Derivation of Martian Meteorological Parameters Using Ground-Based Telescopes and Forward-Modelling
- Paper number
IAC-06-A3.P.3.04
- Author
Mr. Andrew Simpson, Macquarie University, Australia
- Coauthor
Dr. Jeremy Bailey, Australia
- Coauthor
Ms. Sarah Chamberlain, Australia
- Coauthor
Dr. David Crisp, United States
- Coauthor
Prof. Malcolm Walter, Australia
- Year
2006
- Abstract
Despite the increasing number of spacecraft sent to Mars in recent times, many Martian atmospheric properties remain relatively unconstrained [1]. Indeed, the Martian surface pressure has only been continuously monitored at a total of three locations [2,3]. A more complete set of meteorological data is important both for the characterisation of the atmosphere and as input for GCMs used in the prediction of atmospheric parameters for future Mars missions.
Near-infrared spectroscopy provides a method of obtaining much information about the atmospheric state of a planet. In the 1-2.5 µm region spectral lines of CO 2, H 2O, CO, O 2, O 3 and many others are present to varying degrees. These spectral lines give information not only about the composition of the atmosphere but also about its temperature and pressure via spectral band shapes. Many aerosols, such as Martian dust, also strongly influence the radiative output of Mars in this region.
Their lower spatial resolution notwithstanding, ground-based observations offer a number of advantages over orbital observations. The large distance from Earth allows the atmospheric state of an entire Martian hemisphere to be characterised using a single set of spectra. Observations can also be obtained at significantly higher spectral resolution than is currently possible with instruments like PFS [4].
With this in mind, we obtained spectra of Mars around the 1.6 and 2.0 µm CO 2 bands using two separate instruments, CSHELL on NASA IRTF (at R∼ 30000) and GNIRS on Gemini South (at R∼ 18000), during the period October-December 2005. To reduce the data we have not adopted the traditional ’standard star’ approach but rather made use of a forward-modelling algorithm to iteratively match simulated spectra generated using SMART [5] and VSTAR [6] to our observations. The meteorological parameters of our ’best fit’ model are then a close match for the parameters of our observation.
Initial simulations suggest that our modelled spectra closely match observations and single-variable (pressure) matching converges in around 10 passes. We will present the first results of a multivariate implementation of the matching algorithm incorporating surface temperature, pressure and dust opacity.
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Golombek, M. P. et al. 1999, J. Geophys. Res., 104, E4, 8523
Formisano, V. et al. 2005, Planetary & Space Sci., 53, 10, 963
Meadows, V. S., Crisp, D. 1996, J. Geophys. Res., 101, E2, 4595
Bailey, J. 2006, Proc. Mars Atmosphere Workshop (Granada)
- Abstract document
- Manuscript document
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