Title: High-Altitude MMIC Sounding Radiometer - From the IIP to the Global Hawk
Author: Shannon Brown
Organization: Jet Propulsion Laboratory
Co-Authors: Richard Denning, Bjorn Lambrigtsen, Boon Lim, Jordan Tanabe, Alan Tanner, Pekka Kangaslahti, Todd Gaier

This paper describes the JPL High Altitude MMIC Sounding Radiometer and presents the instrument performance through two recent field campaigns on the Global Hawk UAV. HAMSR is a 25 channel cross-track scanning microwave sounder with channels near the 60 and 118 GHz oxygen lines and the 183 GHz water vapor line. HAMSR owes its current state-of-the art performance to three ESTO programs, the IIP, ACT and AITT. HAMSR was originally designed and built at the Jet Propulsion Laboratory through the first NASA Instrument Incubator call in 1998. Subsequent to this, HAMSR participated in three NASA hurricane field campaigns, CAMEX-4, TCSP and NAMMA. Beginning in 2008, HAMSR was extensively upgraded under the first NASA Airborne Instrument Technology Transfer (AITT) program to deploy on the NASA Global Hawk (GH) platform and serve as an asset to the NASA sub-orbital program. One of the major upgrades was the addition of a front-end LNA, developed by JPL through the MIMRAM Advanced Component Technology (ACT) project, to the 183 GHz channel which reduces the noise in this channel to less than 0.1K at the sensor resolution (~2km) and enabling HAMSR to observe much smaller scale water vapor features. The 118 GHz receiver was also upgraded using the state-of-the-art ACT developed LNA, lowering the noise figure of this receiver significantly. Another major upgrade was an enhanced data system that provides on-board science processing capability and real-time data access. During the 2010 GRIP hurricane field campaign, this capability was exploited with HAMSR image products displayed within 5 minutes of acquisition in the Google Earth based Real Time Mission Monitor (RTMM) system operated by NASA Marshall. HAMSR data were used in real time by the Global Hawk platform scientists to identify the tropical cyclone circulation center and adjustments the flight path in real time. Because of this, the Global Hawk was able to pass directly over the eye of Hurricane Karl an unprecedented 20 times as it transitioned from a tropical cyclone to a strong category 3 hurricane.

We will show highlights from two recent field campaigns that the upgraded HAMSR participated in, NASA GRIP in 2010 and NOAA WISPAR in 2011, focusing on those observations enabled by the technology upgrades. We will also give an overview of the overall instrument performance and provide an outlook for future flights on the Global Hawk as HAMSR prepares to participate in the NASA Ventures HS3 program.