STUDY ON APPLICATIONS OF C-BAND DUAL LINEAR POLARIZATION RADAR IN METEOROLOGY   总被引：4，自引：0，他引：4       下载免费PDF全文

徐宝祥  王致君  蔡启铭  刘黎平  张鸿发  楚荣忠 《Acta Meteorologica Sinica》1991,(3)

Theoretical study and development of a dual linear polarization weather radar in China are briefly presented.Also discussed are the potential uses of the new radar system in improving the accuracy of areal rainfall measure-ments and analysing the spacial structure of storms and distribution of hydrometecrs in clouds based on theradar observational data from the field experimcnts during the summers of 1987—1989. The results indicatethat a C-band dual polarization weather radar, after considering the microwave attenuation correction, may beemployed to quantitatively measure rainfall and to monitor heavy rain and flood events and becomes an impor-rant means to study storm structure.  相似文献   

REMOTE SENSING OF RAINFALL PARAMETERS BY LASER SCINTILLATION CORRELATION--EXPERIMENT AND ANALYSIS          下载免费PDF全文

Wang Kaixiang  L&#;Daren 《Acta Meteorologica Sinica》1991,5(3):342-351

Remote sensing of rainfall parameters—rainfall rate and size distribution—by raindrop-induced laserbcam scintillation is a new kind of precipitation measurement technique. This paper presented the primaryfield experiment results based on the theory and numerical simulations by Wu and Lü (1984, 1985) and Lü andWu (1984).Rainfall rate and size distribution were deduced from observations of laser beam scintillation andcompared with those of the filter-paper sampling method. Qualitative analysis of the experiment error wasalso given here. All the work showed that the theory is applicable, and under proper experiment conditions,remote sensing of rainfall parameters by laser scintillation correlation is an advanced and accurate technique.  相似文献   

喜玛拉雅山脉降水分布的一种气候估算方法     

林贤超  林振耀 《高原气象》1991,10(1):88-93

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从熵原理得出的暴雨面积和雨量的关系   总被引：7，自引：3，他引：7  

张学文  杨秀松 《高原气象》1991,10(3):225-232

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Application of principal component analysis to understand variability of rainfall     

R. N. Iyengar 《Journal of Earth System Science》1991,100(2):105-126

The usefulness of principal component analysis for understanding the temporal variability of monsoon rainfall is studied. Monthly rainfall data of Karnataka, spread on 50 stations for a period of 82 years have been analysed for interseasonal and interannual variabilities. A subset of the above data comprising 10 stations from the coherent west zone of Karnataka has also been investigated to bring out statistically significant interannual signals in the southwest monsoon rainfall. Conditional probabilities are proposed for a few above normal/below normal transitions. A sample prediction exercise for June–July using such a transition probability has been found to be successful.  相似文献   

陕西汛期降水与前期大气环流遥相关型的联系   总被引：1，自引：0，他引：1  

高智  谢双亭 《南京气象学院学报》1992,15(4):576-583

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上海大气折射指数振动及其与降水量和太阳黑子的关系     

戴铁丕  王丽波  詹煜 《南京气象学院学报》1992,(4)

用交叉谱分析方法研究近地面大气折射指数N单位平均值、月降水总量与太阳黑子相对数之间多频振动特征。结果发现:初夏,N单位与太阳黑子(或降水量)在准5年及准2年(或准7年、准4年及准3年)周期附近有十分密切的关系;初秋,N单位与太阳黑子在准5年、准2年周期附近密切相关;N单位与降水量除在短周期准3年、准2年附近有密切关系外,在长周期准35年附近亦有较密切的关系。  相似文献   

THE RELATIONSHIP BETWEEN TROPICAL PACIFIC SEA SURFACE TEMPERATURE AND SUMMER RAINFALL OVER NORTHWEST CHINA   总被引：4，自引：0，他引：4       下载免费PDF全文

Zhu Bingyuan  Li Dongliang 《Acta Meteorologica Sinica》1992,6(4):470-478

In this paper,the data of summer precipitation in Northwest China were expanded by means of EOF.According tomajor eigenvectors in expansion the area of Northwest China was divided into four natural rainfall regions.Amongthem the region of greatest precipitation variability is found over the East Qinghai-North Shaanxi region,includingEast Qinghai,Central and East Gansu,Ningxia and North Shaanxi.There is apparent teleconnection between the firstand second time-dependent coefficients in EOF expansion and the tropical Pacific SST in the corresponding period andearlier months.The variation of the east tropical Pacific SST in winter and spring is able to predict precipitation trend ofNorthwest China next summer.Moreover,in the El Nino years precipitation trend is opposite to the following year,andthe region from East Qinghai to North Shaanxi is most sensitive.  相似文献   

东亚夏季风水汽输送带及其对中国大暴雨与洪涝灾害的影响   总被引：12，自引：1，他引：12       下载免费PDF全文

丁一汇  柳艳菊  宋亚芳 《水科学进展》1990,31(5):629-643

东亚夏季风每年给中国东部地区带来充沛的降水，是中国水资源的主要来源，同时也常常给中国造成严重的洪涝灾害。东亚夏季风水汽输送的强度、影响范围和持续性在极端暴雨过程中起着关键的作用。这支夏季风气流的水汽输送带可称为东亚季风水汽输送带，与国际上近期提出的"大气河"概念相近，但又不完全相同。东亚夏季风水汽输送带是东亚夏季风最具地区性的特征，也是东亚地区夏季大暴雨和洪涝的制造者。本文根据近百年来的资料，综合评述了东亚夏季风水汽输送带的特征和形成原因，并以海河、黄河、淮河与长江近百年最强的5次持续大暴雨过程为例，分析了季风水汽输送带的重要作用。最后，提出气候变暖可以通过4个方面影响全球水循环，包括气候变暖后大气可容纳更多的水汽、大气环流发生变化、辐射强迫改变以及气溶胶影响的区域性等，这些变化都会对季风水汽输送带产生重要影响。  相似文献   

Estimation for partially observed Markov processes     

M. E. Thompson  T. N. Kaseke 《Stochastic Environmental Research and Risk Assessment (SERRA)》1995,9(1):33-47

Many stochastic process models for environmental data sets assume a process of relatively simple structure which is in some sense partially observed. That is, there is an underlying process (X_n, n 0) or (X_t, t 0) for which the parameters are of interest and physically meaningful, and an observable process (Y_n, n 0) or (Y_t, t 0) which depends on the X process but not otherwise on those parameters. Examples are wide ranging: the Y process may be the X process with missing observations; the Y process may be the X process observed with a noise component; the X process might constitute a random environment for the Y process, as with hidden Markov models; the Y process might be a lower dimensional function or reduction of the X process. In principle, maximum likelihood estimation for the X process parameters can be carried out by some form of the EM algorithm applied to the Y process data. In the paper we review some current methods for exact and approximate maximum likelihood estimation. We illustrate some of the issues by considering how to estimate the parameters of a stochastic Nash cascade model for runoff. In the case of k reservoirs, the outputs of these reservoirs form a k dimensional vector Markov process, of which only the kth coordinate process is observed, usually at a discrete sample of time points.  相似文献