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

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/1 min/ – Link to all 1 -minute imagery from GOES-14 • http: //re. ssec. wisc. edu – Real Earth – Global Satellite Data in Real Time