Calibration of an Airborne Interferometric Radar Altimeter over the Qingdao Coast Sea, China
Calibration/Validation (Cal/Val) of satellite altimeters is fundamental for monitoring onboard sensor performance and ensuring long-term data quality. As altimeter technology has been evolving rapidly from profile to wide swath and interferometric altimetry, different requirements regarding Cal/Val...
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| Format: | Article |
| Language: | English |
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MDPI AG
2020-05-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/12/10/1651 |
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| author | Lei Yang Yongsheng Xu Xinghua Zhou Lin Zhu Qiufu Jiang Hanwei Sun Ge Chen Panlong Wang Stelios P. Mertikas Yanguang Fu Qiuhua Tang Fangjie Yu |
| author_facet | Lei Yang Yongsheng Xu Xinghua Zhou Lin Zhu Qiufu Jiang Hanwei Sun Ge Chen Panlong Wang Stelios P. Mertikas Yanguang Fu Qiuhua Tang Fangjie Yu |
| author_sort | Lei Yang |
| collection | DOAJ |
| description | Calibration/Validation (Cal/Val) of satellite altimeters is fundamental for monitoring onboard sensor performance and ensuring long-term data quality. As altimeter technology has been evolving rapidly from profile to wide swath and interferometric altimetry, different requirements regarding Cal/Val have emerged. Most current Cal/Val technology has been developed for conventional profile altimeters, whereby satellite observations are compared against measurements at one point along orbit lines. However, the application of this type of Cal/Val technique to swath interferometric altimeters with two-dimensional measurements is difficult. Here, we propose a new strategy for the evaluation of interferometric altimeters based on comparison of wave-induced sea surface elevation (WSSE) spectra from one- and two-dimensional measurements. This method assumes that the WSSE variance of an equilibrium wave field is uniform and can be measured equivalently in the space or time domains. The method was first tested with simulated data and then used to evaluate the performance of an airborne interferometric radar altimeter system (AIRAS) using Global Navigation Satellite System (GNSS) buoy measurements. The differences between the WSSE variances from the AIRAS and two GNSS buoys were below 8 cm<sup>2</sup>, corresponding to a standard deviation of 2.8 cm, which could serve as a reference for the WSSE error over the scale range of waves. The correlation coefficient between the AIRAS and GNSS buoys was approximately 0.90, indicating that the error was small relative to the WSSE signals. In addition, the sea surface height (SSH) difference measured by the AIRAS was compared with that derived from the GNSS buoys at two sites. The results indicated that the error of the SSH difference was 3 cm. This approach represents a possible technique for the Cal/Val of future spaceborne/airborne interferometric altimeters; however, additional experiments and applications are needed to verify the feasibility of this method. |
| first_indexed | 2024-03-10T19:41:07Z |
| format | Article |
| id | doaj.art-ea0efd5530fa4be48de59fa6541b947f |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-10T19:41:07Z |
| publishDate | 2020-05-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-ea0efd5530fa4be48de59fa6541b947f2023-11-20T01:18:16ZengMDPI AGRemote Sensing2072-42922020-05-011210165110.3390/rs12101651Calibration of an Airborne Interferometric Radar Altimeter over the Qingdao Coast Sea, ChinaLei Yang0Yongsheng Xu1Xinghua Zhou2Lin Zhu3Qiufu Jiang4Hanwei Sun5Ge Chen6Panlong Wang7Stelios P. Mertikas8Yanguang Fu9Qiuhua Tang10Fangjie Yu11Marine Survey Research Center, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, ChinaQingdao National Laboratory for Marine Science and Technology, Qingdao 266373, ChinaMarine Survey Research Center, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, ChinaCollege of Geodesy and Geomatics, Shandong University of Science and Technology, Qingdao 266590, ChinaLaboratory for Ocean and Climate Dynamics, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, ChinaBeijing Institute of Radio Measurement, Beijing 100854, ChinaQingdao National Laboratory for Marine Science and Technology, Qingdao 266373, ChinaGeodetic Data Processing Centre of Ministry of Natural Resources, Xi’an 710000, ChinaGeodesy and Geomatics Engineering Laboratory, Technical University of Crete, GR-73100 Chania, GreeceMarine Survey Research Center, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, ChinaMarine Survey Research Center, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, ChinaQingdao National Laboratory for Marine Science and Technology, Qingdao 266373, ChinaCalibration/Validation (Cal/Val) of satellite altimeters is fundamental for monitoring onboard sensor performance and ensuring long-term data quality. As altimeter technology has been evolving rapidly from profile to wide swath and interferometric altimetry, different requirements regarding Cal/Val have emerged. Most current Cal/Val technology has been developed for conventional profile altimeters, whereby satellite observations are compared against measurements at one point along orbit lines. However, the application of this type of Cal/Val technique to swath interferometric altimeters with two-dimensional measurements is difficult. Here, we propose a new strategy for the evaluation of interferometric altimeters based on comparison of wave-induced sea surface elevation (WSSE) spectra from one- and two-dimensional measurements. This method assumes that the WSSE variance of an equilibrium wave field is uniform and can be measured equivalently in the space or time domains. The method was first tested with simulated data and then used to evaluate the performance of an airborne interferometric radar altimeter system (AIRAS) using Global Navigation Satellite System (GNSS) buoy measurements. The differences between the WSSE variances from the AIRAS and two GNSS buoys were below 8 cm<sup>2</sup>, corresponding to a standard deviation of 2.8 cm, which could serve as a reference for the WSSE error over the scale range of waves. The correlation coefficient between the AIRAS and GNSS buoys was approximately 0.90, indicating that the error was small relative to the WSSE signals. In addition, the sea surface height (SSH) difference measured by the AIRAS was compared with that derived from the GNSS buoys at two sites. The results indicated that the error of the SSH difference was 3 cm. This approach represents a possible technique for the Cal/Val of future spaceborne/airborne interferometric altimeters; however, additional experiments and applications are needed to verify the feasibility of this method.https://www.mdpi.com/2072-4292/12/10/1651interferometric altimeterGuanlanGNSS buoypower spectrum densitywavenumbercalibration |
| spellingShingle | Lei Yang Yongsheng Xu Xinghua Zhou Lin Zhu Qiufu Jiang Hanwei Sun Ge Chen Panlong Wang Stelios P. Mertikas Yanguang Fu Qiuhua Tang Fangjie Yu Calibration of an Airborne Interferometric Radar Altimeter over the Qingdao Coast Sea, China Remote Sensing interferometric altimeter Guanlan GNSS buoy power spectrum density wavenumber calibration |
| title | Calibration of an Airborne Interferometric Radar Altimeter over the Qingdao Coast Sea, China |
| title_full | Calibration of an Airborne Interferometric Radar Altimeter over the Qingdao Coast Sea, China |
| title_fullStr | Calibration of an Airborne Interferometric Radar Altimeter over the Qingdao Coast Sea, China |
| title_full_unstemmed | Calibration of an Airborne Interferometric Radar Altimeter over the Qingdao Coast Sea, China |
| title_short | Calibration of an Airborne Interferometric Radar Altimeter over the Qingdao Coast Sea, China |
| title_sort | calibration of an airborne interferometric radar altimeter over the qingdao coast sea china |
| topic | interferometric altimeter Guanlan GNSS buoy power spectrum density wavenumber calibration |
| url | https://www.mdpi.com/2072-4292/12/10/1651 |
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