P50     Forecasting intense summer synoptic-scale cyclones over the Arctic Ocean.

Bromwich, David H., Lesheng Bai, Byrd Polar & Climate Research Center, The Ohio State University, Zhiquan Liu, NCAR, and Hailing Zhang, COSMIC Program Office, UCAR

Intense summer cyclones can substantially impact the sea ice cover of the Arctic Ocean. With climate change and the consequent decrease of Arctic sea ice especially during summer and autumn, forecasting major synoptic cyclones has become a prime issue in support of access to the treacherous ice-prone Arctic Ocean. Forecasting experiments are conducted with the polar version of the Weather Research and Forecasting (Polar WRF) model to determine the skill with which the behavior of these events can be projected over a 6-day time span. Extreme cyclone cases from August 2012 (“Great Arctic Cyclone”) and August 2016 are studied. Lateral boundary conditions for the forecasts are provided by the NCEP Global Forecast System (GFS). Initial conditions come the GFS that are modified by two regional data assimilation approaches using conventional and satellite radiances collected from the Global Telecommunications System by NCEP: 3DVAR and incremental 4DVAR. Specified sea surface temperatures and sea ice conditions are used, and impact of static (current forecasting practice) versus time varying specifications are evaluated. Forecast skill is benchmarked against the regional Arctic System Reanalysis version 2 and the global ERA5 reanalysis from ECMWF.