Analysis of convective and stratiform precipitation characteristics in the summers of 2014–2019 over Northwest China based on GPM observations

Abstract

The research on three-dimension of precipitation is far less than sufficient due to limited satellite observation over Northwest China. In this study, the characteristics of convective and stratiform precipitation, and the relationships between the two types of precipitation and several atmospheric parameters for the summers of 2014–2019 over Northwest China are explored based on GPM observations, ERA5 reanalysis products and Integrated Global Radiosonde Archive dataset. Stratiform precipitation is dominant over Northwest China and four typical regions, i.e., the Tianshan Mountain (region A), Tarim Basin (region B), Qilian Mountain (region C) and eastern part of Northwest China (region D), are selected. The storm top height of convective precipitation is 2–3 km higher than that of stratiform precipitation, and the highest value (near 16 km) occurs in region C and the lowest value (about 10 km) occurs in region B. Moreover, convective and stratiform precipitation profiles over Northwest China are similar to those over East China. Below 4 km, the largest rain rate appears in region A for convective precipitation and in region D for stratiform precipitation, and the maximum latent heat appears at 4–6 km. The peak frequency of convective precipitation occurs in the afternoon among four regions, whereas the diurnal cycles for stratiform precipitation display a bimodal pattern with the two peaks that more likely occur in the morning and late afternoon. Furthermore, the precipitation intensity changes with total column water vapor and follows an approximate quadratic function in four regions. The precipitation conversion rate and CAPE of convective precipitation are evidently larger than those of stratiform precipitation. A pattern of convergence in the lower troposphere and divergence in the upper troposphere appears, which is conducive to the development of precipitation except region B where downdrafts prevail. Additionally, the most significant warming and humidification exhibit in the middle and lower troposphere respectively during precipitation. This study not only displays the features of convective and stratiform precipitation over Northwest China from the perspective of satellite remote sensing, but also the patterns of atmospheric parameters during precipitation would provide a reference for numerical simulation over arid-semiarid regions of China.