Ground-Based and Airborne (PMS 2-D Probe Canister-Mounted) 183 GHz Water Vapor Radiometer

Pazmany, Andrew ProSensing Inc.

Category: Instruments

ProSensing Inc. has developed a G-band (183 GHz, 1.5 mm wavelength) water vapor radiometer (GVR) for the measurement of low concentrations of atmospheric water vapor and liquid water. The instrument’s precipitable water vapor measurement precision is approximately 0.01 mm in dry (<2 mm vapor column) conditions. The ground-based version of the instrument was first deployed at ProSensing’s facility in Amherst, MA in February 2005, then at the North Slope of Alaska DOE ARM site in Barrow AK in April 2005, where it has been continuously operating since. An airborne version, designed to operate from a standard PMS 2-D probe canister, is now being tested. Key System Parameters: ·Four double sideband channels at 183.31 +- 1, +-3 +-7 and +-14 GHz ·Noise temperature: 1750K (1 GHz), 1610K (3 GHz), 1600K (7 GHz) and 2170K (14 GHz) ·Integrated hot (~350 K) and warm (~300 K) calibration loads ·Measurement precision (NEDT): 0.2K with 500 ms averaging time ·Measurement stability (Allan STD): <0.05 K over 1000 seconds ·Antenna: 4" reflector with offset scalar feed, 2 deg. beamwidth ·All-weather operation with a radome and a 500 CFM Blower and Hood (ground-based) ·Designed to operation from a standard PMS 2-D probe canister (airborne) ·Temperature range tested in an environmental chamber from -45 to +10 C (airborne has not been tested) This poster will describe details of the ground-based and airborne GVR designs and calibration, and will present examples of brightness temperature measurements and retrieved integrated water vapor and liquid water collected at the ProSensing facility in Amherst, MA and at the North Slope of Alaska DOE ARM site in Barrow AK. At this meeting, Cadeddu will present an analysis of the GVR Barrow data and comparisons of the retrieved precipitable water vapor and cloud liquid water with values from other sensors. Temperature and water vapor profiling improvements with combined GVR and microwave radiometer data will be presented by Liljegren et al. References: Cadeddu, M., P., J. C. Liljegren, and A. L. Pazmany, “Measurements and Retrievals from a New 183-GHz Water Vapor Radiometer in the Arctic.” ARM Science Team Meeting, Albuquerque, NM 2006. Liljegren J. C., M. P. Cadeddu and A. L. Pazmany, “Retrievals of Atmospheric Temperature and Water Vapor Profiles in the Arctic.” ARM Science Team Meeting, Albuquerque, NM 2006. This work at ProSensing Inc. was funded by a Department of Energy Phase II SBIR contract # DE-FG02-02ER83440.

This poster will be displayed at the ARM Science Team Meeting.