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201.
A case of mesoscale convective complex(MCC)which evolved into a vortex is documented in this paper.As theMCC entered into the dissipating phase,a well-defined spirally banded structure became visible in the satellite image.The blackbody temperature(TBB)of the residual cold-cloud-shield indicates the vortex existed in the layer from 400 to250 hPa.According to the upper air analysis,the upper level vortex was an anticyclone.The MCC-generated vortex wasvisualized in the satellite images because it was located in the subtropical high where the wind field was very weak. 相似文献
202.
使用气象卫星资料,分析了1989年7月发生在四川东部的4个中尺度对流系统的特征,第一个系统是由3个对流云团合并而成,生成后快速向前移动,第二个为向后传播。第三个系统生成后,系统的西南部不断生成新的对流单体,使之维持准静止状态,最后一个系统的初期呈胞状结构,后与冷锋结合,成为冷锋云系的一部分,这4个系统都是西南低涡暖切变形势下的产物,随着形势演变,其大尺度环境略有差异。 相似文献
203.
东北地区中尺度对流复合体的卫星云图特征 总被引:5,自引:0,他引:5
通过10年(1983-1992年)卫星云图资料的分析,综合归纳了东北地区中尺度对流复合体(NMCC)的基本特征及其发展演变过程,由于受地理条件的影响,NMCC与美国大平原以及我国西北和华北平原上的MCC有明显差别,作为一类特殊的对流性天气系统,NMCC与一般中尺度对流云图特征有明显差异。 相似文献
204.
205.
根据日本GMS资料和部分常规资料,对我国南方地区春末夏初的10个中尺度对流复合体(MCCs)做了分析。它们的基本特征与美国MCC相近。它们主要活动在夜间,一般在山地背风一侧斜坡上或坡底附近形成;并在对流层中低层中低纬度地区几个天气系统的迭加处获得发展;向东偏南方向移动,与700~500 hPa之间的平均气流方向大体一致,冷云罩面积约为1.4×105 km2,比美洲的(2~3×105 km2)略小;持续时间为12小时左右,比美洲的(10小时)稍长。云区形状呈椭圆形,但偏心率≥0.6。云顶最低温度一般在-86℃以下,出现在冷云罩面积达到最大之前4~6小时。 相似文献
206.
Tao Zuyu Wang Hongqing Bai Jie Zhu Wenqin Shi Dingpu Yang Hongmei 《Acta Meteorologica Sinica》1995,9(2):184-189
A case of mesoscale convective complex(MCC) which evolved into a vortex is documented in this paper.As the MCC entered into the dissipating phase,a well-defined spirally banded structure became visible in the satellite image.The blackbody temperature(TBB) of the residual cold-cloud-shield indicates the vortex existed in the layer from 400 to 250 hPa.According to the upper air analysis,the upper level vortex was an anticyclone.The MCC-generated vortex was visualized in the satellite images because it was located in the subtropical high where the wind field was very weak. 相似文献
207.
Tian Yongxiang 《Acta Meteorologica Sinica》1995,9(3):338-348
The tropical cyclone motion is numerically simulated with a quasi-geostrophic baroclinic model.The flow field of a tropical cyclone is decomposed into its axisymmetric and asymmetric components.The relation between the ventilation flow vector and the motion vector of the tropical cyclone is investigated.The results of numerical experiments indicate:(1) There are both large-scale beta gyres and small-scale gyres in the asyrnmetric flow field.(2) The interaction between small-scale gyres and large-scale beta gyres leads to the oscillation of translation speed and translation direction for the tropical cyclone.(3) There are the large deviations between the ventilation flow vector calculated by means of Fiorino and Elsberry's method and the motion vector of tropical cyclone.(4) The ventilation flow vector computed using the improved method closely correlates with the motion vector of the tropical cyclone. 相似文献
208.
Temporal and spatial rainfall patterns were analysed to describe the distribution of daily rainfall across a medium‐sized (379km2) tropical catchment. Investigations were carried out to assess whether a climatological variogram model was appropriate for mapping rainfall taking into consideration the changing rainfall characteristics through the wet season. Exploratory, frequency and moving average analyses of 30 years' daily precipitation data were used to describe the reliability and structure of the rainfall regime. Four phases in the wet season were distinguished, with the peak period (mid‐August to mid‐September) representing the wettest period. A low‐cost rain gauge network of 36 plastic gauges with overflow reservoirs was installed and monitored to obtain spatially distributed rainfall data. Geostatistical techniques were used to develop global and wet season phase climatological variograms. The unscaled climatological variograms were cross‐validated and compared using a range of rainfall events. Ordinary Kriging was used as the interpolation method. The global climatological variogram performed better, and was used to optimize the number and location of rain gauges in the network. The research showed that although distinct wet season phases could be established based on the temporal analysis of daily rainfall characteristics, the interpolation of daily rainfall across a medium‐sized catchment based on spatial analysis was better served by using the global rather than the wet season phase climatological variogram model. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
209.
210.
S. Abhilash Someshwar Das S. R. Kalsi M. Das Gupta K. Mohankumar John P. George S. K. Banerjee S. B. Thampi D. Pradhan 《Pure and Applied Geophysics》2007,164(8-9):1491-1509
Pre-monsoon rainfall around Kolkata (northeastern part of India) is mostly of convective origin as 80% of the seasonal rainfall
is produced by Mesoscale Convective Systems (MCS). Accurate prediction of the intensity and structure of these convective
cloud clusters becomes challenging, mostly because the convective clouds within these clusters are short lived and the inaccuracy
in the models initial state to represent the mesoscale details of the true atmospheric state. Besides the role in observing
the internal structure of the precipitating systems, Doppler Weather Radar (DWR) provides an important data source for mesoscale
and microscale weather analysis and forecasting. An attempt has been made to initialize the storm-scale numerical model using
retrieved wind fields from single Doppler radar. In the present study, Doppler wind velocities from the Kolkata Doppler weather
radar are assimilated into a mesoscale model, MM5 model using the three-dimensional variational data assimilation (3DVAR)
system for the prediction of intense convective events that occurred during 0600 UTC on 5 May and 0000 UTC on 7 May, 2005.
In order to evaluate the impact of the DWR wind data in simulating these severe storms, three experiments were carried out.
The results show that assimilation of Doppler radar wind data has a positive impact on the prediction of intensity, organization
and propagation of rain bands associated with these mesoscale convective systems. The assimilation system has to be modified
further to incorporate the radar reflectivity data so that simulation of the microphysical and thermodynamic structure of
these convective storms can be improved. 相似文献