Numerical Study of the Impact of Land Cover Change on Structure and Evolution of the Sea Breeze Front over Hainan Island

The sea breeze front (SBF) is the landward edge of the sea breeze circulation, which has characteristics similar to the cold front. SBF is a key object of coastal meteorological research because it can trigger strong convection even in disastrous weather, such as thunderstorms in coastal areas. Herein, a typical SBF over Hainan Island is examined using the weather research and forecasting model. Sensitive experiments were designed to explore the effect of land cover changes on the structure and evolution of SBF and its possible mechanism. Results revealed that the effect of land cover change on SBF is determined by the comprehensive influence of multiple surface and vegetation attributes. The dynamic effects of afforestation inhibit the development of SBF, while the thermal effects promote it, which means that the influence of afforestation on SBF is because of the competition between two opposite forces. The decreased albedo and increased leaf area index result in a small increase in sensible heat fluxes, which can increase the temperature difference between land and sea—the driving force of sea breeze. The increase in surface roughness can decrease the wind speed, inland propagation, and vertical velocity of SBF. However, the difference in SBF between the FOREST and CNTL experiments is small due to the large forest land use of Hainan Island. Meanwhile, the thermal and dynamic effects of deforestation are beneficial in promoting the development of SBF. The increased albedo and decreased leaf area index result in a significant decrease in latent heat flux and an increase in sensible heat flux in the afternoon. Thus, the warming and humidification effects of deforestation on the lower atmosphere are obvious, which increases the sea-land temperature gradient. Meanwhile, the decrease in surface roughness causes an increase in the wind speed. Consequently, the wind speed, inland propagation, and vertical velocity of SBF are significantly increased.