Surface Energy Budgets in Short-Term Rapid Arctic Sea Ice Loss Modulated by Background Conditions

In this paper, the surface energy budget is explored for rapid sea ice decline events on the short-term time scale in summer during two periods: P1 (1979-2000) and P2 (2001-2021) over Laptev Sea and Eastern Siberian-Chukchi-Beaufort (ES-B) seas, respectively. Results show that Arctic rapid sea ice decline events are closely associated with an atmospheric zonal dipole structure, which consists of a cold cyclonic anomaly and a downstream warm anticyclonic anomaly. The upstream sea ice decline is mainly due to the enhanced downward longwave radiation (DLR) resulted from the transport of warm and moist air, whereas the downstream sea ice decline is primarily owing to the enhanced downward shortwave radiation (DSR) as a result of less low-level cloud cover associated with downward motion. The evolution and propagation of the atmospheric dipole structure influences the surface energy budget for the whole sea ice decline process. To be specific, the enhanced DSR plays a primary role at the beginning of sea ice melt. For rapid sea ice loss events over Laptev Sea, the enhanced DSR plays a determined role for the whole rapid sea ice decline process whether during P1 or during P2. However, for rapid sea ice loss events over ES-B seas, the increased DLR and surface turbulent heat fluxes play the dominant role for the whole sea ice decline process during P1, and the increased DSR and surface turbulent heat fluxes have a dominating influence during P2. Whether the surface energy budgets have a change during the sea ice decline depends on the evolution and propagation of the zonal dipole structure, which is modulated by the background states. Our work provides a comprehensive analysis for rapid Arctic sea ice decline events on the short-term time scale under different climatic backgrounds, which is beneficial for our understanding of Arctic climate system.