Neutral Atmospheres

Mueller-Wodarg, Ingo; Strobel, D. F.; Moses, J. I.; Waite, J. H.; Crovisier, J.; Yelle, R. V.; Bougher, S. W.; Roble, R. G.

doi:10.1007/s11214-008-9404-6

Cited by 34 publications

(24 citation statements)

References 235 publications

(239 reference statements)

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“…For mid-tolate L dwarfs, CH 4 absorption can remain observable near 3.3 µm for higher temperatures (Noll et al 2000;Stephens et al 2009). As the temperature drops, CH 4 absorption remains dominant in the spectra of Y dwarfs arXiv:2001.05037v1 [astro-ph.EP] 14 Jan 2020 (Cushing et al 2011;Kirkpatrick et al 2012) and is also present in the atmospheres of the giant planets (Irwin et al 2005;Mueller-Wodarg et al 2008) and Titan (Karkoschka 1994;Atreya et al 2006).…”

Section: Introductionmentioning

confidence: 99%

An Accurate, Extensive, and Practical Line List of Methane for the HITEMP Database

Hargreaves¹,

Gordon²,

Rey

et al. 2020

ApJS

152

102

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A methane line list for the HITEMP spectroscopic database, covering 0-13,400 cm −1 (>746 nm), is presented. To create this compilation, ab initio line lists of 12 CH 4 from Rey et al. (2017) ApJ, 847, 105 (provided at separate temperatures in the TheoReTS information system), are now combined with HITRAN2016 methane data to produce a single line list suitable for high-temperature line-byline calculations up to 2000 K. An effective-temperature interpolation model was created in order to represent continuum-like features at any temperature of interest. This model is advantageous to previously-used approaches that employ so-called "super-lines", which are suitable only at a given temperature and require separate line lists for different temperatures. The resultant HITEMP line list contains ∼32 million lines and is significantly more flexible than alternative line lists of methane, while accuracy required for astrophysical or combustion applications is retained. Comparisons against experimental observations of methane absorption at high temperatures have been used to demonstrate the accuracy of the new work. The line list includes both strong lines and quasi-continuum features and is provided in the common user-friendly HITRAN/HITEMP format, making it the most practical methane line list for radiative transfer modeling at high-temperature conditions.

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Section: Introductionmentioning

confidence: 99%

An Accurate, Extensive, and Practical Line List of Methane for the HITEMP Database

Hargreaves¹,

Gordon²,

Rey

et al. 2020

ApJS

152

102

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“…Prior to MAVEN (the Mars Atmosphere and Volatile Evolution Mission), the Martian upper atmosphere thermal structure (both dayside and nightside) was poorly constrained by a limited number of both in situ and remote sensing measurements at diverse locations, seasons, and periods scattered throughout the solar cycle (see reviews by Stewart [], Bougher et al [], Mueller‐Wodarg et al [], and Bougher et al []). The vertical thermal structure of the upper atmosphere has been sampled many times but only in specific latitude and local time zones and mostly during solar minimum to moderate conditions [ Bougher et al , ].…”

Section: Introductionmentioning

confidence: 99%

The structure and variability of Mars dayside thermosphere from MAVEN NGIMS and IUVS measurements: Seasonal and solar activity trends in scale heights and temperatures

et al. 2017

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Mars dayside thermospheric temperature and scale height trends were examined using measurements from the Neutral Gas Ion Mass Spectrometer (NGIMS) and the Imaging Ultraviolet Spectrograph (IUVS) on the Mars Atmosphere Volatile EvolutioN (MAVEN) spacecraft. Average scale heights (over 150–180 km for solar zenith angles ≤75°) from several different sampling periods were obtained from each instrument. NGIMS and IUVS scale height trends were found to be in good agreement, with both showing scale heights decreasing after perihelion and reaching a low value near aphelion (13.6 to 9.4 km). Between these two seasonal extremes, the temperature decreased by ∼70 K (from 240 to 170 K). These trends were also analyzed with respect to the changing solar flux reaching the planet, using the Lyman alpha irradiance measured by the Extreme Ultraviolet Monitor (EUVM) on MAVEN. Scale heights responded strongly to the changing solar flux. During this part of the MAVEN mission (October 2014 to May 2016), it was concluded that over longer timescales (at least several months), dayside thermospheric temperatures are chiefly driven by changing solar forcing, although it is the effects of changing heliocentric distance rather than changing solar activity which seem to have the greatest impact. Furthermore, effects of solar forcing were not observed on shorter timescales (less than a month), suggesting local wave effects may dominate solar forcing on these timescales. Finally, temperatures from two NGIMS sampling periods were compared to temperatures from the Mars Global Ionosphere‐Thermosphere Model (M‐GITM) and found to be in good agreement.

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“…Section 3 will discuss the corresponding MAVEN measurements to be obtained and their application to these problems. Presently, the Martian upper atmosphere thermal structure is poorly constrained by a limited number of both in-situ and remote sensing measurements at selected locations, seasons, and periods scattered throughout the solar cycle (see reviews by Stewart 1987;Bougher 1995;Bougher et al 2000Müeller-Wodarg et al 2008). In particular, the vertical thermal structure of the upper atmosphere has been sampled many times, but only in limited latitude/local time zones, and mostly during solar minimum to moderate conditions (see review by .…”

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confidence: 99%

The Aeronomy of Mars: Characterization by MAVEN of the Upper Atmosphere Reservoir That Regulates Volatile Escape

et al. 2014

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The Mars thermosphere-ionosphere-exosphere (TIE) system constitutes the atmospheric reservoir (i.e. available cold and hot planetary neutral and thermal ion species) that regulates present day escape processes from the planet. The characterization of this TIE system, including its spatial and temporal (e.g., solar cycle, seasonal, diurnal, episodic) variability is needed to determine present day escape rates. Without knowledge of the physics and chemistry creating this TIE region and driving its variations, it is not possible to constrain either the short term or long term histories of atmosphere escape from Mars. MAVEN (Mars Atmosphere and Volatile Evolution Mission) will make both in-situ and remote measurements of the state variables of the Martian TIE system. A full characterization of the thermosphere (∼100-250 km) and ionosphere (∼100-400 km) structure (and its variability) will be conducted with the collection of spacecraft in-situ measurements that systematically span most local times and latitudes, over a regular sampling of Mars seasons, and throughout the bottom half of the solar cycle. Such sampling will far surpass that available from existing spacecraft and ground-based datasets. In addition, remote measurements will provide a systematic mapping of the composition and structure of Mars neutral upper atmosphere and coronae (e.g. H, C, N, O), as well as probe lower altitudes. Such a detailed characterization is a necessary first step toward answering MAVEN's three main science questions (see Jakosky et al. 2014, this issue). This information will be used to determine present day escape rates from Mars, and provide an estimate of integrated loss to space throughout Mars history.

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Neutral Atmospheres

Cited by 34 publications

References 235 publications

An Accurate, Extensive, and Practical Line List of Methane for the HITEMP Database

An Accurate, Extensive, and Practical Line List of Methane for the HITEMP Database

The structure and variability of Mars dayside thermosphere from MAVEN NGIMS and IUVS measurements: Seasonal and solar activity trends in scale heights and temperatures

The Aeronomy of Mars: Characterization by MAVEN of the Upper Atmosphere Reservoir That Regulates Volatile Escape

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