The Ocean-Land-Atmosphere Model (OLAM). Part I: Shallow-water tests

Robert L. Walko, Roni Avissar

Research output: Contribution to journalArticlepeer-review


The Ocean-Land-Atmosphere Model (OLAM) has been developed to extend the capabilities of the Regional Atmospheric Modeling System (RAMS) to a global model domain. OLAM adopts many features of its predecessor, including physical parameterizations, initialization methods, data assimilation, logic and coding structure, and I/O formats. However, its dynamic core is new and is based on a global geodesic grid with triangular mesh cells and a finite-volume discretization of the full compressible Navier-Stokes equations. Local mesh refinement can be activated in OLAM to cover selected geographic areas at very high resolution and hence to simulate atmospheric systems typically studied in regional models. This paper is one in a series whose purpose is to describe the formulation of OLAM and to validate the model's performance through test results. This paper focuses on global-scale dynamics that can be represented by the shallow-water equations, and provides details of the spatial and temporal discretizations, which contain some unique algorithms that previously have not been applied to atmospheric models. Validation tests are performed using five standard shallow-water simulations that are commonly used benchmarks for global models. OLAM results for all tests are comparable to results from other global models.

Original languageEnglish (US)
Pages (from-to)4033-4044
Number of pages12
JournalMonthly Weather Review
Issue number11
StatePublished - 2008
Externally publishedYes

ASJC Scopus subject areas

  • Atmospheric Science


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