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From Satellites: Timed GUVI

Polar provides images of an entire hemisphere of the Earth, but it takes 17 hours to complete an orbit. The TIMED satellite takes only 97 minutes to orbit the Earth. The GUVI camera on TIMED takes images that show the intensity of ultraviolet light coming from the upper atmosphere - but only in a narrow swath. The following movie constructed from the GUVI instrument shows intense auroras occurring over the northern and southern polar regions during solar storms in April 2002, with auroras extending into much lower latitudes than usual. Several data tracks, acquired during multiple spacecraft passes, are superimposed over an Earth image to show the location of the auroras. In this video, the Earth image transitions into two to show the location of the aurora over both poles simultaneously. The northern polar region is shown on the left and the southern on the right.

When you click on the TIMED GUVI Live Data link, you will get to a page GUVI Gallery like the image below.

Now click on the Level 1B Survey Product Gallery. You will see a page similar to the image below.

A few settings must be checked or changed. Look along the top of the image.

1. The Day menu will start with the most current date with data available when you open the window. In the image above the Day is set to the 236th day of 2003. Choose the day you wish to investigate. You can go back to Jan. 7, 2002. It takes several days for the GUVI scientists to prepare the images, so you won't see the image from the current day.
2. The ORBIT # list starts with the first orbit of the date you chose. The ORBIT # tells the number of orbits since the launch of the TIMED Satellite.
3. DATA VIEWS offers a choice of polar or equatorial views. You will want to experiment with these choices, but generally you will want the polar image.
4. WAVELENGTHS offers choices of ultraviolet wavelengths. For your observations it is suggested that you set this to LBH1.
5. After you have adjusted the settings, click on RETRIEVE IMAGE.

This image (above) shows the swath of data taken during the 9,248th orbit that occured on the 236th day (Aug 24) of 2003. The image is looking down from above the North Pole with North America to the left. The text to the upper right says the orbit started August 23 at 22:25:38 UT and ended 2 minutes and 47 seconds into August 24. This swath goes over eastern United States, so we would subtract 4 hours to get the time of the data on the East Coast. So this image shows eastern US between 1800 and 2000 hours (6:00pm to 8:00pm). The blue color over eastern Russia (low UV light) is because it is night. Most of the yellow and greenish over the Atlantic and the eastern US is due to sunlight. The red and yellow (bright UV light) forms a partial circle over the Artic and is due to an aurora.

When you click on NEXT ORBIT you can see the swath an hour and a half later. Several orbits later the following image was constructed.

This image shows that it is night over western US, Canada and Alaska. How can you tell? A strong aurora (red and orange) is visible over northern Alaska, the Artic and Russia. The green that extends southward in Russia and China shows that the Sun is shining on that side.

Next Step: IMAGE FUV »

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