Friday, June 27, 2014

Green Summer

Landsat is a program of polar orbiting satellites that started in 1972. While orbiting they scan the earth measuring different wavelengths of light, essentially taking a picture. Over the course of several days they have passed over most the earth. Currently, Landsat 7 and Landsat 8 are in operation. One primary purpose of the Landsat program is to keep a record of the changing land use in the world. 

On June 12, 2014 it passed over Utah and created this image. It's amazing how green this desert in the west can get. What a wonderful place to call home!
Source: Landsat
The large body of water is Utah Lake. Strawberry reservoir is to the east. Down the middle is the Wasatch Range and Uintah National Forest.

I wasn't in Utah at the time of this picture, but I'm in the one below! This is Charlottesville, Virginia on June 2, 2014.
Source: Landsat
It's hard to pick out landmarks (so many trees and I'm not too familiar with the area), but I-64 is the main road running west to east and US-29 is the road running north to south.

The newest satellite in the program, Landsat 8, measures 11 bands of radiation. Only three bands are needed to create a true color image (red, green, and blue visible light) and the other bands give us additional information. More information about what each band measures can be found here.

One cool thing we can do with the 11 bands is distinguish snow from clouds. The algorithm that processes the images gives snow a bluish tint. Shown below is an image of the Uintah Basin on January 12, 2014. The bluish tint is an indicator of snow.
Source: Landsat
These images are important for air quality research because we only see high levels of ozone pollution in the Uintah Basin when the ground is covered in snow.

To explore Landsat images, go to http://landsatlook.usgs.gov/.




MODIS is another instrument on a polar orbiting satellite. 
You can find MODIS images in near-real-time here
(Warning: This site will use all the RAM on your computer.)

A post about MODIS can be found here.

No comments:

Post a Comment