General Circulation and Baroclinic Waves in the Atmosphere of Zonally Uniform Earth-Like Model Planets

The boundary conditions at the Earth’s surface have a significant influence on the planetary and synoptic scale flows that form in the atmosphere. In the Earth’s real atmosphere, it is difficult to isolate and study the influence of boundary conditions, because the spatial structure of large-scale flows and their temporal variations are strongly influenced by the distribution of land and ocean, surface relief, the hydrological cycle, and other factors. It is possible to study the role of the underlying surface using idealized models of Earth-like planets. This paper presents a comparative analysis of the structure and dynamics of the atmospheric general circulation and baroclinic waves for idealized, zonally homogeneous planets. Numerical experiments are performed using the WRF-ARW software package for the built-in characteristics of the Earth’s atmosphere and the terrestrial parameters of planetary motion and insolation. Three model configurations are considered: a desert planet (DP), a desert planet with an equatorial ocean (EOP), and an aquaplanet (AP) with a fixed meridional temperature distribution. It is shown that the DP is characterized by strong seasonal variations, leading to remarkable features both in the structure of the mean general circulation and in the distribution of velocity and temperature pulsations. On an EOP, the meridional velocity and temperature pulsations are similar to those observed in the Earth’s atmosphere. They are concentrated at midlatitudes and separated by height, with the maximum of temperature pulsations in the lower part of the troposphere and the maximum of velocity in its upper part. On the AP, the temperature pulsations are significantly smaller in amplitude and shifted into the middle layers of the troposphere. Simulations have shown that, despite zonally homogeneous boundary conditions and the absence of relief, the intensity, lifetime, phase, and group velocity of the baroclinic waves vary significantly on all the model planets. On a DP and an EOP, there is a pronounced season of maximum wave activity. On the AP, there are no strong seasonal variations, but long intervals of westward blocking are observed. The spectral composition of the baroclinic waves and their seasonal variability have been analyzed.