A. Männik, R. Rõõm
Abstract
The paper describes the numerical
model of atmospheric dynamics, designed as the
nonhydrostatic extension to the hydrostatic kernel of HIRLA.
The theoretical concept, initiated in Part I, is brought to
numerical codes.
The anelastic hybrid-coordinate model is formulated
both in the continuous and discrete representations, and the
numerical code with the explicit-Eulerian time stepping scheme
is implemented in the HIRLA environment.
In the development of numerical code, the
main attention is paid to the creation of
the elliptic solver for the baric geopotential equation.
For this, an orthogonal basis is applied in all three coordinates,
including the vertical hybrid coordinate.
The nonhomogeneous boundary conditions are
handled by introduction of singular sources on lateral and
bottom boundaries.
The paper ends with numerical examples, demonstrating the capabilities of
the model. The maximum horizontal resolution of the model is
approximately 0.5 km. Due to the application of surface pressure adjustment,
the accessible time step is rather large
(60 s at the 11 km, 40-50 s at the 2.2 km,
and 20-30 s at the 1 km resolution)
and makes the model applicable in high-resolution simulations.