GOES Chat

GOES Chat 22 January 1997 edition

Public Relations

The Public Affairs Office (PAO) at NASA Goddard Space Flight Center has our best GOES movies on video tape. The movies are raw weather footage with a title at the beginning of each segment (no audio track). If you are an educational institution or a commercial firm, PAO can make copies for you:
Ernie Shannon (eshannon@pop100.gsfc.nasa.gov) 301-286-6256

"Natural color" poster of the globe (Hurricane Andrew seen by GOES-7) with GOES-8 in the foreground, including the NASA and NOAA logos. More information is available on the colorized Earth image.
The GOES Project Office at NASA-GSFC put a new antenna on the roof of Building 22 to support post-launch testing and to provide remote sensing datasets for public distribution.
GOES-I, "The Next Generation", a promotional movie showing progress towards increasingly sophisticated imagery.
A movie shows how increasingly sophisticated use of 1, 2, and 3 channels opens the door to multispectral studies of cloud types. NASA's Mission to Planet Earth (MTPE) should be able to monitor cloud details using GOES-8.
A GOES-7 3-channel false-color composite image during hurricane Hugo was used on an Earth Observing System (EOS) poster to tout NASA's global climate research program.

Novelties

Animated zoom movie, from GOES to Landsat resolution over a stratocumulus cloud deck, from a series of satellite images prepared from the NASA FIRE experiment off the coast of southern California. Cloud structure is fractal to well below the 1 km visible resolution available from GOES.
An accidental GOES-7 shot of the quarter moon on 14 June 1994 shows how faint the moon actually is in the visible, and how much of a temperature gradient there is in the infrared.
Because GOES rotates its field-of-view to follow the Earth during the day, the occasional moon-shot looks ragged and skewed as the 8-detector scanner steps from north-to-south while background objects move to the east.
During the annular solar eclipse on 10 May 1994, GOES-7's routine imagery was used to make a mini-movie, constructed from higher resolution frames at SSEC.
In 1992, GOES-7 captured hurricane Andrew (96 frame, 672 kbyte movie) during its crossing of Florida and dissipation over New Orleans.
GOES-7 IR imagery overlaid with the national radar for a few stormy days in mid-summer 1994, an MPEG movie demonstrating the modernization of the National Weather Service. The movie presages the transition to using GOES imagery for filling in the gaps in the new observing systems -- watch for obviously stormy areas without echoes, and decide if radar is good enough by itself.
You can take pictures of satellites in geosynchronous orbit from light polluted cities, using equipment by Celestial Computing.

Imaging notes

Enthusiastic amateurs can easily receive broadcast images from weather satellites by setting up their own antennas for a few $100 to a few $1000.
There are about 12,000 lines with 20,000 samples per line in a full earth visible image from GOES-8. This over-sampling along a line, by a factor of 7/4, would result in oval earth pictures if shown as-is. Round-earth pictures from GOES-8 have been preprocessed to keep you from going: "What?" when you see the original sampling, such as this small picture (512x512), or this bigger picture (1024x1024), or this less harsh contrast enhancement from May 20th.
GOES-7 visible pixels are 6-bit data, with the bright end compressed so that all bright clouds are saturated white. Moreover, the 8 visible detectors on GOES-7 have significantly different responses, causing repeated 8-line patterns unless they are readjusted regularly. GOES-8's greater linearity and dynamic range improve this situation, as you can see in the the storms around Cuba.
The original 10-bit data from GOES-8 is a much wider intensity range than the eye, which is no more than 32 grey levels, or 5-bit data. Hardcopy is limited to 16 grey levels at best, usually blurred by halftoning. To make a nice looking greyscale image within this limited range, we perform histogram equalization, but that does not help when the field contains bright cloudtops and dark ocean, unless you equalize in regions of similar brightness.

Trivia

Girls Opportunities in Engineering and Science (GOES).
Hurricane basemap for the Atlantic.
Data from geosynchronous satellites operating around the world can be used to construct global cloud cover composites every 3 hours.
The GOES-I/M's Imager and Sounder instruments are almost mirror images of each other.
The GOES-I/M spacecraft's "solar sail" (a long fiberglass boom) actually points straight north, aligned with the Earth's spin axis, to balance the heavy solar panel that points south. Many illustrations erroneously point the boom at the Earth, such as our own mini-poster.
Space Systems/Loral's GOES logo reads the same upside-down, thanks to a famous artist, Scott Kim.

Kim Bryson, a botany major from Miami University of Ohio and summer student with the GOES Project Office, organized the GOES home pages in the summer of 1994. They look a lot different now.