Welcome to “Tide” and “Gyre”, supercomputers for operational weather forecasting

Last thursday, the National Weather Service (NWS) brought online its two new “clone” IBM supercomputers, Tide and Gyre, for operational weather forecasting. The machines are the workhorses of the NWS National Centers for Environmental Prediction (NCEP)'s Weather and Climate Operational Supercomputing System (WCOSS). The two identical supercomputers are located in different places (primary machine at Reston, VA; backup at Orlando, FL).

Patrick Thibodeau's write-up at Computerworld seems to have led media coverage of the event. He refers to last year's Hurricane Sandy, which engendered “a belief that the European Center for Medium-Range Weather Forecasts (ECMWF) had a better storm track model further out. Criticism over the U.S. forecasting ability has followed post Sandy.” Bringing the new computers online, replacing the previously used pair of IBM supercomputers, is a step in the right direction. (A planned phase II of the transition will lead to further improvements.) However, the U.S. will also need to maintain investments in Earth-observing weather satellites, as noted (for instance) by Stephen Stirling of the New Jersey Star Ledger.

The NWS computers do work of national importance, and it is reassuring to read about the verification and validation of the systems prior to going live. Further details can be found in this post by Steve Tracton at the Washington Post. He describes sensitive dependence on initial conditions, manifested as a divergence in forecasts from the same forecast model run on both the old and new supercomputers. This phenomenon, as he points out, is closely related to the path-breaking work on chaos in meteorology and computational science by the late Edward N. Lorenz (1963, 1989).

Update (29 Aug 2013):  see also the NOAA press release.

 References

 

E.N. Lorenz, 1963: Deterministic nonperiodic flow. J. Atmos. Sci., 20: 130-141.

E. N. Lorenz, 1989: Computational chaos -- a prelude to computational instability.  Physica D, 35: 299-317.