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by Carol Rasmussen
This article is reprinted by permission from the October
2000 Staff Notes
Monthly.
A "bare bones" version of the Weather
Research and Forecast model will shortly be released to a group of interested
users. WRF (pronounced "worf") will offer resolution that's about an order of
magnitude better than existing operational mesoscale models."
When we look down the road to greater computer power, we want to have horizontal
grids of a couple kilometers so we can resolve small-scale weather features as
they're evolving," says Joe Klemp, who is leading the development effort
at MMM. WRF's other collaborators include NOAA's National Centers for Environmental
Prediction (NCEP) and Forecast Systems Laboratory (FSL), the University of Oklahoma's
Center for Analysis and Prediction of Storms, and the Air Force Weather Agency.
WRF has a three-layer structure. John Michalakes (MMM), a visiting computer
scientist from Argonne National Laboratory working on WRF development, explains:
A driver layer deals with computer architecture (and also such issues as
managing nested grids) so that the user can run the model on distributed-memory,
shared-memory, vector, or cluster machines without having to modify it. Theoretically,
WRF's driver layer could be used for other models -- including general circulation
models. However, Michalakes points out that it would have to be modified to deal
with, for example, spectral transforms and coupling among component models, since
these features aren't yet part of WRF.
The other main layer, the model dynamics and physics, is the only one
that will be "visible" to a user. Joining the driver layer to the model layer
is a mediation layer, which Michalakes describes as "a glue layer that
has to know a little bit about both other layers so they can interact."
This structure gives WRF a flexibility that will be needed to serve both researchers
and forecasters. "There was rapid recognition among all the participating organizations
that there was value in developing a common modeling system," Klemp says. "With
WRF, at least there's a potential for streamlining a lot of technology transfer."
Development of the model got started without a lot of WRF-specific funding.
"We've been trying to forge ahead on the resources available," says Klemp, who
adds that the development team, which includes software engineers and scientists,
works together very well. "Our success is in developing a real team attitude.
[The engineers] don't just tell us what to do and leage us to do it or not; there's
a lot of going back and forth until we agree on the best way to do it."
Michalakes concurs: "There's a joint appreciation, respect, and feeling of
ownership by the respective members of the team."
Back to "Planning a new paradigm:
The future of high-end modeling at NCAR"
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