Wave studies with the radar altimeter

Abstract

In this paper we review the physical understanding and the algorithms necessary to extract waveinformation from the radar altimeter return from the sea surface. This allows us to assess the progress made since the launch of Seasat, to identifyareas where further work is necessary in order to developour understanding of the basic mechanisms of radar interaction with the sea surface, and to suggest how new wave parameters might be obtained from the radar return. Followingon from this we review the wavestudiesthat have beencarried out using Seasat and Geosat altimeter data and present some new results, on the joint probability distribution of significant waveheight and wind speed, which we have obtained recentlyfrom Seasat data.

Effect of High-Frequency Sea Waves on Wave Period Retrieval from Radar Altimeter and Buoy Data

“…Altimeters are known for their ability to estimate significant wave height, and this was confirmed by the comparison of the present study, even in low-wind conditions. As shown in Figure 4, the data of altimeter Hs A almost perfectly agrees with that of buoy Hs B , as determined by Equation (2), where the CC is 0.98 and the RMSD is 0.2 m.…”

“…Altimeters are known for their ability to estimate significant wave height, and this was confirmed by the comparison of the present study, even in low-wind conditions. As shown in Figure 4, the data of altimeter almost perfectly agrees with that of buoy , as determined by Equation (2), where the CC is 0.98 and the RMSD is 0.2 m. In order to examine the reason for the remaining discrepancy between T A a and T B a , H s and MSS are examined because they are directly related to m 0 and m 4 , respectively, which are used in the derivation of T a . Altimeters are known for their ability to estimate significant wave height, and this was confirmed by the comparison of the present study, even in low-wind conditions.…”

“…Alternatively, radar altimeters have the capability of estimating H s and wind speed, in addition to the sea surface height. Moreover, subsequent studies have also indicated the possibility of retrieving T z from H s and the backscatter coefficient σ 0 , measurements of altimeters, and numerous empirical models have been proposed in the last two decades (e.g., [2][3][4][5][6]). However, these models perform worse in low-wind conditions than in high-wind conditions.…”

Measuring Ocean Waves with Altimeters and Synthetic Aperture Radars

“…Recently and Challenor et al (1988) have analysed one year of Geosat data to look at global monthly and annual means of Hs in the period November 1986 to November 1987. For the July-September period results were very similar to Seasat's.…”

“…Challenor & Srokosz (1988) carried out a preliminary study of the joint distribution of Hs and U 10 using Seasat data covering the whole period of the mission. Five 10' squares in different regions of the world's ocean were chosen for study and from all the available data a joint probability density functions (pdf) for Hs and U 10 were calculated.…”