04/26/2010

Understanding Effects of Surface Albedo on Cloud and Radiation Processes

Summary

Land surface albedo (a measure of how much sun light is reflected back from the Earth’s surface) plays an essential role in the energy budgets at the surface and at the top of the atmosphere. DOE Atmospheric System Research scientists investigated the relationship between the land surface albedo, cloud properties, and atmospheric radiative fluxes. Using a year-long, high resolution, cloud model simulation and Atmospheric Radiation Measurement Climate Research Facility data they discovered a critical value of the surface albedo. For albedo greater than the critical value, the upward solar flux at the top of the atmosphere for thin clouds is proportional to the surface albedo while for thick clouds the upward flux at the top of the atmosphere is not much affected by the surface albedo. Additionally, for thick clouds, the downward solar flux at the surface is primarily influenced by surface albedo and reflection from the cloud-base. Discovery of these new relationships will be useful to validate and improve the treatment of cloud-radiation processes in global climate models.

References

Park, S., and X. Wu, 2010: Effects of Surface Albedo on Cloud and Radiation Processes in Cloud-Resolving Model Simulations. Journal of Atmospheric Sciences, 67.