[gradsusr] help with interpolation

Jeff Duda jeffduda319 at gmail.com
Fri Apr 11 15:43:21 EDT 2014


Hello,
I'm trying to interpolate fine grid data onto a coarser grid.  Here's what
I get

ga-> define nam4u = lterp(ugrdprs,ugrdprs.2(time=15Z09APR2014))
Notice:  Automatic Grid Interpolation Taking Place
Data Request Error: Invalid grid coordinates
  World coordinates convert to non-integer  grid coordinates
    Variable = ugrdprs.2  Dimension = 2
Operation Error:  Error from lterp function
  Error ocurred at column 1

The control files are:
(for file 1)
dset /var/grib/tmp/nam.20140411/2014041112_nam_4km_grads.grib2
index /var/grib/tmp/nam.20140411/2014041112_nam_4km_grads.grib2.idx
undef 9.999E+20
title /var/grib/tmp/nam.20140411/2014041112_nam_4km_grads.grib2
* produced by g2ctl v0.0.7
* command line options:
/var/grib/tmp/nam.20140411/2014041112_nam_4km_grads.grib2
* griddef=1:0:(1473 x 1025):grid_template=30:winds(grid): Lambert
Conformal: (1473 x 1025) input WE:SN output WE:SN res 8 Lat1 12.190000 Lon1
226.541000 LoV 265.000000 LatD 25.000000 Latin1 25.000000 Latin2 25.000000
LatSP 0.000000 LonSP 0.000000 Nor
dtype grib2
pdef 1473 1025 lccr 12.190000 -133.459 1 1 25.000000 25.000000 -95
5079.000000 5079.000000
xdef 2191 linear -152.852997 0.0472378093781546
ydef 1040 linear 12.190000 0.0472378093781546
tdef 61 linear 12Z11apr2014 1hr
* PROFILE hPa
zdef 42 levels 100000 97500 95000 92500 90000 87500 85000 82500 80000 77500
75000 72500 70000 67500 65000 62500 60000 57500 55000 52500 50000 47500
45000 42500 40000 37500 35000 32500 30000 27500 25000 22500 20000 17500
15000 12500 10000 7500 5000 3000 2000 1000
options pascals
vars 302
...
...
...
UGRDprs    42,100  0,2,2 ** (1000 975 950 925 900.. 75 50 30 20 10)
U-Component of Wind [m/s]

(for file 2)
dset ^gfs.t12z.pgrb2f03
index ^gfs.t12z.pgrb2f03.idx
undef 9.999E+20
title gfs.t12z.pgrb2f03
* produced by g2ctl v0.0.7
* command line options: gfs.t12z.pgrb2f03
* griddef=1.1:0:(720 x 361):grid_template=0:winds(N/S): lat-lon grid:(720 x
361) units 1e-06 input WE:NS output WE:SN res 48 lat 90.000000 to
-90.000000 by 0.500000 lon 0.000000 to 359.500000 by 0.500000
#points=259920:winds(N/S)

dtype grib2
ydef 361 linear -90.000000 0.5
xdef 720 linear -180.0 0.5
tdef 1 linear 15Z09apr2014 1mo
* PROFILE hPa
zdef 26 levels 100000 97500 95000 92500 90000 85000 80000 75000 70000 65000
60000 55000 50000 45000 40000 35000 30000 25000 20000 15000 10000 7000 5000
3000 2000 1000
options pascals
vars 164
...
...
...
UGRDprs    26,100  0,2,2 ** (1000 975 950 925 900.. 70 50 30 20 10)
U-Component of Wind [m/s]

I would guess that the source of the error is with the discrepancy in the
vertical levels available.  But is it really?

Jeff Duda

-- 
Jeff Duda
Graduate research assistant
University of Oklahoma School of Meteorology
Center for Analysis and Prediction of Storms
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