A Simple Method for Testing Brightness Temperatures from Satellite Microwave Radiometers

Lojou, Jean-Yves; Bernard, R.; Eymard, Laurence

doi:10.1175/1520-0426(1994)011<0387:asmftb>2.0.co;2

Cited by 22 publications

(7 citation statements)

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“…It is not our objective here to perform a detailed and an extensive comparison of these three steps for the two radiometers. A transfer function retrieval scheme is described byLojou et al [1994] for the EMR part and by S. J. Keihm et al…”

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confidence: 99%

A comparison between TOPEX microwave radiometer, ERS 1 microwave radiometer, and European Centre for Medium‐Range Weather Forecasting derived wet tropospheric corrections

Stum¹

1994

J. Geophys. Res.

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A comparison study has been carried out between the two wet tropospheric corrections in the TOPEX/POSEIDON merged geophysical data records. It is shown that the TOPEX microwave radiometer (TMR) wet tropospheric correction monitors 100‐ to 1000‐km water vapor scales better than the European Centre for Medium‐Range Weather Forecasting (ECMWF) derived wet tropospheric correction. The standard deviation for both corrections is about 3 cm, with a tendency for the ECMWF model to give higher humidities than TMR in very wet atmospheres. The ECMWF correction is of fairly high quality and could be used if the TMR fails. The TOPEX and ERS 1 microwave radiometer wet tropospheric corrections are also compared in the vicinity of TOPEX/ERS 1 crossovers. The standard deviation at crossovers is about 1 cm, with no bias. Along‐track comparison shows that the two radiometers perform similarly, except in high winds or rain. The small discrepancies may be due to differences in the antenna beams or in the geophysical transfer functions.

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mentioning

confidence: 99%

A comparison between TOPEX microwave radiometer, ERS 1 microwave radiometer, and European Centre for Medium‐Range Weather Forecasting derived wet tropospheric corrections

Stum¹

1994

J. Geophys. Res.

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“…The detailed comparison with meteorological measurements will be achieved following the method developed by Lojou et al (1994). It consists of applying radiative transfer model to ECMWF analyses over oceans (meteorological fields containing the information from all available routine observations), to obtain simulated brightness temperatures at places co-located with the satellite track.…”

Section: Resultsmentioning

confidence: 99%

“…The model used for ATSR/M is simpler, based on Ulaby et al (1981) for the atmospheric radiative transfer and Stogryn (1971Stogryn ( , 1972 and Hollinger, private Downloaded by ["Queen's University Libraries, Kingston"] at 04:24 05 January 2015 communication, for the surface, and provides the brightness temperature at frequencies lower than 40GHz. Its complete description can be found in Lojou (1990) and Lojou et al (1994).…”

Section: Geophysical Parameter Retrieval 321 Radiative Transfermentioning

confidence: 99%

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The ERS-1 microwave radiometer

Eymard¹,

Cornec²,

Tabary³

1994

International Journal of Remote Sensing

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The microwave radiometer on board ERS-I developed at CRPE has two channels at 23·8 and 36·5GHz. It is a nadir pointing sensor, aimed at the correction of the altimeter tropospheric path delay. It also provides the precipitable water and cloud liquid water over oceans along the satellite track. However, the measured brightness temperatures can be used to characterize polar ice and land surface properties. This paper summarises the characteristics of the instrument, describes the scientific requirements for data processing and presents its first results after launch.

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“…The brightness temperatures should preferably be calibrated and corrected if necessary before retrieving geophysical parameters, allowing to develop and apply algorithms independently developed. In this purpose, Lojou et al (1993) proposed to test and correct brightness temperatures by comparing them with calculated values, using collocated observations (from model analyses or other sources) and a direct radiative transfer model. This comparison establishes the limits and advantages of using analysed fields of a forecast model for validating satellite microwave radiometer data:…”

Section: Discussionmentioning

confidence: 99%

Validation of microwave radiometer geophysical parameters using meteorological model analyses

Eymard¹,

Bernard²,

Lojou³

1993

International Journal of Remote Sensing

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Data measured by microwave radiometers are brightness temperatures, from which, using algorithms, geophysical parameters arc retrieved. Errors in these parameters can be due either to the algorithms or to instrumental deficiencies affecting the brightness temperatures. Only geophysical data can be validated directly since dedicated meteorological experiments cannot be performed frequently enough or in a sufficient number of places during the satellites lifetime. To achieve such a global validation, we propose to use global meteorological model analyses, which contain the information of all routine observations after checking their quality. In this article, we test this approach by comparing Nimbus-7/SMMR geophysical data with ECMWF model analyses. Data from five months in 1979 are examined, and deviations between both data sets are analysed in terms of satellite or model errors. This comparison reveals SMMR problems in SSTand surface wind data, and local model errors in the precipitable water. Therefore, a good knowledge of model behaviour is necessary for using its analyses in satellite data validation, yet it appears as a useful tool, working at scales ranging from regional to global, and in time, from a particular event to a season or more.

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A Simple Method for Testing Brightness Temperatures from Satellite Microwave Radiometers

Cited by 22 publications

References 0 publications

A comparison between TOPEX microwave radiometer, ERS 1 microwave radiometer, and European Centre for Medium‐Range Weather Forecasting derived wet tropospheric corrections

A comparison between TOPEX microwave radiometer, ERS 1 microwave radiometer, and European Centre for Medium‐Range Weather Forecasting derived wet tropospheric corrections

The ERS-1 microwave radiometer

Validation of microwave radiometer geophysical parameters using meteorological model analyses

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