Simulation of land-sea breeze effect on the diurnal cycle of convective activity in the Eastern Coast of North Sumatra using WRF model

Land-sea breeze can generate the growth of convective clouds and rainfall that cause hydrometeorological disasters. Early identification of the diurnal cycle of convective activities can help in mitigating the impact of disasters. The eastern coast of North Sumatra is directly adjacent to the Malacca Strait that is suitable for the land-sea breeze model simulation. The land-sea breeze circulation affects the atmospheric dynamics. This study aimed to simulate the land-sea breeze circulation using the WRF model and analyzed its effect on the diurnal cycle of convective activity. The convective activity was identified using convective index, moisture transport, and rainfall distribution. ECMWF data from 2016 to 2017 were processed to determine the land-sea breeze rainy days based on Six Filtering Method and heavy rainfall definition. The Himawari-8 satellite data was used to calculate the convective index, and the specific humidity and wind from FNL data was used to calculate the moisture transport. The GSMaP rainfall data was used to depict the diurnal rainfall distribution over Sumatra. The prevailing sea breeze on the eastern coast of North Sumatra was the northeasterly wind. Sea breeze intrusion on the north coast of North Sumatra is characterized by a decrease in temperature, rising humidity, and easterly wind. Spatially, there is a time lag of about 1–2 hours from the peak convection to the formation of rainfall in the eastern coast region of North Sumatra. Peak diurnal rainfall in the eastern coast of North Sumatra generally occurs during midnight.