In order to better exploit the detection advantages of wind profile radar in upper layer, the detection data of ST wind profile radar during 2014-2017 from Huainan Climate and Environment Observatory (HCEO), Institute of Atmospheric Physics, Chinese Academy of Sciences, were used to evaluate the detection performance of ST wind profile radar under different detection mode combinations, and the influence of meteorological environment on detection performance was explored. On this basis, the applicability of detection mode combinations was discriminated in practical operations. The results show that ST wind profile radar can achieve different detection purposes by combining high or low modes with switching altitude. However, there are differences in detection performance under different combinations of mode. On the one hand, the detection performance of radar gradually decreases before the mode conversion and rapidly increases after the mode conversion, while it gradually decreases with height under the high mode. On the other hand, the detection performance of radar doesn’t change significantly in process of the conversion, while it gradually decreases after the high mode to a certain height. In addition, the reducing degree of detection performance gradually increases as the transition altitude approach in autumn and winter. The precipitation reduces the detection performance in lower and middle layers of troposphere. So, we select suitable mode combination based on the detection performance of radar to atmospheric boundary layer, troposphere and stratosphere.

Based on the detailed information on transmission line lightning strike and meteorological elements data in 6 hours before transmission line lightning strikes from 1990 to 2017 in Shijiazhuang of Hebei Province, the statistical methods such as occurrence probability, occurrence frequency, linear trend and fluctuation amplitude were used to analyze occurrence regularity of transmission line lightning strikes, variation of timing wind, pressure, relative humidity, air temperature and ground temperature in 6 hours before transmission line lightning strikes. By defining the cumulative occurrence frequency of transmission line lightning strikes, the meteorological element indicators of occurrence of transmission line lightning strikes were determined, and the accuracy of level prediction of transmission line lightning strike accidents in Jingxing county of Shijiazhuang on 9 August 2018 was tested by comparing the EC numerical prediction with the automatic station data. The results show that the transmission line lightning strike accidents increased significantly and there were three peaks in Shijiazhuang in recent years, occurring mainly from afternoon to morning in summer, in August there was the highest probability, and in a day it was highest from 03:00 BST to 04:00 BST. In addition, when there was easterly wind, air pressure and relative humidity were rising, or when air temperature and land surface temperature were dropping, transmission line lightning strike accidents occurred frequently. Within 6 hours, when air pressure rose by 0.0-2.0 hPa, air humidity increased by 0-14%, air temperature dropped by 0-3.0 ℃, land surface temperature dropped by 0-6.5 ℃, and with the east wind as the central wind direction, the timing wind direction was within the range of 90°, the occurrence regularity and meteorological indicators of lightning strikes on transmission lines were well predicted and tested on 9 August 2018, which had certain guiding significance for preventing lightning strike accidents.

Abstract: Based on the every 3-hour precipitation data from ERA-Interim dataset of European Centre for Medium-Range Weather Forecast (ECMWF) during 1979-2017, the spatial and temporal variation characteristics of precipitation in Qilian Mountain and its surrounding areas in the past 39 years were analyzed. The results show that the average annual precipitation in the study area was 232.4 mm, the precipitation had an increasing trend with a climate trend rate of 24.7 mm·(10 a)-1, and precipitation increased obviously in the semi-humid area, with a climate trend rate of 45.9 mm·(10 a)-1. The precipitation had a mutation between 1996 and 1997, and then increased significantly after 2000. The precipitation in the study area was largest in summer, accounting for 54.08% of the annual precipitation, while it was smallest in winter, accounting for 3.88% of the annual precipitation. The maximum monthly precipitation was 45.1 mm in July, while the minimum was 2.7 mm in December. The diurnal variation of precipitation had two peaks, the maximum peak value occurred during 14:00-20:00, and the second peak vaule occurred during 05:00-08:00. Both of the annual precipitation and climate trend rate in the study area had a good correspondence with the altitude. The higher the altitude was, the greater the precipitation would be, and the maximum precipitation was in the high altitude area in the central part of Qilian Mountains. The distribution of annual precipitation was mostly from northwest to southeast, and precipitation in the central and eastern parts of the Qilian Mountains was relatively larger.