Date

January 1994

Document Type

Dissertation

Degree Name

Ph.D.

Department

Dept. of Atmospheric Physics

Institution

Oregon Graduate Institute of Science & Technology

Abstract

The two-dimensional statistical dynamical climate model that has recently been developed at the Global Change Research Center and the Oregon Graduate Institute of Science & Technology (GCRC 2D climate model) is presented and several new results obtained using the model are discussed. The model solves the 2-D primitive equations in finite difference form (mass continuity, Newton's second law, and the first law of thermodynamics) for the prognostic variables zonal mean density, zonal mean zonal velocity, zonal mean meridional velocity, and zonal mean temperature on a grid that has 18 nodes in latitude and 9 vertical nodes (plus the surface). The equation of state, p =ρRT and an assumed hydrostatic atmosphere, Δp =-ρgΔz, are used to diagnostically calculate the zonal mean pressure and vertical velocity for each grid node, and the moisture balance equation is used to estimate the precipitation rate. The performance of the model at simulating the two-dimensional temperature, zonal winds, and mass stream function is explored. The strengths and weaknesses of the model are highlighted and suggestions for future model improvements are given. The parameterization of the transient eddy fluxes of heat and momentum developed by Stone and Yao (1987 and 1990) are used with small modifications. These modifications are shown to help the performance of the model at simulating the observed climate system as well as increase the model's computational stability. Following earlier work that analyzed the response of the zonal wind fields predicted by three GCM simulations for a doubling of atmospheric CO2, the response of the GCRC 2D model's zonal wind fields is also explored for the same experiment. Unlike the GCM simulations, our 2D model results in distinct patterns of change. It is suggested that the observed changes in zonal winds for the 2xCO2 experiment are related to the increase in the upper level temperature gradients predicted by our model and most climate models of adequate sophistication and resolution. We thus suggest that the same mechanism controlling the changes in zonal winds for the 2xCO2 experiment in our model also contributes to the simulated changes in zonal winds of the more complex GCMs.

Identifier

doi:10.6083/M4R49NR5

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