> Subject: Re: ccc-gistemp 0.3.0
> From: Reto Ruedy <rru...@giss.nasa.gov>
> To: Nick Barnes <n...@ravenbrook.com>
> Cc: ccc-gistemp-discuss@googlegroups.com
> Date: Wed, 27 Jan 2010 13:21:27 -0500

> Dear Nick,

> Thank you very much for all the effort you and your people put into
> checking and rewriting our programs. I hope to switch to your version of
> that program, if it produces data files that are compatible with our web
> utilities. If we do so, we will let you know about any additional
> modifications or documentation that we include in your code.

> Any coding introduced only to match our results exactly should
> eventually be removed to make it as simple as possible. Their only
> purpose was to verify the correctness of our code and have no
> significant impact on the results.

> I assume that the tar file bugs you mention have nothing to do with our
> coding and don't affect any results - I add that only because I'm sure
> that this email exchange will end up in the public domain and will be
> assessed by people for whom this is not obvious.

> Thanks and regards,

> Reto

> On Wed, 2010-01-27 at 12:24 +0000, Nick Barnes wrote:
> > Dear Reto,

> > I'm writing to let you know that we made a fresh release of
> > ccc-gistemp last night.  This has quite a bit of clarification,
> > especially in steps 1 and 2, and some new tools to help with comparing
> > results, both from different runs and also against the run you
> > provided in December.  We've removed most of the uses of intermediate
> > data files.  There are also work arounds for some bugs we encountered
> > in tar file handling on some platforms.

> > Here is the release:

> > <http://ccc-gistemp.googlecode.com/files/ccc-gistemp-0.3.0.tar.gz>

> > and here is a file comparing the results from the release to the ones
> > you provided:

> > <http://ccc-gistemp.googlecode.com/files/ccc-gistemp-0.3.0-comparison-...>

> > This latter file was generated by simply running

> >   python tool/regression.py

> > Please feel free to download it and run it, or just browse through the
> > code.  There's not much overall documentation yet (that's a bug!), but
> > anyone familiar with GISTEMP will find it obvious.  step2.py should
> > give you some indication of the sort of work we are doing.

> > Ongoing work will continue this type of clarification through more of
> > the code.  We're also going to modify all of the code to use a single
> > representation of a temperature series, and move any remaining
> > intermediate file I/O out into the tool/ directory.  That will also
> > include some code to round or truncate intermediate data, to match the
> > effect of GISTEMP intermediate files which have been removed.  For
> > instance, GISTEMP STEP2 reads the latitude and longitude of stations
> > from v2.inv (where it is in hundredths of degrees) and then rounds it
> > to tenths of degrees to write to an intermediate file.  Although we no
> > longer have the file, our code explicitly does the rounding step to
> > maintain GISTEMP compatibility (because it affects, in a small way,
> > the behaviour of both step 2 and step 3).

> > I'm hoping to get to a stage at which it is possible to run
> > ccc-gistemp either in a "simple" mode (in which there are no
> > intermediate files and no such rounding) or in a "GISTEMP
> > compatibility" mode - with some intermediate files, and some rounding.
> > If we compute and quantify the differences between these modes, then
> > maybe some future release will do without the compatibility mode
> > altogether.

> > As we arrive at a detailed understanding of the whole code base, we
> > will also write some accompanying documentation to describe the whole
> > algorithm.

> > Regards,

> > Nick Barnes
> > Clear Climate Code project

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