using satellite data over Cheongwon in central Korea. The columnar AOD, with different aerosol types, was compared with the ground-based mass concentrations at Cheongwon, and the relatively high level of the correlations presented between PM2.5 and AOD produced in sulphate. Growth and increases of fine hygroscopic aerosols generated as gas-to-particle conversion particularly in summer contribute to increases of columnar AOD in the East Asian region.  相似文献   

17.
Based on the NCEP/NCAR reanalysis data,China station precipitation data from 1960 to 2008,and aerosol optical depth (AOD) data in northern China from 1980 to 2004,this paper investigates the variability of winter snow/rainfall in northern China and the associated atmospheric circulation and aerosol distribution characteristics by using composite analysis.The results show that winter precipitation in northern China has been generally increasing since the 1960s.Among the winters of 1990-2008,the years with more rain/snow (MRSYs) are 1998,2003,and 2006,while the years with less rain/snow (LRSYs) are 2005,1997,and 2001.Composite analysis finds that the main differences of atmospheric circulation in East Asia between MRSYs and LRSYs are as follows.1) In MRSYs,strong low-level cold air over the northern polar region and Taymyr Peninsula migrates southward to northern China (Northwest,North,and Northeast China),establishing a channel favoring continuous southward transport of cold air.In LRSYs,however,this cold air channel does not exist.2) In MRSYs,the frontal zone and westerlies are over North China,and the low-level geopotential height field from eastern China to West Pacific exhibits an "east high,west low" pattern,which is conducive to easterly and southerly airflows moving northward along 110 E.In LRSYs,the 500-hPa prevailing westerly winds stay far away from China and the low-level southeasterlies move to higher latitudes,which are disadvantageous to the development of precipitation in northern China.3) In MRSYs,large-scale upward motions combined with local-scale updrafts develop into strong slanted climbing airflows,forming a vertical circulation that favors the generation of heavy snows in eastern China.In LRSYs,the vertical circulation moves eastward into the Pacific Ocean.Furthermore,the correlation analysis on AOD and winter precipitation during the period 1980-2004 in northern China reveals that AOD differs significantly between MRSYs and LRSYs and the annual variation of winter rain/snow is positively correlated to the annual variation of AOD with a correlation coefficient of 0.415 at the 0.001 significance level.  相似文献   

18.
The NCEP/NCAR reanalysis, CMAP rainfall and Hadley Centre sea surface temperature (SST) datasets are used to investigate the relationship between the seasonal transition of East Asian monsoon and Asian-Pacific thermal contrast, together with the possible causes. Based on the 250 hPa air temperature over two selected key areas, the Asian-Pacific thermal difference (APTD) index is calculated. Results show that the APTD index is highly consistent with the Asian-Pacific Oscillation (APO) index defined by Zhao et al., in terms of different key areas in different seasons. Moreover, the time point of the seasonal transition of the Asian-Pacific thermal contrast can be well determined by the APTD index, indicative of seasonal variation in East Asian atmospheric circulation from winter to summer. The transition characteristic of the circulation can be summarized as follows. The continental cold high at lower tropospheric level moves eastward to the East China Sea and decreases rapidly in intensity, while the low-level northerlies turn to southerlies. At middle tropospheric level, the East Asia major trough is reduced and moves eastward. Furthermore, the subtropical high strengthens and appears near Philippines. The South Asia high shifts from the east of Philippines to the west of Indochina Peninsula, and the prevailing southerlies change into northerlies in upper troposphere. Meanwhile, both the westerly and easterly jets both jump to the north. The seasonal transition of atmospheric circulation is closely related to the thermal contrast, and the possible mechanism can be concluded as follows. Under the background of the APTD seasonal transition, the southerly wind appears firstly at lower troposphere, which triggers the ascending motion via changing vertical shear of meridional winds. The resultant latent heating accelerates the transition of heating pattern from winter to summer. The summer heating pattern can further promote the adjustment of circulation, which favors the formation and strengthening of the low-level southerly and upper-level northerly winds. As a result, the meridional circulation of the East Asian subtropical monsoon is established through a positive feedback between the circulation and thermal fields. Moreover, the time point of this seasonal transition has a significant positive correlation with the SST anomalies over the tropical central-eastern Pacific Ocean, providing a basis for the short-term climate prediction.  相似文献   

19.
青藏高原积雪与亚洲季风环流年代际变化的关系   总被引:12,自引:1,他引:12  
利用高原测站的月平均雪深资料和NCEP/NCAR再分析资料,分析了20世纪70年代末以来,青藏高原积雪的显著增多与亚洲季风环流转变的联系。研究表明,高原南侧冬春季西风的增强及西风扰动的活跃是造成青藏高原冬春积雪显著增多的主要原因,高原积雪的增多与亚洲夏季风的减弱均是亚洲季风环流转变的结果;20世纪70年代末以来,夏季华东降水的增多、华南降水的减少及华北的干旱化与青藏高原冬春积雪增多及东亚夏季风的减弱是基本同步的,高原冬春积雪与华东夏季降水的正相关、与华北及华南夏季降水的负相关主要是建立在年代际时间尺度上,因此,高原积雪与我国夏季降水关系的研究应以亚洲季风环流的年代际变化为背景。  相似文献   

20.
TBO的原因-异常东亚冬季风与ENSO循环的相互作用   总被引:21,自引:3,他引:21  
基于对 NCEP/ NCAR再分析资料以及其他资料(OLR,降水和气温等)的分析研究,结果表明东亚和西北太平洋地区的对流层环流和气候变化都有明显的准两年振荡(TBO)特征。同时,异常东亚冬季风可以影响次年夏季的大气环流和气候变化,特别是在东亚地区;而异常东亚冬季风和ENSO循环间又有明显相互作用:持续的强(弱)东亚冬季风通过海─气相互作用可以激发 El Ni o(La Ni a), El Ni o(La Ni a)反过来又可通过遥相关或遥响应而导致东亚冬季风偏弱(强)。强或弱的冬季风和ENSO循环是相互衔接在一起的,因此可以认为异常东亚冬季风与ENSO循环的相互作用是TBO对流层准两年振荡)的基本原因。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号