The simulation of aerosol transport over East Asia region

This study was carried out to understand the contribution of PM10 from China emission to Seoul Metropolitan Area (SMA) during high concentration period in January, 2007. The hourly PM10 concentration in Seoul Metropolitan Area had reached up to over 150 μg/m³ on 17th and 23rd of January in 2007. The aerosol transports from China along the Northwestern wind becomes the background concentrations in Korea and the assessment of the amount of contribution from China is very important in managing the air quality improvement plan in SMA.The U.S. EPA's Models-3/CMAQ (Community Multiscale Air Quality) was used to simulate PM10 concentration. The CMAQ performance was evaluated by comparing with the measurements in SMA for the episode period. The predictions were relatively in a good agreement with the measurements.The results show that the PM10 transport from China to Korea is significant and its contribution reaches up to 80% in the episode period. In order to assess more extensively the aerosol transport in East Asia region, the study to run the model in full year with speciated PM component measurements in super site is underway.     

Impact of Long-range Desert Dust Transport on Hydrometeor Formation over Coastal East Asia

Model simulations and hydrological reanalysis data for 2007 are applied to investigate the impact of long-range desert dust transport on hydrometeor formation over coastal East Asia.Results are analyzed from Hong Kong and Shanghai,which are two representative coastal cities of East Asia.Long-range desert dust transport impacts mainly spring and summer clouds and precipitation over coastal East Asia.In spring,clouds and precipitation come mainly from large-scale condensation and are impacted mainly by dust from the Gobi,Sahara,and Thar deserts.These desert dusts can participate in the precipitation within and below the clouds.At lower latitudes,the dust particles act mainly as water nuclei.At higher latitudes,they act as both water nuclei and ice nuclei.The effect of Gobi,Sahara,and Thar dust on large-scale clouds and precipitation becomes stronger at higher latitudes.In summer,clouds and precipitation over coastal East Asia come mainly from convection and are impacted mainly by dust from the Taklamakan,Arabian,and Karakum-Kavir deserts.Most Taklamakan dust particles can participate in precipitation within convective clouds as ice nuclei,while Arabian and Karakum-Kavir dust particles participate only as water nuclei in precipitation below the clouds.The effect of Taklamakan dust on convective clouds and precipitation becomes stronger at lower latitudes.Of all the desert dusts,that from the Gobi and Taklamakan deserts has the relatively largest impact.Gobi dust impacts climate change in coastal East Asia by affecting spring water clouds at higher latitudes.     

TRACE-P期间硫酸盐、硝酸盐和铵盐气溶胶的模拟研究

结合最新评估的东亚地区 1°× 1°污染源资料 ,利用由区域大气模式系统 (RAMS)和区域大气质量模式系统 (CMAQ)耦合的空气质量模式系统 ,对东亚地区 2 0 0 1年春季气溶胶的输送及其化学转化过程进行了研究。为了检验模式系统的模拟效果 ,我们将模拟的硫酸盐、硝酸盐和铵盐气溶胶的浓度与TRACE -P观测期间获取的观测值进行了比较。比较结果显示 ,模拟值与观测值具有相当好的一致性 ,模式很好地反映了气溶胶浓度的分布特征和变化规律 ,再现了许多观测到的重要特征。模拟结果表明 ,中国区域硫酸盐气溶胶浓度高值主要是人为排放的二氧化硫造成的 ,10 0°E以东的中国广大地区的硫酸盐气溶胶柱含量超过了 6mg·m- 2 ,最高值达到 2 4mg·m- 2 ,柱含量 >16mg·m- 2 的区域延伸到中国近海的广大海域。东亚地区的人类活动不仅使污染地区气溶胶柱含量显著增加 ,而且使近海无源区的广大海域的污染加重。本模式系统的建立为今后进一步研究区域大气污染物的变化机理提供了有效的手段。     

Model analysis of seasonal variations in tropospheric ozone and carbon monoxide over East Asia

Temporal-spatial variations in tropospheric ozone concentrations over East Asia in the period from 1 January 2000 to 31 December 2004 were simulated by using the Models-3 Community Multi-scale Air Quality (CMAQ) modeling system with meteorological fields calculated by the Regional Atmospheric Modeling System (RAMS). The simulated concentrations of ozone and carbon monoxide were compared with ground level observations at two remote sites, Ryori (39.03°N, 141.82°E) and Yonagunijima (24.47°N, 123.02°E). The co...     

2010年秋季鞍山气溶胶光学特征变化

利用2010年9-11月鞍山大气成分监测站CE-318太阳光度计观测资料,依据气溶胶光学厚度测量原理,计算得到2010年鞍山秋季大气气溶胶光学厚度、波长指数等大气光学特性数据,通过统计分析,给出鞍山秋季气溶胶光学特性分布特征。结果表明：随着测量AOD波段的降低,AOD值逐渐增大,9月的AOD平均值最大,10月AOD平均值次之,11月AOD平均值最小。从频率分布看,2010年9月 AOD日均值集中分布在0.4-0.6之间,10月和11月AOD日均值集中分布在0.0-0.4之间,表明10-11月大气较为清洁|波长指数日均值的频率分布说明鞍山秋季大气污染物以细粒子为主。500 nm 的AOD值与波长指数成对数关系,两者在9、10月和11月的相关系数分别为0.5145、0.8412和0.2715;9月AOD与PM₁₀、PM_2.5、PM_1.0质量浓度为较小负相关,10月和11月AOD与PM₁₀、PM_2.5、PM_1.0质量浓度成正相关,且10、11月AOD与气溶胶细粒子相关性较为显著。AOD值与能见度在趋势上呈较小的负相关性,可能是由于高层气溶胶粒子对气溶胶光学厚度产生了主要影响。     

A Three-Dimensional Simulation of HO x Concentrations Over East Asia During TRACE-P

The Models-3 Community Multi-scale Air Quality modeling system (CMAQ) coupled with the Regional Atmospheric Modeling System (RAMS) is used to simulate three-dimensional concentration distributions of hydroxyl (OH) and hydroperoxyl (HO₂) radicals over the western Pacific Ocean during the NASA Transport and Chemical Evolution over the Pacific (TRACE-P) field campaign. Modeled values of OH and HO₂ and their closely related chemical species and photolysis rates are compared with observational data collected onboard the DC-8 aircraft. Comparison shows that the model reasonably reproduced these observed values over a broad range of conditions with an overall tendency to overestimate the measured OH and HO₂ by a factor of 1.56 and 1.24, respectively. A case study of OH, HO₂ and their closely related chemical species and photolysis rates along the DC-8 flights 11 and 12 conducted on 17–18 March 2001 shows that the model reproduces the temporal and spatial variations reasonable well, and produces more reliable OH and HO₂ concentrations in the polluted environment than in the clean marine boundary layer.     

未来东亚地区硫化物沉降及输送的预测

采用东亚未来二氧化硫排放量的预测资料,利用东亚硫化物输送模式拟了未来１５年东亚各地区的硫化物沉降量、相互输送量的变化趋势力其对土壤的影响。结果表明,未来１５年东亚各地区的硫化物沉降量将日益增多,一些地区硫化物沉降量大大超出了土壤对酸沉降的承受能力,对周边地区硫化物的输送量也将进一步加大,形势相当严峻。     

我国和东亚地区硫化物跨边界输送态势研究

本文利用污染物三维欧拉长距离输送实用模式,较详细地模拟了我国和东亚地区硫化物跨地区、跨边界输送态势,分析了东亚地区硫化物输送通量随高度、季节变化的分布特点,讨论了不同地区边界上硫化物的跨边界输送通量及流的收支平衡,并给出了我国和周边国家和地区之间硫化物的相互输送量。结果表明,我国向外输送的硫化物占周边国家和地区总硫沉降的比例并不大,各地区硫沉降的主要来源是自身排放;硫化物长距离输送中硫酸根的输送占重要地位,各地区硫酸根沉降中的外来比例较大。我们初步总结出一个东亚地区硫化物输送的概念模式：在低层,夏季主要自西南向东北输送,冬季长江以北自北向南输送,长江以南由西南向北输送,并在长江中下游地区形成一个较强的硫化物辐合带,在高层,无论冬夏均由西向东输送,并随高空带变化,中层为二者的过渡,春秋季的情形界于冬夏之间,偏向冬季。     

冬季东亚大槽异常与El Nino的关系

通过对东亚大槽强度与El Nino事件的统计分析,揭露了在多数El Nino（反El Nino）事件的前期冬季,东亚大槽强度偏弱（偏强）的事实。对10个El Nino事件的合成分析亦表明,El Nino前冬季东亚西太平洋中高纬地区500 hPa为显著的高度正距平。谱分析进一步指出,冬季东亚大槽强度与赤道东太平洋各季SST有密切的关系,它们都具有显著的3—4年周期振荡,且槽强度的变化超前于SST约4—8个月。     

江淮梅雨期降水异常分布型及其与东亚副热带高空西风急流的关系

利用1980—2010年的NCEP/NCAR再分析资料与江淮地区44个站逐日降水资料,分析了江淮地区1980—2010年梅雨期(6月16日—7月15日)降水的基本空间分布型及其与东亚副热带西风急流的关系。结果表明,江淮梅雨降水的第一分布型为"南正(负)北负(正)",该型受副热带高空西风急流位置的影响,急流位置偏南(北),则雨带位于江淮南(北)部地区;第二分布型为"中间负(正),两边正(负)",该型受副热带高空西风急流强度的影响,急流强度异常偏弱(强),则雨带位于江淮地区西北、东南部(中部)。合成分析表明,高空急流位置异常偏南时,500 h Pa副高偏弱、偏南,850 h Pa江淮南部地区为水汽、风场辐合区,高低空配置有利于降水呈"南正北负"的分布型。高空急流强度异常偏弱时,从我国江淮中东部地区至日本南部,500 h Pa上无明显垂直运动,850 h Pa上有水汽和风场的辐散区,高低空配置有利于降水呈"中间负,两边正"的分布型。     

Simulation of Tropospheric Ozone with MOZART-2： An Evaluation Study over East Asia

Climate changes induced by human activities have attracted a great amount of attention. With this, a coupling system of an atmospheric chemistry model and a climate model is greatly needed in China for better understanding the interaction between atmospheric chemical components and the climate. As the first step to realize this coupling goal, the three-dimensional global atmospheric chemistry transport model MOZART-2 (the global Model of Ozone and Related Chemical Tracers, version 2) coupled with CAM2 (the Community Atmosphere Model, version 2) is set up and the model results are compared against observations obtained in East Asia in order to evaluate the model performance. Comparison of simulated ozone mixing ratios with ground level observations at Minamitorishima and Ryori and with ozonesonde data at Naha and Tateno in Japan shows that the observed ozone concentrations can be reproduced reasonably well at Minamitorishima but they tend to be slightly overestimated in winter and autumn while underestimated a little in summer at Ryori. The model also captures the general features of surface CO seasonal variations quite well, while it underestimates CO levels at both Minamitorishima and Ryori. The underestimation is primarily associated with the emission inventory adopted in this study. Compared with the ozonesonde data, the simulated vertical gradient and magnitude of ozone can be reasonably well simulated with a little overestimation in winter, especially in the upper troposphere. The model also generally captures the seasonal, latitudinal and altitudinal variations in ozone concentration. Analysis indicates that the underestimation of tropopause height in February contributes to the overestimation of winter ozone in the upper and middle troposphere at Tateno.     

不同分辨率BCC_AGCM模式对东亚区域垂直云量的模拟

基于ISCCP(International Satellite Cloud Climatology Project)和NCEP(National Centers for Environmental Prediction)资料分析了BCC_AGCM2.1(Beijing Climate Center_Atmospheric General Circulation Model 2.1)和BCC_AGCM2.2模拟的云在东亚的垂直分布特点,并探讨了误差来源。两个模式大体上模拟出了总云量的分布形势,较好地模拟出了垂直方向上云量大值带随地形的变化特点,但模拟的总云量偏少。AGCM2.2模拟的云量整体上小于AGCM2.1,除复杂地形外AGCM2.2没有体现出高分辨率的优势。模式对中国东部环流场的模拟效果差导致模拟的云量偏少,尤其是AGCM2.2。模拟的对流层高层相对湿度明显偏大导致高层云量偏大。模式在近海面模拟的相对湿度偏小,四川盆地及周围地区冷季模拟的水汽含量偏少,因而模拟的云量偏少。模式云量对相对湿度的响应能力较好,模拟出了云量对垂直速度和稳定度的响应,但地区差异不明显。模式的云参数化方案中云与相对湿度的关系系数需要调整,应更利于云的生成。     

东亚沙尘源区与下游地区气溶胶光学特性比较

利用AERONET观测资料从气候学的角度比较分析了2001-2011年东亚地区沙尘天气发生时沙尘源区和下游区大气气溶胶光学特性。结果表明：沙尘期间沙尘源区气溶胶光学厚度明显大于下游区,而Angstr?m波长指数却小于下游区,当沙尘暴出现时会降至零甚至负值。气溶胶粒子尺度体积谱分布除敦煌为单峰外,其余各站均呈双峰分布,香河和北京的细粒子浓度明显大于西北地区,这可能是由细的沙尘粒子和污染气溶胶共同造成。在440-1020 nm范围内,中国地区气溶胶单次散射反照率平均值为0.93,韩国和日本站分别为0.93和0.94。沙尘源区与下游区相比,复折射指数实部偏大,虚部偏小。总体来说,沙尘天气下东亚地区在4个波段内平均不对称因子为0.70。     

WRF模式不同云微物理参数化方案对东亚夏季风模拟影响的研究

利用WRF v3.2.1模式,采用其中5种云微物理参数化方案对2007—2011年的东亚夏季风气候进行了模拟研究,结果显示:5种方案均能较好地模拟出我国东部地区夏季降水的基本分布,但各方案对降水中心强度及其分布的模拟仍然存在明显的差异,总体来看,WDM6方案模拟的东亚夏季降水强度明显比其他4种方案大,而Morrison方案对降水的模拟总体效果好于其他4种方案。从云微物理角度来看,5种云微物理参数化方案均能比较合理地描述云水、雨水及冰相粒子的空间分布状态。其中,WSM3方案计算的云水、雨水质量混合比明显比其它方案大,WDM6方案计算的云水质量混合比则较小,而Morrison方案计算的雨水质量混合比较小,再者该方案冷云中霰粒子浓度偏小,因而Morrison方案在粤闽两省的夏季日降水量模拟比其他方案小,从而与TRMM观测结果更为接近。采用5种云微物理参数化方案均能较好地模拟出春、夏季西太平洋副高、雨带和大气水凝物在东亚地区的季节进退过程。5种方案模拟的雨水粒子浓度分布和中纬度雨带在南北进退过程中的位置较为吻合,两者均跟随西太平洋副高北进、南退。对于中低纬度存在的大降水中心来说,其位置少动,并且与该地区存在的的冰晶、雪晶粒子的高值中心具有较好的对应关系,说明在中低纬度地区,与热带对流相伴随的较高层次的冰相粒子数的浓度是决定降水强弱的关键因素。     

21个气候模式对东亚夏季环流模拟的评估II:年际变化

利用欧洲中期天气预报中心的ERA40再分析资料, 评估了参与政府间气候变化专门委员会第四次评估报告的21个全球海气耦合模式对东亚地区夏季大气环流年际变率的模拟能力,结果表明：（1）模式对东亚地区不同要素的年际变率模拟能力整体偏弱, 500 hPa高度场的模拟能力总体优于海平面气压场及850 hPa风场;（2）两大环流系统年际变率的模拟结果评估表明：就相关系数而言,副高强度、面积的模拟能力优于印度低压,多数模式能正确模拟出副高1970s后期增强的趋势;就标准差来看,模式对印度低压、印度低压东伸槽模拟效果相对较好;（3）评估三种季风指数的模拟能力结果显示,环流异常指数模拟效果略好,但多数模式都不能模拟出海陆气压差、经向风、环流异常季风指数的年际变化。     

区域气候模式在东亚地区的应用研究——垂直分辨率与侧边界对夏季季风降水影响研究

将美国国家大气研究中心（NCAR）的区域气候模式（RegCM2-1996）设置在东亚-西太平洋区域（简称东亚区域气候模式RegCM2/EA）。利用该模式研究东亚区域气候模式的几个重要问题，即：垂直分辨率的影响，侧边界条件（如嵌套技术、缓冲区宽度、不同资料）的重要性等。数值试验结果表明：细垂直分辨率模拟的降水分布优于粗分辨率模式，但容易引起“数值点暴雨”；RegCM2/EA与不同来源的大尺度侧边界嵌套，模拟的降水会有明显的不同；当用RegCM2/EA模拟较大区域时，应该取较宽的缓冲区；在各种嵌套方案中，指数松弛嵌套方法最好。这些结果为进一步探讨东亚区域气候模式的特点以及发展与改造区域气候模式提供一定的依据。研究结果还需要用更多的数值试验来验证。     

Sulfur distribution and transport studies in East Asia using eulerian model

A three-dimensional regional Eulerian model of sulfur deposition and transport is developed. Processes treated in the model include emission, transport, diffusion, gas-phase and aqueous-phase chemical process, dry deposition, rainout and washout or sulfur. A “looking up table” method is provided to deal with the gas-phase chemical process including sulfur transfer. Dry-depositon velocity considers the influence of underlying surface, wind, degree of stabil-ity by parameterization. Model calculated values reasonably agrees with observation. Distribution of sulfur deposi-tion and transport in East Asia are also analyzed in this paper. Some amount of sulfur emission of different countries transport across boundaries, but the main origin of sulfur deposition in each country in East Asia is from itself. Furthermore, some transport paths on different layers and outlet or inlet zones are found. According to sulfur bal?ance and budget we concluded that sulfur outlets are bigger than inlets across boundary and emissions are more than deposition in most places of East Asia.     

Leading Pattern of Spring Drought Variability over East Asia and Associated Drivers

Drought events have become more frequent and intense over East Asia in recent decades, leading to hugesocioeconomic impacts. Although the droughts have been studied extensively by cases or for individual regions, theirleading variability and associated causes remain unclear. Based on the Standardized Precipitation Evapotranspiration Index(SPEI) and ERA5 reanalysis product from 1979 to 2020, this study evealuates the severity of spring droughts in East Asiaand investigates their variations and associated drivers. The results indicate that North China and Mongolia have ex perienced remarkable trends toward dryness during spring in recent decades, while southwestern China has witnessed anopposite trend toward wetness. The first Empirical Orthogonal Function mode of SPEI variability reveals a similarseesawing pattern, with more severe dryness in northwestern China, Mongolia, North China, South Korea, and Japan butincreased wetness in Southwestern China and southeast Asia. Further investigation reveals that the anomalously dry (wet)surface in North (Southwestern) China is significantly associated with anomalously high (low) temperature, less (more)precipitation, and reduced (increased) soil moisture during the previous winter and early spring, regulated by an anomalousanticyclone (cyclone) and thus reduced (increased) water vapor convergence. The spring dry-wet pattern in East Asia isalso linked to cold sea surface temperature anomalies in the central-eastern Pacific. The findings of this study haveimportant implications for improving the prediction of spring drought events in East Asia.     

基于AERONET的西亚地区气溶胶光学特性

利用AERONET 10个站点的Level2数据分析得到2010-2017年西亚地区多个气溶胶参数(光学厚度(Aerosol Optical Depth,AOD)、吸收光学厚度(Absorption Aerosol Optical Depth,AAOD)、波长指数α、粒子体积谱和单次散射反照率(Single Scatt...     

Observed Diurnal Cycle of Summer Precipitation over South Asia and East Asia Based on CMORPH and TRMM Satellite Data

The characteristics of the summer precipitation diurnal cycle over South Asia and East Asia during 2001–13 are investigated based on the high spatiotemporal resolution estimates of the CPC(Climate Prediction Center) Morphing(CMORPH) technique. The results show that summer precipitation over South Asia and East Asia possesses a remarkable diurnal cycle, with obvious regional differences. Over the coastal areas, plateau, and high mountains, summer precipitation peaks in the late afternoon; while over low altitude areas, such as valleys, basins, and inshore seas, it peaks during midnight to early morning. In addition to these general features consistent with previous studies, the high resolution CMORPH technique can depict finer regional details, such as the less coherent phase pattern over a few regions. Besides, through comparative analysis of the diurnal cycle strength and precipitation fields, the authors find that for humid areas the summer precipitation diurnal cycle is especially significant over Southeast China, the Sichuan Basin, Hainan Province, Taiwan Province, the Philippines, and Indonesia. And it is relatively weak over the south of Northeast China, central East China, Yunnan Province, the central Indian Peninsula, and most oceanic areas. Comparisons between two satellite datasets—those of the CMORPH and Tropical Rainfall Measuring Mission(TRMM) 3B42 products—are also presented. For summer precipitation and the main diurnal cycle features, the results from both products agree over most regions, except a few areas, e.g., the Tibetan Plateau.