高原低涡和切变线影响下那曲云-降水的宏微观特征对比研究OA

The low-pressure weather systems on the Qinghai-Xizang Plateau not only influence the cloud-precipi-tation over the main body of the Qinghai-Xizang Plateau,but also play a crucial role in the generation and devel-opment of disastrous weather such as rainstorms in the eastern regions of China.This paper makes use of the data from the ground-based Ka-band millimeter-wave cloud radar(Ka-CR),K-band micro-rain radar(K-MRR)and Parsivel2 laser disdrometer in Nagqu during the Third Qinghai-Xizang Plateau Experiment of Atmospheric Scienc-es(TIPEX-III)from July to August 2014 and July to August 2015.Combining with the Yearbook of Plateau Vor-tices and Shear Lines,the ERA-5 atmospheric reanalysis data,and the sounding data from Nagqu Station,First,the observational data of the three devices are processed and subjected to quality control.Subsequently,a com-parative study is carried out on the macro-micro characteristics of cloud-precipitation in Nagqu under the influ-ence of plateau vortices and shear lines,as well as their differences.Additionally,the atmospheric environmen-tal conditions corresponding to the differences in cloud-precipitation structures and physical characteristics are discussed.The results show that:(1)Single-layer clouds dominate over Nagqu,but under the influence of low vortices,a higher proportion of double and multi-layer clouds are formed.The low vortices produce more and deeper convective or high clouds,corresponding to overall higher cloud bases and tops and thicker cloud layers compared to the shear line.In contrast,the overall cloud body of the shear line is relatively thin or there are more middle and low clouds.In terms of precipitation,the proportion of moderate-intensity precipitation under the low vortex is small,but the proportions of weak and strong precipitation are larger.(2)The bright band feature of the low vortex radar echo is more prominent.The probability distributions of the reflectivity factor(Z)and radial velocity(Vr)of the low vortex are more concentrated compared to the shear line.The echoes in the high-frequen-cy region are weaker,but there are also some stronger echoes.The quantile profiles of Vr and spectrum width(W)decrease and increase as the height decreases,reflecting the continuous coalescence and riming growth pro-cesses during the ice particle sedimentation.(3)The concentrations of raindrops of all particle sizes formed by ice particles in the low vortex when they just melted(at an altitude of about 0.9 km above the ground)are higher than those of the shear line.From 0.7 km to the ground,the number concentrations of large raindrops in the low vortex are still higher,while the number concentrations of small raindrops are lower.At the same height,the raindrop spectra under the low vortex are wider than those of the shear line.As height decreases,raindrop colli-sion and coalescence is the primary microphysical process for both weather types,but low vortices exhibit higher efficiency in raindrop collision and coalescence.(4)Comparing the atmospheric environmental conditions,it is found that the atmospheric temperature under the influence of the low vortex is slightly higher than that under the shear line,the relative humidity is significantly higher,and the convective available potential energy is also greater.The differences in thermodynamic and dynamic conditions under the control of these two types of weath-er align with the aforementioned differences in macro-micro parameters of cloud-precipitation.The research results reveal the macro-micro characteristics differences of cloud-precipitation in Nagqu under the influence of the plateau vortex and shear line,providing a reference basis for the early warning and forecasting of disastrous weather on the plateau.