9.6

Interactive Development of an Ice Cloud Properties Retrieval Algorithm for CIRRUS

David A. Santek, CIMSS/Univ. of Wisconsin, Madison, WI; and K. F. Evans and S. A. Ackerman

The goal of the proposed CIRRUS (Cloud InfraRed Radiometer for UnESS^*) mission is to characterize ice cloud properties to gain a better understanding of the global water cycle, and thus to improve climate predictability. The CIRRUS Far-Infrared instrument would be mounted on the ISS (International Space Station) and would be operational for two years.

A retrieval algorithm was developed to extract ice water path and median particle diameter from cirrus clouds using a Bayesian integration method. This algorithm is based on changes in upwelling radiation in the submillimeter wavelengths when cirrus clouds are present. We will simulate retrievals in different regimes (for example, tropical vs. mid-latitude) to determine the performance of the algorithm for the variable conditions found globally. We will include cirrus cloud microphysics derived from in situ cloud probes, measured atmospheric profiles, and ISCCP ( International Satellite Cloud Climatology Project) cloud products in the simulated retrievals. Also, we will investigate the effects of non-spherical particles and the presence of liquid-phase clouds below the cirrus.

To facilitate this effort we will use VisAD, an interactive algorithm development tool. With its remote collaboration feature, our geographically scattered research team will be able to interact with the algorithm, data, and parameters simultaneously. We will not only report on the status of the retrieval simulations, but also our experiences with working in a collaborative and interactive environment.