sellonlatbox question
Added by Noelia Otero about 10 years ago
Hi everyone,
I used sellonlatbox to select differents regions, and I have a question (sorry if it's obvious, but I'm confused now).
If I select: cdo sellonlatbox,-20,40,70,30 ifile ofile, ofile contains then, negative longitude (from 20W-40E)
but if I select for instance: cdo sellonlatbox,-120,-60,60,10 ofile contains positive longitude : (240-300)..
(longitude in ifile are defined :0.0-360)
I wanted to know if I miss something ?
Many thanks in advance!
Cheers
Noelia
Replies (2)
RE: sellonlatbox question - Added by Ralf Mueller about 10 years ago
I cannot confirm this. Lets make a check
[ram@thingol:~/data/examples]cdo -f nc topo topo.nc [13:38:43|14-04-24] cdo topo: ( 0.00s ) [ram@thingol:~/data/examples]cdo griddes topo.nc [13:38:49|14-04-24] # # gridID 2 # gridtype = lonlat gridsize = 259200 xname = lon xlongname = longitude xunits = degrees_east yname = lat ylongname = latitude yunits = degrees_north xsize = 720 ysize = 360 xfirst = -179.75 xinc = 0.5 yfirst = -89.75 yinc = 0.5 cdo griddes: Processed 1 variable ( 0.00s )
topo.nc no has positive and negative lons. Let's see, what comes out of the sellonlatbox calls you mentioned[ram@thingol:~/data/examples]cdo griddes -sellonlatbox,-20,40,70,30 topo.nc [13:38:56|14-04-24] cdo griddes: Started child process "sellonlatbox,-20,40,70,30 topo.nc (pipe1.1)". # # gridID 7 # gridtype = lonlat gridsize = 9600 xname = lon xlongname = longitude xunits = degrees_east yname = lat ylongname = latitude yunits = degrees_north xsize = 120 ysize = 80 xfirst = -19.75 xinc = 0.5 yfirst = 30.25 yinc = 0.5 cdo(2) sellonlatbox: Processed 259200 values from 1 variable over 1 timestep ( 0.00s ) cdo griddes: Processed 1 variable ( 0.00s ) [ram@thingol:~/data/examples]cdo griddes -sellonlatbox,-120,060,60,10 topo.nc [13:39:32|14-04-24] cdo griddes: Started child process "sellonlatbox,-120,60,60,10 topo.nc (pipe1.1)". # # gridID 7 # gridtype = lonlat gridsize = 36000 xname = lon xlongname = longitude xunits = degrees_east yname = lat ylongname = latitude yunits = degrees_north xsize = 360 ysize = 100 xfirst = -119.75 xinc = 0.5 yfirst = 10.25 yinc = 0.5 cdo(2) sellonlatbox: Processed 259200 values from 1 variable over 1 timestep ( 0.00s ) cdo griddes: Processed 1 variable ( 0.00s )
This down not show the behaviour you were describing. May be it only works with strictly positive lons:
[ram@thingol:~/data/examples]ncap2 -A -s 'lon=(lon+179.75)' topo.nc _t.nc [13:43:24|14-04-24] [ram@thingol:~/data/examples]ncap2 -A -s 'lat=(lat+89.75)' _t.nc __t.nc [13:43:33|14-04-24] [ram@thingol:~/data/examples]cdo griddes __t.nc [13:48:02|14-04-24] # # gridID 2 # gridtype = lonlat gridsize = 259200 xname = lon xlongname = longitude xunits = degrees_east yname = lat ylongname = latitude yunits = degrees_north xsize = 720 ysize = 360 xfirst = 0 xinc = 0.5 yfirst = 0 yinc = 0.5 cdo griddes: Processed 1 variable ( 0.00s )
Now the results are
[ram@thingol:~/data/examples]cdo griddes -sellonlatbox,-20,40,70,30 __t.nc [13:48:22|14-04-24] cdo griddes: Started child process "sellonlatbox,-20,40,70,30 __t.nc (pipe1.1)". # # gridID 7 # gridtype = lonlat gridsize = 9801 xname = lon xlongname = longitude xunits = degrees_east yname = lat ylongname = latitude yunits = degrees_north xsize = 121 ysize = 81 xfirst = -20 xinc = 0.5 yfirst = 30 yinc = 0.5 cdo(2) sellonlatbox: Processed 259200 values from 1 variable over 1 timestep ( 0.00s ) cdo griddes: Processed 1 variable ( 0.00s ) [ram@thingol:~/data/examples]cdo griddes -sellonlatbox,-120,60,60,10 __t.nc [13:48:54|14-04-24] cdo griddes: Started child process "sellonlatbox,-120,60,60,10 __t.nc (pipe1.1)". # # gridID 7 # gridtype = lonlat gridsize = 36461 xname = lon xlongname = longitude xunits = degrees_east yname = lat ylongname = latitude yunits = degrees_north xsize = 361 ysize = 101 xfirst = -120 xinc = 0.5 yfirst = 10 yinc = 0.5 cdo(2) sellonlatbox: Processed 259200 values from 1 variable over 1 timestep ( 0.00s ) cdo griddes: Processed 1 variable ( 0.00s )
Looks like what you expected, cdo-1.6.3 was used