[ferret_users] Plotting curvilinear vectors

["Stephen R. Guimond" <guimond@xxxxxxxxxxxxx>]

Group,
 I have a series of wind vectors in the lat,lon,u,v format and have 
tried two methods to plot them (1) using the curvilinear version of 
VECTOR and (2) using the plot_vectors.jnl script.  Method 1 gives me 
incorrect vectors, the script I used is attached 
(curvilinear_regrid.jnl).  These winds are from a hurricane and from 
the plot, don't have the standard cyclonic flow.  Method 2 works good 
for giving me the right picture (i.e. cyclonic flow), but I am having 
trouble making a vector key.  I tried overlaying random vectors using a 
specified vector length, but the arrowhead size, scaling, etc are 
different (quikscat.jnl) and looks funny.   Ideally, I would like to 
get the right plot with method 1 so I can use the many qualifiers (i.e. 
key) associated with VECTOR, that the plot_vectors.jnl script doesn't 
have.  Any idea why the winds are messed up in method 1?

Thanks much,
Steve

=======================================================
Stephen R. Guimond
Graduate Research Assistant
Center for Ocean-Atmospheric Prediction Studies (COAPS)
Tallahassee, FL 32304
=======================================================

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Attachment: bad_winds.gif
Description: GIF image

Attachment: good_winds.gif
Description: GIF image

 ! NOAA/PMEL TMAP
 ! FERRET v5.60  
 ! IRIX 6.5 - 04/07/04
 ! 20-Feb-06 15:00     

def axis/x=1:20:1 xax
def axis/y=1:72:1/modulo yax
def grid/x=xax/y=yax g1
file/grid=g1/var="lat,lon,u,v" fort.8

set var/bad=-9999. u;set var/bad=-9999. v

def axis/y=1:73:1 nyax
def grid/like=g1/y=nyax g2
let nlat = lat[g=g2]
let nlon = lon[g=g2]
let nu = u[g=g2]
let nv = v[g=g2]

!let speed = (nu^2 + nv^2)^0.5
!fill speed,nlon,nlat

vector nu,nv,nlon,nlat

exit
 ! NOAA/PMEL TMAP
 ! FERRET v5.60  
 ! IRIX 6.5 - 04/07/04
 ! 17-Nov-06 17:02     

file/var="lat,lon,u,v" fort.8

set var/bad = -9999. u
set var/bad = -9999. v

let nu = u/8
let nv = v/8

go basemap x=280:300 y=25:35 5

go plot_vectors nu nv lon lat 2



exit






let nrefu = 15/8
let nrefv = 0

!go plot_vectors nrefu nrefv 290 30

let array_u = i[i=1:2]*j[j=1:2]*0 + 15

let array_v = i[i=1:2]*j[j=1:2]*0 + 0

let array_lon = i[i=1:2]*j[j=1:2]*0 + 360

let array_lat = i[i=1:2]*j[j=1:2]*0 + 90


vector/overlay/len=15.0 array_u,array_v,array_lon,array_lat


exit