Study of Land-Atmosphere Interactions Using Satellite Data Assimilation

The boundary layer contains the exchange of heat and moisture fluxes between the land surface and the atmosphere and is the bottom boundary for atmospheric circulation.  Accurate prediction of boundary layer depth and surface fluxes is crucial to a better understanding of land-atmosphere interactions.  The study of the impact of assimilation of satellite surface temperatures on boundary layer growth, fluxes and soil moisture represents a connection between the satellite observations and the land-atmosphere interactions.

The research (a) uses a 1-D hydrological model forced by meteorological and satellite observations for prediction of soil moisture, surface temperature and fluxes of latent, sensible, ground heat and net radiation, (b) uses the surface soil moisture, surface temperature and sensible heat flux as boundary conditions to a boundary layer model to predict boundary layer depth, (c) compares the simulated values of soil moisture, surface temperature, fluxes of latent, sensible, ground heat and net radiation and boundary layer depth with observations from the CASES-97 experiment, (d) compares the simulated surface temperature with that observed from satellites (GOES, AVHRR and TOVS) and “adjust” the model surface temperature, (e) uses this updated surface temperature, update the soil moisture, fluxes of latent, sensible, ground heat and net radiation and boundary layer depth, (f) compares these updated values to the CASES-97 observations and (g) examines the sensitivity of change in boundary layer thickness to the change in surface temperature, soil moisture and sensible heat flux due to updating.

The comparisons of the model and the observed values of surface temperature, soil moisture, heat fluxes and boundary layer thickness for the assimilated and un-assimilated cases are being carried out.  The importance of accurate estimate of surface temperature in computation of boundary layer thickness will be demonstrated.