青藏高原雪盖异常对我国环流和降水的影响   总被引：34，自引：4，他引：34       下载免费PDF全文

徐国昌  李珊 《应用气象学报》1994,5(1):62-67

利用美国NOAA NESDIS提供的1975—1986年青藏高原地区卫星雪盖资料，作出了各月冬季青藏高原雪盖频率图。发现1—3月是高原雪盖面积最大的月份，在此期间高原雪盖面积有明显的持续性，并与欧亚雪盖面积有较高的一致性。根据3月高原雪盖异常与中国环流和降水的关系，发现高原雪盖异常的后延冷却效应较弱，大约不足一个月；3月高原多雪以后，5月东亚北风加大，南岭以北降水偏少，少雪年则相反。  相似文献   

水分不足地区降水资源供需平衡模式   总被引：3，自引：0，他引：3       下载免费PDF全文

张家诚 《应用气象学报》1994,5(4):496-500

在自然界与人类系统水分平衡概念的基础上，提出了作降水评价的供需平衡模式。该模式对全面发挥由降水所形成的各种主要水资源成分的潜力是有用的。用此模式作了个例试验，并提出在水分不足地区缓解水分欠缺的途径。  相似文献   

差巴嘎蒿繁殖若干问题的探讨   总被引：9，自引：0，他引：9  

李进 《中国沙漠》1994,14(3):60-65

差巴嘎蒿（Ａｒｔｅｍａｓｉａｈａｌｏｄｅｎｄｒｏｎ）营养繁殖的最佳材料是当年生带根基部营养枝；降水量是影响营养繁殖成活率的主导因子，栽植后５日内降水之和（ｘ）与成活率（ｙ）的相关系数为０．９７０１，回归方程为：ｙ＝３４．０２３６＋４１．０４６７１ｇｘ。营养繁殖应在有一定降水的条件下及时进行，最佳时间在６月中旬。不宜利用种子繁殖建立人工植被。  相似文献   

Research Status and Progress of Balloon-borne Cloud and Precipitation Particles Probe     

Peng Wang  Lei Liu  Xichuan Liu  Shuai Hu  Shijun Zhao  Wenming Ji  Taichang Gao 《地球科学进展》1986,35(7):704-714

The accurate observation of the microphysical structure of cloud and precipitation plays an important role in understanding the formation of clouds and precipitation. In-situ measurement using measuring instruments carried by meteorological balloons is an effective way to obtain the microphysical properties of cloud and precipitation particles, which is a supplementary means for aircraft to observe cloud and precipitation particles. This observation method plays a more and more important role in in-situ measurement. According to the difference of the working principle of the existing balloon-borne cloud and precipitation particles probes, the detectors can be divided into particle impact-sampling sensors, particle imaging sensors, light-scattering sensors, light intensity attenuation sensors and charge measurement sensors. The working principles, key technologies and main advantages and disadvantages of typical instruments were summarized, and their applications to detailed cloud structure acquisition, cloud remote sensing method establishment, cloud and precipitation physical process research and parameterization, and scientific observation of thunderstorm clouds were briefly introduced. Finally, the development trend of balloon-borne cloud precipitation particle detectors was prospected, which will provide reference for related technical research and equipment development.  相似文献   

临汾地震安全性评价的极值理论方法     

彭美煊 《高原地震》1995,(1)

本文根据极值理论建立了烈度超越给定值Ｉｊ的平均重现期公式，根据最大熵原理建立了未来Ｔ年烈度超越给定值Ｉｊ的概率和烈度超越给定值Ｉｊ的平均重现期之间的关系式。利用１０２２─１９９３年的地震资料，计算了临汾（３６．１０°Ｎ，１１１．５０°Ｅ）周围４级以上地震在临汾造成的烈度，绘制了未来１００年临汾的烈度超越概率曲线（地震危险性曲线）。结果表明，计算场地烈度的极值理论方法可作为地震危险性分析的综合概率法的补充和验证。  相似文献   

对流和层状云系电活动,对流及降水特性的相关分析   总被引：27，自引：11，他引：27  

张义军  华贵义 《高原气象》1995,14(4):396-405

通过对６次不同云系电特性、回波、对流及降水特性的综合分析，探讨了它们之间的相关性。结果表明：除不稳定能量外，－１０℃层和０℃层高度以及他们之间的高度差、０℃层与云顶的高度差也是表征雷暴动力和电特性的重要参量；雷暴云起电过程对冰相作用有较强的依赖性；雷暴中的电活动与对流活动成正相关，闪电多发生在３０ｄＢｚ强回波高度大于－１０℃层高度时段内，强烈的电活动与强降雨有很好的对应关系，而与一般性降雨对应关系较差；在雷暴消散期，闪电可能会影响雷暴的特性  相似文献   

云南省40年降水的基本特征   总被引：5，自引：0，他引：5  

缪启龙  肖伟 《气象科学》1995,15(3):293-299

根据云南省１９５１－１９９０年１８个站的降水资料，用正交函数展开，由方差贡献最大的前三个特征向量场分析了云南省降水距平均的典型分布，指出云南省全省范围内的降水距平同号较少发生，而是较多的发一降水距平异号。进而分析了四十年降水的年际变化特征，并分析了青藏高原积雪对云南降水的影响。  相似文献   

热带太平洋海表温度年际变化对降水季节内振荡的影响   总被引：6，自引：0，他引：6  

Li Wei  Yu Rucong  Zhang Xuehong 《大气科学进展》2001,18(3):429-444

根据 １９８２—１９９２年期间的日平均 ＭＳＵ（Ｓｐｅｎｃｅｒ, １９９３）海洋降水和 ５天平均的ＣＭＡＰ（Ｘｉｅ＆ Ａｒｋｉｎ, １９９７）降水观测资料,分析了热带太平洋大气季节内振荡（ＭＪＯ）的年际变化特征。在太平洋海表温度（ＳＳＴ）年际变化的正常年份（１９８２—８３年, １９８６—８８年, １９９１—９２年）,均有明显的ＭＪＯ信号传到日界线以东并在中、东太平洋维持数月。热带ＭＪＯ活动强度的年际变化与局地ＳＳＴ的变化存在正相关。中、东太平洋降水的季节内振荡的年际变化与热带太平洋ＳＳＴ的最强正相关在Ｎｉｎｏ３区附近。以观测ＳＳＴ场强迫ＣＣＭ３大气模式的数值试验基本上真实地再现了１１年期间热带太平洋降水季节内振荡的年际变化总趋势,但模拟季节内振荡的强度较观测平均偏弱。对比分别采用周平均和月平均ＳＳＴ强迫场的积分结果,发现在中、东太平洋,二个积分模拟的降水季节内振荡强度的年际变化接近并且趋势与观测基本一致,而在西太平洋二个积分的模拟结果差别较大。这表明在热带中、东太平洋,ＳＳＴ强迫的年际变化对ＭＪＯ强度的变化有强的制约。而在ＭＪＯ总体活跃的热带西太平洋,ＳＳＴ强迫场的季节变化对模拟ＭＪＯ活动也有较大影响。ＣＣＭ３模拟  相似文献   

On the relationship of thunderstorm ice hydrometeor characteristics and total lightning measurements   总被引：1，自引：0，他引：1  

Wiebke Deierling  John Latham  Walter A. Petersen  Scott M. Ellis  Hugh J. Christian  Jr.   《Atmospheric Research》2005,76(1-4):114

Satellite-borne and ground-based devices for the detection of lightning offer the opportunity to explore relationships–on all significant scales up to global–between lightning frequency, f, and other thundercloud parameters. Calculations predict that f is proportional to the product of the downflux p of solid precipitation and the upward mass flux, I, of ice crystals. This prediction has received support from limited computational studies. The physical reasons for such a relationship are explained in terms of the paramount role of ice in the electrification of thunderstorms. Herein, this prediction is subjected to further, preliminary examination through analysis of lightning and dual-polarimetric radar data collected during the STERAO experiment conducted in Northern Colorado during the summer of 1996. The analysis has yielded some highly provisional support for this flux hypothesis. Computed trends of radar derived hydrometeor fractions of solid precipitation and small ice show correlation to the total lightning frequency and raise the possibility of determining values of p and/or I from lightning measurements.It is shown that the extent to which the observed correlations between f and both solid precipitation and small ice trends are or are not strong can provide an indication as to whether the lightning activity is limited by the available concentrations of precipitating or non-precipitating ice in the upper regions of the charging zone of the thundercloud, where most of the charge transfer occurs. It is demonstrated that the most accurate determinations of precipitation rate p from measurements of lighting frequency f are likely to be for conditions where the field-growth is limited by the availability of graupel pellets. It is shown that the simultaneous time variations of f and solid precipitation trends of the type obtained in the STERAO experiment could enable us to determine the nature of the dominant glaciation process operative in the thunderclouds studied.  相似文献   

Verifying warnings for point precipitation     

Willi Schmid  Marc Wüest   《Atmospheric Research》2005,77(1-4):347

Short-term risk forecasts of point precipitation are obtained with COTREC/RainCast, a technique for extrapolation of radar images. The risk forecasts are updated every 5 min for the next 0–2 h. Risk levels are defined for moderate, heavy and extreme precipitation. Warning messages are generated if, at the locations of 23 rain gauges, these risk levels are reached or exceeded. The time-resolved gauge data are used to judge if the warning messages are in time, early or late.Data over a period of 4 months (summer 2002) are used for verification. The largest number of warnings (1790) was obtained for moderate precipitation. About 55% of these warnings were in time, 23% were early and 22% were late. This finding is in a good agreement with the defined risk level for warnings (50%), indicating that the model for calculating the risk factors is reliable. Less warnings in time, and more late warnings were found for heavy and extreme precipitation. Hence, the risk levels need to be lowered for heavy and extreme precipitation, in order to reduce the number of late warnings.  相似文献