Russian Federation
BISAC SCI019000 Earth Sciences / General
In October 2018, the Chinese-French satellite CFOSAT was launched into low-earth orbit, which carries the French SWIM spectrometer and the Chinese scatterometer RFSCAT. The SWIM (Ku-band) spectrometer measures the normalized radar cross section (NRCS) at small incidence angles (0∘–11∘) and for the first time measurements are performed at different azimuthal angles in a size-limited area where sea waves can be considered homogeneous. At small incidence angles, the backscattering mechanism is quasi-specular and the reflected field is calculated in the Kirchhoff approximation. Due to this, it becomes possible to retrieve the parameters of large-scale, in comparison with the length of the electromagnetic wave, sea waves (hereinafter referred to as large-scale waves). It has been shown that the common approach to measuring the mean square slopes (𝑚𝑠𝑠) of large-scale waves leads to large errors. For the measurement scheme at three azimuthal angles, an algorithm was developed for determining the direction of propagation of the dominant wave system, the 𝑚𝑠𝑠 of large-scale waves along the sounding direction and the unnormalized correlation coefficient between the slopes of large-scale waves along the 𝑋 and 𝑌 axes (hereinafter referred to as the correlation coefficient), which requires solving a system of transcendental equations. If we neglect the correlation coefficient in comparison with the 𝑚𝑠𝑠 of large-scale waves, then the solution is in an analytical form. The results of the simplified algorithm are compared with the exact solution. The values of the 𝑚𝑠𝑠 of large-scale waves obtained with the simplified approach can be used both to estimate the intensity of sea waves and as the initial conditions for solving the transcendental equation. The developed algorithms will be used to process the data of the SWIM spectrometer, which will allow for the first time to retrieval a two-dimensional field of large-scale wave slopes. KEYWORDS: Mean square slopes of large-scale waves; normalized radar cross section; small incidence angles; spectrometer SWIM; retrieval algorithms.
Mean square slopes of large-scale waves; normalized radar cross section; small incidence angles; spectrometer SWIM; retrieval algorithms
1. Barrick, D. E. (1968), Rough surface scattering based on the specular point theory, IEEE Transactions Antenna and Propagation, 16, No. 4, 449-554, Crossref
2. Bass, F. G., I. M. Fuks (1972), Wave Scattering on a Statistically Rough Surface, 424 pp. Nauka, Moscow. (in Russian)
3. Birol, F., E. Blayo, J. M. Brankart, et al. (2002),Advanced Altimeter Data Assimilation for the Development of Operational Oceanography, INSU, France.(https://www.aviso.altimetry.fr/fileadmin/documents/OSTST/2002 b/verron.pdf)
4. Boisot, O., F. Nouguier, et al. (2015), The GO4Model in Near Nadir Microwave Scattering From the Sea Surface, IEEE Transactions on Geoscience and Remote Sensing, 53, No. 11, 5889-5900, Crossref
5. Chen, P., G. Zheng, et al. (2017), Quasi Gaussian probability density function of sea wave slopes from near nadir Kuband radar observations, Remote Sensing of Environment, 217, 86-100, Crossref
6. Chu, X., Y. He, et al. (2012a), Relationships between Kuband radar backscatter and integrated wind and waves parameters at low incidence angles, IEEE Transactions on Geoscience and Remote Sensing, 50, No. 11, 4599-4609, Crossref
7. Chu, X., Y. He, G. Chen (2012b), Asymmetry and anisotropy of microwave backscatter at low incidence angles, IEEE Transactions on Geoscience and Remote Sensing, 50, No. 10, 4014-4024, Crossref
8. Cox, C., W. Munk (1954), Measurements of the roughness of the sea surface from photographs of the sun glitter, J. Opt. Soc. Amer., 44, No. 11,838-850, Crossref
9. Danilytchev, M., B. Kutuza, A. Nikolaev (2009), The application of sea wave slope distribution empirical dependencies in estimation of interaction between microwave radiation and rough sea surface, IEEE Transactions on Geoscience and Remote Sensing, 47, No. 2, 652-661, Crossref
10. Freilich, M. H., B. A. Vanhoff (2003), The relation between winds, surface roughness, and radar backscatter at low incidence angles from TRMM Precipitation Radar measurements, Journal of Atmospheric and Oceanic Technology, 20, No. 4, 549-562, Crossref
11. Garnakeryan, A. A., A. S. Sosunov (1978), Radiolocation of the Sea Surface, 144 pp. Izdatel’stvo Rostovskogo Universiteta, Rostov. (in Russian)
12. GPM (2014), GPM Data Utilization Handbook. First Edition, 92 pp. JAXA, Tokyo.
13. Isakovich, M. A. (1952), Scattering of waves from a statistically rough surface, Zhurnal Ehksperimental’noi i Teoreticheskoi Fiziki, 23, No. 3, 305-314. (in Russian)
14. Karaev, V., M. Kanevsky, et al. (2006), A rotating knife beam altimeter for wide swath remote sensing of the ocean: wind and waves, Sensors, 6,260-281, Crossref
15. Karaev, V., M. Kanevsky, et al. (2010), The concept of the advanced space microwave radar for remote sensing of the ocean at small incidence angles, PORSEC 2010 Proceedings p. 23, PORSEC, Taiwan.
16. Karaev, V., M. Panfilova, et al. (2012), Retrieval of the variance of the slopes of largescale waves from radar measurements in the microwave range, Issledovanie Zemli iz Kosmosa, No. 4, 62-77. (in Russian)
17. Karaev, V., M. Panfilova, et al. (2018), Experiment at the International Space Station: a microwave radar with scanning fan beam antenna at nadir probing, 25 years of Progress in Radar Altimetry Symposium, 2018, Abstracts p. 232-233, ESA, Portugal.
18. Karaev, V., L. Mitnik, et al. (2019), Mean square slopes of sea waves in cyclone area from dual frequency precipitation radar and microwave radiometer, Proc. of IGARSS 2019 p. 8109-8112, IGARSS, Crossref
19. Martina, M. J., M. Balmasedab, L. Bertinoc, et al.(2015), Status and future of data assimilation in operational oceanography, Journal of Operational Oceanography, 8, No. S1, s28-s48, Crossref
20. Mitnik, L., V. Kuleshov, et al. (2020), Retrieval of mean square slopes of sea waves, surface wind speed, total water vapor content and total cloud liquid water content in Hagibis typhoon area from satellite active and passive microwave, International Geoscience and Remote Sensing Symposium (IGARSS 2020), Proceedings p. 5709-5712, IGARSS, Crossref
21. Nouguier, F., A. Mouche, et al. (2014), Analysis of dual frequency ocean backscatter measurements at Ku and Kaband using near nadir incidence GPM radar data, Journal of Latex Class Files, 13, No. 9,1-5, Crossref
22. Nouguier, F., A. Mouche, et al. (2016), Analysis of Dual Frequency Ocean Backscatter Measurements at Ku and Ka Bands Using Near Nadir Incidence GPM Radar Data, IEEE Geoscience and Remote Sensing Letters, 13, No. 9, 1310-1314, Crossref
23. Panfilova, M., V. Karaev, J. Guo (2018), Oil slick observation at low incidence angles in Kuband, Journal of Geophysical Research, Oceans, 123, No.3, 1924-1936, Crossref
24. Panfilova, M., V. Karaev, et al. (2020a), Advanced view at the Ocean Surface, Journal of Geophysical Research, Oceans, 125, No. 11, Crossref
25. Panfilova, M., M. Ryabkova, et al. (2020b), Retrieval of the statistical characteristics of wind waves from the width and shift of the Doppler spectrum of the backscattered microwave signal at low incidence angles, IEEE Transactions on Geoscience and Remote Sensing, 20, No. 3, 2225-2231, Crossref
26. Pokazeev, K. V., A. S. Zapevalov (2019), Determining higher order cumulants of sea surface slopes by quasivertical radio sounding data, Vestnik Moskovskogo Universiteta, Seriya 3: Fizika, Astronomiya, 3,73-76, Crossref
27. Ryabkova, M., V. Karaev, et al. (2019), A reviewof wave spectra models as applied to the problem ofradar probing of the sea surface, Journal of Geophysical Research, Oceans, 124, 1-31, Crossref
28. Tran, N., B. Chapron, D. Vandemark (2007), Effects of long waves on Kuband ocean radar backscatter at low incidence angles using TRMM and altimeter data, IEEE Transactions on Geoscience and Remote Sensing, 4, No. 4, 542-546, Crossref
29. TRMM (2001), TRMM Data Users Handbook(2001), 226 pp. NASDA, Tokyo.
30. Valenzuela, G. (1978), Theories for the interaction of electromagnetic and oceanic waves - A review,Boundary Layer Meteorology, 13, 61-86, Crossref
31. Yan, Q., J. Zhang, et al. (2019), Analysis of Kuand Ka Band Sea Surface Backscattering Characteristics at LowIncidence Angles Based on the GPMDualFrequency Precipitation Radar Measurements, Remote Sensing, 11,754, Crossref
32. Zapevalov, A. S. (2020), Distribution of the variance of the sea surface slopes over the spatial ranges of the waves that create them, Sovremennye Problemy Distantsionnogo Zondirovaniya Zemli iz Kosmosa, 17,No. 1, 211-219, (in Russian)
