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uv2sfvpG

Computes the stream function and velocity potential via spherical harmonics given u and v on a gaussian grid.

Prototype

	function uv2sfvpG (
		u  : numeric,  
		v  : numeric   
	)

	return_val [2,dimsizes(u)] :  float or double

Arguments

u
v

wind components (input, arrays with two or more dimensions, rightmost two dimensions must be nlat x nlon)

  • input values must be in ascending latitude order
  • input array must be on a global grid

Return value

The returned array will be dimensioned 2 x dimsizes(u), where the 0-th element of the leftmost dimension contains the stream function and the 1-th element of the leftmost dimension contains the velocity potential (both in ascending latitude order). The array returned will be of type double if the input is double, and float otherwise.

Description

Given wind components u and v, uv2sfvpG computes the stream function and the velocity potential. uv2sfvpG operates on a gaussian grid.

This function does not handle missing values (defined by the _FillValue attribute). If any missing values are encountered in a particular 2D input grid, then all of the values in the corresponding output grids will be set to the missing value defined by the output grids' _FillValue attributes.

Input arrays should not include the cyclic (wraparound) points when invoking this function, or any procedure or function which uses spherical harmonics (Spherepack).

If the input arrays u and v are on a fixed grid, uv2sfvpF should be used. Also, note that uv2sfvpG is the function version of uv2sfvpg.

See Also

uv2sfvpg, uv2sfvpF, uv2sfvpf, uv2vrg

Examples

Example 1

Compute the stream function and velocity potential, given the u and v wind components on a gaussian grid.

begin
  nlat  = 128                                       ; dimensions
  mlon  = 256
  mlon1 = mlon+1
  fbfile = "uv300.hs"
                                       ; Generic Workstation setup 
  nrec  = fbinnumrec(fbfile)       ; total number of records in the file
  ntim  = nrec/2                       ; number of time steps in dataset

  uvmsg = 1e+36

  do i = 0,nrec-1,2                    
   month = 1                         ; January
   if (i .ge. 2) then
       month = 7                     ; July
   end if   

   work = fbinrecread(fbfile,i  ,(/nlat,mlon1/),"float")
   u    = work(:,0:mlon-1)
   work = fbinrecread(fbfile,i+1,(/nlat,mlon1/),"float")
   v    = work(:,0:mlon-1)

   sfvp  = uv2sfvpG (u,v)             ; u,v ==> stream function + velocity pot
  end do
end

Errors

If jer or ker is equal to:

1 : error in the specification of nlat
2 : error in the specification of nlon
4 : error in the specification of N (jer only)