Doppler centroid anomaly : a direct measurement of ocean surface currents from space

Updated april 17 2007

Author : dr.fab

Cape Hatteras : feb 6, 2003


Radial component of sea surface scatterers overlaid on sea surface roughness map. The radial direction is mostly toward the east, southing about 10 deg. SAR wind field on the right

Cape Hatteras : mar 19, 2003


The radial direction is mostly toward the east, southing about 10 deg. On this merged sea surface roughness(intensity) and radial surface velocities (color) derived from the new Doppler grid in WSS products (left), the Gulf stream meanders are clearly visibles in the doppler derived velocity map and the sea surface roughness fronts at the edges of the meanders confirms the presence of current fronts at convergent and divergent zones. Chlorophyle concentration index and sea surface temperature derived from MODIS AQUA 2h20 after ASAR scene with clear sky conditions (right) is showing us a rather good agreament between chlorophyle/temperature fronts and sea surface roughness/radial current fronts


Ancilliary Model and complementary remote sensing data are given to help the interpretation of composite ssr/Doppler derived velocities. On the left, Mercator ocean model surface current output for the same day as ASAR acquisition is showing us the predicted Gulf Stream path. On the right, Hycom (RSMAS) ocean model surface current output for the same day as ASAR acquisition is showing us a Gulf Stream path that is in better accordance with Doppler information.

Florida strait : Jul 5, 2005

The radial direction is mostly toward the east, northing about 10 deg.

Norvegian coastal current eddies : Oct 4, 2005


The radial direction is mostly toward the east, northing about 15 deg. SAR wind field and sea surface temperature are given to highlight the presence of northing coastal current.

Graphics generated with SARTool

ASAR Wide Swath data : copyright ESA

HYCOM model : copyright RSMAS

MERCATOR model : copyright MERCATOR

SALTO-DUACS : copyright CLS

MODIS AQUA SST and CHL-A: copyright NASA

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