Do changes in poleward atmospheric heat transport force or respond to polar amplification?

Changes in atmospheric heat transport into the polar regions under global warming are impacted by competing influences from tropical moistening and polar amplified surface warming. From an energy diffusion perspective, preferential moistening of the lower latitudes tends to push more energy into the polar regions whereas polar amplified temperature changes tend to push more energy equatorward. This talk attempts to disentangle these competing tropical and high latitude imprints on observed and modeled historical trends in poleward atmospheric heat transport to ask: does atmospheric heat transport force or respond to polar amplification? We leverage the hemispheric contrast of the observed polar amplification of warming, the moist/dry partitioning and seasonality of atmospheric heat transport trends to pursue this question.
We begin by analyzing the temporal evolution of high frequency (daily timescale) Arctic warming/sea ice loss events from the perspective of the atmospheric energy budget. Winter sea ice loss events are initiated by pulses of localized atmospheric heat transport convergence which warm the atmospheric column and melt sea ice over the course of several days. Following the ice melt, the open ocean evaporates energy into the air, further heating the column and resulting in an atmospheric heat transport divergence out of the region lasting several days. Averaged over the course of the two phases of the event (approximately one week) there is only a small anomaly in atmospheric heat transport into the region because the atmospheric forcing and response to the warming nearly cancel one another in their impacts on atmospheric heat transport.
We attempt to take the lessons learned from high frequency variability of Arctic warming to understand long-term trends in atmospheric heat transport into the polar regions of bothe hemispheres in observations and models. Poleward atmospheric heat transport into the Southern Ocean has increased over the satellite era whereas the trends in heat transport into the Arctic are more neutral. Enhanced atmospheric heat transport into the Southern Ocean is consistent with the diffusive response to delayed Southern Ocean warming and these trends are consistently modeled in AMIP simulation with prescribed trends in sea surface temperatures but are under predicted in fully coupled historical runs. The seasonality and partitioning of atmospheric heat transport trends into moist/dry and eddy/overturning circulations is also analyzed.