Accessing Arctic Sea Ice Extent Data for Intercomparison Study

1. Climate News Study • A member of the general public has found a copy of the (attached) graphic on the New York Times website. They see the tag line as NSIDC and want to find the data that was used to make the chart. This person also found the (attached) scatterometry image attributed to Dr. David Long at BYU and wants to intercompare these two data sources. Before doing that they must locate the original data used to produce the graphics.

2. Climate News Study

3. Instructions • Define the steps needed to fulfill the scenario • Steps needed for access to the data • Data types or data sets needed • Suggest a strategy that fulfills the steps • Which of these steps in your strategy are available through NSIDC, JPL (or internet) resources? • What specific observations do you have about the NSIDC or JPL data system while working this scenario? • Comment on the efficacy of web sties or specific web pages --- use screen capture of web pages to show specifics

4. Step 1 • Define the steps needed to fulfill the scenario • Steps needed for access to the data • Data types or data sets needed • Observations: • Before doing 1.1 above, I would do 1.2. Carefully reading the scenario indicates that my task is: Find the data used to make the NSIDC chart and the data used to make the David Long scatterometer image, thus enabling an intercomparison of the two datasets • Therefore, I need: • NSIDC Arctic Sea Ice Extent time series for 2007, 2008, and the 1979-2000 mean • David Long (BYU) scatterometer data covering the Arctic

5. Step 2 2. Suggest a strategy that fulfills the steps • Observations • The first thing I would do to find the source data for the NSIDC Artic Sea Ice Extent data would be to do a Google search, even though I already know it comes from NSIDC. • I search for “NSIDC Artic Sea Ice Extent” and click on the first return, Cryospheric Climate Indicators: Sea Ice Index • This takes me to http://nsidc.org/data/seaice_index/, which looks like the right place to be to find the data • Perusing the page, I quickly find “archived data and images” link on the left, then click it. • I want data not images, so I click on “Get Extent and Concentration Data” • There is a README.txt file on the FTP site I am taken to. I read it and am annoyed when it tells me to go to another page, http://nsidc.org/data/g02135.html. Of course, I can’t click on on the link (this is an FTP plain text file) so I have to copy and paste URL to my browser window.

6. Step 2 2. Suggest a strategy that fulfills the steps • Observations (continued) • So, I create a new tab and paste that URL into. Still annoyed… especially when the link “Product Web Site” takes me back where I started. I don’t want to be there, so I hit the back button. • The metadata link is nice to see, so I read that. I still don’t see a format description, so I go to my other tab with the FTP site open. • I click on “Apr”, then on “N_04_area.txt” and discover that the format is so simple it did not need a separate description. I think the README.txt file was misleading… it should have told me more specifically what each of the “Jan”, “Feb”, etc. directories contained, and that images and data are there and self-documented. • Then I am annoyed again because I have to do all this clicking for all 12 months, or at least the 5 months in the chart. The climatology is not pre-generated, so I have to compute that myself (it is easy to do, but why not provide that as well?) • I am not a heavy GIS user, but do occasionally read shapefiles into Matlab so I am glad to see those are available as well.

7. Step 2 2. Suggest a strategy that fulfills the steps • Observations (continued) • At this point I have the source data for the NSIDC chart. Now I turn my attention to the David Long (BYU) data. • Again, I turn to Google and do a search on “David Long BYU Scatterometer” • First two hits are on his student list and some other members list, so I follow the third link which takes me back to NSIDC to http://nsidc.org/cgi-bin/get_metadata.pl?id=nsidc-0261 • I review the metadata record that is returned… I am familiar with metadata so am not frightened away, but many users might be at this point • I find the online resource element, but then focus on “VIEW PROJECT HOME PAGE” which takes me to BYU web site

8. Step 2 2. Suggest a strategy that fulfills the steps • Observations (continued) • I am now at http://www.scp.byu.edu/derived.html • I read this and see “Sea Ice Extent Products”, which mentions QuikSCAT and NSCAT and looks like the most likely place. Fortunately I know these are scatterometers, so I click on it. • I now have a page that talks about “Eggs” and “Slices” for the Arctic and Antarctic. I have no idea what there are, but clicking on either returns a huge HTML table listing a million and one images. • Fortunately I see the small link for “AVE or grd” so I follow that, then drilling down, down, down to ftp://ftp.scp.byu.edu/data/qscat/2006/aux/qaeh/Arc/002/C/ before I ever see a file I might be able to download… but I don’t bother at this point because I have no idea what all these subdirectories are.

9. Step 3 and Step 4 3. Which of these steps in your strategy are available through NSIDC, JPL (or internet) resources? • Observations • I was able to easily find the NSIDC data at NSIDC in a form I could use. Unfortunately, even though they had metadata about the David Long data, I still seemed to have to go to his web and FTP sites. Those sites assumed a high level of familiarity with the scatterometer data, which I do not have. 4. What specific observations do you have about the NSIDC or JPL data system while working this scenario? • Observations • The NSIDC system seemed fairly clean and intuitive. In my comments I mentioned a minor or improvement or two, but the overall impression is positive and certainly more usable than David Long’s interface (though, once armed with some basics his site might be fairly usable too).

10. Step 5 5. Comment on the efficacy of web sties or specific web pages --- use screen capture of web pages to show specifics • Observations • I’ve made several observations as I’ve gone through the process, but a more general look at the NSIDC gives a positive impression - I like that there are relatively few links, and quick links to the data.