A simple method for retrieving significant wave height from Dopplerized X-band radar
Retrieving spectral wave parameters such as the peak wave direction and wave period from marine radar backscatter intensity is very well developed. However, the retrieval of significant wave height is difficult because the radar image spectrum (a backscatter intensity variance spectrum) has to be tr...
Main Authors: | , , |
---|---|
Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2017-02-01
|
Series: | Ocean Science |
Online Access: | http://www.ocean-sci.net/13/95/2017/os-13-95-2017.pdf |
Summary: | Retrieving spectral wave parameters such as the peak wave direction and wave
period from marine radar backscatter intensity is very well developed.
However, the retrieval of significant wave height is difficult because the
radar image spectrum (a backscatter intensity variance spectrum) has to be
transferred to a wave spectrum (a surface elevation variance spectrum) using
a modulation transfer function (MTF) which requires extensive calibration for
each individual radar setup. In contrast to the backscatter intensity, the
Doppler velocity measured by a coherent radar is induced by the radial
velocity (or line-of-sight velocity) of the surface scattering and its
periodic component is mainly the contribution of surface waves. Therefore,
the variance of the Doppler velocity can be utilized to retrieve the
significant wave height. Analyzing
approximately 100 days of Doppler velocity measurements of a
coherent-on-receive radar operating at X-band with vertical polarization in
transmit and receive, a simple relation was derived and validated to retrieve
significant wave heights. Comparison to wave measurements of a wave rider
buoy as well as an acoustic wave and current profiler resulted in a root mean
square error of 0.24 m with a bias of 0.08 m. Furthermore, the different
sources of error are discussed and investigated. |
---|---|
ISSN: | 1812-0784 1812-0792 |