vrdv2uvf, vrdv2uvg

Given vorticity and divergence, compute the wind components via Spherepack.

Synopsis

    procedure vrdv2uvf(
        vr : float,
        dv : float,
        ud : float,
        vd : float
    )

    procedure vrdv2uvg(
        vr : float,
        dv : float,
        ud : float,
        vd : float
    )

Arguments

vr

vorticity array (input, array with two or more dimensions, last two dimensions must be nlat x nlon and input values must be in ascending latitude order)

dv

divergence array (input, same dimensions as dv, values will be in ascending latitude order)

ud, vd

wind components (output, same dimensions as vr and dv, values will be in ascending latitude order)

Description

Note: For the arrays whose last two dimensions are nlat x nlon, the rest of the dimensions (if any) are collectively referred to as nt. If the input/output arrays are just two dimensions, then nt can either be considered equal to 1 or nothing at all.

Arrays which have dimensions nt x nlat x nlon should not include the cyclic (wraparound) points when invoking the procedures and functions which use spherical harmonics (Spherepack).

For example, if an array x has dimensions nlat = 64 and nlon = 129, where the "129" represents the cyclic points, then the user should pass the data to the procedure/function via:

    z = sample ( x([...],:,0:nlon-2) )  ; does not include cyclic points

Example

begin
  nlat  =  64                                       ; dimensions
  mlon  = 128
  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

  work  = new ( (/nlat,mlon1/), float, uvmsg )
  u     = new ( (/nlat,mlon /), float, uvmsg )  ; source u
  v     = new ( (/nlat,mlon /), float, uvmsg )  ; source v
  dvx   = new ( (/nlat,mlon /), float, uvmsg )  ; divergence (same as dv)
  vrx   = new ( (/nlat,mlon /), float, uvmsg )  ; vorticity  (same as vr)
  sf    = new ( (/nlat,mlon /), float, uvmsg )  ; stream function
  vp    = new ( (/nlat,mlon /), float, uvmsg )  ; velocity potential
  uy    = new ( (/nlat,mlon /), float, uvmsg )  ; latitudinal derivative (u)
  vy    = new ( (/nlat,mlon /), float, uvmsg )  ; latitudinal derivative (v)
  uu    = new ( (/nlat,mlon /), float, uvmsg )  ; reconstructed u
  vv    = new ( (/nlat,mlon /), float, uvmsg )  ; reconstructed v
  ux    = new ( (/nlat,mlon /), float, uvmsg )  ; reconstructed u
  vx    = new ( (/nlat,mlon /), float, uvmsg )  ; reconstructed v

  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)

   dv = uv2dvG   (u,v)               ; u,v ==> divergence
   vr = uv2vrG   (u,v)               ; u,v ==> vorticity (rel)
   uv2vrdvg (u,v, vrx,dvx)           ; u,v ==> div and vort 
   uv2sfvpg (u,v, sf,vp)             ; u,v ==> stream function + velocity pot
   ud    = new ( (/nlat,mlon /), float, uvmsg )
   vd    = new ( (/nlat,mlon /), float, uvmsg )
   ur    = new ( (/nlat,mlon /), float, uvmsg )

   dv2uvg   (dv,  ud,vd)             ; dv  ==> divergent  wind components
   vr2uvg   (vr,  ur,vr)             ; vr  ==> rotational wind components
   vrdv2uvg (vr,dv,   uu,vv)         ; vr,dv > reconstruct original wind
   vrdv2uvg (vrx,dvx, ux,vx)         ; vr,dv > reconstruct original wind
  end do
end

Error messages

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

Reference Manual Control Panel

NG4.1 Home, Index, Examples, Glossary, Feedback, Ref Contents, Ref WhereAmI?