The NASA High-Altitude Imaging Wind and Rain Airborne Profiler

The High-Altitude Imaging Wind and Rain Airborne Profiler (HIWRAP) is a dual-frequency (Ka- and Ku-bands), dual-beam (30° and 40° incidence angles), and conical scanning Doppler radar designed for operation on the NASA high-altitude (~19 km) Global Hawk Unmanned Aerial System. HIWRAP was developed under the support of the NASA Instrument Incubator Program for studies of tropical storms and severe weather events. It utilizes solid-state transmitters along with a novel transmit and receive waveform scheme that results in a system with compact size, light weight, less power consumption, and lower cost compared to radars currently in use for precipitation and Doppler wind measurements. By combining volume backscattering measurements at Ku- and Ka-bands, HIWRAP is capable of imaging radar reflectivity and 3-D wind fields in clouds and precipitation. In addition, HIWRAP is also capable of measuring surface winds in an approach similar to SeaWinds on QuikSCAT. HIWRAP operating frequencies are similar to those used by the NASA Global Precipitation Measurement (GPM) Dual-frequency Precipitation Radar, making it suitable for providing airborne validation data for the GPM mission. This paper describes the scientific motivation for the development of HIWRAP as well as the system hardware, aircraft integration, and recent flight activities. Data from recent science flights are also presented.