Affiliation:
1. School of Atmospheric Sciences Sun Yat‐Sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) Zhuhai China
2. Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies Sun Yat‐Sen University Zhuhai China
3. Key Laboratory of Tropical Atmosphere‐Ocean System Sun Yat‐Sen University Ministry of Education Zhuhai China
4. Institute of Tropical and Marine Meteorology China Meteorological Administration Guangzhou China
Abstract
AbstractForecasting warm‐sector rainfall (WR) remains a major challenge, primarily due to weak synoptic forcing. Through cloud‐permitting numerical simulations, in addition to direct triggering mechanism from low‐level jets, we identify the important role of gravity waves in a heavy WR event in South China via convective preconditioning. The preconditioning manifests as mid‐level moistening and destabilization with wave‐like variations. This process is driven by fast‐propagating (∼24 m s−1) n = 2 waves, associated with lower‐tropospheric ascents and upper‐tropospheric descents. Waves are generated during the evolution of northern frontal rainfall (FR). As FR intensifies, surges in low‐level diabatic cooling mainly resulting from microphysical processes, trigger n = 2 waves, which further precondition the environment along their path. In contrast, a sensitivity experiment involving stably developing FR fails to reproduce the preconditioning process by waves and the subsequent occurrence of WR. Overall, our study illuminates a new pathway through which FR significantly influences WR via gravity waves.
Funder
National Natural Science Foundation of China
Sun Yat-sen University
China Meteorological Administration
Basic and Applied Basic Research Foundation of Guangdong Province
Publisher
American Geophysical Union (AGU)