Investigating post-impact climate scenarios for early Mars with a 3D GCM
Abstract
The nature of the early martian climate has been long debated within the Mars community, with observations of valley networks implying a late Noachian/early Hesperian climate with extended periods of above-freezing temperatures and possibly recurring precipitation (Fassett & Head 2008, Icarus 195, 61; Hynek et al., 2010, JGR Planets, 115, E09008), while climate models produce cold and icy versions of early Mars (Forget et al., 2013, Icarus 21, 81). Volcanism and impacts have been proposed as mechanisms to introduce greenhouse gases and energy that might produce global warm and wet conditions or cause local melting in an otherwise cold and icy environment. Segura et al. (2008, JGR Planets 113, E11007) find using a 1-D atmospheric model that significant rainfall and periods of above-freezing temperatures lasting months to years can follow impacts from objects between 30 and 100 km in diameter. We use the NASA ARC Mars Global Climate Model (GCM) to expand on this work and investigate the possibility of globally increasing surface temperatures and inducing rainfall following large impacts, now considering the global effects of dynamics, topography, etc. The kinetic energy from a large impact can raise surface and atmospheric temperatures as hot rock vaporized or melted on impact is transported globally (Segura et al., 2008, JGR Planets 113, E11007). Water vapor is also injected into the atmosphere both from the impactor itself and from subsurface ice that is vaporized and excavated during crater formation (Segura et al., 2008, JGR Planets 113, E11007). Simple scaling relations are used to predict the quantities of water and energy deposited into the atmosphere following impacts from objects 30 to 100 km in size that are 12.5% water by volume and traveling at 8 km/s on impact. We present preliminary 3D GCM results of the effects of these post-impact conditions on early Mars climate scenarios.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.P21C2133S
- Keywords:
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- 6225 Mars;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTSDE: 5405 Atmospheres;
- PLANETARY SCIENCES: SOLID SURFACE PLANETSDE: 5419 Hydrology and fluvial processes;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS