Tuesday, August 16, 2011

A Javascript worldview for surface temp.

You may have noticed that I generally prefer simple spherical (orthographic) projections for displaying global fields. Even though it takes several projections to convey all the information.

But I use lat/lon maps for comparisons, and more recently, Hammer projections for comparison with NOAA and MP.

Spherical projections take up space, but this can be resolved by creating a poor man's Google Earth (OK, GE is free) with Javascript. In the plot below, of the July temperature data using GISS's colors and baseline (1951-80), you'll see a pattern of squares, top left. This corresponds to eight views. The directions are as if the earth was encased in a cube, with one apex above the N pole. The views are from the directions of the eight corners. N Pole is the square at the top, the next three are around near the Tropic of Cancer, etc. Just click - the red square marks where you are.
Picture below the jump




Below the jump - same for NOAA



This time, for variety, I've positioned the views differently. The viewing cube is tangent to the pole, so the foci are points along a N and S latitude, at about 40°. The squares to click on follow that pattern.(Due to a slight inadequacy in the current JS, please don't click on this one before clicking on the top one).

5 comments:

  1. It's not GE .. but excellent interactive visualisation for this data!!

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  2. It's a big improvement, but it would be better if you could click and drag to rotate the globe in the manner of Google Earth when zoomed out.

    I have no idea how difficult this would be to implement though.

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  3. Anon,
    On dragging, the main thing is that it is only reasonable (in terms of downloadable resources) to provide about 8 views (you'll notice a pause when you first click, which is the downloading). So there wouldn't be a continuous response.

    It would be possible to make dragging work in a jerky way - say by flipping one view every cm of drag. But I don't think it would be very intuitive.

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