Radiative Transfer and Regional Climate Change

We first address the importance of three-dimensional (3D) radiative transfer over mountains/snow in the regional context along with its parameterization in terms of deviations from the conventional plane-parallel model commonly used in climate models. This is followed by a discussion on the development of a new approach for light absorption and scattering by black carbon (BC) and snow grains in which the aggregation shape and internal mixing property of BC and the morphology of snow grains are accounted for by using a combination of the geometric-optics and surface-wave approach. It is submitted that in addition to surface temperature increase produced by global warming, understanding of the reduction of snow albedo over intense topography must take into consideration its 3D and inhomogeneous nature and the associated deposition of BC into snow layers as a coupled regional climate system.