The BLL2PS routine interpolates a budget-type scalar field from
a global latitude-longitude cylindrical grid (including the
poles) to a matched pair of Polar Stereographic grids centered
on the respective poles, where the orientation longitude
of the Southern Hemisphere grid is 180 degrees opposite
that of the Northern Hemisphere grid. This interpolation
is designed to approximate an area-average conserving
interpolation from fine to coarse resolution but to become
a bilinear interpolation from coarse to fine resolution.
This is accomplished by bilinearly interpolating to a much
finer Polar Stereographic grid and then area-averaging to
the output grid. The current configuration interpolates
to an extravagant 121 points in every output grid box.
This routine also would interpolate associated bitmaps.
This routine is configured only for (i,j,k) order grids.
This routine is fully vectorized and multitasked.
USAGE: CALL BLL2PS(IBM,IM,JM,KM,NPS,KB,TRUE,XMESH,ORIENT,
Input argument list:
IBM - INTEGER BITMAP IDENTIFIER
(0 FOR NO BITMAP, 1 TO INTERPOLATE BITMAP)
IM - INTEGER NUMBER OF INPUT LONGITUDES
JM - INTEGER NUMBER OF INPUT LATITUDES
KM - INTEGER NUMBER OF FIELDS TO INTERPOLATE
NPS - INTEGER ODD ORDER OF THE POLAR STEREOGRAPHIC GRIDS
(CENTER POINTS ARE THE POLE POINTS)
KB - INTEGER SKIP NUMBER BETWEEN INPUT FIELDS
TRUE - REAL LATITUDE AT WHICH PS GRID IS TRUE (USUALLY 60.)
XMESH - REAL GRID LENGTH AT TRUE LATITUDE (M)
ORIENT - REAL LONGITUDE AT BOTTOM OF NORTHERN PS GRID
(SOUTHERN PS GRID WILL HAVE OPPOSITE ORIENTATION.)
LB - LOGICAL (IM,JM,KM) BITMAP IF IBM=1
B - REAL (IM,JM,KM) SCALAR FIELD TO INTERPOLATE
Output argument list:
LBN - LOGICAL (NPS,NPS,KM) NORTHERN PS BITMAP IF IBM=1
BN - REAL (IM,JM,KM) INTERPOLATED NORTHERN PS FIELD
LBN - LOGICAL (NPS,NPS,KM) SOUTHERN PS BITMAP IF IBM=1
BN - REAL (IM,JM,KM) INTERPOLATED SOUTHERN PS FIELD
REMARKS: FORTRAN 90 EXTENSIONS ARE USED.
||Library contains routines to be
be used for a variety of spectral transform functions. (Fortran90)
Date posted: 2/23/2007