Tower-observed structural evolution of the low-level boundary layer before, during, and after gust front passage in a coastal area at low latitude

• DOI: 10.1016/j.wace.2022.100429
• Publication Date: 2022-03-11T17:52:02Z
• Authors: Jielan Xie; Changxing Lan; Honglong Yang; Ruiquan Gao; Chao Lu; Baomin Wang; Pak Wai Chan; Shaojia Fan; Lei Li
• Keywords: Ground temperature inversion; Meteorology. Climatology; 356-m meteorology tower; Gust front; QC851-999; Atmospheric boundary layer; 01 natural sciences; 0105 earth and related environmental sciences

A gust front is generated when the cold downdraft from a thunderstorm reaches the surface, causing the warm air mass at the surface to lift. This is always accompanied by gusts and strong winds, and results in severe destruction of property and loss of life, especially in city areas. Despite the potentially adverse effects associated with this weather phenomenon, the microphysical structure of gust fronts remains unclear, owing to a lack of high temporal–spatial resolution observations, and because research on the thermodynamic structure of gust fronts is insufficient. This study mainly analysed the atmospheric boundary layer (ABL) structure before, during, and after the passage of two selected gust fronts, using meteorological data obtained from a 356-m tall meteorology tower located in the eastern Pearl River Estuary area. The thermodynamic structure of the ABL was of particular interest. The results show that meteorological factors fluctuated significantly and simultaneously at the 13 observation altitudes from the bottom to the top of the meteorology tower, and significant changes in the vertical distribution of the analysed parameters were observed during the passage of the gust fronts. The ABL structure transformed from an unstable state before the passage of the gust fronts to a stable state after they had passed, and a ground temperature inversion was evident. Moreover, the temperature inversion lasted for several hours after the dissipation of the gust fronts, and occurred intermittently, with the inversion centre shifting up or down and showing multiple intensity centres. The turbulence also showed a strengthening trend during gust front passage. Furthermore, we determined that the thermal and mechanical turbulence affected the maintenance of the temperature inversion. The results of this study will contribute to our knowledge on the microphysics of the ABL of gust fronts, and will further benefit the correction of numerical modelling of severe weather.