Characteristics and Mechanisms of the Sudden Warming Events in the Nocturnal Atmospheric Boundary Layer： A Case Study Using WRF

• Published in: Acta meteorologica Sinica Vol. 29; no. 5; pp. 747 - 763
• Main Author: 马媛媛 杨毅 胡小明 甘茹蕙
• Format: Journal Article
• Language: English
• Published: Beijing The Chinese Meteorological Society 01.10.2015; Center for Analysis and Prediction of Storms/School of Meteorology, University of Oklahoma, Norman, OK 73072, USA; Key Laboratory of Arid Climate Change and Disaster Reduction of Gansu Province, Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China%Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing University of Information Science & Technology, Nanjing 210044, China
• Subjects: Atmospheric Protection/Air Quality Control/Air Pollution; Atmospheric Sciences; Earth and Environmental Science; Earth Sciences; Geophysics and Environmental Physics; Meteorology; WRF模式; 中国西北部; 事件机制; 变暖; 大气边界层; 案例; 模型模拟; 黄土高原; USA; China, People's Rep., Loess Plateau; Australia; China, People's Rep., Gansu Prov; Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL); enhanced vertical mixing; nocturnal warming events; wind shear; Weather Research and Forecasting (WRF)
• ISSN: 2095-6037; 0894-0525; 2198-0934; 2191-4788
• DOI: 10.1007/s13351-015-4101-3

Although sudden nocturnal warming events near the earth＇s surface in Australia and the United States have been examined in previous studies, similar events observed occasionally over the Loess Plateau of Northwest China have not yet been investigated. The factors that lead to these warming events in such areas with their unique topography and climate remain not clear. To understand the formation mechanisms and associated thermal and dynamical features, a nocturnal warming event recorded in Gansu Province （northwest of the Loess Plateau） in June 2007 was investigated by using observations and model simulations with the Weather Research and Forecasting （WRF） model. Observations showed that this near-surface warming event lasted for 4 h and the temperature increased by 2.5℃. During this event, a decrease in humidity occurred simultaneously with the increase of temperature. The model simulation showed that the nocturnal warming was caused mainly by the transport of warmer and drier air aloft downward to the surface through enhanced vertical mixing. Wind shear played an important role in inducing the elevated vertical mixing, and it was enhanced by the continuous development of the atmospheric baroclinicity, which converted more potential energy to kinetic energy.