I’m trying to use GMT ver 6.3.0 on an iMac (12.3.1) to plot contours of correlations between a principal component (PC) time series and the data time series used to generate the PC. The result should be a map of correlations over a tropical pacific region from 90W to 230 W. and ~ -10 S to 10 N.
The lon - lat - correlation values on a 1.0 deg lon X 0.3333 deg lat grid are in a text file called eof.xyz:
-229.50 -9.83 0.8244
-228.50 -9.83 0.7973
-227.50 -9.83 0.7303
-226.50 -9.83 0.6468
-225.50 -9.83 -9999.0000
-224.50 -9.83 -9999.0000
-223.50 -9.83 -9999.0000
-222.50 -9.83 -9999.0000
-221.50 -9.83 -9999.0000
.........................
.........................
-98.50 10.17 -0.0890
-97.50 10.17 -0.0969
-96.50 10.17 -0.1081
-95.50 10.17 -0.1353
-94.50 10.17 -0.1644
-93.50 10.17 -0.2029
-92.50 10.17 -0.2444
-91.50 10.17 -0.3059
-90.50 10.17 -0.3697
#
#
# In a c-shell script I first plot the equatorial Pacific map...
gmt pscoast -R-230.0/-90.0/-10.0000/10.333333 -Ba15/a10WSne -Dc -P -G120/120/120 -K -X1.5 -Y8.0 -JQ-160.0/6.0 >! map.ps
#
# ... then convert eof.xyz to temp.grd
gmt xyz2grd eof.xyz -Gtemp.grd -J -I1.0/0.333333333 -Ddegree/degree/sshg/=/=/=/= -R -V
#
# Next, all null values (-9999.0000 ) in temp.grd are reassigned as NaN in a temp0.grd file
gmt grdclip temp.grd -Gtemp0.grd -Sa1.0/NaN -Sb-1.0/NaN -V
#
# A first grdcontour call contours all positive correlation values @ 0.10 increments in red
gmt grdcontour temp0.grd -R -B -J -P -A0.10 -LP -W0.75p,red -K -O -V >> map.ps
#
# A second call contours all negative correlation values @ 0.10 increments in blue
gmt grdcontour temp0.grd -R -B -J -P -A0.10 -LN -W0.75p,blue -O -V >> map.ps
Problem is, no contours are plotted. When I try to dump the contours to a txt file using -Dtemplate.txt, nothing ends up in template.txt. I don’t see anything in the following verbose output of the xyz2grd-grdclip-grdcontour calls that looks out of place. Both grdcontour calls say they are tracing the contours but no contours are generated in template.txt or plotted in map.ps. Any idea what I might be doing wrong?
xyz2grd [INFORMATION]: Processing input table data
xyz2grd [INFORMATION]: Cartesian input grid
xyz2grd [INFORMATION]: Cartesian input grid
xyz2grd [INFORMATION]: n_columns = 141 n_rows = 62 nm = 8742 size = 8742
xyz2grd [INFORMATION]: Reading Data Table from file eof.xyz
xyz2grd [INFORMATION]: Data records read: 8540 used: 8540 nodes filled: 2911 nodes empty: 5831 [set to NaN]
xyz2grd [INFORMATION]: Extend grid via copy onto larger memory-aligned grid
xyz2grd [INFORMATION]: Writing grid to file temp.grd
xyz2grd [INFORMATION]: Proj4 string to be converted to WKT:
+proj=eqc +lat_ts=0 +lat_0=0 +lon_0=-160 +x_0=0 +y_0=0 +units=m +a=6378137.000 +b=6356752.314 +ellps=WGS84 +datum=WGS84 +units=m +no_defs
xyz2grd [INFORMATION]: WKT converted from proj4 string:
PROJCS["unknown",
GEOGCS["unknown",
DATUM["unknown",
SPHEROID["unknown",6378137,298.257220143428]],
PRIMEM["Greenwich",0,
AUTHORITY["EPSG","8901"]],
UNIT["degree",0.0174532925199433,
AUTHORITY["EPSG","9122"]]],
PROJECTION["Equirectangular"],
PARAMETER["standard_parallel_1",0],
PARAMETER["central_meridian",-160],
PARAMETER["false_easting",0],
PARAMETER["false_northing",0],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Easting",EAST],
AXIS["Northing",NORTH]]
grdclip [INFORMATION]: Processing input grid
grdclip [INFORMATION]: Round-off patrol changed grid limit for ymin from -9.999999836065573 to -9.999999836065573
grdclip [INFORMATION]: Round-off patrol changed grid limit for ymax from 10.33333316393443 to 10.33333316393443
grdclip [INFORMATION]: Cartesian input grid
grdclip [INFORMATION]: Reading grid from file temp.grd
grdclip [INFORMATION]: Cartesian input grid
grdclip [INFORMATION]: gmt_grd_BC_set: Set boundary condition for all edges: natural
grdclip [INFORMATION]: gmt_grd_BC_set: Set boundary condition for left edge: natural
grdclip [INFORMATION]: gmt_grd_BC_set: Set boundary condition for right edge: natural
grdclip [INFORMATION]: gmt_grd_BC_set: Set boundary condition for bottom edge: natural
grdclip [INFORMATION]: gmt_grd_BC_set: Set boundary condition for top edge: natural
grdclip [INFORMATION]: Writing grid to file temp0.grd
grdclip [INFORMATION]: 119 values < -1 set to nan
grdclip [INFORMATION]: 0 values grdcontour [INFORMATION]: Processing input grid
grdcontour [INFORMATION]: Spherical approximation used
grdcontour [INFORMATION]: Map scale is 2594.55 km per inch or 1:1.02148e+08.
grdcontour [INFORMATION]: Reading grid from file temp0.grd
grdcontour [INFORMATION]: gmt_grd_BC_set: Set boundary condition for all edges: natural
grdcontour [INFORMATION]: gmt_grd_BC_set: Set boundary condition for left edge: natural
grdcontour [INFORMATION]: gmt_grd_BC_set: Set boundary condition for right edge: natural
grdcontour [INFORMATION]: gmt_grd_BC_set: Set boundary condition for bottom edge: natural
grdcontour [INFORMATION]: gmt_grd_BC_set: Set boundary condition for top edge: natural
grdcontour [INFORMATION]: Tracing the 0 contour
grdcontour [INFORMATION]: Tracing the 0.1 contour
grdcontour [INFORMATION]: Tracing the 0.2 contour
grdcontour [INFORMATION]: Tracing the 0.3 contour
grdcontour [INFORMATION]: Tracing the 0.4 contour
grdcontour [INFORMATION]: Tracing the 0.5 contour
grdcontour [INFORMATION]: Tracing the 0.6 contour
grdcontour [INFORMATION]: Tracing the 0.7 contour
grdcontour [INFORMATION]: Tracing the 0.8 contour
grdcontour [INFORMATION]: Processing input grid
grdcontour [INFORMATION]: Spherical approximation used
grdcontour [INFORMATION]: Map scale is 2594.55 km per inch or 1:1.02148e+08.
grdcontour [INFORMATION]: Reading grid from file temp0.grd
grdcontour [INFORMATION]: gmt_grd_BC_set: Set boundary condition for all edges: natural
grdcontour [INFORMATION]: gmt_grd_BC_set: Set boundary condition for left edge: natural
grdcontour [INFORMATION]: gmt_grd_BC_set: Set boundary condition for right edge: natural
grdcontour [INFORMATION]: gmt_grd_BC_set: Set boundary condition for bottom edge: natural
grdcontour [INFORMATION]: gmt_grd_BC_set: Set boundary condition for top edge: natural
grdcontour [INFORMATION]: Tracing the -0.8 contour
grdcontour [INFORMATION]: Tracing the -0.7 contour
grdcontour [INFORMATION]: Tracing the -0.6 contour
grdcontour [INFORMATION]: Tracing the -0.5 contour
grdcontour [INFORMATION]: Tracing the -0.4 contour
grdcontour [INFORMATION]: Tracing the -0.3 contour
grdcontour [INFORMATION]: Tracing the -0.2 contour
grdcontour [INFORMATION]: Tracing the -0.1 contour
grdcontour [INFORMATION]: Tracing the 0 contour