Converting Speed and Direction to U,V Vector Components

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Converting Speed and Direction to U,V Vector Components

Postby dmoroni » Fri Jan 15, 2016 4:22 pm

For Level 2 scatterometer wind vector datasets, what convention does the wind direction represent, and how can I convert the wind speed and direction to the standard U (zonal) and V (meridional) components?

The oceanographic, or flow vector, convention for wind direction is adopted for all standard Level 2 ocean surface wind vector datasets distributed through the PO.DAAC ASCAT, QuikSCAT, Oceansat-2, RapidScat, and SeaWinds on ADEOS-2. Under this convention, a wind direction of 0° implies a flow toward the north. This is in contrast to the meteorological, or “out of”, convention, for which a “north” wind (0° direction) flows from the north. Conversion between the two conventions is performed by simply reversing the directions (i.e., adding 180° modulo 360°).

Under the oceanographic convention, to convert wind speed and direction to the standard U and V vector components, where U is zonal and V is meridional, please follow the following mathematical formulas:

  • U = wind_speed*SIN(wind_direction)
  • V = wind_speed*COS(wind_direction)
dmoroni
 
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