{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T00:19:25Z","timestamp":1760228365185,"version":"build-2065373602"},"reference-count":42,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2022,5,13]],"date-time":"2022-05-13T00:00:00Z","timestamp":1652400000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"\u201cWenHai\u201d Project Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology (Qingdao)","award":["2021WHZZB1600"],"award-info":[{"award-number":["2021WHZZB1600"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Satellite radar altimeters have been successfully used for sea surface height (SSH) measurement for decades, gaining great insight in oceanography, meteorology, marine geology, etc. To further improve the observation precision and spatial resolution, radar altimeters have evolved from real aperture to synthetic aperture, from the Ku-band to Ka-band. Future synthetic aperture radar (SAR) altimeter of the Ka-band is expected to achieve better performance than its predecessors. To verify the SAR altimeter data processing method and explore the system advantage of the Ka-band, a Ku\/Ka dual-band SAR altimeter airborne experiment was carried out over South China Sea on 6 November 2021. Through dedicated hardware design, this campaign has acquired the Ku and Ka dual-band echo data simultaneously. The airborne data are processed to estimate the SSH retrieval precision after a series of procedures (including height compensation, range migration correction, multi-look processing, waveform re-tracking). To accustom to the airborne experiment design, a SAR echo model that fully considers both the attitude variation of the aircraft and the elliptical footprint of radar beam is established. The retrieved SSH data are compared with the public SSH data along the flight path at the experiment day, showing good consistence for both bands. By calculating the theoretical precision of waveform re-tracking and re-processing the dual-band airborne data into different bandwidths, it is demonstrated that the Ku\/Ka precision ratio is possible to achieve 1.4 within the 27 km offshore area, which indicates that Ka-band has better performance.<\/jats:p>","DOI":"10.3390\/rs14102362","type":"journal-article","created":{"date-parts":[[2022,5,15]],"date-time":"2022-05-15T09:48:22Z","timestamp":1652608102000},"page":"2362","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Performance Analysis of Ku\/Ka Dual-Band SAR Altimeter from an Airborne Experiment over South China Sea"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8170-9502","authenticated-orcid":false,"given":"Xiaonan","family":"Liu","sequence":"first","affiliation":[{"name":"Beijing Institute of Radio Measurement, Beijing 100854, China"},{"name":"The Graduate School of Second Academy of China Aerospace, Beijing 100854, China"}]},{"given":"Weiya","family":"Kong","sequence":"additional","affiliation":[{"name":"Beijing Institute of Radio Measurement, Beijing 100854, China"}]},{"given":"Hanwei","family":"Sun","sequence":"additional","affiliation":[{"name":"Beijing Institute of Radio Measurement, Beijing 100854, China"}]},{"given":"Yaobing","family":"Lu","sequence":"additional","affiliation":[{"name":"Beijing Institute of Radio Measurement, Beijing 100854, China"}]}],"member":"1968","published-online":{"date-parts":[[2022,5,13]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"10039","DOI":"10.1029\/96JB03223","article-title":"Marine gravity anomaly from Geosat and ERS 1 satellite altimetry","volume":"102","author":"Sandwell","year":"1997","journal-title":"J. Geophys. Res. Solid Earth"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"24541","DOI":"10.1029\/94JC01640","article-title":"Comparison of TOPEX sea surface heights and tide gauge sea levels","volume":"99","author":"Mitchum","year":"1994","journal-title":"J. Geophys. Res. Oceans"},{"unstructured":"Bannoura, W.J., Wade, A., and Srinivas, D.N. (2005, January 17\u201323). NOAA ocean surface topography mission Jason-2 project overview. Proceedings of the OCEANS 2005 MTS\/IEEE, Washington, DC, USA.","key":"ref_3"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1402","DOI":"10.1093\/gji\/ggt469","article-title":"Retracking CryoSat-2, Envisat and Jason-1 radar altimetry waveforms for improved gravity field recovery","volume":"196","author":"Garcia","year":"2013","journal-title":"Geophys. J. Int."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1371","DOI":"10.1016\/j.asr.2017.12.018","article-title":"Coastal SAR and PLRM altimeter in German bright and west Baltic sea","volume":"62","author":"Dinardo","year":"2018","journal-title":"Adv. Space Res."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"112395","DOI":"10.1016\/j.rse.2021.112395","article-title":"The Copernicus Sentinel-6 mission: Enhanced continuity of satellite sea level measurements from space","volume":"258","author":"Donlon","year":"2021","journal-title":"Remote Sens. Environ."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1578","DOI":"10.1109\/36.718861","article-title":"The delay\/Doppler radar altimeter","volume":"36","author":"Raney","year":"1998","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"148","DOI":"10.1109\/TGRS.2016.2601958","article-title":"CryoSat-2 SAR-mode over oceans: Processing methods, global assessment, and benefits","volume":"55","author":"Boy","year":"2017","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"doi-asserted-by":"crossref","unstructured":"Dinardo, S., Lucas, B., and Benveniste, J. (2015, January 26\u201331). Sentinel-3 STM SAR ocean retracking algorithm and SAMOSA model. Proceedings of the 2015 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Milan, Italy.","key":"ref_9","DOI":"10.1109\/IGARSS.2015.7327036"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"2610","DOI":"10.1109\/TGRS.2018.2875622","article-title":"Pulse-to-pulse correlation effects in high PRF low-resolution mode altimeters","volume":"57","author":"Egido","year":"2019","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"doi-asserted-by":"crossref","unstructured":"Ludwig, M., Daganzo-Eusebio, E., and Davidson, M. (2013, January 21\u201326). Ka-Band radar missions for earth observation. Proceedings of the 2013 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Melbourne, Australia.","key":"ref_11","DOI":"10.1109\/IGARSS.2013.6723275"},{"doi-asserted-by":"crossref","unstructured":"Richard, J., Phalippou, L., Robert, F., Stenou, N., Thouvenot, E., and Sengenes, P. (2007, January 23\u201328). An advanced concept of radar altimetry over oceans with improved performances and ocean sampling: AltiKa. Proceedings of the 2007 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Barcelona, Spain.","key":"ref_12","DOI":"10.1109\/IGARSS.2007.4423609"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"4863","DOI":"10.1109\/JSTARS.2015.2469757","article-title":"Intercomparison of geophysical parameters from Saral\/AltiKa and Jason-2 altimeters","volume":"8","author":"Kumar","year":"2015","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"doi-asserted-by":"crossref","unstructured":"Vaze, P., Kaki, S., Limonadi, D., Esteban-Fernandez, D., and Zohar, G. (2018, January 3\u201310). The surface water and ocean topography mission. Proceedings of the 2018 IEEE Aerospace Conference, Big Sky, MT, USA.","key":"ref_14","DOI":"10.1109\/AERO.2018.8396504"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"194","DOI":"10.3389\/fmars.2019.00194","article-title":"Concept design of the \u201cGuanlan\u201d science mission: China\u2019s novel contribution to space oceanography","volume":"6","author":"Chen","year":"2019","journal-title":"Front. Mar. Sci."},{"doi-asserted-by":"crossref","unstructured":"Yang, L., Xu, Y.S., Zhou, X.H., Zhu, L., Jiang, Q., Sun, H., Chen, G., Wang, P., Mertikas, S.P., and Fu, Y. (2020). Calibration of an airborne interferometric radar altimeter over the Qingdao coast sea, China. Remote Sens., 12.","key":"ref_16","DOI":"10.3390\/rs12101651"},{"unstructured":"(2022, April 11). Copernicus Marine Service. Available online: https:\/\/resources.marine.copernicus.eu.","key":"ref_17"},{"doi-asserted-by":"crossref","unstructured":"Nusantara, C.A.D.S., Hakim, A.R., and Adytia, D. (2020, January 5\u20136). Instantaneous height of sea surface: A comparison between local field observation and the simulated level from global models. Proceedings of the 2020 International Conference on Data Science and Its Applications (ICoDSA), Bandung, Indonesia.","key":"ref_18","DOI":"10.1109\/ICoDSA50139.2020.9212852"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"67","DOI":"10.1109\/TAP.1977.1141536","article-title":"The average impulse response of a rough surface and its applications","volume":"25","author":"Brown","year":"1977","journal-title":"IEEE Trans. Antennas Propag."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"2517","DOI":"10.1109\/TGRS.2008.918863","article-title":"Beam sharpening of Delay\/Doppler altimeter data through chirp Zeta transform","volume":"46","author":"Guccione","year":"2008","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"doi-asserted-by":"crossref","unstructured":"Scagliola, M., Guccione, P., and Giudici, D. (2018, January 22\u201327). Fully focused SAR processing for radar altimeter: A frequency domain approach. Proceedings of the 2018 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Valencia, Spain.","key":"ref_21","DOI":"10.1109\/IGARSS.2018.8519119"},{"doi-asserted-by":"crossref","unstructured":"Tournadre, J., and Chapron, B. (October, January 26). Altimeter as an imager of the sea surface roughness: Comparison of SAR and LRM modes. Proceedings of the 2020 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Waikoloa, HI, USA.","key":"ref_22","DOI":"10.1109\/IGARSS39084.2020.9323226"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"2305","DOI":"10.1109\/TGRS.2004.834352","article-title":"The mean echo and echo cross product from a beamforming interferometric altimeter and their application to elevation measurement","volume":"42","author":"Wingham","year":"2004","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"392","DOI":"10.1109\/TGRS.2016.2607122","article-title":"Fully focused SAR altimetry: Theory and applications","volume":"55","author":"Egido","year":"2017","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"911","DOI":"10.1109\/TGRS.2014.2330423","article-title":"SAR altimeter backscattered waveform model","volume":"53","author":"Ray","year":"2015","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"doi-asserted-by":"crossref","unstructured":"Bai, Y., Wang, Y., Zhang, Y., and Zhao, C. (August, January 28). The effects of random error on the measurement results of wide-swath interferometric imaging radar altimeter. Proceedings of the 2019 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Yokohama, Japan.","key":"ref_26","DOI":"10.1109\/IGARSS.2019.8898751"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"2539","DOI":"10.1109\/TGRS.2017.2756854","article-title":"A semianalytical model of the synthetic aperture, interferometric radar altimeter mean echo, and echo cross-product and its statistical fluctuations","volume":"56","author":"Wingham","year":"2018","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"480","DOI":"10.1109\/LGRS.2020.2980635","article-title":"Datation and range calibration of radar altimeter exploiting fully focused SAR processing","volume":"18","author":"Scagliola","year":"2021","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1537","DOI":"10.1109\/LGRS.2017.2720847","article-title":"An accurate semianalytical waveform model for mispointed SAR interferometric altimeters","volume":"14","author":"Recchia","year":"2017","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1448","DOI":"10.1109\/TGRS.2018.2866773","article-title":"Improved sea state bias estimation for altimeter reference missions with altimeter-only three-parameter models","volume":"57","author":"Pires","year":"2019","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"598","DOI":"10.1109\/TGRS.2014.2326177","article-title":"Including antenna mispointing in a semi-analytical model for Delay\/Doppler altimetry","volume":"53","author":"Halimi","year":"2015","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"doi-asserted-by":"crossref","unstructured":"Recchia, L., Scagliola, M., and Giudici, D. (2018, January 22\u201327). Doppler ambiguities masking for altimeter waveforms: A model based approach. Proceedings of the 2018 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Valencia, Spain.","key":"ref_32","DOI":"10.1109\/IGARSS.2018.8518395"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"9927","DOI":"10.1109\/TGRS.2021.3064236","article-title":"Benefits of the adaptive algorithm for retracking altimeter nadir echoes: Results from simulations and CFOSAT\/SWIM observations","volume":"9","author":"Tourain","year":"2021","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"doi-asserted-by":"crossref","unstructured":"Guo, J., Di, W., Yuan, J., Niu, Y., and Li, Z. (2018, January 18\u201320). Satellite radar altimetric waveform simulation and retracking over coastal sea based on singular spectrum analysis. Proceedings of the 5th International Workshop on Earth Observation and Remote Sensing Applications (EORSA), Xi\u2019an, China.","key":"ref_34","DOI":"10.1109\/EORSA.2018.8598643"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"4248","DOI":"10.1109\/TGRS.2013.2280595","article-title":"A semi-analytical model for Delay\/Doppler altimetry and its estimation algorithm","volume":"52","author":"Halimi","year":"2014","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"doi-asserted-by":"crossref","unstructured":"Phalippou, L., and Enjolras, V. (2007, January 23\u201328). Re-tracking of SAR altimeter ocean power-waveforms and related accuracies of the retrieved sea surface height, significant wave height and wind speed. Proceedings of the 2007 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Barcelona, Spain.","key":"ref_36","DOI":"10.1109\/IGARSS.2007.4423608"},{"unstructured":"Halimi, A., Mailhes, C., and Tourneret, J. (2013, January 9\u201313). Cram\u00e9r-Rao bounds and estimation algorithms for delay\/Doppler and conventional altimetry. Proceedings of the 21st European Signal Processing Conference (EUSIPCO 2013), Marrakech, Morocco.","key":"ref_37"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"596","DOI":"10.1109\/LGRS.2010.2042425","article-title":"GNSS-derived path delay: An approach to compute the wet tropospheric correction for coastal altimetry","volume":"7","author":"Fernandes","year":"2010","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"9849","DOI":"10.1109\/TGRS.2019.2929737","article-title":"Impact of the new ERA5 reanalysis in the computation of radar altimeter wet path delays","volume":"57","author":"Vieira","year":"2019","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"189","DOI":"10.1080\/01490410290051527","article-title":"Absolute calibration of the TOPEX\/POSEIDON altimeters using UK tide gauges, GPS, and precise, local Geoid-Differences","volume":"25","author":"Dong","year":"2002","journal-title":"Mar. Geod."},{"unstructured":"Lin, Y. (2018). Development and Applications of a GNSS Buoy for Monitoring Tides and Ocean Waves in Coastal Areas. [Ph.D. Thesis, National Cheng Kung University].","key":"ref_41"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"315","DOI":"10.1109\/36.214909","article-title":"Prelaunch performance of the NASA altimeter for the TOPEX\/POSEIDON project","volume":"31","author":"Marth","year":"1993","journal-title":"IEEE Trans. Geosci. Remote Sens."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/14\/10\/2362\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T23:10:34Z","timestamp":1760137834000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/14\/10\/2362"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,5,13]]},"references-count":42,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2022,5]]}},"alternative-id":["rs14102362"],"URL":"https:\/\/doi.org\/10.3390\/rs14102362","relation":{},"ISSN":["2072-4292"],"issn-type":[{"type":"electronic","value":"2072-4292"}],"subject":[],"published":{"date-parts":[[2022,5,13]]}}}