Profiling Clouds and Precipitation at Four Frequencies Using an Integrated Suite of Three High-Altitude Down-Looking Radars

The high-altitude (~20 km) NASA ER-2 aircraft has flown remote sensing instruments for over three decades to study clouds and precipitation. The first active profiling instrument on the ER-2 was a nadir pointing lidar Cloud Lidar System (CLS) in the early 1980’s, followed by a dual-beam nadir viewing X-band radar called ER-2 Doppler Radar in the 1990’s. The ER-2 is capable of flying over most weather systems including hurricanes, severe weather, and high cirrus. It provides a top down view of clouds and precipitation that offers additional information than provided by ground-based or lower altitude aircraft. In the early 2000’s, a W-band nadir-pointing radar called Cloud Radar System (CRS) was developed to fly along with EDOP. These radars flew in several NASA field campaigns. In the last 8-10 years, we developed a dual-frequency conical scan, Ku- and Ka-band radar called High-altitude Imaging Wind and Rain Airborne Profiler (HIWRAP) that was developed for hurricane studies with the NASA Global Hawk UAS. Finally, EDOP was updated with a new radar called ER-2 X-band Radar (EXRAD) that provides nadir and conical/cross-track scan measurements. In 2014, HIWRAP and EXRAD were adapted to fly on the ER-2 along with CRS to provide a combined 4-frequency measurements (X, Ku, Ka, W) at nadir. These three radars with a combined 4 frequencies, has flown in two major field campaigns, Integrated Precipitation and Hydrology Experiment (IPHEX) in 2011, and Olympic Mountain Experiment (OLYMPEX) in 2015.

This paper will present a summary of the ER-2 radar measurements, highlights from the IPHEX and OLYMPEX field campaigns, and how these measurements are being used for the improvement of current spaceborne radar retrieval algorithms (Global Precipitation Mission (GPM)), and for helping define requirements for future missions such as the NASA Decadal Cloud, Convection, and Precipitation (CCP) mission. We will also describe how building versatile and compact airborne radars that can be flown on different platforms can improve their utility.