Abstract
Abstract. Tomographic methods offer great potential for retrieving three-dimensional spatial distributions of cloud liquid water from radiometric observations by passive microwave sensors. Fixed tomographic systems require multiple radiometers, while mobile systems can use just a single radiometer. Part 1 (this paper) examines the results from a limited cloud tomography trial with a single-radiometer airborne system carried out as part of the 2003 AMSR-E validation campaign over Wakasa Bay of the Sea of Japan. During this trial, the Polarimetric Scanning Radiometer (PSR) and Microwave Imaging Radiometer (MIR) aboard the NASA P-3 research aircraft provided a useful dataset for testing the cloud tomography method over a system of low-level clouds. We do tomographic retrievals with a constrained inversion algorithm using three configurations: PSR, MIR, and combined PSR and MIR data. The liquid water paths from the PSR retrieval are consistent with those from the MIR retrieval. The retrieved cloud field based on the combined data appears to be physically plausible and consistent with the cloud image obtained by a cloud radar. We find that some vertically-uniform clouds appear at high altitudes in the retrieved field where the radar shows clear sky. This is likely due to the sub-optimal data collection strategy. This sets the stage for Part 2 of this study that aims to define optimal data collection strategies using observation system simulation experiments.
Highlights
The study of climate and climate change has long been hindered by a poor understanding of the effect of clouds (Ramanathan et al, 1989)
The Microwave Imaging Radiometer (MIR) data from the Wakasa Bay field campaign were calibrated by the Microwave Sensors Branch of NASA/Goddard Space Flight Center and were made available at National Snow and Ice Data Center (NSIDC) (Wang et al, 2004)
We evaluate the tomographic retrievals by examining the consistency between the retrievals and the cloud radar image and by comparing the resultant liquid water path (LWP) from the three retrieval experiments
Summary
The study of climate and climate change has long been hindered by a poor understanding of the effect of clouds (Ramanathan et al, 1989). The second paper focused on the development of tomographic retrieval algo- The 2003 Wakasa Bay field campaign was a cooperative rithms that make use of various types of constraints based on effort between the Japan Aerospace Exploration Agency a priori knowledge to improve the retrieval. It was demon- (JAXA), and NASA AMSR-E teams focusing on the physical strated that appropriate constraints can improve the accuracy validation of shallow snowfall and rainfall retrievals from the of the tomographic retrieval by one order of magnitude.
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