Abstract
High-latitude spring snow cover extent in the Northern Hemisphere has declined significantly in the past three decades. Remote sensing estimates indicate that June snow covered area has declined by as much as 40 percent, compared to the 1970s. These declines have been associated with increased spring albedo, earlier spring runoff freshet into the Arctic Ocean, and an earlier onset of spring. In this presentation, we will discuss the application of the Regional Arctic System Model (RASM), a fully-coupled regional earth-system model applied over the pan-Arctic domain. RASM has been developed to improve the representation and understanding of key high-latitude physical processes, and to advance multi-decadal climate prediction capabilities in the region. RASM is composed of the Weather Research and Forecasting (WRF) atmospheric model, the Variable Infiltration Capacity (VIC) hydrology model, the RVIC streamflow routing model, the Parallel Ocean Program (POP) model, and the Los Alamos Sea Ice model (CICE). The individual component models are coupled using the Community Earth System Model (CESM) coupling infrastructure (CPL7). The current version of RASM is configured with a 1/48˚ ice-ocean grid and 25km land-atmosphere grid. We compare RASM simulated snow cover extent, surface albedo, and streamflow to in-situ and remote sensing products, highlighting the challenges and modeling advances in simulating observed climatology and trends in recent decades. We find that, while RASM captures the multi-decadal climatology of spring snow cover extent quite well, biases in precipitation and surface temperature contribute to the underestimation in the rate of change in snow cover extent and streamflow.