Abstract:
Multi-frequency passive microwave sensors herald a new dawn for combined land
and atmosphere observations. Past efforts to utilize microwave remote sensing of
atmosphere and land surface have proceeded by treating these two areas in a parallel
fashion. In this research, a unified approach is presented that can be used to improve
both quantitative and qualitative understanding of land and atmosphere constituents.
A coupled Land Atmosphere Radiative-Transfer Model (LA-RTM) that can
be used as a forward model in retrieval algorithms, or as an observation operator in
data-assimilation schemes is developed. This model is validated using data collected
during the 2003 Advanced Microwave Scanning Radiometer on board the Earth
Observing Satellite (AMSR/AMSR-E) validation experiment over Wakasa Bay in
Japan and the Coordinated Enhanced Observing Period (CEOP) dataset for the
Tibetan Plateau collected in April and August 2004. These datasets comprise
satellite (AMSR-R) observations, ground-based microwave radiometers
(GBMRs) and radiosonde atmosphere soundings. In both sites, good agreement
between simulated and observed brightness temperatures is demonstrated. To facil-
itate fast retrievals, a retrieval scheme is proposed that uses LA-RTM as a forward
model to generate a look-up table (LUT) for varying land-surface conditions. This
LUT is used to retrieve soil-moisture and surface-roughness conditions for the
target site. Using this scheme, retrieved soil moisture at in situ stations was shown
to have fairly good agreement with observations.
