Student's Guide - Experiments
NSF Polar Programs UV Monitoring Network
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The following experiments are based on data from the National Science Foundation's (NSF) UV monitoring network. They allow one to access real data from the NSF server and make science with it. If you have questions, contact us.


1. Ultraviolet Radiation at different latitudes

This experiment will test how UV radiation varies with latitude.

First, access NSF data by going to the Data Request Form. Enter 1/1/99 and 1/1/00 into the fields for the date, check the box "UV Index", and select "San Diego" as the site. Then hit the "submit" button. After you have done this, a new page will be displayed with the data that you requested: the UV Index at San Diego during the time period of 1/1/99 to 1/1/00. Download and graph the data! (Click here to see some hints how to graph).

When you are done, return again to the Data Request Form. Repeat the procedure but instead select "Barrow" as the site (Barrow is located at the northern most point of Alaska).

After you have graphed both sets of data on the same graph, what do you notice? Which site has a higher amount of UV, the site with a higher (i.e. Barrow) or lower (i.e. San Diego) latitude? What are the reasons for the differences? Why do you think that there are no data for Barrow in January and December? Why do you think are the resulting curves not smooth but show some ripple?

If you like, repeat the experiment for another year, or compare Antarctic UV radiation levels with those in San Diego (remember that summer is shifted by 6 months between the northern and southern hemisphere)!


2. UV levels in Antarctica during different seasons

This experiment will test the difference in UV levels between seasons in the Antarctic, to see the effects of the ozone hole on the level of UV radiation.

First, access again NSF data by going to the Data Request Form. Then, enter 9/21/98 and 12/21/98 into the fields for the dates, these being the spring months in Antarctica. Select South Pole for the site and "UV Index". Hit submit, graph the data that is given to you (Hints on how to graph are here), and return to the Data Request Form. Repeat this process but instead using 12/22/98 and 3/21/99 as the dates, these being the summer months in Antarctica. After you have graphed both sets of data, what do you see? Which time of year has the higher levels of UV? Spring or summer? Can you see the effect of the ozone hole on UV (Hint: Look closely at the November and early December data!)?


3. Relation between ozone and UV

This experiment will test how the thickness of the ozone layer and UV levels relate to each other.

First, get UV Index data from the NSF monitoring network by going to the Data Request Form. Choose the Antarctic site (McMurdo, Palmer, or South Pole) that you'd like to perform the experiment on, select a time period (e.g. 9/1/98 - 12/31/98), and UV Index.

Then, access TOMS satellite ozone data and get the ozone data for the same site and period (You will see a long list of sites; look for "McMurdo Station, Ant (USA)", "Palmer Station, Ant (USA)", or "Amundsen-Scott, Ant (USA)", which is the name of the South Pole station.  

You should now see a large table on the screen. Getting the ozone data out of this table is a bit tricky. First save the table to your hard-disk in "text" format (Choose "Save as" from the "File" menu of your web browser, and then select "Text file (*.txt)" from the "Save as type" option menu). From this file, you need column 2 (year), column 3 (Day), and column 11 (ozone). The number in the "day" column is the number of days since the beginning of a given year. Day 1 is January 1, day 32 is February 1, and so on. December 31 is either day 365 or 366 in case of a leap year.

Try to match up the dates of the UV and ozone data. At the end, you should have 3 columns in your spreadsheet: date, UV Index and ozone.

Now graph UV Index and ozone in two separate graphs (Hints on how to graph are still here). What do you notice about the graph? Does the amount of UV compared to ozone vary directly or inversely? What does this tell you about their relationship? Can you explain this relationship?


More experiments

By now, you may have experienced that it's quite fun "digging" in data and making some science with it. But that was only a start. Make up questions by yourself and try finding the answers by downloading the appropriate data. All you need is the Data Request Form! For example:
  • Compare the annual and diurnal cycles in the UV Index at various locations with the variation in UV-A. Is the UV Index or UV-A more centered during noon-time? What do you think is the reason for the difference? (Hint: Think of the different effects of ozone on the UV Index and UV-A radiation!)

  • How do the effects of clouds show up in the data? Is the UV Index affected the same way by clouds as UV-A radiation?

  • Back to the Guide Index

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