Wednesday, April 20, 2022

Global projections for TempLS temperature reporting.

A couple of years ago I described here my way of implementing equal area projections for global data, and in particular the Mollweide and Robinson projections. Robinson would not have been a high priority, except that GISS ofers it for its temperature projections, so I can use that for comparison.

Events intruded, and I didn't implement it for routine use immediately, and when I later did, then of course mission creep crept in, and I thought of ways to use the pixel mapping methods for the actual integration (not that I am lackimg options).

However, it really should be done. The rectangular lat/lon method that I use conveys the necessary information in an easily understood way, and I will still be using it for some internal purposes, but it overweights behaviour near the poles visually. I calculated. Here is a table of the % by pixel of colors in my plots for March 2022, shown also below. Color 11 is the warmest (>4°C)

Color: 2 3 4 5 6 7 8 9 10 11

March was a month in which the Arctic was very warm, and you can see that there were more than twice s many of the warmest pixels in the lat/lon projection (approx 8% vs 4%). The other projections are close to the true % on the sphere.

I plan to show the three projections in a single frame, with navigation buttons. Robinson will show initially, but you can cycle to Mollweide or lat/lon using the buttons below.


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