GOES Data on the Internet - A Tutorial

Abstract

NOAA is not in the business of providing real-time data directly to the public. So, other government agencies, educational institutions, and commercial organizations collect and distribute GOES images. With the recent opening of the information highway, GOES images are now routinely offered at several internet sites for scientific applications and public enjoyment.

This document describes the most popular sites and image formats available to the public at the end of 1995.

Table of contents

• GOES data formats
• GOES presentation formats
• GOES public data servers
• References

GOES data formats

• pixel data as numerical values (perhaps packed and/or compressed),
• descriptive headers and/or trailers,
• a rule (implicit) for converting the numerical values to display format.

For GOES data, the most commonly used public-domain image formats on the internet are GIF, JPEG, HDF, TIFF and MPEG. The only proprietary format in wide-spread use for GOES imagery is the MCIDAS satellite data format.

Summary

Glossary with Notes

GIF - Graphics Interchange Format

In the 1980's, Compuserve developed GIF as an open standard for exchange of digital color pictures among personal computers. GIF was adopted as the standard image format for Web browsers.

JPEG - Joint Photographic and Engineering Group

In the early 1990's, computer graphics organizations agreed upon JPEG, which actually are a suite of 29 encoding options for making a highly compressed but lossy file format. JPEG optimizes the appearance of color photographs on a TV monitor by selectively truncating the high-frequency color components that are not easily transmitted on TV or noticed by the human eye. Today, inexpensive commercial software/hardware implementations provide only a simple "compression ratio" option. NOAA is planning to adopt JPEG compression for future high-speed GOES Imagers.

MPEG - Moving Picture Experts Group

In the mid-1990's, MPEG was devised to show movies on broadcast TV, including audio. MPEG imagery is based on JPEG, and it also uses only the difference between successive frames to update images, resulting in highly compressed but lossy movies. Commercial MPEG codecs are now under vigorous development.

TIFF - Tagged Image File Format

In the 1980's, TIFF format originated for transporting 8-bit digital greyscale imagery within the print industry, and is currently managed by the Aldus Corp.. In the 1990's, TIFF was also adopted by the mini-computer and medical communities for storage and exchange of high-precision lossless digital images from modern "remote sensing" diagnostic systems. The TIFF standard is currently managed by Adobe Corp.. TIFF now encompasses almost every major raster-image encoding scheme (Ritter, 1995). Consequently, few TIFF readers can handle all possible options.

HDF - Heirarchical Data Format

The National Center for Supercomputing Applications (NCSA) at the University of Illinois (UI) invented HDF in the 1980's to deal with the problems of transporting multi-dimensional numerical model data along with image visualizations of its contents. In the 1990's, the HDF format was adopted and extended by NASA for distributing datasets from its Earth Observing System (EOS). HDF reader and writer libraries are still under development.

MCIDAS - Man-Computer Interactive Display and Analysis System

Int the 1980's, The Space Sciences Engineering Center (SSEC) at the University of Wisconsin (UW) invented MCIDAS format to deal specifically with calibation and earth-location information with NOAA satellite images. The most recent SSEC documentation of MCIDAS file format for satellite data, is the 1993 edition. SSEC is now working on the 1995 edition, which will accomodate the new GOES-I/M features. MCIDAS readers, writers, and datasaets must be purchased from SSEC.

RGB - Red, Green, Blue

computer words for each color on a monitor

CYMK - Cyan, Yellow, Magenta, blacK

computer words for each color in a printer

YCnCb - Luminance and 2-color Chrominance

computer words for brightness and color on broadcast TV

LUT - Look Up Table

256 color palette for 8-bit pixels

RLE - Run-Length Encoded

uses abbreviations for repeated bit patterns

LZW - Lempel-Ziv and Welsh

patented RLE compression scheme

DC - Direct Cosine Transform

"harmonic" analysis of NxN pixels, truncate finest details

GOES presentation formats

GOES public data servers

Major internet servers of real-time GOES images

Notes on real-time, part-time, and off-line GOES servers

• The GOES Project Scientist maintains a large personal list of Web references to universities and research labs at URL ../text/interesting.servers.html. This site also has extensive information about the GOES Project as a whole.
• Global geosynchronous observations at Ames Research Center (ARC). This is the biggest public database of geosynchronous images at infrared resolution (4 km) for the past several days from: GMS-5, GOES-7, and GOES-8. The GMS-5 and GOES-7 data are also re-gridded into latitude-longitude coordinates with an outline map overlay.
• NASA-GSFC provides real-time GOES images from GOES-8 and GOES-9 at visible resolution (1 km) for dozens of sectors in the western hemisphere -- every inhabited area and all the storm- and climate-driven oceanic areas.
• NOAA's cooperative institutes post recent GOES data on the net:
  • SSEC at the University of Wisconsin
    • GOES pages
    • real-time Data pages
  • CIRA at Colorado State
    • Earth Station
• NOAA does not put GOES operational images on the internet for public use. GOES digital and hardcopy satellite products can be ordered off-line from NOAA-NESDIS via the National Climatic Data Center in Asheville, NC.:

  NCDC
  Federal Building
  151 Patton Avenue
  Asheville, NC  28801-5001
  
  Phone  704-271-4800 option#5
  Fax    704-271-4876
  email  satorder@ncdc.noaa.gov
  

• The GOES Space Environment Monitor (SEM) data is sent to the NOAA Space Environment Lab (SEL), where they analyse and forecast the Sun's "weather", with on-line images and graphs of particle counts from GOES-7 and GOES-8.
• The Naval Research Lab in Monterey, CA provides GOES and GMS images that are focused on Naval and west coast weather considerations.
• A QuickTime movie of the last 12 hours of cloud imagery over the U.S. is posted at Earth Watch.
• All of the weather and image file servers are listed in the excellent "Sources of Meteorological Data" FAQ posted on the usenet news group sci.geo.meteorology.

References

• ADOBE, 1995: TIFF, Revision 6.0, http://www.adobe.com/PDFs/TN/TIFF6.pdf
• Brown, C.W. and Shepherd, B.J., 1995: Graphics File Formats, Manning Publ. Co..
• Hamilton, E., 1991: JPEG File Interchange Format, C-Cube Microsystems, Milpitas, CA, jpeg-info@uunet.uu.net.
• NCSA, 1994: Heirarchical Data Format (HDF), University of Illinois, http://www.ncsa.uiuc.edu/SDG/Software/HDF/HDFIntro.html
• Ritter, N., 1995: The unoffical TIFF home page, http://www-mipl.jpl.nasa.gov/~ndr/tiff/index.html
• SSEC, 1993: MCIDAS file format, University of Wisconsin.
• SSEC, 1995: MCIDAS file format for GOES-I/M (draft), University of Wisconsin.

Key URLs for GOES stuff

NOAA weekly report on the GOES Project

http://www.osdpd.noaa.gov/EBB/post/goeswky.asc

NASA GOES Project Pages - status reports, image scrapbooks, and technical details

../goesproject.html

SSEC GOES pages and data products

http://oldthunder.ssec.wisc.edu/goes/goes.html

Realtime GOES and GMS full-earths at 4 km resolution - GIF, JPEG and HDF

ftp://explorer.arc.nasa.gov/pub/Weather

Realtime GOES sectors at full resolution for most of the Americas - TIFF and JPEG

ftp://rsd.gsfc.nasa.gov/pub/

Realtime screen-resolution globe and CONUS with map overlays - GIF

http://www.ssec.wisc.edu/data/index.html

Realtime screen-resolution globe and CONUS with map overlays - JPEG

http://www.cira.colostate.edu/earthsta/overview.htm

Other on-line sources of GOES stuff

../text/goesds.html

Vendors of GOES stuff

../text/goesvendors.html

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This information resource was created by one irresponsible employee of NASA.
It is in the public domain and permission is granted to use, duplicate, modify and redistribute it.
Please give credit for the satellite images to NASA-Goddard Space Flight Center.
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