Regimes of Scattering Behavior from Particulate Media: Implcations for Snow containing Black Carbon

Abstract:

As is well known from the remote sensing of minerals, absorption features in infrared spectra can change drastically with changes in particle size. These changes are the product of two competing effects: volume scattering where increasing particle size leads to a net increase in absorption, and surface scattering where increasing particle size decreases net absorption. Depending on the relative contribution of volume and surface scattering, absorption features can appear as troughs in reflectivity spectra (volume scattering), sharp peaks (surface scattering), or may disappear out right.

Solid ice has a significant absorption feature near 12 microns, that is a candidate for the retrieval of snow morphology from infrared remote sensing. In this presentation, we first overview a new phenomenological theory of the reflectivity of particulate media, with an emphasize on different regimes of scattering behavior. We then investigate the 12 micron feature of pure snow and snow containing black carbon, with an emphasize on how this feature is expected to change with changes in snow grain size, and with varying amounts of black carbon.