Archive for the ‘Uncategorized’ Category
Site updates
Posted by Nick.Barnes | Filed under Uncategorized
After several late nights trying to correct misapprehensions in a few places in the blogosphere, I have updated the goals and about pages to remove any ambiguity between this project as it currently stands and the CCC project at Ravenbrook which immediately preceded it.
Hopefully now some critics will join us and work to improve climate science software.
Project history
Posted by Nick.Barnes | Filed under Uncategorized
A potted history of the project so far:
- I had the idea for the project in 2007, after the first release of GISTEMP code. I saw it criticised online for various failings, from the ridiculous (e.g. “I demanded this code and now you’ve released it I don’t understand it”) to the sublime (e.g. the many attacks on a line of code which quite legitimately translated temperatures in Fahrenheit into tenths of degrees Celsius). It was plain to me that any software with results which might determine critical public policy should be more accessible than this. Ideally it ought to be possible for any interested member of the public to download the source code and inspect it.
- I presented my ideas to colleagues at Ravenbrook Limited in the spring of 2008. It was agreed that Ravenbrook should pursue such a project on a pro bono basis: we’d use our systems to host an open-source project, but nobody would be paid for their time.
- David Jones and I got started on the code over the summer of 2008, and presented our first results at PyconUK in September 2008.
- There was considerable interest at the conference and online, including a number of offers of help. Wanting to widen participation in the project, but not keen to host and support the infrastructure, we decided to use a Google Code project, and a Google Groups mailing list, and to consider a wiki or blog. We set those up and various volunteers started work, including John Keyes who later created and hosts this blog and Paul Ollis who has contributed a considerable amount of code.
- Our real lives intervened, and David and I didn’t do anything very much on the CCC project until the autumn of 2009, when we restarted work on the Python reimplementation and on this blog. Just in time for the CRU email hacking incident to stir up a lot of public interest in climate code quality.
We find bug in GISTEMP; GISS fixes it
Posted by Nick.Barnes | Filed under Uncategorized
Reto Ruedy of GISS has changed GISTEMP to fix a collection of minor bugs in STEP5′s SBBXotoBX.f, which David Jones and I found while re-implementing STEP5 in Python. The fix did not have any effects on the final numeric outputs of GISTEMP.
This particular program combined land and ocean temperature data. Each sub-box (an area of about 64,000 km^2) is given an “ocean weight”, depending on the amount of ocean data and the distance of the nearest surface station. Then the land and ocean series for each sub-box are given weights depending on the ocean weight and on the number of valid monthly temperatures. Then the 200 series for each box (the land and ocean series for each of 100 sub-boxes) are combined in order of decreasing weight to form a single series for the box.
The error was in the way the land and ocean series were combined after sorting into order: sometimes the index of an entry in the sorted set was used to index into the unsorted set.
As it happens, with the parameters used for this program, in particular the Rintrp parameter set to zero, this error has no effect because the ocean weight is always either 1 or 0, so after sorting the second half of the set of data series always has zero weight.
In email to David and myself, Reto Ruedy expressed thanks to us and to the CCC-GISTEMP project.