A ‘New Arctic’ and increases in evaporation rates: A look at a new dataset to assess these changes
Conference room (level 4)
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 vertical moisture fluxes that affect surface energy budgets, larger occurrences of low-level clouds, and higher near-surface humidity and temperatures. The vertical moisture flux (i.e., evaporation) plays an important role in the Arctic energy budget, the water vapor feedback, and Arctic amplification. However, it is one of the most uncertain variables, especially in this “new Arctic” climate system, which is dominated by large ice-free ocean areas for a longer portion of the year. 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 the Atmospheric Infrared Sounder (AIRS), Version 6 (V6) and the ECMWF's ERA-Interim reanalysis input data as well as our recent moisture flux scheme and the ERA-Interim scheme. Using our updated scheme, the daily moisture flux is calculated from 2003-2013. Moisture flux rates from the Arctic Ocean and surrounding seas were found to have increased between 2003 and 2013 by 7.2 × 10−4 g m−2 s−1 per year (equivalent to 1.79 W m−2 per year in latent heat). This is a 7% increase in the average moisture flux each year and a 0.12% increase in the yearly global ocean latent heat flux, with some months increasing more than others. The largest increases seen are in the Arctic coastal seas during the spring and fall where there has been a reduction in sea ice cover and an increase in sea surface temperatures. Increases in the moisture flux from the surface also correspond to increases in low-level clouds.