Stability of Semi-implicit Atmospheric Models with Respect to the Reference Temperature Profile

摘要

The dependence of the linear stability of two-time-level semi-implicit schemes on choice of the reference temperature profile is studied. Analysis is made for large time steps, keeping general form of such model parameters as the number of vertical levels, their distribution, and the values of the viscosity coefficients. The obtained results reveal more restrictive conditions on the reference temperature profile than those for three-time-level schemes. Nevertheless, general conclusions are consistent with the previous analysis: instability generated by inappropriate choice of the temperature profile is absolute and the scheme stability can be recovered by setting the reference temperature to be warmer than the actual one.