The spatial integration of irregular temperature data (CRUTEM4) using spherical triangulation removes any coverage bias.
I have made a spherical triangulation of the CRUTEM4 station data combined with HSST3 ocean temperature data. This is essentially Hadcrut4.5, but instead of using a (lat,lon) grid, it is averaged over the surface of a sphere including the poles.
So how does this compare to existing temperature data? The next plot shows the annual global temperature anomaly as compared to the standard Hadcrut4 values and those of Cowtan & Way.
The spherical results are essentially identical to those of Cowtan and Way! They use a complex 2D kriging algorithm to interpolate the 5 degree T(lat,lon) values into higher latitudes, partly guided by UAH satellite data.
This result demonstrates that spatial integration of irregular temperature data (CRUTEM4) using 3D spherical triangulation alone removes any coverage bias.
- Thanks to Tim Osborne for providing IDL code that processes CRUTEM4 station data.
- Thanks to Nick Stokes for the basic idea. He uses something similar in TempLS
Download data for Hadcrut4.5 Spherical Triangulation (ST):