Mechanisms of Night Sudden Intense Warming Event in the East of Xi’an Area and Numerical Model Calibration Method
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Abstract:
Based on the data of meteorological stations over Shaanxi Province, NCEP/NCAR and ERA5 global reanalysis data, an in-depth analysis is conducted on the abnormal temperature jump process in the eastern part of Xi’an during the early morning hours of December 10, 2019. The results show that: (1) This night sudden intense warming event developed rapidly and locally. It wasn’t easy to forecast. (2) The dry northwest airflow at 500 hPa and the dry warm air at 850 hPa were beneficial to the sinking adiabatic heating. There was inversion near the surface in Xi’an, which hindered the vertical exchange of atmospheric heat. The 2 m temperature in the east of Xi’an was significantly warmer than that in the surrounding areas. It lasted for a long time, creating favourable conditions for the nighttime warming in this area. (3) In this event, the adiabatic warming effect was strengthened with the eastward movement of the Xinjiang high ridge. The strong warm advection had been maintained in the lower layer of the eastern Xi’an area for a long time. In addition, because of the continuous invasion of weak cold air and the barrier effect of Lishan Mountain, the warm air near the ground in the Lintong area was compressed sharply. Under the four factors, the night temperature in the Lintong area increased significantly. (4) 18 night sudden intense warming cases in the Lintong area are analyzed, and the occurrence criteria are summarized. The correction scheme is put forward and tested combined with the numerical model prediction products. The scheme has a positive correction effect in the Lintong area, providing a reference for the night temperature prediction.
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Supported by:Beijing E-Tiller Technology Development Co., Ltd.
Supported by:Beijing E-Tiller Technology Development Co., Ltd.