Diurnal Variations of the Land–Sea Breeze and Its Related Precipitation over South China

Abstract

Convection-permitting numerical experiments using the Weather Research and Forecasting (WRF) Model are performed to examine the diurnal cycles of land and sea breeze and its related precipitation over the south China coastal region during the mei-yu season. The focus of the analyses is a 10-day simulation initialized with the average of the 0000 UTC gridded global analyses during the 2007–09 mei-yu seasons (11 May–24 June) with diurnally varying cyclic lateral boundary conditions. Despite differences in the rainfall intensity and locations, the simulation verified well against averages of 3-yr ground-based radar, surface, and CMORPH observations and successfully simulated the diurnal variation and propagation of rainfall associated with the land and sea breeze over the south China coastal region. The nocturnal offshore rainfall in this region is found to be induced by the convergence line between the prevailing low-level monsoonal wind and the land breeze. Inhomogeneity of rainfall intensity can be found along the coastline, with heavier rainfall occurring in the region with coastal orography. In the night, the mountain–plain solenoid produced by the coastal terrain can combine with the land breeze to enhance offshore convergence. In the daytime, rainfall propagates inland with the inland penetration of the sea breeze, which can be slowed by the coastal mountains. The cold pool dynamics also plays an essential role in the inland penetration of precipitation and the sea breeze. Dynamic lifting produced by the sea-breeze front is strong enough to produce precipitation, while the intensity of precipitation can be dramatically increased with the latent heating effect.

Impact of Synoptic‐Scale Factors on Rainfall Forecast in Different Stages of a Persistent Heavy Rainfall Event in South China

“…Although land–sea breeze could be an essential mechanism that controls the diurnal variation of coastal rainfall in south China (Chen et al, , ), the precipitation over the two stages in this event was probably not dominated by land–sea breeze. The land–sea breeze and associated diurnal cycle of precipitation were relatively weak (not shown) due to high southerly wind (Chen et al, ; Wang & Sobel, ).…”

The influence of sea- and land-breeze circulations on the diurnal variability in precipitation over a tropical island

“…Another sensitivity experiment NOVAP was performed similarly to the IDEAL experiment except that the evaporation of liquid water, which prevents the cold pool generation from moisture convection process, was turned off. A similar methodology has been used to study diurnal cycles of precipitation in many different regions (Trier et al, 2010;Sun and Zhang, 2012;Bao and Zhang, 2013;Chen et al, 2016Chen et al, , 2017. The biggest advantage of this method is that it is able to capture the general characteristics of the diurnal cycle of precipitation and the related dynamical processes instead of just focusing on a single case.…”

“…Interactions between land breeze and prevailing wind are likely to produce precipitation over the coastal area or tropical islands (Keenan et al, 1988;Chen et al, 2017). Recent studies (Bao et al, 2013;Chen et al, 2016Chen et al, , 2017 have also found that convectively driven cold pools and latent cooling, as well as environmental wind and moisture, may play important roles in the propagation and maintenance of diurnal rainfall in coastal regions. How cold pools and latent cooling affect the diurnal cycle of rainfall and related LSB over a tropical island has not been studied extensively.…”

Influence of Synoptic Pattern and Low‐Level Wind Speed on Intensity and Diurnal Variations of Orographic Convection in Summer Over Pearl River Delta, South China

“…Recent studies have suggested that diurnal cycles of rainfall and convection over South China exhibit pronounced regional and intraseasonal variations (G. Chen et al, ; X. Chen, Zhao, et al, ; X. Chen et al, ; Jiang et al, ). Morning rainfall is dominant over offshore regions because of the surface convergence between the northerly land breeze and the prevailing southerly low‐level monsoonal wind (G. Chen et al, ; X. Chen et al, ; X. Chen et al, ). The rainfall and convection over the inland northeastern mountainous area exhibits two diurnal peaks.…”

“…Chen et al, 2015;Jiang et al, 2017). Morning rainfall is dominant over offshore regions because of the surface convergence between the northerly land breeze and the prevailing southerly low-level monsoonal wind (G. Chen et al, 2018;X. Chen et al, 2016;X.…”