A study on parallel performance of the EULAG f90/95 code

The paper presents several aspects of the computational performance of the EULAG F90/95 code, originally written in Fortran 77. EULAG is a well-established research fluid solver characterized by robust numerics. It is suitable for a wide range of scales of the geophysical flows and is considered as a prospective dynamical core of a future weather forecast model of the COSMO consortium. The code parallelization is based on Message Passing Interface (MPI) communication protocol. In the paper, the numerical model's parallel performance is examined using an idealized test case that involves a warm precipitating thermal developing over an undulated terrain. Also the efficiency of the basic code structures/subroutines is tested separately. It includes advection, elliptic pressure solver, preconditioner, Laplace equation solver and moist thermodynamics. In addition, the effects of horizontal domain decomposition and of the choice of machine precision on the computational efficiency are analyzed.