High Altitude MMIC Sounding Radiometer (HAMSR)

The High Altitude MMIC Sounding Radiometer (HAMSR) is an atmospheric sounder intended for aircraft deployment. It was designed and built at the Jet Propulsion Laboratory under the NASA Instrument Incubator Program and uses advanced technology to achieve excellent performance in a small package. It was first deployed in the field in the 2001 Fourth Convection and Moisture Experiment (CAMEX-4) - a hurricane field campaign organized jointly by NASA and the Hurricane Research Division (HRD) of NOAA in Florida. HAMSR has participated in multiple field campaigns, such as the Tropical Cloud Systems and Processes (TCSP), Genisis and Rapid Intensification Processes (GRIP), and Huricane and Severe Storm Sentinel (HS3). The primary data products generated with HAMSR consist of calibrated brightness temperatures in two temperature sounding bands and one water vapor sounding bands. Derived products include vertical temperature profiles and water vapor and liquid water profiles from the ground to the flight altitude, and experimental products include estimates of precipitation, ice water path and distribution in clouds and above convective cells, and convective intensity. HAMSR provides observations similar to those obtained with microwave sounders currently operating on NASA, NOAA and ESA spacecraft, and this offers an opportunity for valuable comparative analyses.

Instrument Specifications

HAMSR is a microwave temperature and humidity sounder instrument that looks at the microwave spectrum. Typically, it is flown at the bottom part of an aircraft where it can look straight down from the air to the ground, right through the atmosphere. HAMSR is a self-calibrating cross-track scanning instrument. Its scan mirror makes a full revolution in little more than 1 second. During that period, it obtains a number of overlapping spatial samples of the atmospheric scene below and several view of two internal calibration targets. From an altitude of 20 km, its field of view about 40 km wide on the ground.

The direct measurements are brightness temperatures for each field of view in 25 channels over 3 spectral bands. Additional information on measurements includes:

• Coverage from surface to flight altitude (<100 mb)
• ~ 2 km vertical resolution
• ~ 2 km horizontal resolution (at nadir, at the surface)
• ~ 40 km wide swath (at the surface)
• 8 channels in the 50-GHz band: primary T-sounding
• 10 channels in 118-GHz band: secondary T-sounding
• 7 channels in 183-GHz band: q- sounding