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Re: [ferret_users] Along-shore and cross-shore windstress calculation



Dear All,

Now I have another concern related to the calculation of along-shore and offshore components of wind.
I calculated the direction of wind (angle) by following method.

Let rad = 4.*atan(1.0)/180
Let wdir = atan2(u,v)/rad +180

This gives the angle of wind in terms of meteorological direction.
So, easterly winds will have angle 90 degrees, westerly - 270 degrees, northerly - 360, southerly - 180 degrees.

However, when winds direction changes from northerly to north-easterly (or vice-versa), the change in direction of wind (angle) is very large (from 360 to 30 degrees)
Please check the image attached with email and observe the change in angle of wind in Arabian Sea (Indian Ocean), Atlantic Ocean (west African coast), Eastern Pacific Ocean.

In above three regions you can observe the above situation when northerly winds become north-easterly. 
(Color plot is wind direction (angle) and vectors are wind stress)

Should I go ahead with the above results and calculate the along-shore and offshore components?
Or is there any way to treat such change in direction in better way?

Regards!

Vivek

On Thu, Jun 28, 2018 at 5:56 PM vivek shilimkar <vivek.shilimkar@xxxxxxxxx> wrote:
Dear Dr. Ryo and William,

Thank you so much for your reply.
I understand the Dr. William's method very quickly and prefer to use that.

Regards!

Vivek