Analysis on the Cause and Forecast Deviation of an Extreme Rainstorm in Changsha Urban Area

Using NCEP reanalysis data,high-altitude and ground observation data,numerical model data,satellite and radar data,formation cause and forecast deviation of an extreme rainstorm process in Changsha urban area at night on June 9,2020 were analyzed.The results showed that(1)the extreme rainstorm process developed near the surface convergence line,with strong localization,short duration and large hourly rainfall intensity.(2)Under the high temperature and high humidity environment,the low-level cold advection and the hot low-pressure system interacted,and the potential con-vective unstable energy was released,and a strong convective weather was formed.(3)The convergence of water vapor in the lower layer and the strong upward movement provided sufficient water vapor for the rainstorm.The low-centroid thunderstorm was the main reason for the extreme rainstorm.(4)The forecast deviation of the numerical model to the low-level shear line and the mesoscale convergence line was an important reason for the forecast deviation of the heavy rainfall area.

Study on Relationship between Summer Electricity and Meteorology in Changsha City

[ Objective] The research aimed to study relationship between summer electricity and meteorological factors. [ Method] Electrical load characteristics in Changsha during 2007 -2010 were analyzed. Correlation analysis between electrical load and meteorological factors （daily average temperature, the maximum temperature, the minimum temperature, rainfall, wind, relative humidity and atmospheric pressure） during July - September of 2007 -2010 was conducted. [ Result] Changes of the meteorological factors could directly affect electrical load, and temperature was the first influence factor. Prediction model of summer electrical load in Changsha was established by regression analysis method.[ Conclusion] The research could provide reference basis for prediction of the electrical load in Changsha.

Application of New Type of Detection Data in a Heavy Rainfall Process in Changsha

Using detection data with high space-time resolution from the wind profile radar and millimeter wave cloud radar of Changsha station, and combining observation data of ground automatic station, heavy precipitation process in Changsha area from June 29 to July 1, 2017 was analyzed. The results showed that the atmospheric temperature advection was calculated by inversion of wind profile radar data of boundary layer, and it could intuitively analyze changes of atmospheric temperature advection before and after precipitation process. The variation characteristics of intensity, thickness and height of warm and cold advection in the upper and lower levels were highly related to the evolution of the precipitation process. The millimeter wave cloud radar can better reflect the vertical structure and evolution of the cloud over the observatory, and had certain indications for the structure characteristics of cloud before the starting of precipitation. When the strong reflectivity started to approach the ground, it also meant that heavy precipitation began to appear.

Characteristics Analysis of the Temperature inside and outside the Themometer Shelter in Changsha during Summer

A statistical analysis on the simultaneous observation data of the temperature inside and outside the themometer shelter in Changsha during summer of 2011 and 2012 was carried out. The results show that the temperature outside the themometer shelter is higher（ lower） than that inside the themometer shelter in the daytime（ nighttime）. However,there exists a similar variation trend for the average temperature and the extremely maximum temperature inside and outside the themometer shelter in summer. The average temperature and the extremely maximum temperature outside the themometer shelter are higher than that inside the themometer shelter. Furthermore,there exists a difference between the temperatures inside and outside the themometer shelter during different weather conditions. The difference of average temperature reaches 1. 2 ℃ in rainy day,2. 8 ℃ in cloudy day and 3. 1 ℃ in sunny day,and the extremely maximum temperature difference reaches 6. 4 ℃. Especially for the days of high temperature ≥35 ℃,there is 61 high temperature days inside the themometer shelter,while there is 125 high temperature days inside the themometer shelter during 2011- 2012. Furthermore,the extremely maximum temperatures inside and outside the themometer shelter are 38. 9 and42. 0 ℃ respectively. Rainfall and showery rain are the most effective ways to relieve the high temperature in summer. Therefore,the difference between the temperatures inside and outside the themometer shelter should be taken into account in the high temperature forecast and public meteorological service.

Analysis of the Impact of Nepal＇s Giant Earthquake on China＇s Climate in 2015

The situation of a great earthquake in Nepal from April to May in 2015 was described, and the abnormal atmospheric circulation and cli- mate when the great earthquake occurred were analyzed. Because of the great influence of the great earthquake on the atmosphere, the atmos- pheric circulation and climate in the late stage of Nepal will be affected. The great earthquake had transient effects on China＇s climate. Firstly, tem- perature from the ground to high altitudes increased abnormally; secondly, after the occurrence of the great earthquake, extremely low pressure generated in the earthquake region, and cold and warm airflow converged, so that heavy rainfall occurred to the southwest of the plateau. Thirdly, it cut off southwesterly airflow transporting water vapor to regions south of the Yangtze River, so that hot and dry weather appeared in the regions in late April. Moreover, the great earthquake affected China＇s climate in a short term. Nepal＇s giant earthquake increased zonal circulation cell at lat- itudes, and the circulation cell could make subtropical high over Western Pacific strengthen and extend westward to control regions south of the Yan- gtze River, so that hot and dry weather appeared in regions south of the Yangtze River in summer. In the next year after the great earthquake oc- curred, the earthquake is conducive to the strengthening and maintaining of Meiyu zone in the Yangtze River basin, and large floods will appear easily in the Yangtze River basin.