GMS-GrADS

This directory contains what would become useful tools when you want to analyze GMS-5 data which are brought to you via GMS-5 ( Japan Meteorological Agency), former Takagi-Lab Recieving Station (Institute of Industrial Science, Universtiy of Tokyo) and the Kochi Universtiy Weather Home by myself.

A freely distributed grid data analysis system, GrADS, may be obtained from the GrADS Home Page.

pgm2bin.c A short C program to make float-point binary data from a pgm-format data file and calibration table for the data. The input pgm must be cropped with pnmcut.
You need netpbm or pbmplus tools.
A sample data made by using pgm2bin sh.980924IR1.bin and sh.980924IR1.bin.ctl
In this particular example, you should somehow manage to make UNDEF data: I made a short C program, undef.c to do this.

Here is a csh script to make the data. Since you are not here in Kochi University, forget about the hostnames and directories. You may need to get the data from 8mm tape distribution or from the Web.

#!/bin/csh
touch sh.980924IR1.bin
foreach i ( 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421 2422 2423 )
if ("2414" != $i && "2415" != $i ) then
 rcp nimbus:/www/Public/sat/GAME/1998/Sep/IR1/GMS59809${i}IR1.pgm.gz .
 zcat GMS59809${i}IR1.pgm.gz | pnmcut 1240 700 80 60 > sh.9809${i}IR1.pgm
 rm GMS59809${i}IR1.pgm.gz
 rcp nimbus:/www/Public/sat/GAME/1998/Sep/CAL/GMS59809${i}CAL.dat.gz .
 zcat GMS59809${i}CAL.dat.gz |  awk -F: '/IR1 Temperature/ {print $2}' > GMS59809${i}CAL-IR1.dat
 ./pgm2bin GMS59809${i}CAL-IR1.dat sh.9809${i}IR1.pgm >> sh.980924IR1.bin
 rm GMS59809${i}CAL-IR1.dat GMS59809${i}CAL.dat.gz sh.9809${i}IR1.pgm
else
 ./undef >> sh.980924IR1.bin
endif
end

And, please do not forget to make the CAL data.

Here is a record of inputs to produce a longitude-time cross section coutour map. (boldface is the keyboard input)

boreas% grads -l

Grid Analysis and Display System (GrADS) Version 1.7Beta9
Copyright (c) 1988-1997 by Brian Doty 
Center for Ocean-Land-Atmosphere Studies
Institute for Global Environment and Society 
All Rights Reserved

Config: v1.7Beta9 32-bit big-endian readline sdf/xdf hdf-sds lats athena im/image-output

Issue 'q config' command for more information.

GX Package Initialization: Size = 11 8.5 
ga-> open shbin.ctl
Scanning description file:  shbin.ctl
Data file sh.980924IR1.bin is open as file 1
LON set to 132 135.95 
LAT set to 32 34.95 
LEV set to 1 1 
Time values set: 1998:9:24:0 1998:9:24:0 
ga-> set time 0z24sep1998 23z24sep1998
Time values set: 1998:9:24:0 1998:9:24:23 
ga-> set lon 133.5 133.5
LON set to 133.5 133.5 
ga-> d tbb
Contouring: -60 to 20 interval 10

Then, you will get an image like this.

Appendix: A short note on PGM format

In the GMSxxx.pgm files, RAWBITS format is used. Therefore,

the first "line" which containing the "magic number" is "P5".
Our mapping software put a line of "comment" next which is safely ignored but must be cared if you are going to read the file with, for example, fgets().
the third line is width and height in ASCII integer. You can pick up the data size from this value.
the fourth line is "255" for IR channels, "63" for VIS channel.

You can read these lines with "head -4" command with UNIX system. So, the programming in C will become like:

fgets(buf,80,fp); /* skip P5 */
fgets(buf,80,fp); /* skip comment */
fgets(buf,80,fp); /* read a line with width & height */
sscanf(buf,"%d %d",&width,&height);
fgets(buf,80,fp); /* skip 255 */
/* next comes raw byte stream */
for (y=0; y<height; y++) {
  for (x=0; x<width; x++) {
    data[y][x] = fgetc(fp);
  }
}

Note that you must tackle with the libp?m in the netpbm package if you care more on the PGM format variations.
Or, you may use a trick to strip the comments off by:

pnmtorast GMSxxx.pgm | rasttopnm > GMSxxx-tmp.pgm

GMS-GrADS

Appendix: A short note on PGM format

Tokio Kikuchi, Kochi Universtiy