Controls on Northern Hemisphere snow albedo feedback quantified using satellite Earth observations

Observation based estimates of controls on snow albedo feedback (SAF) are needed to constrain the snow and albedo parameterizations in general circulation model (GCM) projections of air temperature over the Northern Hemisphere (NH) landmass. The total April-May NH SAF, corresponding to the sum of the effect of temperature on surface albedo over snow covered surfaces ('metamorphism') and over surfaces transitioning from snow covered to snow free conditions ('snow cover'), is derived with daily NH snow cover and surface albedo products using Advanced Very High Resolution Radiometer Polar Pathfinder satellite data and surface air temperature from ERA40 reanalysis data between 1982-1999. Without using snow cover information, the estimated total SAF, for land surfaces north of 30 degrees N, of -0.93 +/- 0.06% K-1 was not significantly different (95% confidence) from estimates based on International Satellite Cloud Climatology Project surface albedo data. The SAF, constrained to only snow covered areas, grew to -1.06 +/- 0.08%K-1 with similar magnitudes for the 'snow cover' and 'metamorphosis' components. The SAF pattern was significantly correlated with the 'snow cover' component pattern over both North America and Eurasia but only over Eurasia for the 'metamorphosis' component. However, in contrast to GCM model based diagnoses of SAF, the control on the 'snow cover' component related to the albedo contrast of snow covered and snow free surfaces was not strongly correlated to the total SAF. Citation: Fernandes, R., H. Zhao, X. Wang, J. Key, X. Qu, and A. Hall (2009), Controls on Northern Hemisphere snow albedo feedback quantified using satellite Earth observations, Geophys. Res. Lett., 36, L21702, doi: 10.1029/2009GL040057.