Computes the vorticity via spherical harmonics, given the u and v wind components on a gaussian grid.
function uv2vrG ( u : numeric, v : numeric ) return_val [dimsizes(u)] : float or double
wind components (input, arrays with two or more dimensions, last two dimensions must be nlat x nlon)
- input values must be in ascending latitude order
- input array must be on a global grid
A double array is returned if u or v are double; a float array is returned otherwise. The returned array will be of dimension size dimsizes (u).
Given wind components u and v, uv2vrG computes the vorticity and returns it as an array with the same dimensions as u and v (values will be in ascending latitude order). uv2vrG 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 default missing value appropriate to the type of the output.
Note: For the arrays whose last two dimensions are nlat x nlon, the rest of the dimensions (if any) are collectively referred to as N. If the input/output arrays are just two dimensions, then N can either be considered equal to 1 or nothing at all.
Arrays which have dimensions N x nlat x nlon should not include the cyclic (wraparound) points when invoking the procedures and functions which use spherical harmonics (Spherepack).
Use uv2vrG_Wrap if retention of metadata is desired.
Note, if the input arrays are not global or contain missing data, then it is recommended that uv2vr_cfd be used.
Compute the vorticity given u and v on a gaussian grid. Also, compute the rotational wind components.
begin nlat = 128 ; dimensions mlon = 256 mlon1 = mlon+1 fbfile = "uv300.hs" 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) vr = uv2vrG (u,v) ; u,v ==> vorticity (rel) uvr = vr2uvG (vr) ; vr ==> rotational wind components end do end
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)