Tropospheric response to varying approaches of prescribing Siberian snow anomalies

Abstract:

Variability in Siberian snow extent during the fall has been shown to impact northern hemisphere winter weather through its influence on surface heating patterns and resulting wave activity fluxes. More recently, sea ice variability has also been implicated as a potential driver of winter weather and extremes, leading to a number of studies comparing the impact of prescribed sea ice and snow cover anomalies. Whilst many GCMs have the inbuilt functionality to prescribe sea ice and SSTs, this is generally not the case for snow. It is therefore important to establish a realistic and consistent method of prescribing snow anomalies. We report on a suite of GCM experiments that investigate the sensitivity of the atmospheric response to the timing of a single, large anomaly of snow water equivalent. Albedo and surface fluxes in these perturbed snow experiments are compared to observations from daily MEaSUREs snow extent and AMSR-E/Aqua snow water equivalent. We then use wave flux and atmospheric mode (e.g. the NAO) diagnostics to track the response of the troposphere to the timing of these anomalies.