Posted by Nick.Barnes | Filed under announcement
I am proud to announce release 0.2.0 of ccc-gistemp. This is an all-Python reimplementation of GISTEMP, the NASA GISS surface temperature analysis. Please feel free to download and play with it. It will automatically fetch input data across the internet, and produce textual and graphical result files.
This release works on Windows, Linux, Mac OS X, FreeBSD, and probably anywhere else you can get Python to work. The only dependency is on Python (2.5.2 or later, as we discovered today that the code to fetch input data trips over a bug in earlier Python libraries).
The results of running this release match GISTEMP results very closely indeed:
In fact, the annual global, northern hemisphere, and southern hemisphere anomaly results are identical, as are the southern hemisphere monthly anomalies. The global monthly anomalies differ 7 times, out of more than 1000, each time by one digit in the least-significant place.
This ends phase 1 of the CCC-GISTEMP project. However, although there is no remaining Fortran, ksh, or C source code, much of step1.py is still GISS code, and a lot of the large-scale structure of the code is still dictated by its 1980s Fortran heritage. For instance, the data is broken up into pieces because it couldn’t all fit into memory at once [ed: 2010-01-19: this particular instance is Issue 25 and it's now fixed]. This obscures the underlying algorithms being applied. Phase 2 of CCC-GISTEMP will refactor the code to eliminate this obscurity. We expect one side-effect to be an increase in speed.
Thanks to all who have contributed, including David Jones, Paul Ollis, Gareth Rees, John Keyes, and Richard Hendricks. Thanks also to Reto Ruedy at GISS, who has been helpful and responsive.