The Observed and Simulated Major Summer Climate Features in Northwest China and Their Sensitivity to Land Surface Processes

• Published in: Acta meteorologica Sinica Vol. 28; no. 5; pp. 836 - 848
• Main Author: 李倩 薛永康
• Format: Journal Article
• Language: English
• Published: Heidelberg The Chinese Meteorological Society 01.10.2014; Center for Monsoon System Research, Institute of Atmospheric Physics, Chinese Academy of Sciences,Beijing 100190, China%Department of Geography, University of California, Los Angeles, CA 90095-1524, USA; Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA 90095-1524, USA
• Subjects: Atmospheric Protection/Air Quality Control/Air Pollution; Atmospheric Sciences; Earth and Environmental Science; Earth Sciences; Geophysics and Environmental Physics; Meteorology; 中国西北地区; 半干旱地区; 反气旋环流; 塔克拉玛干沙漠; 夏季降水; 敏感性试验; 气候特点; 陆面过程; China, People's Rep., Xinjiang; China, People's Rep., Xinjiang, Taklimakan Desert; China, People's Rep; Northwest China (NWC); atmospheric general circulation model; land cover change; land surface processes; arid and semi-arid regions
• ISSN: 0894-0525; 2095-6037; 2198-0934; 2191-4788
• DOI: 10.1007/s13351-014-4010-x

Northwest China （NWC） is a typical arid and semi-arid region. In this study, the main summer climate features over NWC are presented and the performance of an atmospheric general circulation model （NCEP GCM/SSiB） over this region is evaluated. Satellite-derived vegetation products are applied in the model. Based on comparison with observational data and Reanalysis II data, the model generally captures major features of the NWC summer energy balance and circulation. These features include： a high surface tem- perature center dominating the planetary boundary layer; widespread descending motion; an anticyclone （cyclone） located in the lower and middle （upper） troposphere, covering most parts of central NWC; and the precipitation located mainly in the high elevation areas surrounding NWC. The sensitivity of the summer energy balance and circulation over NWC and surrounding regions to land surface processes is assessed with specified land cover change. In the sensitivity experiment, the degradation over most parts of NWC, except the Taklimakan desert, decreases the surface-absorbed radiation and leads to weaker surface thermal effects. In northern Xinjiang and surrounding regions, less latent heating causes stronger anomalous lower-level anticyclonic circulation and upper-level cyclonic circulation, leading to less summer precipitation and higher surface temperature. Meanwhile, the dry conditions in the Hexi Corridor produce less change in the latent heat flux. The circulation change to the north of this area plays a domi- nant role in indirectly changing lower-level cyclonic conditions, producing more convergence, weaker vertical descending motion, and thus an increase in the precipitation over this region.