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| Titel |
Modeling Early Mars Climate |
| VerfasserIn |
Nataly Ozak, Itay Halevy, Oded Aharonson |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250080118
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| Zusammenfassung |
| Mars is presently cold and dry but geomorphological, sedimentary and mineralogical
observations indicate the presence of liquid water on its surface [Baker, 2001; Squyres et al.,
2004; Poulet et al., 2005]. Taking into account the expected dimmer early sun, an optically
thick atmospheric greenhouse is required to reach a thermal balance optimal for the
existence of liquid water on Mars. Infrared scattering by CO2 clouds [Kasting, 1991],
compensates for their shortwave cooling effect [Forget and Pierrehumbert, 1997] but
a variety of climate models, from simple one-dimensional radiative-convective
columns to full global circulation models, still require several bars of CO2 to reach
near-melting conditions [Forget et al., 2012; Wordsworth et al., 2012]. Yung et al.
[1997] suggested that trace amounts of volcanically emitted SO2 would inhibit CO2
condensation, allowing a surface temperature increase capable of supporting liquid
water. Halevy et al. [2007] modeled the coupled sulfur and carbon cycles to explore
the effects of ppb to ppm levels of SO2 on the climate and surface chemistry of
early Mars. Subsequent global climate model simulations [Johnson et al., 2008]
support the suggestion that strong greenhouse warming by SO2 increased early
surface temperatures. In addition to gases, the effect of various aerosols, such as
mineral dust, organic hazes and sulfur-bearing particles, remains unexplored. We have
developed a rapid 1-D radiative transfer code using correlated-k distributions of
gaseous absorption, instead of a computationally demanding line-by-line model.
The radiative transfer backbone of the model is based on the line-by-line model
of Halevy et al. [2009], as well as the high-resolution absorption spectra used to
generate the k-coefficients required for the new, efficient model. The model allows
calculation of simultaneous absorption and multiple-scattering at all wavelengths and is,
therefore, especially suitable for exploring the effect of atmospheric particles on the
radiative transfer. With this model we explore a range of atmospheric compositions,
which can maintain a climate capable of sustaining liquid water at the Martian
surface. We also explore the effect that mineral dust may have had in Mars’ early
climate. |
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