In order to thoroughly eliminate noise in the upper layers,
Rayleigh friction and Newtonian cooling type smoothing are
included in the top seven layers. Specifically, the terms
and are added to the x and ycomponents of the
equations of motion, respectively, and the term is
added to the equation of temperature. Here,
and
represent the relaxation time for damping and smoothing,
respectively, and are functions of height. represents zonal
mean temperature. The values of andin Table 1 are
used for calculations. The values of
and
adopted for the uppermost layer, which is 3 hours, are based on
the SKYHI general circulation model of Geophysical Fluid
Dynamics Laboratory (Manzini and Hamilton, 1993). Furthermore,
the choice of the number of layers into which the Rayleigh
friction and Newtonian cooling type smoothing are incorporated
is based on the results from a number of test experiments. If
the upper damping layer consists of only five layers,
integration over a long time period becomes infeasible for the
case of S = 1800 W/m^{2}.

verical level   τ_{m}, τ_{H} 
k = 32   10800 
k = 31   21600 
k = 30   32400 
k = 29   43200 
k = 28   54000 
k = 27   64800 
k = 26   75600 
Table 1: Relaxation time for the upper damping
layer. k = 32 indicates the uppermost layer. The
relaxation time for this layer is 3 hours. 