Assessing synergistic radar and radiometer capability in retrieving ice
cloud microphysics based on hybrid Bayesian algorithms
Abstract
The 2017 National Academy of Sciences Decadal Survey highlighted several
high priority objectives to be pursued during the next decadal
timeframe, and the next-generation Cloud Convection Precipitation (CCP)
observing system is thereby contemplated. In this study, we investigate
the capability for ice cloud remote sensing of two CCP candidate
observing systems that include a W-band cloud radar and a
submillimeter-wave radiometer by developing hybrid Bayesian algorithms
for the active-only, passive-only, and synergistic retrievals. The
hybrid Bayesian algorithms combine the Bayesian MCI and optimization
process to retrieve quantities and uncertainty estimates. The radar-only
retrievals employ an optimal estimation methodology, while the
radiometer-involved retrievals employ ensemble approaches to maximize
the posterior probability density function. The a priori information is
obtained from the Tropical Composition, Cloud and Climate Coupling (TC4)
in situ data and CloudSat radar observations. Simulation experiments are
conducted to evaluate the retrieval accuracies by comparing the
retrieved parameters with the known values. The experiment results
suggest that the radiometer measurements provide little information on
the vertical distributions of ice cloud microphysics. Radar observations
have better capacity for retrieving water content compared to particle
number concentration. The synergistic information is demonstrated to be
helpful in improving retrieval accuracies, especially for the ice water
path retrievals. The end-to-end simulation experiments also provide a
framework that could be extended to the inclusion of other remote
sensors to further assess the CCP observing system in future studies.