Mechanisms for the Regulation of Minimum Mid-tropospheric and Surface Temperatures at High Latitudes

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A mechanism that may regulate both mid-tropospheric and surface air temperatures (SATs) in the Arctic region during the winter season will be examined. Regulation of observed mid-tropospheric arctic temperatures is hypothesized as follows: winter air in the Arctic has repeated contact with open ocean which allows warming to occur quickly through moist convection from the surface upward through at least the mid troposphere; and as these warmed air columns move over snow and ice covered surfaces, they cool from the bottom upwards, however, this process happens so slowly that it regulates SATs. The end result is that a warmer mid-troposphere will result in a warmer near surface layer during Arctic winter because of radiative equilibrium processes. The PIs will (1) perform a detailed observational analysis of the 500mb temperature field in the 4 x daily National Centers for Environmental Prediction reanalysis to track individual warming and cooling patterns spatially, and (2) use a low resolution General Circulation Model (planet simulator) and increase high latitude SSTs by several degree to examine the hypotheses proposed. Intellectual merit: Completion of this work will offer new insights into the mechanism that regulates the Arctic wintertime surface and mid-troposphere air temperatures. Broader impacts: The research will increase our understanding of the processes involved in the regulation of the wintertime Arctic surface and mid-troposphere air temperature. It has a potential to improve these processes' representation in general circulation models. It also provides learning experiences and training for a research assistant.