Thursday, April 12, 2007

Wunderground and free public data

The following post may seem like I am meandering but there is a point, I promise, stay with me.

We in the American northeast have been enjoying a pretty late winter this year, meaning, it's a hell of a lot colder than April is supposed to be. The place I used to live was, in general, much warmer, and I got to thinking of the temperature difference between where I used to live. This got me hitting Wunderground, a weather site I started checking thanks to my Mom (an amateur weather guru who often knows more about my weather from 3000 miles away than I do). One of the cool things about Wunderground is that they make it easy to download historical weather data. For example, after about 10 minutes of clicking and Excelling I made this
Which shows the temperature difference between where I lived in grad school and where I live now. The y-axis is the difference in average daily temperature (°F) between old home and new home; values above 0 mean it is warmer at BWRU, and values below 0 mean it is warmer here at ESRU. The line is a five day running average. Why 5 days? I have no idea, but I'd appreciate a good reason if anyone can think of one. There are a couple things I noticed after putting this together. First, we had a really warm winter here at ESRU, until well into January it really wasn't much warmer back at BWRU. Second, there is an odd apparent periodicity in the running average, with a fortnightly recurrence. You can sum up my statistical analysis of this feature with the words "Jack Squat," but it is still potentially interesting. The maximum difference was just a month ago, March 6th when it was 59° colder here than there.

OK, great, it is colder in the northeast than a western school at a lower latitude, big shocker. Doing this though reminded me of an exercise I came up with when teaching an earth hazards course in 2004, again using Wunderground. In February of 2004 there was flash flooding in the southern part of San Francisco. Pretty exciting, there was water rushing down stairwells and elevator shafts at San Francisco State University. At this time I was teaching this earth hazards course at an area school, so I used Wunderground to come up with this homework. I had the students get the rainfall data for two days from the same station, the flash flood day (2/25/2004) and another day, a few months earlier that had some serious rainfall but resulted in no flash flooding (12/29/2003). This is the graph they were supposed to come up with

The y-axis is rainfall rate (in inches per hour), and the x-axis is time. The total rainfall for both days was actually remarkably similar, actually 12/29 had more cumulative rainfall, but the flash flood day had all that rain packed into less than an hour, instead of spread out over the day. Basically I was driving home the point that flash floods, unlike regional floods, come from large amounts of rain in small amounts of time.
What both of these exercises got me thinking about is free public data sets. Wunderground does not provide the kind of really rigorous data I'd use if I was working on an actual publishable study, but as a teaching tool or means of illustrating basic earth science concepts, it is fantastic. So Wunderground is great for relatively recent weather data. What about other public earth science related data repositories?

5 comments:

Thermochronic said...

the second graph has an error, the y-axis is labeled in/yr, should be in/hr.

Brian said...

hmmm....i went on wunderground and searched around for a bit...where do you access the historical data? I'm sure it was right in front of my face...

As for earth science data repositories, I know the paleontologists (now called paleobiologists) have a growing open database...ummm....the USGS has a crapload of old seismic-reflection data given to them by oil companies, but it's not a very easy thing to do 'quick and dirty' like you've shown for wunderground.

Thermochronic said...

To get the historical data, first pick a city you want to know the weather for. Then scroll down to where it says History and Almanac. There you can enter in a date to get the hitorical data. Once you click the "Go" button, the results page will have lots more options for seeing long periods of data, etc. At the bottom of the results table is the option to download it as a comma delimited text file. Boom! Insto-data.

GeologyJoe said...

ya gotta love good data.

Christy said...

I often use the snowpack data from the Natural Resources Conservation Service. There is a boatload of measurements that can be used in a great variety of ways. Another great resource is Colorado's (I assume every state has a similar agency)Division of Water Resources web page.