Impact of the Local Oscillator Calibration Rate on the SMOS Measurements and Retrieved Salinities
10 pages, 14 figures, 1 tabl3
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| Language: | English |
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Institute of Electrical and Electronics Engineers
2013-02
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| Subjects: | Calibration, Noise, Receivers, Sea measurements, Temperature measurement, Thermal noise, Brightness temperature, Microwave imaging radiometer by aperture synthesis, Soil Moisture and Ocean Salinity, Interferometry, Radiometer, Salinity, MIRAS, SMOS, |
| Online Access: | http://hdl.handle.net/10261/81703 |
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dig-icm-es-10261-817032023-01-03T12:58:43Z Impact of the Local Oscillator Calibration Rate on the SMOS Measurements and Retrieved Salinities Gabarró, Carolina González Gambau, Verónica Corbella, Ignasi Torres, Francesc Martínez, Justino Portabella, Marcos Font, Jordi Calibration Noise Receivers Sea measurements Temperature measurement Thermal noise Brightness temperature Microwave imaging radiometer by aperture synthesis Soil Moisture and Ocean Salinity Interferometry Radiometer Salinity MIRAS SMOS 10 pages, 14 figures, 1 tabl3 The local oscillators (LOs) of the Soil Moisture and Ocean Salinity mission payload are used to shift the operating frequency of the 72 receivers to an optimal intermediate frequency needed for the signal processing. The LO temperature variations produce phase errors in the visibility, which result in a blurring of the reconstructed brightness temperature (Tb) image. At the end of the commissioning phase, it was decided to calibrate the LO every 10 min while waiting for a more in-depth analysis. During short periods of time, the LO calibration has been performed every 2 min to assess the impact of a higher calibration rate on the quality of the data. In this paper, by means of a decimation experiment, the relative errors of 6- and 10-min calibration interval data sets are estimated using the 2 min as a reference. A noticeable systematic across- and along-track pattern of amplitude $pm$0.3 K is observed for Tb differences between 10 and 2 min, whereas this is reduced between 6 and 2 min. A simulation experiment confirms that the nature of such systematic pattern is due to the visibility phase errors induced by the LO calibration rate. Such pattern is propagated into the sea surface salinity (SSS) retrievals. Overall, the SSS error increase (relative to the 2 min SSS data) is about 0.39 and 0.14 psu for the 10- and 6-min data sets, respectively. This paper shows that a LO calibration rate of at least 6 min would noticeably improve the SSS retrievals The SMOS Level 2 Prototype Processor development was funded by the European Space Agency under different contracts Peer reviewed 2013-09-10T07:28:38Z 2013-09-10T07:28:38Z 2013-02 artículo http://purl.org/coar/resource_type/c_6501 IEEE Transactions on Geoscience and Remote Sensing 51(9): 4633-4642 (2013) 0196-2892 http://hdl.handle.net/10261/81703 10.1109/TGRS.2012.2233744 en https://doi.org/10.1109/TGRS.2012.2233744 none Institute of Electrical and Electronics Engineers |
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Calibration Noise Receivers Sea measurements Temperature measurement Thermal noise Brightness temperature Microwave imaging radiometer by aperture synthesis Soil Moisture and Ocean Salinity Interferometry Radiometer Salinity MIRAS SMOS Calibration Noise Receivers Sea measurements Temperature measurement Thermal noise Brightness temperature Microwave imaging radiometer by aperture synthesis Soil Moisture and Ocean Salinity Interferometry Radiometer Salinity MIRAS SMOS |
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Calibration Noise Receivers Sea measurements Temperature measurement Thermal noise Brightness temperature Microwave imaging radiometer by aperture synthesis Soil Moisture and Ocean Salinity Interferometry Radiometer Salinity MIRAS SMOS Calibration Noise Receivers Sea measurements Temperature measurement Thermal noise Brightness temperature Microwave imaging radiometer by aperture synthesis Soil Moisture and Ocean Salinity Interferometry Radiometer Salinity MIRAS SMOS Gabarró, Carolina González Gambau, Verónica Corbella, Ignasi Torres, Francesc Martínez, Justino Portabella, Marcos Font, Jordi Impact of the Local Oscillator Calibration Rate on the SMOS Measurements and Retrieved Salinities |
| description |
10 pages, 14 figures, 1 tabl3 |
| format |
artículo |
| topic_facet |
Calibration Noise Receivers Sea measurements Temperature measurement Thermal noise Brightness temperature Microwave imaging radiometer by aperture synthesis Soil Moisture and Ocean Salinity Interferometry Radiometer Salinity MIRAS SMOS |
| author |
Gabarró, Carolina González Gambau, Verónica Corbella, Ignasi Torres, Francesc Martínez, Justino Portabella, Marcos Font, Jordi |
| author_facet |
Gabarró, Carolina González Gambau, Verónica Corbella, Ignasi Torres, Francesc Martínez, Justino Portabella, Marcos Font, Jordi |
| author_sort |
Gabarró, Carolina |
| title |
Impact of the Local Oscillator Calibration Rate on the SMOS Measurements and Retrieved Salinities |
| title_short |
Impact of the Local Oscillator Calibration Rate on the SMOS Measurements and Retrieved Salinities |
| title_full |
Impact of the Local Oscillator Calibration Rate on the SMOS Measurements and Retrieved Salinities |
| title_fullStr |
Impact of the Local Oscillator Calibration Rate on the SMOS Measurements and Retrieved Salinities |
| title_full_unstemmed |
Impact of the Local Oscillator Calibration Rate on the SMOS Measurements and Retrieved Salinities |
| title_sort |
impact of the local oscillator calibration rate on the smos measurements and retrieved salinities |
| publisher |
Institute of Electrical and Electronics Engineers |
| publishDate |
2013-02 |
| url |
http://hdl.handle.net/10261/81703 |
| work_keys_str_mv |
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| _version_ |
1777665958597361664 |