Numerical Modeling of Arctic Boundary Layer during Arctic Sea State 2015

Significant environmental changes are occurring in the Arctic region.  One of the most striking changes observed is the drastic decrease in multi-year sea ice concentrations and summer sea ice cover.  In response to the emerging Arctic ocean, an on-going Office of Naval Research Departmental Research Initiative (DRI) is focusing on improving understanding of the changing sea state and boundary layer physics (Sea State/Boundary Layer).  One of the goals of this DRI is to understand the physics of heat and mass transfer from the ocean to the atmosphere, and the seasonal variability of fluxes during summer ice retreat and autumn ice advance.  Observational data collected over the Beaufort and Chukchi Seas during the October 2015 expedition of the research vessel Sikuliaq provided an opportunity for evaluating model performance in capturing the atmospheric boundary layer structure over changing sea-ice conditions during the Arctic refreeze season and ultimately improving Arctic weather prediction.

In this study we examine the impact of the evolving sea ice states on the Arctic atmospheric conditions using the Navy’s regional numerical weather prediction model (Coupled Ocean/Atmosphere Mesoscale Prediction System - COAMPS^®) driven by the sea ice surface conditions predicted by the Arctic Cap Nowcast/Forecast System (ACNFS).  ACNFS is a coupled sea ice and ocean model that generates real-time forecasts of ice concentration, ice edge location, ice thickness, ice draft and ice drift for all sea ice covered areas in the northern hemisphere (poleward of 40N).  These fields are used by COAMPS as the surface boundary condition, which directly modulates distribution of turbulent and radiative surface fluxes.  The improved physical parameterizations in COAMPS are compared with the benchmark simulations and evaluated for the Arctic conditions.  Systematic verification of the boundary layer structure over the evolving sea ice with high heterogeneity is performed against the Arctic surface observations and data from the Sea State/Boundary Layer experiment.