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POP

The Parallel Ocean Program

The Parallel Ocean Program (POP) developed at LANL is one of many efforts in the Department of Energy's CHAMMP program aimed at increased understanding of the earth's climate through the use of modeling and high performance computing. POP has been used to perform the highest resolution (1/5 degree on average) global ocean simulation ever undertaken using the Thinking Machines CM5 computer located at LANL's Advanced Computing Laboratory (ACL).

POP is a descendant of the Bryan-Cox model that is used frequently in ocean simulations. This earlier model has been substantially improved and adapted for use with massively parallel computers. Some of these improvements are:

• a surface pressure formulation that allows for an unlimited number of land masses (with no additional computational cost) and unsmoothed bottom topography.
• an implicit free surface technique that allows the air-sea interface to evolve freely.
• the equations of motion are formulated and discretized to allow the use of any locally orthogonal horizontal grid (instead of just latitude/longitude) which, for example, can let the Arctic ocean be resolved without the standard problems of convergence of meridians at the North Pole.
• the code is written in Fortran90 and is capable of running on a variety of parallel and serial computer architectures.

A primary motivation for performing such high resolution simulations is to resolve eddy motions that can play an important role in the dynamics of the ocean. Two examples of this are eddies shed by the Agulhas Current and in meanders of the Gulf Stream.

Currently, efforts are underway to couple POP to NCAR's Community Climate Model (CCM) and a sea ice model also being developed at LANL.

Assorted Images

Surface Heat Flux (day 1 of coupled model, scale is +-500 W/m**2)
Yucatan Channel (POP)
Yucatan Channel (CME 1/6)
Yucatan Channel (CME 1/3)
Drifters in the North Atlantic
View from the North Pole (with Temperature)
View from the North Pole (without Temperature, tiff file)
View from the Atlantic (without Temperature, black background, tiff file)
View from the Atlantic (without Temperature, white background, tiff file)

For more information about POP, contact Matt Maltrud at maltrud@lanl.gov.