Quantification of Cryosphere Radiative Effect on Climate Change using satellite measurements

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Wednesday, 7 January 2015
Deepak Singh, University of Michigan, Ann Arbor, MI; and M. G. Flanner

Cryosphere Radiative Effect (CrRE) is the instantaneous influence of snow- and ice-cover on Earth's top of atmosphere (TOA) solar energy budget. Since snow- and ice-covered surfaces are the most reflective on Earth and have variable extent over the surface (due to seasons), Earth's cryosphere can greatly alter the planet's albedo and therefore, determine the sensitivity of climate to anthropogenic and external forcings. This albedo feedback is one of the three most powerful positive feedback mechanisms operating within the current climate system. CrRE depends not only on snow and sea-ice coverage, but also on local insolation, cloud cover and properties of the snow, ice and their underlying surface that determines reflectance. Our work focuses on developing a publicly-available global, gridded, time-resolved dataset of CrRE and its uncertainty, using remote sensing observation of the change in surface albedo induced by the presence of snow and sea-ice, combined with radiative kernels that provide TOA radiative impacts. Ice-free ocean albedo is much less variable than that of snow-free land, but on the other hand, sea-ice albedo varies strongly with season ice age and melt progression. We partition CrRE into land snow and sea-ice contributions, and provide statistics including global, hemispheric and continental CrRE averages which can serve as climate indicators. Preliminary results from our technique indicate that global annual-mean land-based CrRE during 2001-2013 was about -2.6 Wm-2. Seasonal and regional trends during this time period are evident and will be presented.