兰州市冬季空气污染的天气成因分析及浓度预报   总被引：9，自引：0，他引：9  

王宝鉴  许东蓓  蒲彦玲  王鹏祥  王锡稳 《干旱气象》2001,19(4):18-21

兰州是全国冬季大气污染最严重的城市之一 ,通过对污染与天气形势的分析 ,给出了影响冬季兰州污染的天气分型 ;对 3种主要空气污染物TSP、SO2 、NOX 浓度值与同期表征逆温特征的逆温参数及地面气象要素作了统计分析 ,结果表明 :(1)污染物浓度与逆温层厚度呈显著正相关 ;(2 )污染物浓度与平均温度、能见度、风速、总云量、相对湿度成负相关 ,与温差、气压成正相关。最后针对不同天气分型 ,给出了冬半年兰州污染物浓度预报方程 ,经检验预报效果良好  相似文献   

极区大气臭氧变化对中国气候影响的数值模拟   总被引：2，自引：5，他引：2  

徐国强  朱乾根  刘宣飞 《高原气象》2001,20(3):275-282

首先利用TOMS资料分析了南北极区大气臭氧总量的季节变化特征。结果表明 ,南北极区的臭氧减少都是春季下降最快 ,然后通过数值试验得到 ,极区大气臭氧减少将造成高低层温度差值分布大致相反 ,由于臭氧减少也将使我国的大气环流形势和降水分布特征发生改变。在我国的不同区域 ,各气象要素的变化也具有不同特征。  相似文献   

THE STUDY OF STORM RAINFALL CAUSED BY INTERACTION BETWEEN THE NON-ZONAL HIGH LEVEL JET STREAK AND TYPHOON IN THE DISTANCE   总被引：1，自引：1，他引：1  

丁治英  张兴强  何金海  徐海明 《热带气象学报(英文版)》2001,7(2):187-198

In this paper, statistics were analyzed concerning correlation between the storm rainfall far from typhoon and non-zonal upper-level jet stream. The results show that the jet stream at 200 hPa is constantly SW (90.2 %) during the period in which storm rainfall occurs. Rainfall area lies in the right rear regions of the jet axes. While the storm intensifies, the jet tends to be stronger and turn non-zonal. With the MM4 model, numerical simulation and diagnosis were carried out for Typhoon No.9711 (Winnie) on August 19 to 20, 1997. The distant storm rainfall is tightly correlative to the jet and low-level typhoon trough. The divergence field of jet is related to the v component. The upper level can cause the allobaric wind convergence at low level. This is the result of the form of low-level typhoon trough and the strength of the storm. By scale analysis, it is found that there is a branch of middle scale transverse inverse circulation in the right entrance regions behind the jet below the 300-hPa level, which is very important to the maintenance and strengthening of storm rainfall. This branch of inverse circulation is relative to the reinforcement of jet's non-zonal characteristics. From the field of mesoscale divergence field and non-zonal wind field, we know that the stronger symmetry caused by transverse circulation in the two sides of the jet, rainfall’s feedback and reinforcement of jet’s non-zonal characteristics had lead to positive feedback mechanism that was favorable of storm rainfall’s strengthening.  相似文献   

1998年盛夏松花江、嫩江流域暴雨过程的云顶黑体温度分析     

许秀红  王承伟  白人海  石定朴  徐宝祥 《黑龙江气象》2001,(1):12-16

用带能滤波分析方法及GMS静止卫星红外云图的云顶黑体温度（TBB）等值线分析方法，并用地面逐时降水资料、T106分析资料、静止卫星云图逐时TBB场资料，分析了1998年8月上旬松花江及嫩江流动的中尺度扰动场和中尺度雨团（≥5.0mm/h)对应的TBB场，揭示不同类型的中尺度雨团在TBB场上发生、发展、移动及消亡的规律。其规律对短期及短时预报有一定的指示意义。  相似文献   

CHARACTERISTICS OF VEGETATION COVER, ROUGHNESS AND ALBEDO DISTRIBUTION OVER CHINA^*          下载免费PDF全文

ZHANG Zhengqiu  ZHOU Xiuji  LI Weiliang  XU Xingkui 《Acta Meteorologica Sinica》2001,15(1):86-94

To build land surface dataset for climate model,with application of remote sensing technique as well as the Geographic Information System(GIS),the data of surface type,roughness and albedo over China in 1997 were retrieved,resolutions being 10 km×10 km.Based on these data,an analysis is conducted on the geographic distributions and seasonal variations of surface vegetation cover and roughness as well as albedo over China.Results show that surface vegetation cover is mainly located to the south of Yangtze River,in Southwest and Northeast China andsparse vegetation cover is in the Northwest.The variation of land surface cover affects the variations of land surface roughness and albedo.High albedo occurred in the north of Xinjiang Autonomous Region,the north of Northeast China and the Qinghai-Xizang Plateau in winter,in correspondence with the location of snow cover.For most part of China,surface roughness decreases and albedo increases in winter,while the roughness increases and the albedo decreases in summer,which could mainly result from land surface cover(snow cover and vegetation cover)and soil moisture changes.This shows that the geographic distribution and seasonal variation of the albedo are almost opposite to those of the roughness,in agreement with theoretical results.Temporally,the amplitude of surface roughness change is quite small in comparison with the roughness itself.  相似文献   

VERTICAL STRUCTURE OF SECOND-MOMENT TURBULENT VARIABLES^*          下载免费PDF全文

AL-JIBOORI. M.H. XU Yumao  QIAN Yongfu 《Acta Meteorologica Sinica》2001,15(2):218-232

Two kinds of observational data,fluctuation and mean profile measurements,from a 325 m meteorological tower in Beijing,China,are used to evaluate local scales of velocity and temperature for higher heights by flux-gradient mean profiles and eddy-correlation techniques.A comparison of these methods each other was made in terms of vertical turbulence fluxes for momentum and beat at the same heigbt.The vertical profiles of non-dimensional second moments.such as vertical turbulent fluxes of momentum and heat.velocity and temperature standard deviations,were derived by local similarity theory.The local similarity relations expressed that the vertical distributions of non-dimensional second moment variables were found to be functions of z/Λ and z/h in the stable boundary layer and the function of z/Z_i for the convective boundary layer,where A the local Monin Obukhov(M-O) length. h the height of stable boundary layer and Z_i the height of mixed-layer.These relations are shown to agree well with the observational data.  相似文献   

REMOTE SENSING OF THE SEASONAL VARIATION IN COLUMN ABUNDANCE OF ATMOSPHERIC CH₄^*          下载免费PDF全文

WEI Heli  LIU Qinghong  XU Qingshan  ZHAO Fengsheng  SONG Zhengfang 《Acta Meteorologica Sinica》2001,15(2):249-256

Infrared solar spectra on clear days were measured automatically by an infrared solar spectrometer(ISS) with 0.4 cm^-1 resolution developed by us.A line-by line(LBL) computation method was used to calculate theoretical atmospheric absorption.In the wavelength range of 3.410-3.438 μm.the absorption is mainly due to atmospheric methane and water vapor.Columnatmospheric methane was retrieved from the recorded infrared solar spectra.The seasonal variation of column atmospheric methane in Hefei has been obtained from the measuremental data of nearly 18 months since the April of 1997.and found that it is similar to that of background data.The instruments.principles of measurement and some of results were introduced,and the results are also discussed briefly in the paper.  相似文献   

腰盘黄间隙的CT测量及其临床价值   总被引：2，自引：1，他引：2  

杨涛  许安荣  葛锋铭  卫光明  童吉华 《CT理论与应用研究》2001,10(3):33-35

目的 评价盘黄间隙对腰椎间盘突出的诊断价值。材料与方法 回顾性分析２００例腰椎间盘ＣＴ扫描资料，记录Ｌ３－Ｓ１间盘形态及双侧黄韧带厚度、盘黄间隙的宽度，分析这些结构与盘黄间隙狭窄及其对腰神经根压迫的关系。结果１９６个间盘突出或膨出，７８处黄韧带厚度＞５ｍｍ，腰盘黄间隙（ＤＦＬＳ）为腰间盘平面位于椎管外侧份间盘与黄韧带间的间隙。１７２侧显示腰神经根鞘受压，相应盘黄间隙平均宽度为（３．６± ０．８）ｍｍ。结论 ＤＦＬＳ＆ｐｏｕｎｄ；５ｍｍ为狭窄，主要原因包括；间盘突出或膨出、黄韧带肥厚等。它可以作为腰间盘突出伴神经根压迫的可靠依据。  相似文献   

急性颈段脊柱外伤的MRI检查价值     

任忠清  徐凯  程广军  冯守信 《CT理论与应用研究》2001,10(3):36-38

目的：分析MRI在颈段脊柱急性外伤中的诊断价值，方法：回顾性分析53例急性颈部脊柱外伤患者的MRI表观特点，并与CT及X线平片比较，结果：椎体骨折41例，椎体脱位3例，脊髓损伤30例，椎间盘损伤7例，结论：MRI可以对颈椎损伤形态，及脊髓韧带椎间盘等软组织损伤作出明确的诊断，是急性颈椎损伤患者最佳的检查方法。  相似文献   

华北地区震群活动的阶段性特征   总被引：10，自引：0，他引：10  

宋治平  徐平  薛艳 《地震》2001,21(1):47-52

通过对华北地区1970年以来震群活动的分析表明，唐山地震的震群活动显示出一定的迁移性和阶段性。应用流变介质包体孕震模型的理论进行了初步力学分析。张北地震的预测检验表明，震群活动的迁移性与阶段性对强震的中期预测具有一定指导意义。  相似文献