Abstract Trends and features of Atmospheric Boundary Layer (ABL) over southern part of the 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.

中文翻译：

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大气边界层高度和表面参数：印度西海岸的趋势和关系

摘要 使用 MERRA 数据集在 1980-2018 年不同季节结合海洋和大陆影响研究了印度西海岸南部大气边界层 (ABL) 的趋势和特征。在西海岸的西风区域观察到 ABL 高度 (ABLH) 显着下降。预计浅层 ABL 将在大气中引起放大的响应，并加强该地区极端事件的形成。还观察到它的变化与其他表层参数有关，例如比湿度、温度、地表纬向风、理查森数、CAPE（对流可用势能）以及感热和潜热通量。在季风前观察到比湿度（地表纬向风）的显着增加（减少）趋势，季风和后季风季节，这种趋势与 ABL 高度有显着相关性。CAPE在季风前期的白天有明显的增加趋势，这可能导致强烈雷暴的形成。由于地表西风纬向风减弱，地表动力不稳定性显着降低，这对 ABL 高度的下降趋势具有重要作用。地表感热通量在季风前和季风后季节（季风季节）具有显着的减少（增加）趋势。季风期间地表潜热通量显示出下降趋势，这可能是由于 ABL 高度降低和在较低水平捕获水分以及地表温度升高的综合影响。