Verification of a CONUS Satellite Cloud Product Using Aircraft Observations

Aircraft icing and turbulence are important aviation hazards. According to the National Transportation Safety Board (NTSB), they accounted for a combined 15% of all weather related aircraft accidents from 2008 - 2020. They also accounted for a combined 9% of all fatal weather related aircraft accidents for the same time period. As such, the Federal Aviation Administration (FAA) is funding multiple assessments of icing and turbulence forecast products. With the upcoming transition from the 13-km Rapid Refresh model to the 3-km Rapid Refresh Forecast System as input for FAA forecast products such as the Forecast Icing Product (FIP) and the Graphical Turbulence Guidance (GTG), the question of how well the underlying model is forecasting the location of clouds is increasingly important. In the case of FIP, the increased resolution has led to a drastic decrease in the size of forecast objects (or, viewed differently, an increase in the variability of the field) making it possible to consider the question of whether forecast errors are due to errors within the icing algorithm or errors in the placement (or phase) of clouds in the model. For turbulence, the forecast upgrade accompanying the model change includes the addition of an in-cloud turbulence field to the output. Once again, the question of when the errors can be ascribed to the algorithm or the underlying model information is relevant.

In order to determine errors in the underlying model it is necessary to have good observations of clouds. Improvements in satellite technology and in the processing of satellite-derived information have led to new satellite cloud products. One such product is the satellite Cloud Vertical Cross-section (CVC) out of the Cooperative Institute for Research in the Atmosphere (CIRA). This product is part of a 3-D satellite cloud height field that reports the existence and phase of clouds at 1000 ft vertical resolution. The results presented herein are from an investigation of the quality of the CVC over the contiguous United States (CONUS) utilizing aircraft-based observations of water vapor. The purpose of this research was to determine the suitability of using the satellite cloud fields as observation datasets against which aviation forecast products can be evaluated. A total period of four months of CVC data, representative of each season, was evaluated. This presentation will discuss not only the results of the comparison, but also suggestions on how to best use satellite cloud fields in future assessments.