Uncertainties in space-based estimates of clouds and precipitation: Implications for deriving global diabatic heating

There is an intimate coupling between the climate, energy budget, and global hydrologic cycle. The problem of establishing observational evidence for these connections and climate change in general, poses a significant challenge to the observational community. This dissertation seeks to address the components of this problem related to observing the hydrologic cycle and its role in modulating the tropical energy budget, from space-based measurements.; This work reports on a new technique which makes use of cloud and precipitation information from the Tropical Rainfall Measuring Mission to estimate the principal components of the tropical energy budget and to examine the mechanisms by which clouds and precipitation modify it. Three distinct retrieval algorithms are employed to determine the three-dimensional structure of cloud and precipitation in the tropical atmosphere. The resulting representation of the three-dimensional structure of cloud and precipitation in the tropical atmosphere is then used as input to a broadband radiative transfer model to derive profiles of short- and longwave fluxes.; In the absence of additional tuning or constraints, the procedure described in the present work provides monthly-mean estimates of column radiative heating accurate to ∼30% and cloud radiative forcing with accuracies ranging from approximately 40% for raining pixels to 75% in non-precipitating clouds. It is shown that the dominant source of uncertainty in both the retrieval and radiative transfer models is a lack of vertical cloud boundary information inherent in the passive measurements. These results highlight the need for future algorithms to look toward making use of synergies between active and passive observations to simultaneously retrieve cloud and precipitation optical properties and their vertical distribution and ensure consistency between a wider variety of information sources. As a first step towards this undertaking, a new method for retrieving profiles of rainfall from spaceborne radars based on an optimal estimation technique is also introduced. The method is readily adapted to include information from a variety of sources and provides a suite of diagnostic tools with which to assess its performance. Preliminary results from synthetic retrievals highlight the utility of the algorithm for estimating profiles of precipitation up to 60 mmh-1 at 14 GHz and up to 8 mmh-1 at 94 GHz, provided some form of attenuation constraint is implemented. (Abstract shortened by UMI.)...