Modular ocean model

The modular ocean model (MOM) is a three-dimensional ocean circulation model designed primarily for studying the ocean climate system. The model is developed and supported primarily by researchers at the National Oceanic and Atmospheric Administration's Geophysical Fluid Dynamics Laboratory (GFDL).

Overview

The MOM model series owes its genesis to work at GFDL in the late 1960s by Kirk Bryan and Mike Cox. This code, along with a version generated at GFDL by Bert Semtner is the ancestor of many of the level-coordinate ocean model codes run around the world today. In the late 1980s, Ron Pacanowski, Keith Dixon, and Tony Rosati at GFDL rewrote the code in a modular form, enabling different options and configurations to be more easily generated and new physical parameterizations to be more easily included. This version became known as Modular Ocean Model v1.0 (MOM1). Subsequent development of the code by Pacanowski, Stephen Griffies and Matt Harrison at GFDL with considerable input from a scientific community of hundreds of users has resulted in significant evolution of the code up to the current version, designated MOM4. The development effort is currently headed by Stephen Griffies.

MOM has traditionally been a level-coordinate ocean model, in which the ocean is divided into boxes whose bottoms are located at fixed depths. Such a representation makes it easy to solve the momentum equations and the well-mixed, weakly stratified layer known as the ocean mixed layer near the ocean surface. However, level coordinate models have problems when it comes to the representation of thin bottom boundary layers (Winton et al., 1998) and thick sea ice. Additionally, because mixing in the ocean interior is largely along lines of constant potential density rather than along lines of constant depth, mixing must be rotated relative to the coordinate grid- a process that can be computationally expensive. By contrast, in codes which represent the ocean in terms of constant-density layers (which represent the flow in the ocean interior much more faithfully)- representation of the ocean mixed layer becomes a challenge.

MOM4 is used as a code base for the ocean component of the GFDL coupled models used in the IPCC assessment reports, including the GFDL CM2.X model series. Earlier versions have been used in hundreds of scientific papers by authors around the world. MOM3 is used as the basis for the El Nino prediction system employed by the National Centers for Environmental Prediction.

See also

• Geophysical Fluid Dynamics Laboratory

External links

• http://www.gfdl.noaa.gov/~lat/webpages/om/om_webpage.html
• http://www.gfdl.noaa.gov/~smg/pointers/geo_physics_abstracts/guide.pdf For a detailed guide to the codes and parameterizations of subgridscale processes.