gdwdfuv

FORTRAN

 
integer gdwdfuv, ier
ier = gdwdfuv(gdid, spdllout, dirlldout, uugdin, vvgdin, lat, lon, n)
integer gdid, n
real spdllout(n), dirllout(n), uugdin(*), vvgdin(*), lat(n), lon(n)

C

 
int c_gdwdfuv(int gdid,  float *spdllout, float *dirllout, float *uugdin, float *vvgdin,
              float *lat, float *lon, int npts)

Routine description

gdwdfuv converts, on grid gdid, grid winds (uu/vv) to meteorological winds (speed/direction). The lat/lon coordinates of each point have to be present.

 

Description of parameters

gdid

a valid grid identifier (returned by ezqkdef or ezgdef) that will be used as the source (input) grid.

spdllout, dirllout

Output rotated winds, in grid coordinates based on gdid. There is 1:1 relationship with spdllout, dirllout, lat and lon; that is, interpolated values at point lat(1), lon(1) are spdllout(1) and dirllout(1).

uugdin, vvgdin

Input (source) winds. uugdin and vvgdin are assumed to have the dimensions referred by gdid (the input grid).

lat

Stream of latitude points

lon

Stream of longitude points

n

Number of points

?

Sample FORTRAN code :

The following code read 500 mb grid winds on a GEM grid, and converts them to meteorological wind speed and direction. Assume necessary memory space has been allocated.

 
      datev  = -1
      etiket = '        '
      typvar = ' '
      nomuu  = 'UU'
      nomvv  = 'VV'
            
      ip1 = 500
      ip2 = 0
      ip3 = -1
      iun = 13
      
***   read fld info and data
      uukey = FSTINF(iun, NI, NJ, NK, datev, etiket, ip1, ip2, ip3, typvar, nomuu) 
      ier = FSTPRM(uukey, DATEO, DEET, NPAS, NI, NJ, NK, NBITS, DATYP, IP1,
     $     IP2, IP3, TYPVAR, NOMVAR, ETIKET, GRTYP, IG1, IG2, IG3,
     $     IG4, SWA, LNG, DLTF, UBC, EX1, EX2, EX3)
      ier = FSTLUK(uugem, key, NI, NJ, NK)
      vvkey = FSTINF(iun, NI, NJ, NK, datev, etiket, ip1, ip2, ip3, typvar,nomvv) 
      ier = FSTPRM(vvkey, DATEO, DEET, NPAS, NI, NJ, NK, NBITS, DATYP, IP1,
     $     IP2, IP3, TYPVAR, NOMVAR, ETIKET, GRTYP, IG1, IG2, IG3,
     $     IG4, SWA, LNG, DLTF, UBC, EX1, EX2, EX3)
      ier = FSTLUK(vvgem, key, NI, NJ, NK)
      
***   Define input grid         
      
      gdgem = ezqkdef(nigem,njgem ,'Z',ig1, ig2, ig3, ig4, iun)
***   Define latlon values and wind speed/directions
      ier = gdll(gdgem, lat, lon)
***   Do wind coordinate conversion. Returned values are in spd,dir coordinates,
***   spdllout is wind speed
***   dirllout is meteorological wind direction
      call gdwdfuv(gdgem, spdllout, dirllout, uugem, vvgem, lat, lon, nigem*njgem)

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