Cloud Phase

The goal of the Advanced Satellite Aviation Weather Program is to increase and optimize the usage of satellite data sets within the existing FAA Product Development Team (PDT) structure and to transfer advanced satellite expertise to the teams. For in–flight icing, we are addressing this goal by acquiring and evaluating GOES–derived cloud microphysics products developed by the NASA Langley Cloud and Radiation Research Group and by experimenting with methods to integrate those products into the NCAR Current Icing Product (CIP). We have conducted multiple evaluation efforts including comparisons of the satellite–derived cloud products with research aircraft data, voice pilot reports (PIREPS), and ground–based measurements using a case–study approach. We also performed a preliminary integration of the satellite–derived phase and liquid water path products into CIP for a set of single layer cloud case studies.

Highlights

Comparison of Satellite-Derived Liquid Water Path to Pilot-Reported Icing Severity

NCAR staff have collaborated with NASA Glenn Research Center flight crews to forecast and monitor icing conditions for Twin Otter icing missions since 1998. The past two years they incorporated the NASA Langley satellite products into their forecast procedures. Several products were found to be useful for diagnosing where icing is and is not; liquid water path (LWP, the total integrated liquid through an atmospheric column) was found to be one of the more promising products. While there is no reason to expect a direct correlation between LWP the actual liquid water content at any point in a cloud (and thus icing conditions experienced by aircraft flying there), LWP appeared to be well–related to the presence of icing encountered by the Twin Otter. To test this concept more quantitatively, a set of PIREPs stratified by reported severity level was compared to LWP. While the variation of LWP with severity category was not strictly monotonic, there was a positive correlation between the two quantities. This demonstrated feasibility for inclusion in the CIP fuzzy–logic algorithm, which seeks clues for the presence of icing conditions.

Use of Advanced Satellite Products to Estimate Cloud Top Height and Temperature

Results suggest that the NASA Langley products can significantly improve the current CIP cloud top height scheme. The blended scheme can reduce the cloud top height, icing volume, and perhaps the false alarm rate significantly while minimizing loss of probability of detection of icing locations. Improvements are most evident in daytime when all satellite channels are available and fields are smooth and uniform; night time satellite–based schemes will require smoothing or filtering to handle noisy–appearing data.

Future Plans

1. Develop fuzzy logic parameters for those NASA Langley satellite cloud products which have shown correlations with PIREP icing severity in various meteorological scenarios. Incorporate products into Current Icing Potential (CIP) system and evaluate performance.
2. In conjunction with the FAA InFlight Icing PDT , develop a plan for operational implementation of CIP with ASAP satellite products.
3. Investigate use of emerging satellite products and alternate methods of applying existing products to icing detection problems.
4. Coordinate with NASA LaRC to obtain cloud products operationally via the Columbia supercomputer.
5. Provide feedback to NASA LaRC on product quality and timeliness.