A kinetic energy budget on the severe wind production that causes a serious state grid failure in Southern Xinjiang China. (20th May 2020)

• Record Type: Journal Article
• Authors: Fu, Shen‐Ming; Jin, Shuang‐Long; Shen, Wei; Li, Dan‐Yu; Liu, Bin; Sun, Jian‐Hua
• Is Part Of: Atmospheric science letters. Volume 21:Number 7(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-05-20
• Subjects: Divergent wind -- Kinetic energy -- Rotational wind -- State Grid -- Windstorm; Atmospheric physics -- Periodicals; 551
• DOI: 10.1002/asl.977
• Languages: English
• ISSNs: 1530-261X

Abstract

Abstract: Based on the European Centre for Medium‐Range Weather Forecasts (ECMWF) ERA5 reanalysis data, in this study, formation mechanisms of a severe windstorm that caused successive trippings of the transmission lines in Southern Xinjiang were investigated. The strong windstorm occurred within a lower‐tropospheric warm region due to adiabatic heating of the descending motions ahead of a shortwave trough in the westerly wind (the blocking effects of high mountain was a key reason for the strong descending motions). The kinetic energy (KE) budget indicates two typically different stages appeared in the variation of the windstorm. The former stage showed a rapid wind KE enhancement in the lower troposphere. The KE increase was mainly governed by the downward stretching of high KE (i.e., downward momentum transportation) from the middle troposphere (rather than from the upper‐level jet) and the KE production due to the work on rotational wind by the pressure gradient force. The latter stage showed a rapid KE decrease mainly due to the transport of KE by the rotational wind and the pressure gradient force's negative work on the rotational wind. In contrast, the vertical advection of KE still acted as transporting high KE from middle troposphere to lower troposphere, which resisted the KE reduce at the lower levels. Abstract : In this study, formation mechanisms of a severe windstorm that caused successive trippings of the transmission lines in Southern Xinjiang were investigated by applying a kinetic energy (KE) diagnosis with the European Centre for Medium‐Range Weather Forecasts (ECMWF) ERA5 reanalysis data. Results indicate that the strong windstorm occurred within a lower‐tropospheric descending region that was located ahead of a shortwave trough in the westerly wind. Two typically different stages appeared in the variation of the windstorm. The former stage showed a rapid wind KE enhancement in the lower troposphere. The KE increase was mainly governed by the downward momentum transportation from the middle troposphere and the KE production due to the work on rotational wind by the pressure gradient force. The latter stage showed a rapid KE decrease mainly due to the transport of KE by the rotational wind and the pressure gradient force's negative work on the rotational wind, although the notable downward momentum transportation still maintained strong intensity.