Application of Satellite- and NWP-Derived Wind Profiles to Military Airdrop Operations

Abstract

he Joint Precision Airdrop System (JPADS) has revolutionized military high-altitude airdrop capability, allowing delivery of equipment and supplies to smaller drop zones from higher altitudes than was previously possible. This capability relies on accurate wind data, currently provided by GPS dropsondes released in the vicinity of the drop zone shortly before the airdrop. This research investigates the potential for a wind-profiling algorithm to generate the required wind data from passive IR and microwave satellite soundings, eliminating the requirement for a hazardous dropsonde pass near the drop zone. The Atmospheric Infrared Sounder (AIRS) provides a 3D temperature field and determines the heights of 100 standard levels. From these data, the slopes of the isobaric pressure surfaces and temperature gradients are used to calculate wind speed and direction using the thermal wind relationship. The accuracy of these satellite-derived wind profiles is evaluated through comparison with rawinsonde measurements near the coordinates and time of the AIRS sounding. Further investigation of the wind profile accuracy is made by a comparison with numerical weather prediction (NWP) data worldwide, and the effect of cloud cover in the vicinity of the target coordinates is analyzed. The AIRS-derived winds are found to be less accurate than short-term NWP winds for the JPADS application, but the technique developed may be applied to alternate applications, such as use in the stratosphere, where NWP winds are not widely available. The agreement between satellite-retrieved temperatures and measurements at altitudes above 30 km indicates the AIRS data could be used to create accurate, 3D fields of optical turbulence strengths for directed-energy applications.