近10年东亚沙尘气溶胶辐射强迫与温度响应

利用一个耦合了在线沙尘模型的区域气候模式RegCM3,对2000-2009年东亚沙尘气溶胶辐射强迫及温度响应进行了数值模拟。结果表明：（1）东亚沙尘气溶胶分布具有明显的地理差异和季节差异,柱含量高值区主要位于塔克拉玛干沙漠和巴丹吉林沙漠,最大值均在1 000mg.m-2以上;从季节分布来看,春季最大,冬季次之,秋季最小...     

气候变化对东亚沙尘气溶胶影响的数值模拟

使用RegCM3-dust区域气候模式,单向嵌套MIROC3．2-hires全球模式输出结果,在IPCCA1B温室气体排放情景下,对中国及东亚地区进行了当代（1991年-2000年）和未来（2091年-2100年）水平分辨率为50km的气候以及沙尘气溶胶数值模拟试验。结果表明,模式对中国地区地面气温、降水和东亚沙尘气溶胶空间分布模拟较好。未来东亚沙尘气溶胶年平均起沙通量增加2％,其中12月-3月由于地表积雪量的减少而增加,4月-11月由于10m风速的减小而减少,不同强度的强起沙事件同样12月-3月增加,4月-11月减少。年平均沙尘气溶胶柱含量增加14％,其中3月-5月和8月略减少,其它月份增加。沙尘气溶胶引起地面（SRF）负辐射强迫和沙尘源区大气顶（TOA）正辐射强迫、下游地区TOA负辐射强迫,受沙尘气溶胶辐射强迫的影响,地面起沙通量和柱含量减少。     

中国地区春季沙尘气溶胶短波辐射气候效应数值模拟研究

利用耦合了起沙模型(MEDM)的区域气候模式RegCM3,模拟研究了2000年春季中国地区沙尘气溶胶短波辐射气候效应。结果表明,春季中国沙尘气溶胶垂直负荷的大值区主要位于南疆盆地和阿拉善高原。引入沙尘气溶胶后,中国地区地表均出现负的辐射强迫,地面气温普遍降低,中低层(400 hPa层以下)大气温度则呈上升趋势。沙尘源区及其下游地区总云量及降水主要呈减少趋势,云量与降水的分布特征与空中流场的变化趋势一致性较好。     

新疆和田市沙尘气溶胶浓度及粒径分布特征研究

沙尘气溶胶不仅影响天气和气候,而且对海洋生态及全球物质循环具有重要的作用.塔克拉玛干沙漠作为我国和东亚地区重要的沙尘气溶胶源区,其西南缘和田市沙尘气溶胶浓度及粒径分布特征尚不明确,将不利于该区域沙尘气溶胶远距离输送和沉降的机理研究.因此,本文利用粒子分级采样仪,通过对和田市不同天气(晴天、浮尘、扬沙天气)下沙尘气溶胶浓...     

基于静稳天气下气球探空实验的中国沙漠地区沙尘气溶胶的垂直分布（英文）

塔克拉玛干沙漠是亚洲沙尘气溶胶的重要源地。为探讨塔克拉玛干地区沙尘气溶胶的理化特性与时空变化,研究其环境与气候效应,本文分析了四个季节在中国敦煌(塔克拉玛干沙漠内)取得的探空气球观测数据,包括气溶胶的数浓度、粒径分布、质量浓度及在西风主导下的水平输送通量。气溶胶数浓度的垂直廓线显示,来自沙漠地区的矿物粒子对局地环境与气候有重要影响,且所有季节都存在长距离输送。粒子谱分布显示局地有大量粗粒子输入。结果说明,源于塔克拉玛干沙漠的沙尘气溶胶的背景输送有着重要的科学意义,需进一步研究其对东亚和西太平洋地区环境与气候的影响。     

塔克拉玛干沙漠与撒哈拉沙漠沙尘气溶胶光学特性对比研究

基于2007—2021年CALIPSO和MODIS主、被动卫星遥感探测数据,对塔克拉玛干沙漠和撒哈拉沙漠的气溶胶光学特性时空分布特征进行探究及对比分析。结果表明：（1）两大沙漠的沙尘气溶胶对总气溶胶的贡献率最大,气溶胶类型季节变化的相对单一性反映了塔克拉玛干沙漠和撒哈拉沙漠地区存在沙漠沙尘排放对总气溶胶成分的显著影响;（2）塔克拉玛干沙漠气溶胶光学厚度AOD的峰值出现在春季（春季>夏季>秋季>冬季）,而撒哈拉沙漠AOD的峰值出现在夏季（夏季>春季>秋季>冬季）;（3）撒哈拉沙漠总气溶胶抬升高度与塔克拉玛干沙漠相近,但近地面层消光系数明显小于塔克拉玛干沙漠;塔克拉玛干沙漠的消光系数平均值在所有季节中均大于撒哈拉沙漠,故塔克拉玛干沙漠的沙尘气溶胶AOD比撒哈拉沙漠的大;相比沙漠沙尘气溶胶,塔克拉玛干沙漠和撒哈拉沙漠都无明显的污染沙尘和抬升烟活动。上述研究结果揭示了两大沙漠源区沙尘气溶胶光学特性的观测事实与利用大气气溶胶时空变化特征反映区域气候变化的可能性。     

WRF/Chem模式中两种起沙参数化方案对东亚地区一次强沙尘暴过程模拟的影响

利用耦合了GOCART和Shao04两种起沙参数化方案的WRF/Chem模式对2002年3月19~22日发生在东亚地区的强沙尘暴过程进行模拟,着重考察了不同起沙方案对沙尘暴过程模拟的影响。结果表明,耦合了两种不同方案的WRF/Chem总体上均能较合理地模拟出主要的起沙区域、起沙强度的变化以及沙尘浓度的时空演变特征,模式对沙尘源地附近及下游地区地面沙尘浓度时间变化特征的模拟与站点观测结果也十分接近。但总体说来Shao04方案对沙尘起沙的发生以及强度变化过程具有更好的模拟能力,该方案模拟的沙尘浓度与观测更为一致,整体性能要优于GOCART方案。进一步分析发现,由于GOCART方案中采用的临界起沙风速偏小,导致该方案下模拟的沙尘分布范围偏大;另外该方案忽略了蒙古东南部和内蒙古中东部的潜在沙尘源地,从而使得耦合了GOCART方案的模式未能模拟出上述区域的起沙过程,使得该区域及下游地区模拟的沙尘浓度也偏小。但在塔里木盆地,Shao04方案计算的起沙通量偏小,这可能与Shao04方案未能考虑风速较小情况下空气拖曳力夹卷作用对起沙的影响有关,也可能与该方案中采用的土壤质地数据不准确有关。     

东亚地区人为气溶胶直接辐射强迫及其气候效应的数值模拟

利用耦合化学过程的区域气候模式RegCM3,模拟研究3种主要人为排放气溶胶(硫酸盐、黑碳、有机碳)对东亚区域气候的影响.计算分析近20 a来3种气溶胶的时空分布、综合辐射强迫作用及其对地面气温和降水的影响.模拟结果表明:3种气溶胶冬夏季分布有所不同,冬季气溶胶大值区主要分布在南方地区,而夏季大值区北移;气溶胶短波辐射强迫在大气层顶和地面均为负值;气溶胶的加入对东亚地区地表气温有明显影响,冬季降温中心位于四川盆地,夏季降温大值区位于华北地区.气溶胶直接气候效应使得冬季东亚大部分地区降水减少,夏季东亚地区降水与中国南方地区夏季气溶胶浓度有较好的相关关系,中国东部雨带有南移趋势.     

CAM5模式中两气溶胶模块的评估

公共大气模式 (CAM) 被广泛用于气候变化研究中,其5.0版中包含两个气溶胶模块MAM3和MOZART。利用AeroCom (2000年) 多模式中值、IMPROVE (1988—2005年) 和EMEP (2002—2008年) 站点资料对两模块进行了评估。结果表明:MAM3和MOZART模块都能很好地模拟硫酸盐气溶胶的季节变化, 与观测资料相比,模拟结果均在夏季偏高, 相关系数均在0.89左右,2倍误差内。两模块能较好地模拟黑碳气溶胶的时空分布特征, 与观测资料相比,模拟结果偏低,相关系数均在0.62左右, 排放源偏小而清除率偏大是造成黑碳气溶胶偏低的主要原因。两模块对有机碳气溶胶的模拟结果差别较大,大部分站点在3倍误差内,MAM3的结果偏高92.1%,MOZART则偏低58.1%;两模块一次有机碳的结果接近,差异主要源自对二次有机碳的模拟。两模块模拟的海盐气溶胶偏大,这主要是清除率偏小造成的。两模块采用相同的起沙机制,但起沙系数有差异, MAM3的沙尘源强偏大近两倍,模拟总量较大;MOZART的沙尘源强则偏低40%左右,模拟沙尘总量较低。即模式中气溶胶的输送和扩散过程偏弱,说明清除机制还有待改进。     

塔克拉玛干沙漠腹地风蚀起沙特征观测研究

利用塔克拉玛干沙漠腹地塔中气象站2009-2018年的地面观测资料,细致解析塔中地区的风蚀起沙特征,所得结论如下：(1) 临界起沙风速表现出明显的季节变化特征,夏季＞春季＞秋季＞冬季, 塔中地区的临界起沙风速介于4.47-4.92 m/s,日最大值出现09:00-10:00时。(2) 春夏季是沙尘的多发季节。春、夏季,沙尘水平通量的平均值分别为2638.9 kg/m和3298.9 kg/m,起沙持续时间的平均值分别为291.5 h和336.7 h。(3) 风蚀起沙事件更容易发生在白天, 沙尘水平通的最大值出现在10:00-11:00,起沙持续时间的最大值出现在10:00-13:00。(4)风蚀起沙事件在春季主要集中在偏东方向,在夏季主要集中在偏北方向上。     

Comparative inverse analysis of satellite (MODIS) and ground (PM10) observations to estimate dust emissions in East Asia

Soil dust aerosol is the largest contributor to aerosol mass concentrations in the troposphere and has considerable effects on air quality and climate. Arid and semi-arid areas of East Asia are one of the important dust source regions thus it is crucial to understand dust mobilization and accurately estimate dust emissions in East Asia. However, present dust models still contain large uncertainties with dust emissions that remain a significant contributor to the overall uncertainties in the model. In this study, we attempt to reduce these uncertainties by using an inverse modeling technique and obtain optimized dust emissions. We use Moderate Resolution Imaging Spectrometer (MODIS) aerosol optical depths (AODs) and groundbased mass concentrations of particles less than 10 μm in aerodynamic diameter (PM₁₀) observations over East Asia in May 2007. The MODIS AODs are validated with AErosol RObotic NETwork (AERONET) AODs. The inversion uses the maximum a posteriori method and the GEOS-Chem chemical transport model (CTM) as a forward model. The model error is large over dust source regions including the Gobi Desert and Mongolia. We find that inverse modeling analyses from the MODIS and PM₁₀ observations consistently result in decrease of dust emissions over Mongolia and the Gobi Desert. Whereas over the Taklamakan Desert and Manchuria, the inverse modeling analyses from both observations yield contrast results such as increase of dust sources using MODIS AODs, while decrease of those using PM₁₀ observations. We discuss some limitations of both observations to obtain the optimized dust emissions and suggest several strategies for the improvement of dust emission estimates in the model.     

新疆不同降水观测资料的比较及其差异的可能原因

利用新疆地区89个气象站和38个水文站1961~2005年的降水资料,对比分析了这两类降水观测资料在表征新疆地区降水的时间演变特征上所存在的差异,进而探究了造成这种差异的原因,并在此基础上研究了增暖背景下新疆地区降水与地形(包括海拔高度、坡度和坡向)的关系。研究发现:1)从区域平均来看,水文站观测的年降水量(221.4 mm)明显高于气象站的观测值(152.1 mm),其差值为69.3 mm,但是二者具有相同的时空变化特征;2)气象站与水文站降水均值之间的差异,主要受海拔高度的影响,坡度和坡向的影响次之。新疆地区地形地貌复杂,降水时空变化较大,观测数据分布不均匀均可导致对降水的估算存在较大差异,因此多源降水数据相互融合是客观估算该地区降水量及其变化的一个途径。     

Assessment of Individual Direct Radiative Effects of Major Aerosol Species in East Asia

To assess individual direct radiative effects of diverse aerosol species on a regional scale,the air quality modeling system RAMS-CMAQ(Regional Atmospheric Modeling System and Community Multiscale Air Quality) coupled with an aerosol optical properties/radiative transfer module was used to simulate the temporal and spatial distributions of their optical and radiative properties over East Asia throughout 2005.Annual and seasonal averaged aerosol direct radiative forcing(ADRF) of all important aerosols and individual components,such as sulfate,nitrate,ammonium,black carbon(BC),organic carbon(OC),and dust at top-of-atmosphere(TOA) in clear sky are analyzed.Analysis of the model results shows that the annual average ADRF of all important aerosols was in the range of 0 to-18 W m?2,with the maximum values mainly distributed over the Sichuan Basin.The direct radiative effects of sulfate,nitrate,and ammonium make up most of the total ADRF in East Asia,being concentrated mainly over North and Southeast China.The model domain is also divided into seven regions based on different administrative regions or countries to investigate detailed information about regional ADRF variations over East Asia.The model results show that the ADRFs of sulfate,ammonium,BC,and OC were stronger in summer and weaker in winter over most regions of East Asia,except over Southeast Asia.The seasonal variation in the ADRF of nitrate exhibited the opposite trend.A strong ADRF of dust mainly appeared in spring over Northwest China and Mongolia.     

A Modeling Study of Seasonal Variation of Atmospheric Aerosols over East Asia

In this study, a regional air quality model system (RAQMS) was applied to investigate the spatial distributions and seasonal variations of atmospheric aerosols in 2006 over East Asia. Model validations demonstrated that RAQMS was able to reproduce the evolution processes of aerosol components reasonably well. Ground-level PM₁₀ (particles with aerodynamic diameter ≤10 μm) concentrations were highest in spring and lowest in summer and were characterized by three maximum centers: the Taklimakan Desert (～1000 μg m^-3), the Gobi Desert (～400 μg m^-3), and the Huabei Plain (～300 μm^-3) of China. Vertically, high PM₁₀ concentrations ranging from 100 μg m^-3 to 250 μg m^-3 occurred from the surface to an altitude of 6000 m at 30^o--45^oN in spring. In winter, the vertical gradient was so large that most aerosols were restricted in the boundary layer. Both sulfate and ammonium reached their highest concentrations in autumn, while nitrate reached its maximum level in winter. Black carbon and organic carbon aerosol concentrations reached maximums in winter. Soil dust were strongest in spring, whereas sea salt exerted the strongest influence on the coastal regions of eastern China in summer. The estimated burden of anthropogenic aerosols was largest in winter (1621 Gg) and smallest in summer (1040 Gg). The sulfate burden accounted for ～42% of the total anthropogenic aerosol burden. The dust burden was about twice the anthropogenic aerosol burden, implying the potentially important impacts of the natural aerosols on air quality and climate over East Asia.     

A global satellite view of the seasonal distribution of mineral dust and its correlation with atmospheric circulation

Aerosols make a considerable contribution to the climate system through their radiative and cloud condensation nuclei effects, which underlines the need for understanding the origin of aerosols and their transport pathways. Seasonal distribution of mineral dust around the globe and its correlation with atmospheric circulation is investigated using satellite data, and meteorological data from ECMWF. The most important sources of dust are located in North Africa, the Middle East and Southwest Asia with an observed summer maximum, and East Asia with a spring peak. Maximum dust activity over North Africa and the Middle East in summer is attributed to dry convection associated with the summertime low-pressure system, while unstable weather and dry conditions are responsible for the spring peak in dust emission in East Asia. Intercontinental transport of mineral dust by atmospheric circulation has been observed, including trans-Atlantic transport of North African dust, trans-Pacific transport of Asian dust, and transport of dust from the Middle East across the Indian Ocean. The extent of African dust over the Atlantic Ocean and its latitudinal variation with season is related to the large-scale atmospheric circulation, including seasonal changes in the position of the intertropical convergence zone (ITCZ) and variation of wind patterns. North African aerosols extend over longer distances across the North Atlantic in summer because of greater dust emission, an intensified easterly low level jet (LLJ) and strengthening of the Azores-Bermuda anticyclonic circulation. Transport of East Asian aerosol is facilitated by the existence of a LLJ that extends from East Asia to the west coast of North America.     

CAUSATION ANALYSIS OF THE DIRECT CLIMATE EFFECTS OF ANTHROPOGENIC AEROSOL ON EAST-ASIAN SUMMER MONSOON

A regional climate model coupled with an aerosol model is employed to numerically simulate the direct climate effects of the anthropogenic aerosol emitted in South Asia and China in the East Asian summer monsoon during 1988 to 2009. Based on the data of the numerical simulation, composite analysis and correlation analysis are used to make diagnostic study of climate dynamics. Results show that the month of maximum emission of the mean column burden of the anthropogenic aerosol in the main emission areas of South Asia is opposite in phase to that in China. Summer is the season of maximum emission amount in China, but the emission amounts are more in South Asia in spring and winter. On the whole, the mean column burden of the anthropogenic aerosol in China is relatively high compared with that in South Asia. The trend of distribution of aerosol is SW-NE in China, and Sichuan Basin is the emission center of aerosol. The effect of negative short wave radiative forcing alters the gradient of pressure between land and sea, weakening the development of East Asian summer monsoon over the northern part of Yangtze-Huaihe River Basin. We also discuss the feedback effect of East-Asian summer monsoon which is changed by the anthropogenic aerosol on the concentration and distribution of aerosol in China.     

Direct Radiative Forcing and Climatic Effects of Aerosols over East Asia by RegCM3

The authors used a high-resolution regional climate model(RegCM3) coupled with a chemistry/aerosol module to simulate East Asian climate in 2006 and to test the climatic impacts of aerosols on regionalscale climate.The direct radiative forcing and climatic effects of aerosols(dust,sulfate,black carbon,and organic carbon) were discussed.The results indicated that aerosols generally produced negative radiative forcing at the top-of-the-atmosphere(TOA) over most areas of East Asia.The radiative forcing induced by aerosols exhibited significant seasonal and regional variations,with the strongest forcing occurring in summer.The aerosol feedbacks on surface air temperature and precipitation were clear.Surface cooling dominated features over the East Asian continental areas,which varied in the approximate range of-0.5 to-2°C with the maximum up to-3-C in summer over the deserts of West China.The aerosols induced complicated variations of precipitation.Except in summer,the rainfall generally varied in the range of-1 to 1 mm d-1 over most areas of China.     

Direct shortwave radiative forcing of the Asian dust aerosol on dust emission

The physical processes of the feedback mechanism of direct shortwave radiative forcing of the Asian dust aerosol on dust emission has been examined using simulated results with the coupled (with dust shortwave radiative forcing) and the non-coupled model (without dust shortwave radiative forcing) based on the MM5 model and the Asian Dust Aerosol Model on 19 March 2002. The results indicate that a significant dust emission reduction occurs in the high dust concentration (HDC) region of the dust source region whereas an enhanced dust emission appears in the downstream of the dust source region. It is found that Asian dust aerosols raised during the daytime by the strong surface wind cause negative shortwave radiative flux near the surface, which in turn reduces the sensible heat flux causing the cooling of the air, thereby enhancing stable stratification. The dynamic adjustment of the negative radiative flux of the dust induces a positive pressure anomaly over the HDC region and a negative pressure anomaly toward the synoptic low pressure center, resulting in a dipole shape of pressure anomaly field near the surface. The associated secondary circulation of this pressure anomaly together with the reduction of turbulent intensity due to the reduced sensible heat flux reduces the low-level wind speed thereby reducing dust emission in the upstream of the HDC region of the dust source region (Region I), while enhancing the low-level wind speed in the downstream region (Region II), which in turn enhances dust emission. This enhanced dust emission is smaller than the emission reduction in the upstream, resulting in overall dust emission reduction during the daytime.     

一次快速发展气旋导致的沙尘暴天气过程的初步分析

文章概述了我国北方地区春季沙尘天气的特征,并对影响沙尘暴的天气气候背景、单站地面气象要素、环流形势、冷空气的强度及影响路径、沙尘暴的起沙源地、影响时间和范围等进行了分析。结果表明:此过程是蒙古气旋强烈发展所致。巴丹吉林沙漠和浑善达克沙地是沙尘暴的主要沙尘源区;蒙古气旋的爆发性发展和冷锋后大风是起沙的主要动力;在高空急流出口区左侧,气流辐散强迫形成干对流上升气流,该上升气流与湍流输送是沙尘向高空输送的动力机制。