Sea Surface Temperature Fronts

Tutorial 1 :  Dods to ArcInfo Tutorial



Sample image of what the fronts look like. Underneath the lines is a Distance to Front Grid that can be created using the AML available on this site.

The goal of this tutorial is to walk you through the steps needed to get data out of DODS and into ArcInfo. You will need a few things before you can actually walk through the tutorial:


1. A copy of ArcInfo 7.x or greater
2. The current version of Perl installed (click here if you need
to do this)
3. A web connection
4. Install the perl scripts
5. A text file containing dods dates, see below for an example
6. After you run the perl scripts, you will need the AML

If you have all of the above in working order, then you can go ahead and fire up the script by typing the following from a command prompt:
> perl ocean_filelist1d.pl

This will fire up the program, which will prompt you for some imputs. The first thing the program asks for is the path where you will be storing the raw data. This will generate a file I call amlfile.txt, and its purpose is to serve as a listfile for the AML. Once you have all the DODS data and are running the AML, it will query you for an infile. This infile (amlfile.txt) will contain references to the raw generate data, the raw attribute data, and the name of the output coverages. So make sure you name it where your coverages will end up, e.g. d:\arcdata\xproject\gis\coverages\ on my machine (make sure you include the last "\" or forward slash if you are on unix). The initial runtime screen looks like:



The program will then ask you for the file of dates. It's important that the list only contains the numbers for the dates. Do not hit return after the last line, i.e. do not make a new empty line within the file of dates (note how cursor is at the end of the last line). These should look like so:



I had experimented with putting a lat long bounding box option at this end, as you are able to constrict the urls with spatial information. Unfortunately, there are some quirks in the data, such that if you specify part of a range for which there aren't any fronts, you just get no data back, rather than the data that do exist. So it's easier to subset it using SETMASK within Grid.

Now you just have to wait for the data to be returned to you. The five days I used as test days took about 40 seconds on a T1 line. The output files:



The amlfile output looks like this:



OK - you've successfully accessed some data via DODS! To take the next step and learn how to create some coverages and grids in ArcInfo, follow the link.


Intro Tutorial 1 Tutorial 2