Rain on snow (ROS) events were derived from 20km dynamically downscaled ERA-Interim reanalysis and global climate model (GCM) climate projections data. The GCM data were from RCP 8.5 of GFDL-CM3 and NCAR-CCSM4. The amount of liquid precipitation for each day is provided in the database for each grid cell and was determined to be a ROS event by the temperature being at or near freezing and/or the presence of snow on the ground.

Data are provided as NetCDF files closely following Climate and Forecasting (CF) metadata conventions, but may not be fully compliant. It is output on a 20x20km grid in a WRF-derived polar stereographic projection system aggregated at daily timesteps by year.

Background

The ice formed by cold-season rainfall or rain on snow (ROS) has striking impacts on the economy and ecology of Alaska. An understanding of the atmospheric drivers of ROS events is required to better predict them and plan for environmental change. The spatially/temporally sparse network of stations in Alaska makes studying such events challenging, and gridded reanalysis or remote sensing products are necessary to fill the gaps. Recently developed dynamically downscaled climate data provide a new suite of high-resolution variables for investigating historical and projected ROS events across all of Alaska.

Variables include:

Variable | Description

ROS | Rain on snow (mm)

References:

Bieniek, P. A., U. S. Bhatt, J. E. Walsh, R. Lader, B. Griffith, J. K. Roach, and R. L. Thoman, 2018: Assessment of Alaska Rain-on-Snow Events Using Dynamical Downscaling. J. Appl. Meteor. Climatol., 57, 1847–1863, https://doi.org/10.1175/JAMC-D-17-0276.1