The NCAR/NOAA Global Hawk Dropsonde System
Wick et al. accepted for publication in J. Atmos. Oceanic Technol.
A new system enabling the remote deployment of up to 90 dropsondes from the NASA Global Hawk unmanned aircraft was developed through a partnership between the National Center for Atmospheric Research (NCAR) and NOAA. The dropsonde is an instrument, about the size of an empty paper towel roll, that measures the temperature, pressure, and humidity of the atmosphere along with the wind speed and direction while parachuting down from the aircraft from which it was launched. By using the Global Hawk, the dropsondes can be launched from altitudes up to 65,000 ft, higher than most traditional manned aircraft, during flights in excess of 24 hours. To operate from the Global Hawk, a smaller, modified dropsonde along with an entirely new system for their storage and launch had to be developed. In a new ESRL/PSD-led paper to be published in the Journal of Atmospheric and Oceanic Technology, NOAA, NCAR and NASA researchers describe the components and operation of the system and illustrate its unique capabilities through highlights of data application to research on the arctic atmosphere, atmospheric rivers, and tropical cyclones.
Abstract: A new remotely controlled AVAPS® Dropsonde System has been developed for and deployed on the NASA Global Hawk (GH) unmanned aircraft. Design, fabrication, and operation of the system was led by the National Center for Atmospheric Research (NCAR) with support from the National Oceanic and Atmospheric Administration (NOAA) Unmanned Aircraft Systems (UAS) Program. The system has employed the NRD94 dropsonde, a smaller and lighter version of the standard RD94 dropsonde deployed from manned aircraft but with virtually identical sensors. The dropsondes provide in situ atmospheric profiles of temperature, pressure, and humidity at a 2 Hz data rate, and wind speed and direction at 4 Hz. The system is capable of carrying up to 90 dropsondes and can support 8 simultaneous soundings. Operation from the GH means that the dropsondes can be deployed from altitudes up to 19.8 km during flights in excess of 24-hour duration. Dropsonde launch is commanded directly by an operator on the ground in coordination with the aircraft commander. Over 2700 total dropsondes have been deployed from the GH during four major campaigns since 2011. Data are processed in near-real-time and have been employed by forecasters, for assimilation in numerical weather prediction models, and in diverse research studies. Intercomparison studies suggest the performance of the GH NRD94 dropsondes is similar to those deployed from manned aircraft. This paper describes the components and operation of the system and illustrates its unique capabilities through highlights of data application to research on the arctic atmosphere, atmospheric rivers, and tropical cyclones.