The General Circulation of Mars: Models and Observations

Leovy, Conway Β.

doi:10.1016/s0065-2687(08)60229-0

Cited by 28 publications

(20 citation statements)

References 64 publications

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“…(iv) is the martian mid-latitude circulation consistent with a low-dimensional attractor? Leovy (1981aLeovy ( , 1985 suggested that, by analogy with rotating annulus laboratory experiments (Hide and Mason 1975), the greater atmospheric stability and smaller size of Mars might cause its transient baroclinic waves to be far more regular than those on Earth. Such regular, steady and stable traveling wave patterns are frequently observed in rotating annulus experiments under conditions for which the Rossby deformation radius is comparable in scale to the width of the annular channel, for wavenumbers smaller than a limiting value determined by the ratio (b/a) of the outer radius (b) to the inner radius (a) of the annulus itself (Hide and Mason 1975).…”

Section: Regular or Chaotic Waves And Nonlinearity?mentioning

confidence: 99%

The physics of Martian weather and climate: a review

2015

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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.

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Section: Regular or Chaotic Waves And Nonlinearity?mentioning

confidence: 99%

The physics of Martian weather and climate: a review

2015

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“…These include latitudinally averaged seasonal temperature variations [Leovy, 1982[Leovy, , 1985, the global atmospheric circulation [Leovy et al, 1972], medium-and small-scale weather events such as local dust storms Peterfreund and Kieffer, 1979;James and Evans, 1981;Peterfreund, 1985;Kahn et al, 1992], dust devils [Thomas and Gierasch, 1985], clouds that resemble terrestrial extratropical cyclones, and ''polar lows'' [Briggs and Leovy, 1973;Hunt and James, 1979]. The temporal and spatial coverage by these spacecraft were very limited, making regional and local interannual comparisons of weather phenomena nearly impossible.…”

Section: Introductionmentioning

confidence: 99%

Multiyear Mars Orbiter Camera (MOC) observations of repeated Martian weather phenomena during the northern summer season

2002

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[1] The Mars Global Surveyor Mars Orbiter Camera (MGS MOC) has observed several atmospheric events repeat within a few degrees of L s from one year to the next over 3 Mars years during a portion of the northern summer, southern winter seasons (L s = 124°-140°). The repeatability suggests a previously unobserved lack of significant variation in the present Martian northern summer seasonal climate. Nonetheless, interannual variations in the seasonal south polar cap and in the residual north polar cap were observed. These appear to have had a negligible effect in perturbing Mars' weather during the northern summer season.

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“…The 15-µm channel is of particular interest for atmospheric studies as it was designed to retrieve brightness temperatures (T 15 ) in a deep layer of atmosphere centered at roughly 0.5 mb, corresponding to an elevation of 25 km for typical Mars temperatures. The T 15 data have shown a significant seasonal modulation of global mean temperature (Leovy 1985 that is evidently the result of a large seasonal variation in atmospheric dust loading (Zurek et al 1992). The influence of aerosol heating is particularly evident in the rapid increases in global T 15 temperatures following the onset of each of the two 1977 global dust storms.…”

Section: Introductionmentioning

confidence: 99%

The Martian Atmosphere During the Viking Mission, I Infrared Measurements of Atmospheric Temperatures Revisited

Wilson¹

2000

Icarus

112

135

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The Viking Infrared Thermal Mapper 15-µm channel brightness temperature observations (IRTM T 15 ) provide extensive spatial and temporal coverage of martian atmospheric temperatures on diurnal to seasonal time scales. The 15-µm channel was designed so that these temperatures would be representative of a deep layer of atmosphere centered at 0.5 mb (∼25 km). Our re-examination of the IRTM data indicates that the 15-µm channel was additionally sensitive to surface radiance so that air temperature determinations (nominal T 15 ) are significantly biased when the thermal contrast between the surface and atmosphere is large. This bias is suggested by the strong correlation between the diurnal variation of tropical T 15 and surface temperatures for non-dust-storm conditions. We show that numerical modeling of the thermal tides provides a basis for distinguishing between the surface and atmospheric contributions to IRTM T 15 and thus allows the atmospheric component to be estimated. The resulting bias amounts to a ∼15-K offset for midday atmospheric temperatures at subsolar latitudes during relatively clear periods and is negligible at night. The proposed temperature correction results in close agreement between the stimulated and observed patterns of diurnal variation for conditions ranging from clear to dusty.A major consequence of this work is the improved definition of the diurnal, latitudinal, and seasonal variation of martian atmosphere temperatures during the Viking mission. An accounting for the surface temperature bias resolves much of the discrepancy between IRTM and corresponding microwave observations, indicating that there is relatively little interannual variability in global temperatures during the aphelion season (L s ∼ 40• -100 • ). We find further support for this argument in a comparison with T 15 temperatures synthesized from Mariner 9 Infrared Interferometer Spectrometer spectra. The significantly reduced diurnal temperature variations in this season are consistent with the relatively clear atmosphere that is implied by the cooler temperatures. Cooler temperatures and reduced diurnal variation will likely be of significance for the modeling of water ice cloud dynamics in this season.

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The General Circulation of Mars: Models and Observations

Cited by 28 publications

References 64 publications

The physics of Martian weather and climate: a review

The physics of Martian weather and climate: a review

Multiyear Mars Orbiter Camera (MOC) observations of repeated Martian weather phenomena during the northern summer season

The Martian Atmosphere During the Viking Mission, I Infrared Measurements of Atmospheric Temperatures Revisited

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