Retrieval and Experiments of Atmospheric Vertical Motions in Convective Precipitation Clouds

Detecting the vertical motions of the atmosphere in convective clouds is difficult. The cost of aircraft detection is expensive, limited by maximum flight altitude, high detection risk, low frequency, etc. In recent years, remote sensing instruments are applied with the development of detection technology. Ground-based vertical pointing radar has become a reliable way to obtain atmospheric vertical motions, through which the cloud structure and dynamic characteristics of convective precipitation clouds can be obtained, and the distribution and evolution characteristics of the intensity and proportion of atmospheric vertical movement during the mature stage of convection can be monitored in detail. Based on the vertical structure detection data of precipitation clouds from ground to 15 km height by a vertical pointing radar with 5520 MHz C-band Frequency Modulation Continuous Wave (VPR-CFMCW) technology, the vertical motions in the convective precipitation cloud are retrieved, and the vertical structure of convection and evolution characteristics of vertical motions at different heights are analyzed. The VPR-CFMCW is used to carry out the atmospheric vertical motion retrieval experiments on 4 convective precipitation events at the Longmen Station in Guangdong Province during pre-monsoon from 20 April to 22 April in 2019. It is found that the updrafts of the atmosphere before convective precipitation have a positive contribution to the intensity of reflectivity and surface precipitation afterwards. The deep convection is inclined, which causes the vertical section to show a layered structure at certain moments. Convective precipitation is dominated by downdrafts of the entire level, updrafts and downdrafts of the upper-level atmosphere appear alternately, when downdrafts account for the highest proportion in the lower-level, and the updrafts account for an increased proportion above 6 km height. The intensity of atmospheric vertical motions is strong in the upper-level, as strong updrafts and downdrafts exceeding 10 m·s^-1 mostly appear above 6 km height. The vertical motions vary greatly at 4-6 km height. The average downdraft speed is less than 5 m·s^-1 and the average updraft speed is around 2 m·s^-1 under 4 km height. The development of ground-based vertical pointing radar can improve the understanding of vertical structure evolution and dynamic characteristics of convective precipitation clouds.