ANALYTICAL LAND-VEGETATION-ATMOSPHERE MODEL TO STUDY SOIL MOISTURE BIMODALITY

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 Soil moisture through soil water potential controls the transpiration from vegetation. This study investigates how vegetation impacts soil moisture bimodality in coupled analytical land-vegetation-atmosphere model for mid latitude region. The influence of precipitation on soil moisture is direct, but soil moisture through evapotranspiration controls mass and energy transfer between land and atmosphere, thus influencing the precipitation. In the current study, we partitioned evapotranspiration into transpiration and soil evaporation and considered three different vegetation schemes, i.e., static Leaf Area Index (LAI) for barren land and dense evergreen forest and dynamic LAI for the cropland. The investigation found that cropland showed soil moisture bimodality while barren land and dense evergreen forest had unimodal soil moisture distribution. The dominant mode of soil moisture on barren land is on the dry side, while for the dense evergreen forest has a mode on wetter side. This result indicates the importance of dense vegetation in the land-atmosphere coupled system to reduce the probability to dry and hot season. This information can further be utilized to include the role of vegetation activities in land-atmosphere model development.