A heat engine based moist convection parametrization for Jupiter

We have developed a parametrization of Jovian moist convection based on a heat engine model of moist convection. In comparison to other moist convection schemes, this framework allows the computation of the total available convective energy TCAPE and the corresponding mass flux M as dynamic variables from the mean atmospheric state. The effects of this parametrization have been investigated both analytically and numerically. In agreement with previous numerical experiments and observations, the inclusion of moist convection leads to heat and water vapor transport from the water condensation level into higher altitudes. The time development of the modeled convective events was found to be strongly influenced by a rapid reduction of kinetic energy and a subsequent lowering of the cumulus tower's top in response to convective heating. We have tested the sensitivity of the scheme to different variations in the fractional cloud coverage and under the inclusion of external radiative forcing towards a stable/unstable temperature profile. While the time development of convective events differs in response to these variations, the general moist convective heating and moistening of the upper troposphere was a robust feature observed in all experiments. © 2009 Elsevier Ltd

Applications of electrified dust and dust devil electrodynamics to Martian atmospheric electricity

Atmospheric transport and suspension of dust frequently brings electrification, which may be substantial. Electric fields of 10 kV m−1 to 100 kV m−1 have been observed at the surface beneath suspended dust in the terrestrial atmosphere, and some electrification has been observed to persist in dust at levels to 5 km, as well as in volcanic plumes. The interaction between individual particles which causes the electrification is incompletely understood, and multiple processes are thought to be acting. A variation in particle charge with particle size, and the effect of gravitational separation explains to, some extent, the charge structures observed in terrestrial dust storms. More extensive flow-based modelling demonstrates that bulk electric fields in excess of 10 kV m−1 can be obtained rapidly (in less than 10 s) from rotating dust systems (dust devils) and that terrestrial breakdown fields can be obtained. Modelled profiles of electrical conductivity in the Martian atmosphere suggest the possibility of dust electrification, and dust devils have been suggested as a mechanism of charge separation able to maintain current flow between one region of the atmosphere and another, through a global circuit. Fundamental new understanding of Martian atmospheric electricity will result from the ExoMars mission, which carries the DREAMS (Dust characterization, Risk Assessment, and Environment Analyser on the Martian Surface)—MicroARES (Atmospheric Radiation and Electricity Sensor) instrumentation to Mars in 2016 for the first in situ electrical measurements

Extremely Low Frequency Electromagnetic Investigation on Mars

Natural electromagnetic (EM) signals of extremely low frequencies (ELF, 3 Hz-3 kHz) can be used to study many of the electromagnetic processes and properties occurring in the Martian environment. Sources of these signals, related to electrical activity in the atmosphere, are very significant since they can influence radio wave propagation on the planet, the atmospheric composition, and the ionospheric structure. In addition, such EM signals can be employed in many purposes such as: surveying the subsurface of Mars or studying the impact of the space weather on the Martian ionosphere. As ELF waves propagate on very long distances, it is possible to explore properties of the entire planet using single-station recordings. In this study, we propose an experiment that allows measuring ELF signals from the Martian surface. Such measurements can be used for detection of electric discharges in the atmosphere and water reservoirs in the planetary subsurface