Modeling of Transport in the Two-Dimensional Atmospheric Transport and Kinetics Codes SPHERNEW and TRACER.

摘要

The report describes how transport by the wind is modeled in the 2-D atmospheric transport and chemical kinetics codes SPHERNEW and TRACER. The description includes the equations for transport by a specified velocity field,the eddy diffusion approximation for short-term fluctuations in the velocity,other simplifying approximations,the geometric grid,the difference equations,and the coefficient matrix of the grid. The assumption of a constant vertical density distribution was used to derive mass-consistent forms of the difference equations. These forms eliminate the instabilities and unrealistic solutions associated with specified wind fields which are not exactly mass-consistent. An option is allowed for variable weighting between central (second-order) and upstream (first-order) forms of the spatial differencing of the advection terms,to modulate phase and amplitude errors in the advection model. (ERA citation 02:005659)