Seasonal evolution of the dominant modes of the Eurasian snowpack and atmospheric circulation from autumn to the subsequent spring and the associated surface heat budget
This study investigates the seasonal evolution of the dominant modes of the Eurasian snowpack and atmospheric circulation from autumn to the subsequent spring using snow water equivalent (SWE), snow cover frequency (SCF), and 500 hPa geopotential height data. It is found that the Eurasian SWE/SCF and circulation dominant modes are stably coupled from autumn to the subsequent spring. The temporal coherence of the seasonal evolution of the dominant modes is examined. The seasonal evolution of the Eurasian circulation and SWE dominant modes exhibit good coherence, whereas the evolution of the Eurasian SCF dominant mode is incoherent during the autumn–winter transition season. This incoherence is associated with a sign-change in the SCF anomalies in Europe during the autumn–winter transition season, which is related to the wind anomalies over Europe. In addition, the surface heat budget associated with the Eurasian SWE/SCF and circulation dominant modes is analyzed. The sensible heat flux (SHF) related to the wind-induced thermal advection dominates the surface heat budget from autumn to the subsequent spring, with the largest effect during winter. The surface net shortwave radiation is mainly modulated by snow cover rather than cloud cover, which is estimated to be as important as, or likely superior to, the SHF for the surface heat budget during spring. The NCEP–NCAR surface heat flux reanalysis data demonstrate a consistency with the SWE/SCF and air temperature observational data, indicating a good capability for snow–atmosphere interaction analysis.