  Citation: Yang, J.; Liu, E.; Liu, Y.; Lin, Y.; Yin, Y.; Jing, X. Impact of Vertical Wind Shear on Summer Orographic Clouds over Tian Shan Mountains: A Case Study Based on Radar Observation and Numerical Simulation. Remote Sens. 2022, 14, 1583. https://doi.org/10.3390/ rs14071583 Academic Editor: Filomena Romano Received: 14 February 2022 Accepted: 23 March 2022 Published: 25 March 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). remote sensing Article Impact of Vertical Wind Shear on Summer Orographic Clouds over Tian Shan Mountains: A Case Study Based on Radar Observation and Numerical Simulation Jing Yang 1,2 , Enhong Liu 1 , Yubao Liu 1, * , Yanjun Lin 1 , Yan Yin 1 and Xiaoqin Jing 1 1 Key Laboratory for Aerosol Cloud-Precipitation of China Meteorological Administration/Key Laboratory of Meteorological Disaster, Ministry of Education (KLME)/Joint International Research Laboratory of Climate and Environment Change (ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD)/Precision Regional Earth Modeling and Information Center (PRMIC), Nanjing University of Information Science & Technology, Nanjing 210044, China; jing.yang@nuist.edu.cn (J.Y.); 20191203014@nuist.edu.cn (E.L.); 20191201047@nuist.edu.cn (Y.L.); yinyan@nuist.edu.cn (Y.Y.); xiaoqin.jing@nuist.edu.cn (X.J.) 2 Key Laboratory of Cloud and Fog Physical Environment of China Meteorological Administration, Beijing 100081, China * Correspondence: ybliu@nuist.edu.cn Abstract: In this research, a summer orographic precipitation process that occurred over the Tian Shan Mountains on 27 July 2019, was investigated, focusing on the impact of vertical wind shear on clouds. Multiple remote sensors were deployed to measure the ambient conditions and the fine structures of clouds and precipitation, including a radiometer, a vertically pointing micro-rain radar (MRR), and a cloud radar on a truck. In addition, a convection-permitting simulation was conducted to investigate the role of vertical wind shear. The results show that (1) according to the MRR measurements, the precipitation was mainly due to a warm rain process and was mostly light to moderate, with no strong convection occurring; (2) the cloud structures observed by the cloud radar were very different above and below the shear level, and the cloud evolution was strongly controlled by the vertical wind shear, and (3) radar observations and model simulations indicated that vertical wind shear had an inhibiting impact on the vertical development of clouds and was responsible for the formation of multi-layer clouds. The analysis highlights the advantages of the use of millimeter radars to measure the fine structures of orographic clouds; thus, they can be powerful tools with which to improve our understanding of the interactions occurring between vertical wind shear and clouds over complex terrain. Keywords: orographic cloud; vertical wind shear; Tian Shan Mountains; radar measurement; numerical simulation 1. Introduction In the arid northwest of China, orographic precipitation is the most important water resource. There is much interest in studying the orographic clouds and precipitation in this region in various disciplines, such as meteorology, hydrology, ecology, and forestry [1–4]. Tian Shan is among the largest mountain ranges in Central Asia and is home to the head- waters of several major river systems. However, the measurement of the orographic clouds and precipitation over the Tian Shan Mountains is challenging because of the complex terrain and high elevations involved [5,6]. The gauge stations over the Tian Shan Mountains are sparsely distributed and have very limited capabilities, and gauges only provide point measurements of surface precipitation. Radar measurements of clouds and precipitation are also lacking because there is only a single centimeter radar in operation, which covers a very limited area over the mountains. Therefore, the orographic cloud and precipitation processes over the Tian Shan Mountains are still poorly understood. Remote Sens. 2022, 14, 1583. https://doi.org/10.3390/rs14071583 https://www.mdpi.com/journal/remotesensing