CONUS II, a new 20-year convection-permitting simulation over North America: How well does it performs on snowpack?

Abstract:

Changes in the water cycle need to be realistically simulated to provide actionable information for adaptation measures and a reliable water resources strategy in a warmer climate. The 20 years of a convection-permitting simulation (CPM), at 4 km grid spacing over North America, (CONUS-II) has the potential to provide such information by capturing relevant hydrometeorological processes across diverse landscapes and climates.

The CONUS-II is the second generation of continental-scale simulations using the Weather Research and Forecasting (WRF) model in CPM configuration over North America ranging from the subtropics (from 19°N) and up to the subarctic (up to 72°N). CONUS-II downscales bias corrected boundary conditions from the Community Climate System Model. This approach removes systematic biases from the lateral boundary conditions but maintains the circulation from the driving global climate model.

In this study we compare the CONUS-II simulation data against observational data, results from the CONUS-I simulation (previous version) and a coarser resolution (12 km grid spacing) simulation using the same CONUS-II configuration. The purpose of this study is to explore mesoscale phenomena in winter, such as flow interactions with orography and its effects on snowfall over the North American Cordillera (e.g. the barrier jet effect in the coastal mountains). Better representing mesoscale processes in winter is necessary for reliably projecting changes in the water cycle that can be used for water resources management.