Atmospheric Circulation Response to Heat Flux Anomalies in a Two-Dimensional Baroclinic Model of the Atmosphere

Abstract

The response of large-scale atmospheric circulation to the anomalous Barents and Kara sea ice-free surface heating, which has been observed over the past two decades, is considered. For this purpose, a simplified two-dimensional baroclinic atmospheric model obtained by averaging hydrothermodynamic equations over height is used, as well as its two-layer analogue with the effect of anomalous heating and, hence, of horizontal baroclinicity being concentrated within the surface-adjacent 1- to 2-km-thick atmospheric layer, which fits Arctic conditions more closely. Quasi-geostrophic approximations are derived for both models; for a single-layer model (in the adiabatic and inviscid approximation), the formulation is also given in terms of Nambu mechanics. Both models demonstrate the appearance of a center of increased surface air temperature over the area of anomalous heating; a slight decrease in surface pressure there; and, finally, anticyclonic circulation in the bulk of the atmosphere. The model results are shown to be extremely sensitive to the parameterization of the Ekman boundary layer.