Abstract. Slopes of the sea surface are one of
the main characteristics that determine the scattering and reflection of radio
waves from it. The dispersion obtained in different experiments the values of
the variance of sea surface slopes at a fixed wind speed is analyzed. Two
factors are considered. The first factor is the characteristics of the equipment
for measuring the slopes. The second factor is the conditions in which
experiments are being conducted. It is shown that the discrepancies in
the dependences of the dispersion of slopes on wind speed obtained in different
experiments are caused by the peculiarities of the measuring apparatus, which
are related to its spatial resolution. The slopes variance is
reduced quickly if the spatial resolution deteriorates. Dispersions
of slopes determined with the help of optical scanners (measuring the slopes
formed by surface waves of all scales) and slope dispersion determined with the
help of wave buoys (measuring the slopes formed by waves with a length of more
than 6 m) differ approximately by a factor of 10. An
analysis of the influence of the conditions for the development of the wave
field (such as the fetch, age of
the waves) on the dispersion of slopes was carried out on the basis of the
JONSWAP spectrum. It was shown that if the slopes,
formed by waves longer than 1.5 m, the fetch must be considered only if it is
less than 2 km away.
Keywords: symmetrical
dipol antenna, magnetic antenna, matching circuit.
References
1.
Karaev V.Yu., M. Panfilova M.A., Balandina G.N., Chu X. Retrieval of the slope variance by microwave measurements.
Issledovanie Zemli iz Kosmosa - Research of Earth from Space, 2012, No. 4, P. 62-77.
(In Russian)
2. Millet F.W., Arnold D.V., Warnick
K.F., Smith J. Electromagnetic bias estimation using in situ and satellite
data: 1, RMS wave slope. J. Geophys. Res, 2003, 108(C2). 3040,
doi:10.1029/2001JC001095.
3.
Zapevalov A.S. Bragg scattering of centimeter electromagnetic radiation from
the sea surface: the effect of waves longer than bragg components. Izvestiya
Fizika atmosferyi i okeana – Izvestiya. Atmospheric and Oceanic Physics,
2009, V. 45. No 2, Ñ. 253-261. (in Russian)
4. Danilychev M.V., Nikolaev A.N.,
Kutuza B.G. Application of the kirchhoff method for practical calculations in
microwave radiometry of wavy sea surface. Journal of Communications Technology and Electronics, 2009, Vol. 54, No. 8,
P. 869–878. DOI:
10.1134/S1064226909080026
5.
Lebedev N.E., Aleskerova A.A., Plotnikov E.M. The development of optical
methods for sea surface slope measurement. Sovremennye problemy
distantsionnogo zondirovaniya Zemli iz kosmosa, 2016, Vol. 13, No. 3, P.
136-149. (In Russian)
6.
Zapevalov A.S., Ratner Yu.B. Effects of quasi-Gaussian distribution of sea
surface slopes at laser sounding. Optika atmosfery i okeana –
Atmospheric and Oceanic Optics,
2002, V. 15,
No 10, P. 925-928.
(In Russian)
7. Karaev V.Yu., Meshkov E.M., Cotton
D., Chu X. On the problem about determination of the sea wave period based on
radio altimeter data. Radiophysics and Quantum Electronics, 2013. Vol.
56, No. 3, P. 123-134.
8.
Zapevalov A.S., Lebedev N.E. Impact of the spaceborne lidar sounding pulse
duration on the shape of the pulse reflected by the sea surface. Sovremennye
problemy distantsionnogo zondirovaniya Zemli iz kosmosa, 2017, Vol. 14, No.
1, P. 80-87.
(In Russian)
9. Danilychev M.V.. Kutuza B.G..
Nikolayev A.G. The use of the Kirchhoff method for practical calculations in
microwave radiometry of rough sea surfac.
Journal of Communications Technology and Electronics.
2009. V. 54, No 8. Ñ. 915-926.
10. Pustovoitenko V.V., Lebedev N.E.
Comparison of sea surface slope statistical moments obtained by means of
optical scanners and laser inclinometers. Sovremennye problemy
distantsionnogo zondirovaniya Zemli iz kosmosa, 2015, Vol. 12, No. 1, P.
102-109. (In
Russian)
11. Cox C., Munk W. Measurements of
the roughness of the sea surface from photographs of the sun glitter. J. Optical.
Soc. America, 1954, Vol. 44, ¹ 11, P. 838-850.
12. Bréon F.M., Henriot N.
Spaceborne observations of ocean glint reflectance and modeling of wave slope
distributions. J. Geoph. Res, 2006, Vol. 111. No. 6, C06005.
13. Hughes B.A., Grant H.L, Chappell
R.W.A. A fast response surface–wave slope meter and measured wind–wave
components. Deep–Sea Res., 1977, V.24. No. 12, P. 1211–1223.
14.
Khristoforov G.N., Zapevalov A.S., Babii M.V. Statistical characteristics of
the sea surface slopes at different wind speeds. Okeanologiya –
Oceanology, 1992, Vol. 32, Issue 3,
P. 452–459.
15. Kalinin S.A., Leykin, I.A.Measurement of the slopes of wind waves in the Caspian sea. Izvestiya
AN SSSR: Fizika
atmosferyi i okeana - Izvestiya RAS: Atmospheric and Oceanic Physics, 1988.
V. 21,
No 2, Ñ. 1210-1217.
(In Russian)
16. Longuett-Higgins M.S.,
Cartwrighte D.E., Smith N.D. Observation of the directional spectrum of sea
waves using the motions of the floating buoy, Pro. Conf. Ocean Wave Spectra. Englewood Cliffs. N. Y.: Prentice Hall, 1963. P. 111-132.
17.
Zapevalov A.S.. Sea surface slope estimates according to quasi-vertical sensing
in microwave range. Zhurnal Radioelektroniki - Journal of Radio Electronics,
2017, No. 3. Available at
http://jre.cplire.ru/jre/mar17/5/text.pdf. (In Russian)
18.
Hasselmann K., Barnett T.P., Bouws E., Carlson H., Cartwright D.E., Enke K.,
Ewing J.A., Gienapp H., Hasselmann D.E., Kruseman P., Meerburg A., Mller P.,
Olbers D.J, Richter K., Sell W., Walden H. Measurements of wind-wave growth
and swell decay during the Joint North Sea Wave Project (JONSWAP). Ergnzungsheft
zur Deutschen Hydrographischen Zeitschrift Reihe, 1973, A(8) (Nr. 12), P. 1-95.
19.
Pierson W.I., Moskovitz L. A prosed spectral form for fully developed wind seas
based on the similarity method of S.A. Kitaigorodsii. J. Geophysics Res.
1964. Vol. 69, ¹ 24. Ð. 5181-5190.
20.
Kitaygorodskiy S.A. Fizika vzaimodeystviya atmosfery i okeana. [Physics
of interaction of the atmosphere with the ocean.] Leningrad, Gidrometeoizdat
Publ. 1970. 284 p. (In Russian)