[MITgcm-support] how to calculate the relative velocity in the calculation of wind stress in the sea ice areas

[Martin Losch]

Hi Yang,

I hope I understand your question: The wind stress over ocean and ice is calculated from a quadratic lawi (in the model), the form is similar to c_D*|u|*u. For the ocean it is a little more complicated, see Large and Yeager’s report, or Large and Pond (1981,1982) cited in pkg/exf/exf_bulkformulae.F

If useRelativeWind=.TRUE. (in data.exf) then u (uWind in the code) is replaced by uWind - uVel over the ocean (see exf_getffields.F) and by uWind - uIce over sea ice (see pkg/seaice/seaice_get_dynforcing.F, in fact that looks more complicated because when this routine is called uWind is already uWind-uVel, so we do u = uWind + uVel - uIce)

uWind is directly read from a file, then it is modifed according to the value of useRelativeWind, then stress over ocean is computed, then the seaice_model is called and stress is computed over ice. Then stress over ocean is only applied to the ocean and stress over ice is only applied to the ice. Does that make sense to you? Does that answer your questions?

Martin

> On 30 Jun 2016, at 16:55, wuyang at nuist.edu.cn wrote:
> 
> Hello , Martin
> 
>     How to calculate wind stress over the ocean where is covered by the sea ice ? and the wind stress over the sea  ice ?
> 
>     When the relative wind is considered, how to calculate the relative velocity in the calculation of wind stress in the sea ice covered areas ?
> 
> Does the wind used in calculation of wind stress  read directly from the input atmospheric forcing without any  processings in the package of "seaice", except the interpolation?
> 
> 
> Thank you  very much !
> 
> Yang 
>