Principal Investigator: Dr. Steven J. Walter, Jet Propulsion Laboratory, California Institute of Technology

Dr. K. Franklin Evans, University of Colorado
Dr. Graeme Stephens, Colorado State University

Proposal Title: Submillimeter-wave Cloud Ice Radiometer

Cirrus ice clouds affect Earth’s climate and hydrological cycle by reflecting incoming solar energy, trapping outgoing IR radiation, sublimating into vapor, and influencing atmospheric circulation. A lack of data on the global distribution and physical characteristics of cirrus currently restrict the accuracy of both climate and weather models. Existing and planned Earth observation systems will be unable to satisfy these measurement needs. The NASA Instrument Incubator Program (IIP) is supporting a validation effort to develop submillimeter-wave cloud ice radiometry for use in investigating and monitoring cirrus clouds on a global scale.

Submillimeter-wave cloud ice radiometry is a new technique that can be used retrieve the amount of ice present in cirrus clouds, measure the median crystal size, and constrain the mean crystal shape. Validation of this technique requires development of an advanced airborne submillimeter-wave radiometer coordinated with a multi-instrument airborne measurement program. This work will be coupled with a theoretical modeling program to develop and refine retrieval methods. Development of an airborne radiometer will also support airborne science programs and assist in validation of spaceborne cloud sensors. Successful completion of this effort will increase the maturity of cloud ice radiometry, thereby facilitating the adoption of spaceborne submillimeter-wave radiometry as a standard tool for Earth observations. This would represent a major breakthrough for climate modeling by providing observations needed to validate global climate and atmospheric hydrology models.

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