Response of the Land Climate System to Surface Hydrological and Radiative ForcingProposal to NASA NRA-02-OES-06 Multidisciplinary Research in Climate, Chemistry and Global ModelingPrincipal Investigator: Robert E. Dickinson Tel: Fax: Email: robted@eas.gatech.edu Co-Investigators: Guiling Wang 2 , Hongbin Yu1, William Chameides1 1Georgia  Abstract The response of
the land climate system to forcing involves not only the climate system
sensitivity to TOA radiative fluxes, but also other
sensitivities that are orthogonal to the response to TOA radiative
flux changes. These other sensitivities are of comparable importance for
determining climate change over land, i.e. the changes of surface
temperatures and hydrological properties. The current theoretical framework
of sensitivity to TOA fluxes is largely inappropriate to quantify such
questions as what is the climate change resulting from land use changes since
it depends significantly on other dimensions in sensitivity space. Perhaps an
even more important question is the role of land in shorter time scale (e.g. seasonal)
climate prediction, and the processes relevant to this question are largely
orthogonal to TOA flux sensitivity. Hence the main objective of this proposal
will be to develop quantitatively an alternative paradigm, arguably more
appropriate for quantifying climate change at the land surface. Key elements
of the forcing of land are the statistics of surface solar radiation fluxes
and precipitation, and their interaction with the vegetation and soil. The
former are highly dependent on details of clouds and aerosol distributions.
High frequency temporal details are shown to be important. The response has
been known to depend on the partitioning of radiation between canopy and soil
and the partitioning of the precipitation between storage, evapotranspiration, and runoff. The new theme we will
develop is the division among different time scales of the evapotranspiration and runoff. For example, precipitation
that is immediately lost as runoff or evaporation is consequently not stored
in the soil and so does not contribute to predictability of soil moisture or
its feedbacks on precipitation. Hence, the correct modeling of these times
scales is key for representing the contribution of land to seasonal to interannual predictability. The proposed work will use NASA
satellite data for solar radiation, clouds and aerosols, and precipitation albedo, and LAI/FPAR and through their incorporation in a
climate model quantify the processes involved and contribute to the
improvement of various land models. |
Atmospheric Dynamics and
Climate
Georgia Tech