A Comparison of microwave radiometer, lidar, and meteorological balloon observations of water vapor during the Ladimas Campaign
Document ID: 24
Croskey, C. L.
Philbrick, C. Russell
Martone, J. P.
Stevens, Timothy D.
Haris, Paul A. T.
Olivero, J. J.
Puliafito, S. E.
McKinley, S. C.
The Pennsylvania State University, Communications and Space Sciences Laboratory, University Park, PA, U.S.A.
Presented: IEEE Proc. Combined Optical-Microwave Earth and Atmosphere
Abstract
During the fall of 1991, the German Research vessel Polarstern sailed from Bremerhaven, Germany, to the Antarctic carrying a 22-GHz microwave water vapor radiometer, a Nd:YAG lidar with a water vapor Raman data channel, and meteorological balloons. This portion of the LADIMAS (LAuitudinal Dstribution of Middle Atmosphere Structure) campaign provided a unique opportunity to combine the data sets from the three observation techniques over a wide range of geographic latitudes.
The Penn State microwave radiometer was developed at CSSL as part of NASA's Network for Detection of Stratospheric Change and the UARS Correlative Measurement program. It remotely senses water vapor in the atmosphere by observation of the thermally excited 22-GHz resonant line. The instrument has a cryogenically cooled HEMT (High Electron Mobility Transistor) preamplifier to obtain a very low effective noise temperature to enable observations into the mesosphere. Spectral analysis of the radiometer output by a 63-channel filter bank gives the altitude distribution of water vapor. The primary data set for these LADIMAS measurements was for the 40 to 80 km altitude region: however, a 400-MHz broad-band "total power" channel centered over the line also provided a measure of the total water vapor overburden that continued between periodic "tipping curve" calibrations.
The Penn State lidar, which was designed and constructed by the faculty and staff at Penn State University's Applied Research Laboratory (ARL) and Communications and Space Sciences Laboratory (CSSL), has an output of 1.5 J/pulse at 20 Hz. The fundamental wavelength is doubled to obtain 600 mJ pulses at 532 nM and mixed to obtain 250 mJ pulses at 355 nm. The lidar was designed as part of an NSF effort to study the coupling of energetics and dynamics of atmospheric regions and to develop advanced meteorological sounders for the U.S. Navy and other users of meteorological data. The lidar obtained density and temperature profiles from molecular scatter of the gases of the middle atmosphere (25-80 km), density and temperature profiles measured from the ground upward using two-color lidar and Raman detection, molecular nitrogen profiles up to 30 km, and water vapor profiles up to 5 km altitude.
Notes
“A Comparison of Microwave Radiometer, Lidar and Meteorological Balloon Observations of Water Vapor During the LADIMAS Campaign,” C. L. Croskey, C. R. Philbrick, J. P. Martone, T. D. Stevens, P. A. T. Haris, J. J. Olivero, S. E. Puliafito and S. C. McKinley, Proceedings of the IEEE Topical Symposium on Combined Optical-Microwave Earth and Atmosphere Sensing, 203-206, 1993.
Keywords: R. V. Polarstern, microwave, research instrument