Land-Atmosphere Interactions in North West Himalaya

Climate change in the Himalaya has severe ramifications for water resources in the highly populated downstream regions. The Himalaya has experienced a rapid temperature rise in recent decades, which has increased evapotranspiration and water discharge from glacier melting. According to the Clausius-Clapeyron relation, the global atmospheric water content is expected to increase by 7% per degree of warming. The high mountains of Himalaya could retain locally evaporated moisture in its valleys resulting in high precipitation recycling. Warming induced by climate could induce melting of glaciers, which would affect the evapotranspiration from this region. The precipitation recycling is considered a measure of land-atmosphere interaction and strength of the local hydrological cycle. We assess the changes in recycled precipitation due to climate-induced warming and land use land cover change over the North West Himalaya in the past two decades through this work. Given the complex topography and the effect of weather systems such as Western disturbances and the Indian summer monsoon, the precipitation pattern changes drastically from the windward side (south) to the leeward side (rain shadow) of North West Himalaya. These factors pose a challenge to isolate the land-atmosphere feedback mechanisms in the North West Himalaya. Therefore, we use an Eulerian water vapor-tagging technique incorporated in the Weather Research and Forecasting (WRF) model to address the goal. The past climate is modeled using boundary conditions from ERA5 reanalysis. Choice of using WRF model is supported by its ability to dynamically downscale reanalysis datasets to finer resolution and better representation of topography which allows for more precise characterization of regional precipitation and moisture transport. We would also identify the role of land in extreme events such as droughts and cloudburst. This would enable us to determine shifts in recycling precipitation trends and aid in recommending mitigation strategies in North West Himalaya.