资源环境科技发展态势分析平台

Trends and features of Atmospheric Boundary Layer (ABL) over southern part of west coast of India has been studied using MERRA datasets for 1980–2018 during different seasons incorporating the marine and continental influences. A significant decrease in the ABL height (ABLH) has been observed in the westerly regimes of the west coast. The shallow ABL is expected to cause amplified response in the atmosphere and enhance the formation of extreme events over the region. It is also observed that its variation is related with other surface layer parameters such as specific humidity, temperature, surface zonal wind, Richardson number, CAPE (Convective Available Potential Energy) and sensible & latent heat fluxes. A significant increasing (decreasing) trend in specific humidity (surface zonal wind) is observed in pre-monsoon, monsoon and post monsoon seasons and this trend has significant correlation with the ABL height. The CAPE has a significant increasing trend in daytime of pre-monsoon season, which can lead to formation of intense thunderstorms. A significant reduction in the surface dynamic instability due to decrease in surface westerly zonal wind is observed and it has a significant role in the decreasing trend of ABL height. Surface sensible heat flux possesses a significant decreasing (increasing) trend during the pre-monsoon and post monsoon seasons (monsoon season). Surface latent heat flux shows a decreasing trend during the monsoon which may be attributed to the combined effect of decrease in ABL height and trapping of moisture at lower levels together with an increase in surface temperature.