Level 2 OCN Ocean Wind Field (OWI) Component

The OWI component is a ground range gridded estimate of the surface wind speed and direction at 10 m above the surface, derived from SM, IW or EW modes.

The OWI component contains a set of wind vectors for each processed Level-1 input product.The norm is wind speed in m/s and the argument is wind direction in degrees (meteorological convention = clockwise direction from where the wind blows respect to the North).

The spatial resolution of the SAR wind speed is 1 km for SM, IW and EW modes.

The SAR wind retrieval geophysical model functions are designed to retrieve the equivalent neutral stability wind speed at a height of 10 m above the ocean surface. The model responds to changes in roughness at the ocean surface, but cannot respond directly to changes in wind speed due to atmospheric stratification. The equivalent neutral stability wind speed is defined as the mean wind speed that would be observed if there was neutral atmospheric stratification.

NB: Currently, OWI information is provided only on SM, IW or EW OCN products. Some wind information is also reported on the OSW component (with a resolution 20km2), for SM or WV products.

OWI Characteristics
Coordinate System Ground Range
Incidence Angle (°) S1: 22.3 S2: 25.6 S3: 31.2 S4: 36.4 S5: 41.0 S6: 43.8
IW1: 32.9 IW2: 38.4 IW3: 43.1
EW1: 23.7 EW2: 30.9 EW3: 36.2 EW4: 40.9 EW5: 44.5
WV1: 23 WV2: 36.5
Ocean Wind Field Spatial Resolution [km x km] SM: 1X1
Product splits 170km x 80km SM image into 170x80 images of 1km x 1km for OWI estimation.
IW: 1x1
Product splits 170km x 250km IW image into 170x250 images of 1km x 1km for OWI estimation.
EW: 1x1
Product splits 400km x 400km EW image into 400x400 images of 1km x 1km for OWI estimation.
WV: 20x20
Ocean Wind Field Grid Dimensions [azimuth cell x ground range cell] SM: 170x80
IW: 170x250
EW: 400x400
WV: 1x1
Wind Speed [m/s] ∊{0,25}, RMSe < 2.0
Wind Direction [degN] ∊{0,360}, RMSe < 30


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