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Re: [ferret_users] alongshore wind calculation

Thanks Satyesh and Ryo...

On Fri, Aug 31, 2018 at 10:11 AM Satyesh Ghetiya <satyeshghetiya@xxxxxxxxx> wrote:
Yes, true. 

On Thu, Aug 30, 2018 at 3:49 PM, Ryo Furue <furue@xxxxxxxxxx> wrote:

Actually i want to calculate alongshore wind along sumatra  coast that makes an angle 135 with the horizontal plane.

^ As you are mentioning the 135 degree angle, we can do some calculation to convert your normal (towards East) and v (towards North) winds to along/cross -shore winds by simplifying the coast to be straight line with your 135 degree angle. If such simplification is fine for you, then 

Along shore wind =    |v| * ( 1/sqrt(2) ) - |u| * ( 1/sqrt(2) )
Cross shore wind= - [ |v| * ( 1/sqrt(2) ) + |u| * ( 1/sqrt(2) )) ]          

   1/sqrt(2) = sin(45) or cos(45). |v| means magnitude of v.

The absolute values give you wrong results.  It's a simple rotation of the vector (u,v), which obeys the standard transformation.  This wikipedia article shows the transformation of coordinates (x,y) but the transformation of a vector is the same:


G Satyesh

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