Wednesday, December 5, 2012

Station trends - more

This is the second in the series of large datasets made available by XMLHTTPRequest. I had shown a globe map of station trends. I was limited to 3 time periods and even then there was some awkwardness because I had to use a single mesh to save download time.

Now I can do many periods, each with its own mesh. The resulting plot is shown below. All the periods end at present - I could do selected past periods too, but couldn't think of a scheme for preselecting.

I originally called this a cherrypickers guide, because it shows out the locations where the trends have been negative. But it also puts it in proportion - there are more positive trends than negative. The color scheme often obscures that, because I center the rainbow colors on the midpoint of the data, which is often well above the zero trend, which is down among the blues. I think the spatial homogeneity is worth noting. Nearby stations tend to warm and cool together.

Anyway, the plot is below the jump. Or you can go here to see it in a separate window. As with monthly data, you can select different time ranges, ask to see the nodes and mesh - just refresh when you've selected. Click on the small map to reorient the globe. Click on the main globe to bring up the data for the nearest station.

Update: I've put up corresponding data using GHCN adjusted. Check the box and refresh to see it.

How it works

The flat map at top right is your navigator. If you click a point in that, the sphere will rotate so that point appears in the centre.
The buttons below allow modification. Set what you want, and press refresh. You can show stations, and the mesh, and magnify 2×, 4×, or 8× (by setting both). You can click again to unset (and press refresh).

Then you can click in the sphere. At the bottom on the right, the nearest station name, lat/lon and trend will appear. It's easier to do this with stations displayed.

Data details

These are as for the previous post.


  1. Nick:
    Again this is a very helpful display. I always find visualization very helpful. I am no expert but I am familiar with Brazilian temperature records. Most long records come from areas with dramatic recent population growth and as a result UHI effect are likely to be significant. This may explain some of the warming in Brazil.

    1. Thanks, Bernie, yes there have been quite a lot of changes in Brazil - UHI but also land clearing.

      You can click on stations to bring up details, which might help check on UHI. In fact, Brazil has been quite poorly covered in GHCN.