Comparison of NOAA Gulfstream G-IV flight level wind measurements with GPS dropwindsondes

In an effort to improve the accuracy of flight level wind data collected by the NOAA Aircraft Operations Center Gulfstream G-IV aircraft, a series of calibration flights have been conducted in recent years. The goal is to achieve the same accuracy and fidelity of flight level wind data from the G-IV as measured presently by the NOAA WP-3D. This study is an effort to validate flight level winds with respect to the winds obtained after the release of the GPS dropwindsondes.

The study attempts to characterize trends in wind speed variability within the first few seconds after the launch. The analysis included comparison of the flight level aircraft wind data with the mean layer wind data collected from the GPS dropwindsondes, ranging from the first two to twenty five seconds after release from the aircraft. The data came from a variety of missions flown by the G-IV high altitude jet including Hurricane Surveillance flights around Hurricane Isaac (2012) and winter storm flights over the Pacific in January and February 2013.

Accomplishing this characterization requires plotting vectors of mean U and V wind components after the release of the dropwindsondes and allows for their comparison with the associated flight level wind components. Using scatter plots enables trends and noticeable outliers to be detected while examining winds across a set of layers immediately below the aircraft flight level.