الفهرس 
Studying of Vertical Motion Modeling and The Simulation ImprovementsOnly 14 pages are availabe for public view
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Abstract
Department An empirical modification of the barotropic dynamics
framework is attempted in this work. Using the conservation of potential vorticity, we construct
generalized spectral barotropic operators that apply at a single isentropic level. An effective
squared wavenumber is calculated by performing linear regression of each spherical harmonic
component of potential vorticity against the corresponding component of streamfunction.
Four types of predictability experiments with different types of initial and boundary conditions
were verified against model data and reanalysis to determine perfect as well as real world forecast
skill. Spatial maps and vertical cross sections of predictability at different lead times were
analyzed to document the varying influence of initial and boundary conditions on predictability. It
was found that the atmosphere was remarkably sensitive to initial conditions on the week 3-6
forecast range. Particularly, the troposphere over Antarctica, the region over the tropical Indian
Ocean, and the lower stratosphere were affected.
The generalized model is scrutinized in terms of its normal, optimal and singular modes. It is
found that the empirically modified models are more stable than the ones of the barotropic model.
In addition, their optimal modes are more difficult to excite. The singular modes of the modified
operator have very similar patterns but explain less variance than the barotropic ones. This is
consistent with the difficulty in detecting optimal patterns in observations.
We also perform initial value calculations, where ten-day forecasts are made with the model
initialized with low-frequency anomalies. The empirical model shows improvement in the skill with
respect to the barotropic model. Additionally, one- day forecasts are computed for the generalized
and barotropic models. The empirically modified model shows a much closer resemblance to the
observed streamfunction tendency than the barotropic one .