ProSensing Inc. has developed a G-band (183 GHz, 1.5 mm wavelength) water Vapor Radiometer (GVR) for measuring low concentrations of atmospheric water vapor and liquid water. Precipitable Water Vapor (PWV) and Liquid Water Path (LWP) are estimated from brightness temperatures measured by four double-sideband receiver channels, centered at 183.31 +-1, +-3, +-7 and +-14 GHz [1][2]. The three channels close to the vapor line (183.31 +-1, +-3 and +-7 GHz) are most sensitive to PWV, while the +-14 GHz channel is used primarily for the retrieval of LWP. An airborne version of the instrument, packaged and wired to operate from a standard PMS canister, was successfully tested onboard the Canadian National Research Council (NRC) Convair-580 aircraft during the CloudSat and CALIPSO validation flights (C3VP) through the winter of 2006-07. The Airborne GVR is now being installed in the UWyo King Air to participate in the WAICO experiment in February 2008.
In this seminar, basic radiometer concepts will be introduced, details of the Airborne GVR development effort will be outlined and the use of neural networks for the retrieval of PWV and LWP from the GVR brightness temperature measurements will be discussed.
[1] Pazmany, A. L., “A compact 183-GHz radiometer for water vapor and liquid water sensing” IEEE Trans. Geosci.. Remote Sens. Vol. 45, No. 7, pp. 2202-2206, July 2007.
[2] Cadeddu, M. P., J. C. Liljegren and A. L. Pazmany 2007: Measurements and retrievals from a new 183-GHz water-vapor radiometer in the
The Airborne GVR on the NRC Canada Convair-580 aircraft.