• AVISO/Altimetry, 1996: AVISO user handbook for merged TOPEX/Poseidon products. AVI-NT-02-101-CN, Ed. 3.0, 196 pp. [Available from CLS, 8–10 rue Hermes, Parc Technologique du Canal, 31526 Ramonville St-Agne, France.].

  • Bernard, R., A. Le Cornec, L. Eymard, and L. Tabary, 1993: The microwave radiometer aboard ERS-1. Part 1: Characteristics and Performances. IEEE Trans. Geosci. Remote Sens.,31, 1186–1198.

  • CERSAT, 1994: Microwave radiometer products user manual. C1-EX-MUT-A21-02-CN, Issue 2, Revision 0, 05/09/94, 32 pp. [Available from CERSAT, IFREMER, BP 70, 29280 Plouzané, France.].

  • CLS, 1993: Quality assessment of CERSAT microwave radiometer products, 22/12/1993. CLS.OC/NT/93008, Ed. 1, 2 pp. [Available from CERSAT, IFREMER, BP 70, 29280 Plouzané, France.].

  • Eymard, L., L. Tabary, and A. Le Cornec, 1996: The microwave radiometer aboard ERS-1. Part 2: Validation of the retrieved geophysical data. IEEE Trans. Geosci. Remote Sens.,34, 291–303.

    • Crossref
    • Export Citation
  • Fu, L. L, E. J. Christensen, C. A. Yamarone Jr., M. Lefebvre, Y. Ménard, M. Dorrer, and P. Escudier, 1994: TOPEX/Poseidon mission overview. J. Geophys. Res,99, 24 369–24 381.

    • Crossref
    • Export Citation
  • Keihm, S. J., M. A. Janssen, and C. S. Ruf, 1995: TOPEX/Poseidon Microwave Radiometer (TMR). Part 3: Wet troposphere range correction algorithm and pre-launch error budget. IEEE Trans. Geosci. Remote. Sens.,33, 147–161.

    • Crossref
    • Export Citation
  • Liebe, H. J., G. A. Hufford, and M. G. Cotton, 1993: Propagation modeling of moist air and suspended water/ice particles at frequencies below 1000 GHz. Proc. AGARD 52d Special Meeting of the Panel on Electromagnetic Wave Propagation, Palma de Mallorca, Spain, Advisory Group Aerosp. Res. Dev., 1–10.

  • Ruf, C., S. Keihm, M. Janssen, M. Subramanya, and T. Liu, 1994: TOPEX microwave radiometer performance and in-flight calibration. J. Geophys. Res,99, 24 915–24 926.

    • Crossref
    • Export Citation
  • Stum, J., 1994: A comparison between TOPEX microwave radiometer, ERS-1 microwave radiometer, and European Centre for Medium-Range Weather Forecasts derived wet tropospheric corrections. J. Geophys. Res,99, 24 927–24 939.

    • Crossref
    • Export Citation
  • Wilheit, T. T., and A. T. C. Chang, 1980: An algorithm for retrieval of ocean surface and atmospheric parameters from observations of the scanning multichannel microwave radiometer. Radio Sci.,15, 525–544.

    • Crossref
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A Comparison of the Brightness Temperatures and Water Vapor Path Delays Measured by the TOPEX, ERS-1, and ERS-2 Microwave Radiometers

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  • 1 Space Oceanography Division, Collecte Localisation Satellites, Ramonville Saint-Agne, France
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Abstract

Nadir-looking microwave radiometers are flown on altimeter missions to correct the altimeter range for water vapor path delay. This paper describes a technique to intercalibrate the brightness temperatures of the ERS-1 and ERS-2 microwave radiometers by using the TOPEX radiometer as a common reference. The technique is based on the analysis of radiometer measurements made at crossover points between TOPEX, ERS-1, and ERS-2 orbits with less than 1-h time lags. This provides about 1000 comparison points within 4 months and covers most atmospheric and oceanic states. It is shown first that the ERS-2 radiometer brightness temperatures need to be corrected to make them consistent with ERS-1 and thus to ensure the homogeneity of the series of ERS altimeter data. The accuracy of the method is then estimated from the results of a 3-yr TOPEX/ERS-1 data comparison and is shown to be about 0.2 K for the ERS-2 23.8-GHz channel and about 0.4 K for the 36.5-GHz channel. This 3-yr comparison also shows a −1 mm yr−1 drift in the (TOPEX/ERS-1) water vapor path delay difference, which needs to be confirmed with a longer time series. This technique could be used for the calibration of future radiometers placed in similar orbital configurations, such as the one to be flown on ENVISAT (relative to ERS-2 and using TOPEX or JASON as a reference).

Corresponding author address: Mr. Jacques Stum, Collecte Localisation Satellites, 8-10, rue Hermes, Parc Technologique du Canal, 31526 Ramonville Saint-Agne, France.

Email: jacques.stum@cls.cnes.fr

Abstract

Nadir-looking microwave radiometers are flown on altimeter missions to correct the altimeter range for water vapor path delay. This paper describes a technique to intercalibrate the brightness temperatures of the ERS-1 and ERS-2 microwave radiometers by using the TOPEX radiometer as a common reference. The technique is based on the analysis of radiometer measurements made at crossover points between TOPEX, ERS-1, and ERS-2 orbits with less than 1-h time lags. This provides about 1000 comparison points within 4 months and covers most atmospheric and oceanic states. It is shown first that the ERS-2 radiometer brightness temperatures need to be corrected to make them consistent with ERS-1 and thus to ensure the homogeneity of the series of ERS altimeter data. The accuracy of the method is then estimated from the results of a 3-yr TOPEX/ERS-1 data comparison and is shown to be about 0.2 K for the ERS-2 23.8-GHz channel and about 0.4 K for the 36.5-GHz channel. This 3-yr comparison also shows a −1 mm yr−1 drift in the (TOPEX/ERS-1) water vapor path delay difference, which needs to be confirmed with a longer time series. This technique could be used for the calibration of future radiometers placed in similar orbital configurations, such as the one to be flown on ENVISAT (relative to ERS-2 and using TOPEX or JASON as a reference).

Corresponding author address: Mr. Jacques Stum, Collecte Localisation Satellites, 8-10, rue Hermes, Parc Technologique du Canal, 31526 Ramonville Saint-Agne, France.

Email: jacques.stum@cls.cnes.fr

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