For regional AOMIP models, the procedure for calculation of surface stress from sea-level pressure (Proshutinsky, 1997) is as follows:
- Interpolate 6-hourly or daily sea-level pressure Pa onto model-dependent grid.
- Calculate 6 hourly or daily geostrophic wind as: where is the unit vector in the vertical direction.
- Calculate surface wind speed by retarding and turning the geostrophic wind to the left as:
If Wg < 15 m/s:
If Wg ≥ 15 m/s:
For global AOMIP models, it is proposed that the AOMIP surface winds (see above) be blended with those arising directly from the NCEP/NCAR reanalysis product. The blending would occur over the latitude band 60-65 degrees North. The blended data set would have the same 6-hourly or daily temporal resolution as the AOMIP surface winds.