2009年飞机人工增雨作业抗春旱效益评估   总被引：2，自引：0，他引：2  

余芳  刘东升  何奇瑾  刘晓璐  王维佳 《四川气象》2010,(1):72-75

本文介绍了人工增雨作业效益的一种评估方法——区域雨量对比法,以及该方法在实际业务工作中的应用：统计了2009年春季四川省飞机人工增雨的作业情况,采用区域雨量对比法对每次作业进行效益计算,得出每次作业的影响面积、影响区降水、对比区降水、增雨量、增加的降水量等,根据春旱期间的降水情况与旱情缓解情况,对人工增雨抗春旱的效益进行了分析评估,并尝试计算出缩短春旱的持续时间,给出了评估结论,并对该方法的应用进行了讨论。该评估方法对于人工影响天气业务工作,具有一定的实用性和可操作性。  相似文献   

1950—2009年夏季菲律宾低空越赤道气流的变化特征   总被引：2，自引：1，他引：1  

杜启倩  孙照渤  李忠贤  倪东鸿 《气象与减灾研究》2010,33(3):7-15

利用1950—2009年NECP/NCAR的月平均经向风再分析资料,根据夏季(6—8月)菲律宾低空越赤道气流的特征,定义了该支气流的强度指数IS和位置偏移指数IL,并根据这两个指数分析了菲律宾越赤道气流的时间变化特征及对应的环流特征,以及其与亚洲夏季降水的关系。结果表明,IS主要呈现弱、强、弱、强的年代际变化特征,IL主要呈现振荡、稳定、径直转向的年代际变化特征。IS与由低层澳大利亚高压北侧冷空气活跃和西太平洋副热带高压减弱所造成的经向气压梯度的变化有关,IL与澳大利亚地区和赤道低槽区高、低层的南北气压梯度有关。IS与印度尼西亚、孟加拉湾南部、热带西太平洋和澳大利亚东部的降水关系密切,IL与孟加拉湾和中国南海南部的降水关系密切。此外,IL与澳大利亚上空的垂直运动具有密切联系。  相似文献   

A Parameterization Scheme for Regional Average Runoff over Heterogeneous Land Surface Under Climatic Rainfall Forcing          下载免费PDF全文

LIU Jingmiao  DING Yuguo  ZHOU Xiuji  LI Yun 《Acta Meteorologica Sinica》2010,24(1):116-122

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SVD分析揭示的澳大利亚高压年际变化对中国夏季降水的可能影响   总被引：1，自引：0，他引：1  

张蓬勃  管兆勇  孙密娜  曹舒娅 《气象学报》2010,68(6):908-917

澳大利亚高压是东亚夏季风系统的重要成员之一,其对中国夏季气候存在显著影响.为了进一步弄清年际时间尺度上的澳大利亚高压变化对中国东部夏季降水的影响,利用澳大利哑海平面气压和中国夏季降水站点资料,使用SVD和线性回归方法揭示了澳大利亚高压的年际变化与中国夏季降水异常的联系,得到:SVD的第1模态的时间系数与通常使用的澳大利亚高压指数相关可达到0.98.在有无考虑ENSO的影响时,SVD的第1模态均反映出澳大利亚高压的年际变化与中国江南地区夏季降水存在密切联系,也即澳大利亚高压增强(减弱)时,江南地区降水增多(减少).澳大利亚高压对中国夏季降水的可能影响途径为:澳大利哑高压通过影响赤道纬向气流和越赤道气流并通过类似PJ波列的方式影响到中国东部地区:澳大利亚高压增强时,造成西太平洋副热带高压偏南、偏西,同时,105°E处越赤道气流显著加强,为江南地区提供充足水汽源,利于中国江南地区降水;澳大利亚高压减弱时,情况相反;在强(弱)澳大利哑高压年,印度尼西亚及热带辐合带海区SSTA负(正)异常使得低层风场的异常辐散(辐合),激发了澳大利哑南部以及西太平洋地区异常反气旋(气旋)环流,同时江南地区出现异常辐合(辐散),引起大气异常上升(下沉)运动,有利于中国江南地区夏季降水异常偏多(偏少).  相似文献   

Evaluation of TMPA satellite-based research and real-time rainfall estimates during six tropical-related heavy rainfall events over Louisiana, USA     

Emad Habib  Amy Henschke  Robert F. Adler 《Atmospheric Research》2009,94(3):373-388

This study focuses on the evaluation of 3-hourly 0.25° × 0.25° satellite-based rainfall estimates produced by the Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA). The evaluation is performed during six heavy rainfall events that were generated by tropical storms passing over Louisiana, United States. Two surface-based rainfall datasets from gauge and radar observations are used as a ground reference for evaluating the real-time (RT) version of the TMPA product and the post-real-time bias adjusted research version. The evaluation analysis is performed at the native temporal and spatial scales of the TMPA products, 3-hourly and 0.25° × 0.25°. Several graphical and statistical techniques are applied to characterize the deviation of the TMPA estimates from the reference datasets. Both versions of the TMPA products track reasonably well the temporal evolution and fluctuations of surface rainfall during the analyzed storms with moderate to high correlation values of 0.5–0.8. The TMPA estimates reported reasonable levels of rainfall detection especially when light rainfall rates are excluded. On a storm scale, the TMPA products are characterized by varying degrees of bias which was mostly within ± 25% and ± 50% for the research and RT products, respectively. Analysis of the error distribution indicated that, on average, the TMPA products tend to overestimate small rain rates and underestimate large rain rates. Compared to the real-time estimates, the research product shows significant improvement in the overall and conditional bias, and in the correlation coefficients, with slight deterioration in the probability of detecting rainfall occurrences. A fair agreement in terms of reproducing the tail of the distribution of rain rates (i.e., probability of surface rainfall exceeding certain thresholds) was observed especially for the RT estimates. Despite the apparent differences with surface rainfall estimates, the results reported in this study highlight the TMPA potential as a valuable resource of high-resolution rainfall information over many areas in the world that lack capabilities for monitoring landfalling tropical storms.  相似文献   

Estimating actual rainfall from satellite rainfall products     

Jun Yan  Mekonnen Gebremichael   《Atmospheric Research》2009,92(4):481-488

The lack of uncertainty measures in operational satellite rainfall (SR) products leads to a situation where users of the SR products know that there are significant errors in the products, but they have no quantitative information about the distribution of these errors. The authors propose a semiparametric model to characterize the conditional distribution of actual rainfall (AR) given measures from SR products. The model consists of two components: a conditional gamma density given each SR, and a smooth functional relationship between the gamma parameters and SR. The model is developed for monthly rainfall, estimated from a satellite with sampling frequency once a day, averaged over an area of 512 × 512 km² in the Mississippi River basin. The conditional distribution results are more informative than deterministic SR products since the whole conditional distribution enables users to take appropriate actions according to their own risk assessments and cost/benefit analyses.  相似文献   

The ENSO’s Effect on Eastern China Rainfall in the Following Early Summer   总被引：6，自引：0，他引：6  

쇖훐듯  슽죕폮 《大气科学进展》2009,26(2):333-342

ENSO’s effect on the rainfall in eastern China in the following early summer is investigated by using station precipitation data and the ERA-40 reanalysis data from 1958 to 2002. In June, after the El Nino peak, the precipitation is significantly enhanced in the Yangtze River valley while suppressed in the Huaihe River-Yellow River valleys. This relationship between ENSO and the rainfall in eastern China is established possibly through two teleconnections: One is related to the western North Pacific (WNP) ...  相似文献   

A Study on a Heavy Rainfall Event Triggered by an Inverted Typhoon Trough in Shandong Province   总被引：2，自引：0，他引：2       下载免费PDF全文

ZHAO Yu  CUI Xiaopeng  WANG Jianguo 《Acta Meteorologica Sinica》2009,23(4):468-484

A heavy rainfall event that occurred in Shandong Province in 26 28 August 2004 was caused mainly by Typhoon Acre and cold air activities related to a westerly trough. The event was triggered by an inverted typhoon trough, which was closely associated with the intensification of the low-level southeasterly flow and the northward transport of heat and momentum in the periphery of the typhoon low. A numerical simulation of this event is performed using the nonhydrostatic mesoscale model MM5 with two-way interactive and triply-nested grids, and the structure of the inverted typhoon trough is studied. Furthermore, the formation and development mechanism of the inverted typhoon trough and a mesoscale vortex are discussed through a vorticity budget analysis. The results show that the heavy rainfall was induced by the strong convergence between the strong and weak winds within the inverted typhoon trough. Dynamic effects of the low-level jet and the diabatic heating of precipitation played an important role in the development of the inverted typhoon trough and the formation of the mesoscale vortex. The vorticity budget analysis suggests that the divergence term in the low troposphere, the horizontal advection term, and the convection term in the middle troposphere were main contributors to positive vorticity. Nonetheless, at the same pressure level, the effect of the divergence term and that of the adveetion term were opposite to each other. In the middle troposphere, the vertical transport term made a positive contribution while the tilting term made a negative contribution, and the total vorticity tendency was the net result of their counteractions. It is found that the change tendency of the relative vorticity was not uniform horizontally. A strong positive vorticity tendency occurred in the southeast of the mesoscale vortex, which is why the heavy rainfall was concentrated there. The increase of positive vorticity in the low （upper） troposphere was caused by horizontal convergence （upward transport of vorticity from the lower troposphere）. Therefore, the development of the inverted typhoon trough and the formation of the mesoscale vortex were mainly attributed to the vorticity generated in the low troposphere, and also the vertical transport of vorticity from the low and middle troposphere.  相似文献   

喀什地区1961—2005年降水变化特征   总被引：1，自引：0，他引：1  

黄艳  裴江文  羊兴 《沙漠与绿洲气象(新疆气象)》2009,3(3):31-34

选用喀什地区1961－2005年45a的逐月降水量资料,分析了喀什地区平原和山区年降水量的分布特征。结果表明：喀什地区平原和山区年降水量年际变化均表明了在周期波动中有增加的趋势,且具有一定的长期性;平原和山区降水量的年际变化的同步性在不同年代表现不同;喀什地区各季降水变率大体表现为平原地区大,山区小的趋势。  相似文献   

黄河三花区间天气雷达测雨技术应用研究   总被引：1，自引：0，他引：1  

王春青  赵坤  张勇  邱淑会 《水文》2010,30(2)

采用改进窗概率配对方法以及自适应卡尔曼滤波和变分联合的方法分别对郑州和三门峡两部新一代多普勒天气雷达观测资料以及地面自动雨量站资料进行了降水反演和评估,并实现了两部雷达降水反演的拼图.评估结果表明在雷达测雨中,利用改进窗概率配对方法确定的Z-R关系反演的雷达测雨精度要优于目前国内业务雷达采用的经验关系式,而且经过自适应卡尔曼滤波和变分联合处理之后,既保持了雷达观测降水的空间分布特征,也显著提高了雷达测雨的精度.  相似文献