东亚沙尘暴的数值模拟

在有限区域模式ＭＭ４的基础上，发展了一个沙尘暴传输扩散模式，对模式中的源汇的处理作了精细考虑。用１９９１年４月３０日的实况资料检验了模式的性能，结果表明，模式能够模拟沙尘暴的总体特征     

Dust storm in Asia continent and its bio-environmental effects in the North Pacific： A case study of the strongest dust event in April, 2001 in central Asia

The iron hypothesis, first proposed by John Martin in 1990[1], suggests that some surface oceans such as North and Equatorial Pacific Oceans have high nutrient but low chlorophyll (HNLC). Thus iron coming from terrestrial dusts is the primary factor limit…     

毛乌素沙地上空沙尘暴的前向轨迹及其影响范围

基于气象数据、MODIS遥感影像数据和NCEP再分析资料, 利用HYSPLIT模型模拟2000—2019年毛乌素沙地上空不同海拔高度(500, 1000和1500 m)各季节沙尘暴的前向轨迹, 并与遥感影像识别出的沙尘信息进行比较, 识别毛乌素沙地沙尘暴的影响范围。结果显示: 1) 在过去的20年中, 共有143个沙尘暴月和387个沙尘暴日, 并且 2004 年以来, 毛乌素沙地发生沙尘暴的频率逐渐降低; 2) 季节性气候条件对毛乌素沙地沙尘暴的移动路径有很大的影响, 春季沙尘暴发生频率较高, 秋季发生频率最低; 3) 受毛乌素沙地沙尘暴影响的国内地区主要包括陕西省北部、山西省北部、河北省北部和中部、山东省北部和中部、北京市、天津市、内蒙古自治区东部以及东北三省, 国外受影响的地区有朝鲜、日本北部以及俄罗斯与我国交界处, 受影响的海域有渤海、黄海北部和日本海西北部。遥感影像与HYSPLIT模型的比较提供了一种对沙尘运输、扩散和沉积过程进行验证和加深了解的有效工具, 研究结果可以为防灾减灾决策及沙源地治理提供科学的参考依据。     

Territorial Features of Atmospheric Environment in Beijing and Impact of Dust-storm

1Introduction　TheenvironmentproblemsontheEarthcanbeclassifiedasthreekinds ,whicharecalledasthelocalenvironment,terri torialenvironmentandglobalenvironmentproblems ,respec tively .Nowthekindsofanthropogenicactivityhaveledtotheseriousterritorialenvironmentproblemsallovertheworld .Recently ,theterritorialenvironmentproblemsinChinahavebeengraduallyrecognized .　Nowalthoughtheseparateseriouspollutionshavebeende creasedbyremovingandcontrollingthestrongpollutionsources ,theterritorialpollutionprobl…     

用MM5模式和阻力模型计算硫化物的干沉降速度

使用NCEP资料，由中尺度气象模式MM5产生中国东部及附近地区详细的边界层气象场，使用类似于RADM中的阻力模型，计算了该地区2000年3月22—27日硫化物(SO2、SO4^2-)的干沉降速度的区域分布，以及典型地区的干沉降速度随时间的演变；讨论了不同阻力对硫化物干沉降速度的影响．结果表明：随着下垫面类型和气象条件的不同，硫化物的干沉降速率有着明显的时空变化，尤其是当有天气系统(如锋面)时，污染物的干沉降速率明显增大．对SO2来说，不同的下垫面条件、不同的气象条件下，三种阻力的相对重要性不同；对SO4^2-来说，其干沉降速度主要决定于分子扩散阻尼和表面阻尼．     

全球变暖背景下内蒙古地区沙尘暴频次变化的预估

构建一个基于BP神经网络的统计模型, 利用CMIP5模式中历史情景和未来情景的预估数据, 重建1860—2100年内蒙古地区春季沙尘暴频次(分辨率达到日尺度)序列。在此基础上, 研究内蒙古地区沙尘暴未来长期变化特征。结果表明, 在未来情景RCP2.6 和RCP8.5中, 与历史时期(1860—2005年)相比, 内蒙古地区沙尘暴频次持续减少; 影响范围较大的沙尘暴事件占比也持续减少; 在增温更多的RCP8.5情景中, 沙尘暴的减少更加显著; 春季沙尘暴的季节性锁相特征(4月沙尘暴频次达到峰值)不随全球变暖而变化。     

The formation process and cloud physical characteristics for a typical downburstproducing thunderstorm in Beijing

The formation process and characteristics of cloud physical structure of a severe thunderstorm accompanied with strong wind on 23 August, 2001 in Beijing was studied using PSU/NCAR mesoscale model (MM5)coupling with a severe storm model with hail-bin microphysics. The results show that the specific topography and distribution features of cold/warm current in the Beijing region played prominent roles in forming, developing and maintaining the severe storm. Due to solar radiation heating and topographic lifting, the convective cells were easily formed when the westerly airflow passed over high mountainous regions in Beijing. The warm and wet air entered the cloud from its frontage and enhanced the convection, and formed a large amount of graupel/hail particles at the middle and upper portion of the clouds. The precipitation was primarily formed due to melting of graupel/hail particles. The strong downdraft was mainly produced by negative buoyancy due to loading,melting of graupel/hail particles as well as evaporative cooling of rain water. The divergent airflow induced by the strong downdraft led to the disastrous burst winds at the surface and also forced lifting of warm and wet airflow in the moving direction of the storm and formed new clouds that further promoted and maintained the storm development.     

一个欧拉型污染物沉降的中尺度模式

本文提出了一个欧拉型的污染物中尺度数值模式,用以研究大气中污染物的输送、转化和干、湿沉降。模式以Anthes等人发展的中尺度气象模式为基础,加入了污染物质量守恒方程组。在方程中包括了源发射率、物质的平流和湍流输送和参数化的气相化学转化和干沉降。作为这一模式的特点是在三维的中尺度模式中嵌入一个一维时变的雨云物理和化学模块,用以研究污染物的湿沉降。用这个模式讨论了湿沉降规律和中国东部地区的污染物浓度和干湿沉降的分布。     

Dust storms and loess accumulation on the Tibetan Plateau：A case study of dust event on 4 March 2003 in Lhasa

Whether the Tibetan Plateau is a significant dust source area is of great importance, because this is related to the understanding of sources, accumulation and environmental effects of dusts on the Tibetan Plateau and inthe Far East-Pacific Ocean regions as well as to the evointion of coupling of the Tibetan Plateau and atmaspbere-oeean-continent exchange. Synoptic dynamics and remote sensing tracing of a dust storm on 3 to 5 March, 2003 in Lhasa onSouth Tibet demonstrate that the Tibetan Plateau possessesall factors and conditions of generating dust storms. Accompanied with this dust storm is a strong ascending stream onthe Plateau which has raised various sizes of durst particlesinto different levels. The lifted coarse particles were largelyfallen down and accumulated as loess on the eastern TibetanPlateau, and the fine particles were translated by the westerly jet and subsided in the northern Pacific Ocean. The spa-tial-temporal distribution of dust-storms between years 1961and 2000 ou the Plateau shows that duststorms mainly occurin winter and early spring with high frequency, and tile pathof dust storm moves gradually from south to north, which isclosely coupled with the northward moving of the westerlyjet from winter to spring over the Tibetan Plateau. Com-pared with other twelve dust source areas in China. the Ti-betan Plateau is one of the key dust souree areas for thelong-distance transport because its high occurring frequencyand elevation cause fine particles easily to be lifted into thezone of the westerly jet.     

Typical severe dust storms in northern China during 1954 —2002

Based on China抯 available daily observation data from 681 national meteorological stations from 1954 to 2002, a time series of typical severe dust storms in northern China is constructed in terms of the weather process, and the temporal and spatial distribution, and their evolution ten-dency is analyzed. The results indicate that there were 223 relatively typical severe dust storms in northern China from 1954 to 2002, among which the event on April 10—12, 1979 had the largest affected area. Closely associated with the geographical distribution of deserts, sandy lands and the tracks of strong cold air outbreaks, severe dust storms mainly occurred in the Tarim Basin, the eastern part of Northwest China and the northern part of North China. The season with the most frequent severe dust storms was spring, in which the frequency accounts for 82.5% in the whole year, while the least occurrence was in summer and autumn. Dur-ing the past 49 years, the highest frequency of severe dust storms occurred in the 1950s and the lowest was in the 1990s with a general descending tendency, but during 2000—2002 the occurrence was relatively increasing. On the average, the duration of severe dust storms was shortest in the 1990s, about 0.5—1 h shorter than that in the other 4 decades.     

Seasonal variations of dust record in the Muztagata ice cores

Based on the oxygen isotope ratio and microparticle record in ice cores recovered at Mt. Muztagata, Eastern Pamirs, the seasonal variations of atmospheric dust have been reconstructed for the past four decades. High dust concentrations and coarser particle grains have the similar trend with oxygen isotope value. Our statistical results indicate that 50%--60% high dust concentration samples occur during the season with high oxygen isotope values （summer）, while low dust storm frequency during spring and winter. Back-trajectory analysis shows that the air mass hitting Muztagata predominately came from West Asia （such as Iran-Afghanistan Plateau） and Central Asia, which are the main dust source area for Muztagata. Dust storms in those source areas most frequently occur during summer （from May to August）, while frequent dust storm events in northern China mainly occur during spring （March to May）. Regions in the path of Asian dust transport, such as in Japan, the North Pacific, and Greenland, also show high dust concentrations during spring （from March to May）. Our results indicate that dust storms have different seasonality in different regions within Asia.     

天山北麓一例黑风暴天气的成因

利用常规观测资料、地面气象自记记录和静止气象卫星云图资料对1998-04-18由南支冷锋爆发性发展生成的干飑线触发的天山北麓黑风暴天气过程进行了分析。结果表明：强沙尘暴和黑风暴过境时风、压、温、湿在短时间内出现突变,跃变幅度黑风暴远大于强沙尘暴,黑风暴嵌于强沙尘暴时变化幅度比强沙尘暴弱。沙尘壁具有等温性,水平厚度4～9km。影响黑风暴的天气因素中,地面大风形成主要源于冷锋的加强和锋后强冷平流,高空急流的加强及其形成的次级环流使高空动量有效下传到地面则是另一个重要原因。混合层是有利于黑风暴在干旱环境形成的大气层结特征,这次过程深厚混合层的形成是深厚干对流和黑风暴产生的主要原因,而它的形成则是长时间地面加热的结果。     

不同排浆浓度下的尾矿沉积规律研究

排放后的尾矿沉积规律影响尾矿库坝体的稳定性。为研究不同排浆浓度条件下尾矿沉积特性，以云南某尾矿库为研究对象，通过现场试验和室内缩尺的堆坝模型试验，研究了不同排浆浓度下的尾矿沉积规律，分析了单颗尾砂颗粒的临界状态，推导了尾砂颗粒运动—沉积临界速度关系和不同粒径颗粒在干滩上的运移距离公式。研究结果表明：沉积滩面的坝前位置粗尾砂沉积较多，随着距离子坝越远，细粒尾砂沉积越多；在干滩面上尾砂流速与矿浆浓度呈负相关，与尾砂浆体压力呈正相关；较粘稠高浓度尾砂浆体的浓度越大，流动力就越弱，致使沉积形成的坡度越大；排浆浓度的逐渐增大，矿浆沉积长度也随之变长；尾砂颗粒在干滩面的沉积距离与排浆初始速度成正比，与干滩坡度、排浆浓度及颗粒粒径成反比。研究成果可对尾矿库坝体稳定性分析提供一定参考。     

Modeling and simulation of dynamic carbonate deposition in a loess-paleosol sequence

A compartment model of dynamic deposition processes has been developed and tested in the Potou loess section of China. There are four components in the model : carbonate input of eolian dust, carbonate output of erosion, carbonate chemical equilibrium and soil water balance. A climate stochastic model software (CLIMAK) generates the daily weather data. The processes of eolian dust deposition, erosion, and pedogenesis simulate the complex process of carbonate deposition in a loess-paleosol sequence. We consider both climatic change and soil-forming factors. The results indicate that since the Late Pleistocene in Potou section, the mean carbonate fluxes from precipitation, eolian dust and erosion are 0.14g/cm~2/kg, 1.45g/cm~2/ka and 0.23g/cm~2/ka respectively. Of this, 91.2% of the carbonate input is from eolian dust.     

Source of a floating dust episode over the Qingdao region and dust throughput to the ocean

A floating dust weather happened on March 11–12, 1995 over the Qingdao region. Its source’s and throughput to the ocean were studied. The result indicated that the floating dust was caused by the dust storm that started in northwestern China and developed in northern China. 21 × 10⁶t fine soil particles were carried to the ocean during the episode.     

Estimation of dry deposition fluxes of major inorganic species by canopy throughfall approach

Dry deposition is an important deposition pathway of pollutants, at least equally important to wet deposi- tion. To understand the total deposition of pollutants, China is lack of the systematic studies on the method- ologies of dry deposition, measuremen…     

Great progress in study on aerosol and its impact on the global environment

The transport from atmosphere is a more important pathway than that from rivers for certain elements and compounds in the remote ocean. The desert and those arid/semi-arid areas in the northwest of China and the Loess Plateau are the sources of those aerosols over the Pacific. Atmospheric iron is the limiting factor of the productivity in certain ocean regions. The dust storms must now be seen as repeated sources of pollution elements as well as soil elements to the East China Sea and, farther out, to the North Pacific Ocean and even to the USA. The long-range transport of aerosols, especially the dust storm, from China and the positive feedbacks of iron coupled with sulfur in atmosphere might be one of the important mechanisms that would affect the primary productivity in the Pacific and/or the global climate change and deserve to be further studied. It can be seen clearly that the dust storms would affect not only the health of human beings and the local or regional climate, but also the global climate change that has been the focus of environmental study internationally.     

Characteristics and sources of 2002 super dust storm in Beijing

~~Characteristics and sources of 2002 super dust storm in Beijing~~     

2002年兰州市春季大气气溶胶特征分析

利用2002年兰州地区春季背景大气、沙尘天气状况下大气气溶胶的实测资料,得到了不同天气状况下大气气溶胶(TSP)的质量浓度和飘尘(PM10)的粒径分布,着重分析了不同天气状况下大气气溶胶的分布规律及其物理特征.研究发现:TSP中细粒子质量浓度沙尘暴期间比非沙尘暴期间相对减少;背景大气条件下,飘尘对人体健康影响比较严重.     

一种污染物的区域干沉积速度分布的计算方法

建立了一个模拟污染物的区域干沉积速度分布的数学模式，利用它计算了江苏省及周围地区ＳＯ２、硫酸盐、ＨＮＯ３（气）和硝酸盐四种污染物的干沉积速度分布，并通过数值试验研究了干沉积速度的时空变化特征。与国内外的此外场观测资料的比较表明，本模式能够实现对不同条件下污染物干沉积的模拟．