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Readme for the GMS-5_SCSMEX andGMS-5_KWAJEX Data Sets

Access to the GMS-5_SCSMEX and GMS-5_KWAJEX Data Sets



Data Set Description and A Sample Program
Data Access
Points of Contact


This document provides a general description of the GMS-5_SCSMEX and GMS-5_KWAJEX data sets, a sample Fortran program to read the data, and the data access information. These two data sets include albedo and brightness temperature (TB) at pixel resolution (5 km at the subsatellite point) derived from the four channels of the GMS-5. The spatial extent and temporal range of the two data sets correspond to those of the South China Sea Monsoon Experiment (SCSMEX) and the Kwajalein Experiment (KWAJEX), respectively. The GMS-5_SCSMEX data set covers the region from 30 degree N to 5 degree S and from 95 degree E to 135 degree E for the period from May 1998 through August 1998. The GMS-5_KWAJEX data set covers the region from 21 degree N to 4 degree S and from 154 degree E to 179 degree E for the period from July 1999 through September 1999.

The GMS-5 is an operational Japanese geosynchronous weather satellite launched in the spring of 1995. Stationed above the equator at 140 degree E, GMS-5 is currently broadcasting on a roughly hourly schedule. Its Visible and Infrared Spin Scan Radiometer (VISSR) observes about 1/4 of the Earth's surface. The spin-scan images comprise four channels: a visible channel, and three thermal infrared channels at 11 micron, 12 micron, and 6.5 micron. More information about the GMS-5 can be found at GEO-NEWS.

The geolocation algorithm used to generate these two data sets assumes that the satellite, the subsatellite point, and the earth's center are collinear. It does not use landmarks. Therefore, the geolocation error of the GMS-5 images may be up to a few degrees, which may not be acceptable for some users."

Further information about SCSMEX and KWAJEX are provided in the references listed below.


The Goddard Distributed Active Archive Center produced these data sets by applying the geolocation method developed by Dr. Ming-Dah Chou of the Goddard Space Flight Center (Code 913) to the original GMS-5 data. The distribution of these data sets is being funded by NASA's Earth Science Enterprise. The data are not copyrighted; however, we request that when you publish results using these data, please acknowledge as follows:

The authors wish to thank the Distributed Active Archive Center (Code 610.2) at the Goddard Space Flight Center, Greenbelt, MD, 20771, for producing and distributing the data; Dr. Ming-Dah Chou and Mr. Michael Yan of the Goddard Space Flight Center, Greenbelt, MD, 20771 (Code 913), for providing the geolocation algorithm; and the Laboratory for Atmospheres at the Goddard Space Flight Center, Greenbelt, MD, 20771 (, for providing the original data from which these products originate. Goddard's contribution to these activities was sponsored by NASA's Earth Science Enterprise.

Data Set Description and A Sample Program

In general, the data time interval is about one hour; however, missing records do exist. On a reporting time, six data files were generated when the respective original data sets were available. The file names listed below identify the file contents with the file naming convention as:


where chn is a three-letter character denoting the specific channel: vis for visible, ir1 for thermal infrared channel at 11 micron, ir2 for 12 micron, and ir3 for 6.5 micron. yyyy is a four-digit numeral for a year, mm is a two-digit numerals for a month, and tttt is for hour (two-digit) and minute (two-digit). The six-letter character, region, is either "SCSMEX" or "KWAJEX". The postfix, dat, denotes data file containing albedo or TB. The postfix lat or lon denotes latitude or longitude files, respectively, corresponding to a specific albedo or TB data file.

Each data file contains one 2-D array in binary format. For GMS-5_SCSMEX, a data array is 818 columns (approximately along the latitude lines) by 786 rows (approximately along the longitude lines) with a size of about 2.57 MB. For GMS-5_KWAJEX, a data array is 494 columns by 553 rows with a size of about 1.09 MB.

Here we show a sample Fortran program to read a data file:

       implicit none
       integer imx,jmy
       integer i,j
       parameter (imx=818,jmy=786)  ! for GMS-5_SCSMEX DATA
c      parameter (imx=494,jmy=553)  ! for GMS-5_KWAJEX DATA
       real*4 data(imx,jmy)
c  OPEN a data file at a unit, say 20 |
       open (20,file='filename',form='unformatted')
       do  j = 1,jmy
       read (20,err=910) (data(i,j),i=1,imx)
910    call perror ('Error opening dataset')
       stop 910

Undefined value (-999.0) is assigned to a pixel value if that pixel is off the Earth's disk. Also if the data value of a pixel, albedo or TB, is erroneous, it will be replaced by an undefined value. The corresponding geolocation is then assigned as -90 degree for the latitude and 220 degree E for the longitude.

Data Access

The GMS-5_SCSMEX and GMS-5_KWAJEX data sets may be accessed either directly from this document,



or via anonymous FTP at
login: anonymous
password: < your internet address >
cd data/TRMM/Ancillary/TRMM_FE/SCSMEX/GMS-5_SCSMEX or

Two levels of subdirectories, month and day, exist under the year directory. Four channel data files and the corresponding latitude and longitude files are located in the day directories.


Information about SCSMEX and KWAJEX can be found in the following Web sites:

Points of Contact

DAAC Help Desk: Data Producers:

The producer of the GMS-5_SCSMEX and GMS-5_KWAJEX data sets is:

Goddard DAAC Hydrology Data Support Team
Distributed Active Archive Center / Code 610.2
NASA Goddard Space Flight Center
Greenbelt, Maryland 20771

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Last updated: Jun 15, 2012 10:36 AM ET