91ÃÛÌÒ¸ó

Southeast Alaska represents a highly variable hydrologic environment. Headwaters are dominated by alpine glaciers and larger river basins envelop significant glacier area. Daily estimates of streamflow and river temperature provide useful insight into regions undergoing rapid change. Here we present a river temperature model framework that adapts results from two different hydrologic 91ÃÛÌÒ¸ó applied in Southeast Alaska. We force the physically based River Basin Model with energy inputs from a 4 km resolution Regional Arctic System Model (RASM), but vary streamflow inputs based on output from two land surface 91ÃÛÌÒ¸ó: 1) a coupled simulation of RASM-CTSM at 4 km and 2) an offline run of RASM-WRF Hydro Glacier at 1 km. The land surface 91ÃÛÌÒ¸ó primarily differ in glacier treatment, RASM-CTSM uses a traditional five-layer snow model to account for glacial processes, while the RASM-WRF Hydro Glacier model applies the CROCUS snow model for improved glacial snow and firn simulations in river basins with glacier presence. The RASM-WRF Hydro Glacier employs the three-layer snow model from the NoahMP land surface for non-glaciated regions. The 91ÃÛÌÒ¸ó were run for a historical (1991-2020) period, including a parameter sensitivity test for river temperature, and then applied to a mid-century (2035-2064) climate scenario. We assessed model simulations against gage observations at seven basins. In historical simulations, RASM-WRF Hydro Glacier (bias = X%; KGE = Y) outperform RASM-CTSM (bias = X%; KGE = Y) in glaciated basins, while producing nearly identical results in non-glaciated basins, indicating that the advanced treatment of glacier snow and ice by RASM-WRF Hydro Glacier produces more accurate results. Estimates of future changes in discharge and stream temperature, together with glacier contributions to runoff, provide a holistic assessment of hydrologic system change in Southeast Alaska, useful for future investigations of the impacts of hydrological processes in this glacier-dominated landscape.