Satellite Meteorology Basics
Scott Lindstrom
20 February 2016
Two kinds of orbits
Not To Scale!!!
Two kinds of orbits
This is one day’s worth of
satellite passes (for Terra)
4 sequential Suomi NPP Passes
“descending passes”
In these images – satellite is identified,
and wavelength, and day and time
This is a Visible Image :
White regions are maxima in solar reflectance
This shows reflected light
Albedo is highest in white regions: Clouds, Snow, Sand
This is an Infrared Image :
White regions are minima in terrestrial radiation
This shows emitted energy
Cold regions white; warm regions dark
Infrared
In both of these images, you can detect the
land-sea difference
10.7 mm
Visible
Conclusion: the atmosphere is transparent
to radiation at these wavelengths
0.63 mm
This image is from the same time – but at a different wavelength
6.7 mm…Notice that you cannot see the surface. Why?
This image is from the same time – but at a different wavelength
6.7 mm…Notice that you cannot see the surface. Why? Radiation
at 6.7 mm emitted by the surface is absorbed by the atmosphere
This image is from the same time – but at a different wavelength
6.7 mm
This grey-scale makes things hard to distinguish
A color enhancement is a big help!
Question: If you were looking down from outer space, you would
see color. Why don’t you see color in this image?
Question: If you were looking down from outer space, you would see color.
Why don’t you see color in this image over the southwest US
Question: If you were looking down from outer space, you would see color.
Why don’t you see color in this image over the southwest US
Question: If you were looking down from outer space, you would see color.
Why don’t you see color in this image over the southwest US
First image: 0.6465 mm
-- the red part of the electromagnetic spectrum
Second image: 0.5537 mm
-- the green part of the electromagnetic spectrum
Third image: 0.4656 mm
-- the blue part of the electromagnetic spectrum
Combine green, red and blue to get true-color imagery
Satellites have detectors that are sensitive at different wavelengths.
This is the near Infrared – 0.86 mm – land/water differences are stark
Here’s the visible for the same time – land/water differences aren’t quite to
apparent
Water Vapor molecules absorb energy at 1.38 mm – so you can see the clouds
here (cirrus), but not much else.
The ‘window channel’ – 11 mm – the atmosphere is transparent to radiation at
this wavelength (but clouds are not!)
Color Enhancements are helpful
This channel is in the far Infrared – 11.0 mm – energy that is near the peak
emitted by the Earth
Satellites have detectors that are sensitive at different wavelengths
This channel – 6.77 mm – is one where water vapor absorbs energy
Color Enhancements are helpful. Bring out the contrast so your eye more
easily views it. Here: Yellow is warm (low in atmosphere) and green is cold
(high in atmosphere)
Satellite Data Sources
• http://www.ssec.wisc.edu/data/
– A link to a variety geostationary and polar orbiting satellites
• http://www.ssec.wisc.edu/data/geo/
– Latest Loops from all geostationary imagery!
• http://ge.ssec.wisc.edu/modis-today/
– True-color MODIS Imagery over the USA, created daily
• http://www.aos.wisc.edu/weather/wx_obs/Satellite.html
– US- and Wisconsin-centric imagery and animations
• http://www.ssec.wisc.edu/data/1min/
– Link to all 1-minute imagery from GOES-14
• http://re.ssec.wisc.edu
– Real Earth – Global Satellite Data in Real Time