Re: Open Source Climate Modeling was Re: [asa] Crop Yields Face Non-Linear Effects Due to Climate Change

From: David Clounch <>
Date: Tue Sep 15 2009 - 09:02:01 EDT

SGI clusters use intel processors, both Itanium and X86-64. Cray has been
using AMD. SGI is using the Nehalim processors in its new ultraviolet
machine. But hey, who generally needs 100,000+ cores on a common memory

On Tue, Sep 15, 2009 at 7:36 AM, Dave Wallace <>wrote:

> Rich Blinne wrote:
>> The study used CCSM3 (Common Climate System Model 3). This is an open
>> source model so that differential studies can do true apples to apples
>> comparisons. As with all weather and climate circulation models CCSM3 solves
>> Navier-Stokes fluid flow equations which as you probably know is notoriously
>> sensitive to proper initial conditions. When used in climate modeling the
>> approach used by thermodynamics is used in order to get useful results far
>> into the future, averaging. The model is run multiple times, with slightly
>> different initial conditions, and then an average is computed. The spread of
>> the runs gives a sense of how accurate the results are.
> Another good way is to run the models with floating point precision doubled
> for example 128bit float rather than 64 bit float. I realise that not many
> processors support 128 bit float but some do, Power PC/AIX does and I can't
> remember but possibly Sun, Alpha or SGI as well.
> Climate models are counter-intuitive in that they are less accurate on
>> shorter time scales than on longer ones. We want them accurate at *all* time
>> scales, short, medium, and long.
>> How do we know they are more accurate on longer scales? How long is
> longer?
> Dave W
> To unsubscribe, send a message to with
> "unsubscribe asa" (no quotes) as the body of the message.

To unsubscribe, send a message to with
"unsubscribe asa" (no quotes) as the body of the message.
Received on Tue Sep 15 09:02:57 2009

This archive was generated by hypermail 2.1.8 : Tue Sep 15 2009 - 09:02:57 EDT