Linette N. Boisvert - 613 Seminar Series

Earth System Science Interdisciplinary Center (ESSIC), University of Maryland (UMD)

The Arctic sea ice acts as a barrier between the ocean and atmosphere inhibiting the exchange of heat, momentum, and moisture. Recently, the ice pack has been decreasing in area and concentration. This diminished sea ice coverage could potentially allow for larger moisture fluxes that affect surface energy budgets, the occurrence of clouds, and the near-surface humidity and temperature. Using the Monin-Obukhov similarity theory, with adjustments made to better suit the conditions of the Arctic, and observations from NASA’s EOS Aqua satellite, specifically the Atmospheric Infrared Sounder (AIRS) instrument, the daily moisture flux is calculated from 2003-2012.

Currently, reanalyses are known to produce large errors and biases in the Arctic, warranting improved moisture flux algorithms and input data. To improve evaporation estimates, we compare AIRS, Version 6 (AIRS V6) and the ECMWF's ERA-Interim reanalysis input data as well as our recent moisture flux scheme and the ERA-Interim scheme. Skin temperature and 2-m specific humidity (q2m) from AIRS V6 and ERA-Interim were compared with a variety of in situ data. Skin temperatures from ERA-Interim showed a warm bias over sea ice and a cold bias over open seas. ERA-Interim skin temperature had twice as large an error compared to AIRS, but had smaller errors in q2m. Due to these differences, surface latent heat fluxes in the open water in the Beaufort - East Siberian Seas region in September 2007 were up to 55 W m-2 less than those produced with AIRS V6 and our scheme. Since such large errors exist in ERA-Interim's skin temperature product in the Arctic, it is suggested that using AIRS V6 input data would produce more realistic results. To produce more accurate moisture flux estimates in the Arctic, reanalyses like ERA-Interim should also update their parameterizations to such ones that are based on observations from the Arctic.