Search
Member access
ERS-2 SAR Wave Mode Monthly Quality Assessment
This bulletin provides a monthly assessment of the geophysical products from ERS-2 SAR Wave Mode (SAR_WVW_2P). The validation is performed globally using co-located WaveWatch3 (WW3) data from Ifremer. It is based on previous work done by Boost-Technology on Envisat ASAR monitoring.
Backscatter
| |
|
)
)
(left) Backscatter value (?0) [dB] as a function of wind speed. The Upper (resp. lower) line represents the CMOD-IFR2 empirical scattering model for Upwind (resp. crosswind) cases. (right) Histogram of the WVW backscatter value (?0) [dB]
)
Global map of backscatter value (?0) [dB]
Backscatter comparisons
In this part, the WW3 backscatter values refer to the output of the empirical CMOD-IFR2 model fed with ECMWF winds (speed and directions). Incidence angle values of WV points are used to estimate CMOD-IFR2 outputs.
| |
|
| (left) Comparisons between backscatter values ?0 of WVW data and WW3 (i.e. CMOD-IFR2+ECMWF wind). |
(right) Histogram of incidence angle. |
)
)
| |
|
|
)
)
)
Comparisons between backscatter values ?0 of WVW data and WW3 (i.e. CMOD-IFR2+ECMWF wind) for different wind directions; UpWinds (left), CrossWinds (centre) and DownWinds (right)
Significant Wave Height (SWH) analysis
| |
|
| Scatter plot (2D histogram) of Significant Wave Height of WW3 spectra vs. WVW |
Scatter plot of Significant Wave Height of WW3 spectra vs. WVW as a function of wind speed. Bins size are proportional to data occurence |
)
)
)
Global distribution of the difference between WVW SWH and WW3 SWH.
| |
|
|
)
)
)
Regional distribution of the difference between WVW SWH and WW3 SWH.
| |
|
)
)
Distribution of the difference between mean period of WVW and WW3 (a). Scatter plot of mean period of WW3 vs WVW (b).
Regional analysis of the wave directional distribution
| Angular distribution of WW3 wind speed |
Angular distribution of WVW significant wave height |
Angular distribution of WW3 significant height |
| |
|
|
| Northern Hemisphere (30°N < Latitude < 70°N) |
||
| |
|
|
| Tropical Zones (-25°N < Latitude < 25°N) |
||
| |
|
|
| Southern Hemisphere (-70°N < Latitude < -30°N) |
||
| |
|
|
| Global |
||
)
)
)
)
)
)
)
)
)
)
)
)
Mean wave direction relative to SAR
Global comparison between SAR and WW3 mean wave direction relative to SAR (in deg)
)
| |
|
|
)
)
)
Regional comparison between SAR and WW3 mean wave direction relative to SAR (in deg)
Global distribution of the ASAR WVW azimuth cutoff values
| |
|
)
)
Global map of SAR WVW azimuth cut-off values (left), and similar coverage of co-located ECMWF wind speed values (right).
Analysis of the normalized variance
WVW significant wave height vs. image normalized variance
)