Exploring the Tropically Excited Arctic Warming Mechanism: Links between Tropical Convection and Arctic Downward Infrared Radiation
Both the Barrow and the Ny┼lesund station downward IR are preceded by anomalous tropical convection and poleward propagating Rossby wave trains. The wave train associated with Barrow resembles the Pacific/North American teleconnection pattern and that for Ny┼lesund corresponds to a northwest Atlantic wave train. Furthermore, for Barrow, the tropical convection is associated with the Madden-Julian Oscillation. It is found that both wave trains advect water vapor from the midlatitudes into the Arctic. The resulting moisture flux convergence, multiplied by the latent heat of vaporization, closely resembles the regressed ERA-Interim downward IR. These results suggest that the water vapor advected into the Arctic undergoes condensation, with most of the latent heat release being realized in an increase in downward IR rather than a warming of the clouds.