The physics of Martian weather and climate: a review

Abstract

The planet Mars hosts an atmosphere that is perhaps the closest in terms of its meteorology and climate to that of the Earth. But Mars differs from Earth in its greater distance from the Sun, its smaller size, its lack of liquid oceans and its thinner atmosphere, composed mainly of CO 2 . These factors give Mars a rather different climate to that of the Earth. In this article we review various aspects of the martian climate system from a physicist's viewpoint, focusing on the processes that control the martian environment and comparing these with corresponding processes on Earth. These include the radiative and thermodynamical processes that determine the surface temperature and vertical structure of the atmosphere, the fluid dynamics of its atmospheric motions, and the key cycles of mineral dust and volatile transport. In many ways, the climate of Mars is as complicated and diverse as that of the Earth, with complex nonlinear feedbacks that affect its response to variations in external forcing. Recent work has shown that the martian climate is anything but static, but is almost certainly in a continual state of transient response to slowly varying insolation associated with cyclic variations in its orbit and rotation. We conclude with a discussion of the physical processes underlying these longterm climate variations on Mars, and an overview of some of the most intriguing outstanding problems that should be a focus for future observational and theoretical studies.

An Axisymmetric Limit for the Width of the Hadley Cell on Planets With Large Obliquity and Long Seasonality

“…Our solar system terrestrial atmospheres are a good example for a variety of circulations, due to their large variability in planetary characteristics. Of particular interest is the seasonality on Mars and Titan, both exhibiting a different circulation response to the seasonally varying surface temperature (Mitchell & Lora, ; Read et al, ). During the Martian solstice, maximum surface temperature is at the pole; however, the Hadley cell ascending branch is located at midlatitudes (Read et al, ), consistent with the axisymmetric theory using Mars' R t (red dotted line in Figure a).…”

“…The choice of parameter values here is guided by the observed values in the solar system. Δ H , the normalized horizontal temperature difference, gets its largest value for Mars (∼0.4, e.g., Read et al, ), and lowest value for Venus (with nearly zero temperature gradient, e.g., Read, ). The tropopause height, H , taken to be the circulation height scale (Walker & Schneider, ) is highest on Titan and Mars reaching to ∼20 km (e.g.…”

“…The tropopause height, H , taken to be the circulation height scale (Walker & Schneider, ) is highest on Titan and Mars reaching to ∼20 km (e.g. Lora et al, ; Read et al, ).…”

“…The strong seasonality on Mars is due to its thin atmosphere and rocky surface resulting in a low thermal inertia and a short radiative timescale. Mars' Hadley circulation transits from two hemispherically symmetric cells at equinox, to one solstice cell, with air rising at midlatitudes (Read et al, ). Thus, although at solstice, Mars' maximum surface temperature is at the pole, the Hadley cell ascending branch does not reach the pole.…”

State of the Climate in 2016

“…In terms of its atmosphere and climate, Mars is the planet in the solar system most similar to Earth (e.g., Read and Lewis 2004;Read et al 2015). With roughly half the radius of Earth (3396 km compared to 6371 km), Mars has around the same land surface area as Earth.…”