Re: [ferret_users] vectors on polar stereographic map projection

[Ansley Manke <ansley.b.manke@xxxxxxxx>]

Hi - I believe you will need to decimate your vectors before applying 
the stereographic projection and making your plots. One simple way if 
you just want to take every nth vector in x and/or y would be to use 
axis striding (Ferret version 6.02, see 
http://ferret.pmel.noaa.gov/Ferret/Documentation/Release_Notes/v602.html#native_strides).  
These commands will make Ferret treat the x and y axes of the grid as 
sampled every 3rd coordinate in x and 2nd in y.

  yes? use my_data.nc
  yes? set axis/stride=3 `uvec,return=xaxis`
  yes? set axis/stride=2 `uvec,return=yaxis`

This might or might not make sense for your data on this projection, of 
course.

Xiangdong Zhang wrote:
> Dear Ferreters,
>
> I am plotting vectors on a polar stereographic projection map
> by using the script mp_poly_vectors.jnl. The vectors get too 
> dense in the polar area due to the grid cell convergence. I 
> appreciate suggestions regarding controlling the density/number
> arrows and the size of the arrow head. Thanks a lot in advance.
>
> Regards, Xiangdong Zhang
>   

--

~>   ~>   ~>   ~>   ~>   ~>   ~>   ~>   ~>   ~>   ~> 

Ansley Manke, NOAA/PMEL   ansley.b.manke@xxxxxxxx
7600 Sand Point Way NE, Seattle WA
Phone 206-526-6246,  FAX 206-526-6744