Joe Landman wrote:
Gerry Creager wrote:
I'm running WRF on ranger, the 580 TF Sun cluster at utexas.edu. I
can complete the WRF single domain run, using 384 cores in ~30 min
wall clock time. At the WRF Users Conference last week, the number of
folks I talked to running WRF on workstations or "operationally" on
16-64 core clusters was impressive. I suspect a lot of desktop
weather forecasting will, as you suggest, become the norm. The
question, then, is: Are we looking at an enterprise where everyone
with a gaming machine thinks they understand the model well enough to
try predicting the weather, or are some still in awe of Lorenz'
hypothesis about its complexity?
I see a curious phenomenon going on in crash simulation and NVH. We see
an increasing "decoupling" if you will, between the detailed issues of
simulation and coding, and the end user using the simulation system.
That is, the users may know the engineering side, but don't seem to
grasp the finer aspects of the simulation ... what to take as reasonably
accurate, and what to grasp might not be.
I don't see this in chemistry, in large part due to many of the users
also writing their own software.
I think this "decoupling" where developers and users knowledge starts
diverging is both simultaneously painful for the "older" crowd of
developer/users, and opens up interesting opportunities for new users.
Basically it commoditizes the ability to run the codes. The question is
whether or not you can provide better guidance to the users about the
likelihood of it being a reasonable run, while abstracting away the
details of the run.
In my world, we discuss (often amongst ourselves) the concept of
forecast uncertainty. In point of fact, an ensemble, where we tweak
initial conditions, or tweak physics parameters (maintaining initial
conditions; don't ask what happens when one tries to tweak both physics
and initial conditions, but I've had someone try recently) is the
general vehicle we use to document our uncertainty: each member's
variation isn't "improving the model average" but demonstrating a
variance from a central condition.
Among the "users", though, they often look at a group of models,
different initializations, different physics, different results, and
assume that a good forecast is a simple averaging of these.
Therein lies the fundamental difference between the modelers and the
users: The modelers generally have a feel for the weakness of the model
while a lot of users have no such concern. The moel is a black box, and
since it produces a numerical result, it's automatically right. They
don't see different numerical results as a sign that we know our models'
limitations and seek to present said limitations, but that by doing more
model runs, we are strengthening our result.
In some ways, both groups are converging, but in the groups I still work
with, and present to, the level of confidence in my WRF exceeds what I
consider prudent.
gerry
--
Gerry Creager -- [EMAIL PROTECTED]
Texas Mesonet -- AATLT, Texas A&M University
Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.862.3983
Office: 1700 Research Parkway Ste 160, TAMU, College Station, TX 77843
_______________________________________________
Beowulf mailing list, Beowulf@beowulf.org
To change your subscription (digest mode or unsubscribe) visit
http://www.beowulf.org/mailman/listinfo/beowulf
