Analyzing Error in Balloon-Based Wind Measurements due to Spatial Separation Using the North American Regional Reanalysis

Weather balloons have been a longstanding valuable asset to NASA and aerospace meteorology from vehicle development design requirements to day-of-launch activities. Part of their value lies in the ability to accurately measure wind data up to 30 km. However, a caveat to these measurements exists in that balloons drift away from their release point. A previous study using balloons launched at the Kennedy Space Center (KSC) showed this drift could be as far as 200 km. Drifts of significant magnitudes can cause the balloon to measure different environments than the one near the launch facility. Thus it is important to understand how large the errors in balloon-based wind measurements can be due to the horizontal spatial separation between the balloon and the launch pad. The North American Regional Reanalysis (NARR) database is used for this study to quantify that error. NARR wind data from January 1979 to April 2018 at approximately 30 km horizontal grid spacing and 29 vertical pressure levels is analyzed. The initial domain chosen is centered on the grid point nearest to the KSC and all other grid points within 200 km of that center point. Root Mean Square (RMS) deltas are calculated between each grid point and the center grid point representing KSC at concurrent timestamps for both vector and component winds. These errors are broken down into further analyses by distance, height, and bearing. Methods to mitigate underestimation of errors due to the coarseness of the NARR output are also explored.