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On the Importance of Low-Frequency Gravity Modes for the Evolution of Large-Scale Flow in a General Circulation Model
Publisher: American Meteorological Society
Abstract: The impact of low-frequency baroclinic gravity modes on the tropical and extratropical circulation has been studied in a global spectral model. The procedure used was to filter out these gravity modes at every time step ...
Modeling Studies on the Australian Summer Monsoon
Publisher: American Meteorological Society
Abstract: The ability of the Bureau of Meteorology Research Centre global spectral model to simulate features of the Australian summer monsoon during January and February 1987 has been studied. Two timescales were considered: namely, ...
Extended-Range Forecasts for the Southern Hemisphere with the ANMRC Spectral Model
Publisher: American Meteorological Society
Abstract: A series of twelve 4-day forecasts for the Southern Hemisphere was made, including both summer and winter cases using a hemispheric spectral model. The model had a resolution of wavenumber 31 in the horizontal and nine ...
Sensitivity of Low-Latitude Velocity Potential Field in a Numerical Weather Prediction Model to Initial Conditions, Initialization and Physical Processes
Publisher: American Meteorological Society
Abstract: It is shown that the tropical divergent circulation in the nine-level Geophysical Fluid Dynamics Laboratory (GFDL) spectra model is dominated by the lowest frequency gravity modes for vertical mode 4. The importance of ...
Local Geostrophic Wind Correction in the Assimilation of Height Data and its Relationships to the Slow Manifold
Publisher: American Meteorological Society
Abstract: Experiments with insertion of height data in a free surface spectral model were conducted to explain the effectiveness of local geostrophic correction of the wind field in accelerating the assimilation of the height data ...
The Relationship Between Convective Adjustment Hadley Circulation and Normal Modes of the ANMRC Spectral Model
Publisher: American Meteorological Society
Abstract: By expanding model forecasts with and without convection in terms of three-dimensional normal mode functions it is shown that convective adjustment mainly influences gravity modes for vertical mode 4 of the nine-level ANMRC ...
Some Experiments on the Use of Tropical Diabatic Heating Information for Initial State Specification
Publisher: American Meteorological Society
Abstract: The local response to tropical diabatic heating is studied by using diabatic normal mode initialization procedures. It is shown that diabatic initialization is able to produce a well-balanced state in regions of heating ...
Implications of Horizontal Resolution in Spectral Model Integrations
Publisher: American Meteorological Society
Abstract: Free surface and non-divergent spectral models have been integrated using varying resolutions with both analytic and meteorological initial fields. The results have been interpreted in terms of convergence of solutions. ...
Spectral Representation of Three-Dimensional Global Data by Expansion in Normal Mode Functions
Publisher: American Meteorological Society
Abstract: To represent atmospheric data spectrally in three indices (zonal wavenumber, and meridional and vertical modal indices), we propose to use three-dimensional normal mode functions (NMF's) to express the wind and mass fields ...
Use of High-Resolution Structure Functions and Modified Quality Control in the Analysis of Tropical Cyclones
Publisher: American Meteorological Society
Abstract: The sensitivity of analysis of a well-observed tropical cyclone to high-resolution structure functions and modification of the analysis scheme to accept data in the vicinity of the cyclone is studied. It is shown that these ...