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Charles E. Ophardt, Professor of Chemistry, Elmhurst College, Elmhurst, IL 60126,, Copyright 2004

QUES. 4: OZONE DEPLETION - Answer ONE of the questions 4a-d below.

In 1987, an international agreement known as the Montreal Protocol on Substances that Deplete the Ozone Layer was signed by many nations. The Protocol required the that CFC production would be reduced to one-half of the 1986 levels by 1998. Based upon a growing understanding of the cause of the ozone hole and the potential for global ozone depletion, approximately 100 nations in 1990, agreed to a complete ban on the use of CFCs in 2000.

Visualization of the Ozone Hole: Please say WOW when you see these!

A site is available to access contour color maps of the ozone concentrations in various locations in the world. The longest archived series is from a satellite carrying TOMS - Total Ozone Mapping Spectrometer. Another satellite provides daily maps called TOVS. This page is no longer up to date because they are using a different satellite. There is data through 2005. so you can see image of the whole globe, the north pole and the south pole through 2005.

Note: use the above www site to find answers to the above questions and those that follow and alternative site from NASA is. This site can be used for 2006 up to date or back to 2005. You can get a whole series of maps on one page for a month. Click on the month uner the globe to go back to Sept, August, July. When does the ozone hole start? Ozone Watch.

a. Click on Today's Ozone Data and Images to get current real time data or use Ozone Watch. The color contour coding shows low ozone concentrations measured in Dobson units of dark purple, pink, violet colors. White or black colors mean that no data is available. Low Dobson units mean low ozone concentrations.

USE the following to answer QUES. 4a and 4b.
b. Use Earth Probe TOMS, click on "South Pole Ozone - GIF".Then there is a section that will allow you to choose a year (1996-2005) Then pick the year month and day. This is a direct link to an image for a specific date. If you get tired of doing one at a time then continue to c. or use date from Ozone Watch gives a whole month at a time. Ozone Watch
c. It is also possible to get a GIF animation of polar views. This may play slowly or quit.

QUES. 4a: First concentrate on the Antarctica, look at a series of images starting with July 1 and look at one or two dates every month until December. You can use the 2005 dates up to the present, but you may need to go back and get some of the dates for November and December to find when the ozone hole ends. Which months show evidence of the "ozone hole"? Evidence of the ozone hole is when you begin to see contours of blue, purple, pink, or dark purple. See the color bar for the Dobson Units near the bottom of the graphic. In July and August you will see a black spot on the south pole - this is NOT the ozone hole, but only a lack of data due to the fact that the satellite can not work when it is completely dark at the poles as it is in the winter which is July and August. Try to refine the dates for the optimal duration of the ozone hole. Try some dates that are about 15 days apart. You only need to look through one year of data.

What day(s) does the ozone hole begin(probably sometime in August or early September) and end (probably near end of November or early December) ? For the Antarctica Ozone Hole give the approximate date and lowest concentration of ozone, in Dobson units, observed. These dates do not have to be exact, just trying to get some approximate dates. Tell how you know and what colors for Dobson units that you are observing.

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Brief explanation for the ozone hole. The inactive forms of chlorine in hydrochloric acid and chlorine nitrate can react with ice crystals and nitric acid trihydrate crystals in very high cold clouds in the stratosphere over Antarctica. This reaction on the surface produces diatomic chlorine molecule and nitric acid, which quickly dissociate into chlorine atoms in the sunlight of the Antarctic spring. The reactive chlorine atoms start a cycle of destruction of ozone. Chlorine atoms react with ozone to make chlorine monoxide molecules and oxygen molecules. Chlorine monoxide reacts with atomic oxygen to make diatomic oxygen and reactive chlorine atoms to cycle over again. Since there are few gaseous water molecules and virtually no nitrogen dioxide molecules to react with and inactivate the chlorine, the reactive chlorine builds up as chlorine monoxide and recyles to chlorine atoms which continue to destroy more ozone.

Examine the ozone and reactive chlorine versus latitude graph # 1. What is most striking about the relationships shown on the graph? As the latitude increases (getting closer to the South Pole) the ozone concentration _________ while the chlorine concentration __________.

QUES. 4b: Comment about the ozone hole growing in area size and the minimum concentration as the years have increased. Series of monthly ozone maps.
2006 Ozone Hole
- dialy up date on graphs of concentration and size compared to earlier years.
- Do these graphs show that that ozone levels in the ozone hole are getting better, worse, or staying the same?

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QUES. 4c: From Earth Probe TOMS, click on "Global Ozone". Pick a date in July, and year. Use the color contours to list the approximate ozone concentrations in Dobson units over three zones: near the equator, in the mid latitudes (North America/Europe/Asia) and polar regions. Is the distribution of ozone uniform over the surface of the globe? Explain. Besure that you understand the color codes for the Dobson units.
Ozone levels at various lattitudes

U.V, Map of U.S. showing contours of where the most U.V . of the type that damages DNA. Lower numbers equals less U.V . (Contrast aqua contour with purple or brown contour. AND correlate that with the %per year cancer rate.

Based upon this analysis, where would you NOT want to live on a permanent basis because of increased exposure to UV due to lower ozone concentrations and possible increased risk of skin cancer? Closer to poles or closer to the equator? Northern U.S. or Southern U.S.?

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QUES. 4d: Is there any evidence of a similar ozone hole hear the North Pole? Look particularly at dates in March and April. Use Earth Probe TOMS, click on "North Pole Ozone - GIF". Pick some dates in March and April, and year. There is a more definite effect in 1997. You are looking for aqua blue colors right at the north pole as they indicate a lower concentration in Dobson units as indicated by the color bar on the bottom. Again a black hole is just a lack of data and is NOT an ozone hole. Here is a series of North Pole images from 1979 to 1998. Look carefully at the color coding and note that the levels are not as low as those over the South Pole. n the bottom. Again a black hole is just a lack of data and is NOT an ozone hole. The evidence for an ozone hole in the spring at the North pole is not as dramatic and nor as serious as the ozone hole at the South Pole in the southern hemisphere spring (Sept-Nov.) Series of ozone Norh Pole maps - 1979-98.

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