Analysis and inversion of ASAR WM data - assessment of polarization and incidence angle dependencies
Harald Johnsen(2) and Fabrice Collard(1)
(1) BOOST Technologies, 115, rue Claude CHAPPE, Technopole Brest Iroise, 29280 Plouzane, France
(2) Norut, P.O.Box 6434, N-9294 Tromsoe, Norway
ASAR Wave Mode data has been acquired in different swaths (S2 and S4) and polarization (VV and HH) for the assessment of polarization and incidence angle dependencies in the imaging of ocean surface waves and winds.
In this paper we have analysed and inverted the data with respect to surface winds and waves and compared the results. A modification of the geophysical model function (CMOD) and the modulation transfer function is done using a recently published backscattering model. Further to inversion the HH and VV data were calibrated relative and absolute using rain forest data and global collocated ECMWF WAM data, respectively.
The results of the analysis show that for the retrieved wind field the RMSe is the same for the VV and HH polarization data. For the wave field the RMSe and biases are also similar for all integrated wave parameters except the signficant waveheight, which seems to be underestimated (larger bias in HH than in VV). An ad-hoc tuning of the modulation transfer function is used to remove the bias.
The results are promissing in terms of utilization of the Sentinel-1 dual polarized data for ocean surface imaging.
Keywords: ESA European
Space Agency - Agence spatiale europeenne,
observation de la terre, earth observation,
satellite remote sensing,
teledetection, geophysique, altimetrie, radar,
chimique atmospherique, geophysics, altimetry, radar,