Cloud Reflection Observations: Results from the Mars Orbiter Laser Altimeter

Ivanov, A. B.; Muhleman, D. O.

doi:10.1006/icar.2001.6686

Cited by 49 publications

(50 citation statements)

References 19 publications

(23 reference statements)

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“…Admittedly, the occurrence of a supersaturated region does not imply snowfall at a given time and location, but we expect that a supersaturated region is associated with snowfall nearby. The supersaturated region in Figure 2 is confined to the lowest 25 km (for an approximate altitude scale, see Figure 3 below), which is consistent with the altitude range of previous detections of CO 2 clouds [Pettengill and Ford, 2000;Ivanov and Muhleman, 2001].…”

Section: Resultssupporting

confidence: 88%

Atmospheric and surface retrievals in the Mars polar regions from the Thermal Emission Spectrometer measurements

Eluszkiewicz¹,

Moncet²,

Shephard³

et al. 2008

J. Geophys. Res.

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[1] Retrievals of atmospheric temperatures, surface emissivities, and dust opacities in the Mars polar regions from the Thermal Emission Spectrometer (TES) spectra are presented. The retrievals correspond to two types of spectra, characterized by small and large band depths BD 25 in the 25-mm band of solid CO 2 . These two types of spectra have previously been identified with locations covered by slab ice and fluffy CO 2 frost, respectively. Above the first atmospheric scale height, there is a correlation between the degree of saturation in the retrieved atmospheric temperatures and the two types of surface, with the high BD 25 spectra (''cold spots'') showing larger supersaturations around 1 mbar. This supports the hypothesis that cold spots correspond to locations with potential or actual atmospheric precipitation. Furthermore, the retrieved temperature profiles exhibit a warming above 1 mbar (15 km), which appears real even when the limited number of independent pieces of information from the measurement ($3) and coarse vertical resolution of the TES instrument above 15 km are considered. The spectral shape of the retrieved surface emissivities in the cold spot locations is consistent with modeling results attributing high BD 25 to porosity. For the low BD 25 spectra, the retrieved emissivities are spectrally flat but significantly less than unity (0.8-0.9). The cause of these spectrally uniform deviations from blackbody behavior (which are not supported by modeling) remains to be investigated, with a noticeable reduction in the deviation from the blackbody behavior achieved through a zero-radiance-level correction to the TES spectra available from the Planetary Data System.

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Section: Resultssupporting

confidence: 88%

Atmospheric and surface retrievals in the Mars polar regions from the Thermal Emission Spectrometer measurements

Eluszkiewicz¹,

Moncet²,

Shephard³

et al. 2008

J. Geophys. Res.

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“…Forget et al (1995) showed that the low emission zones observed by the infrared thermal mapper (IRTM) instrument aboard Viking (Kieffer et al, 1976) and by Mariner 9 IRIS (Paige et al, 1990), were likely due to the radiative properties of CO 2 snowfalls (falling snow particles or fresh snow deposits). CO 2 snowfall has never been directly observed on Mars, although several authors reported circumstantial evidences of a possible CO 2 snowstorm (Titus et al, 2001;Ivanov and Muhleman, 2001). Nevertheless, climate simulation with general circulation models (GCMs) showed that a fraction of the total CO 2 condensation could take place in the atmosphere, especially when it is dust laden, because of the increased atmospheric emissivity (Pollack et al, 1990).…”

Section: Co 2 Ice Clouds and Snowfalls: Theoretical Considerationsmentioning

confidence: 97%

PFS/MEX observations of the condensing CO2 south polar cap of Mars

Giuranna¹,

Grassi²,

Formisano³

et al. 2008

Icarus

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The condensing CO 2 south polar cap of Mars and the mechanisms of the CO 2 ice accumulation have been studied through the analysis of spectra acquired by the Planetary Fourier Spectrometer (PFS) during the first two years of ESA's Mars Express (MEX) mission. This dataset spans more than half a martian year, from Ls ∼ 330 • to Ls ∼ 194 • , and includes the southern fall season which is found to be extremely important for the study of the residual south polar cap asymmetry. The cap expands symmetrically and with constant speed during the fall season. The maximum extension occurs sometime in the 80 • -90 • Ls range, when the cap edges are as low as −40 • latitude. Inside Hellas and Argyre basins, frost can be stable at lower latitudes due to the higher pressure values, causing the seasonal cap to be asymmetric. Within the seasonal range considered in this paper, the cap edge recession rate is approximately half the rate at which the cap edge expanded. The longitudinal asymmetries reduce during the cap retreat, and disappear around Ls ∼ 145 • . Two different mechanisms are responsible for CO 2 ice accumulation during the fall season, especially in the 50 • -70 • Ls range. Here, CO 2 condensation in the atmosphere, and thus precipitation, is allowed exclusively in the western hemisphere, and particularly in the longitudinal corridor of the perennial cap. In the eastern hemisphere, the cap consists mainly of CO 2 frost deposits, as a consequence of direct vapor deposition. The differences in the nature of the surface ice deposits are the main cause for the residual south polar cap asymmetry. Results from selected PFS orbits have also been compared with the results provided by the martian general circulation model (GCM) of the Laboratoire de Météorologie dynamique (LMD) in Paris, with the aim of putting the observations in the context of the global circulation. This first attempt of cross-validation between PFS measurements and the LMD GCM on the one hand confirms the interpretation of the observations, and on the other hand shows that the climate modeling during the southern polar night on Mars is extremely sensitive to the dynamical forcing.

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“…CO 2 ice particles have been detected both in the lower atmosphere (≤ 20 km) during the polar night (Giuranna 2008;Ivanov and Muhleman 2001;Pettengill and Ford 2000) and in the mesosphere (50-100 km) at equatorial latitudes (Clancy et al 2007;Määttänen et al 2013;Montmessin et al 2007).…”

Section: Expected Performancementioning

confidence: 99%

NOMAD, an Integrated Suite of Three Spectrometers for the ExoMars Trace Gas Mission: Technical Description, Science Objectives and Expected Performance

Vandaele¹,

Moreno²,

Patel³

et al. 2018

Space Sci Rev

111

117

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The NOMAD ("Nadir and Occultation for MArs Discovery") spectrometer suite on board the ExoMars Trace Gas Orbiter (TGO) has been designed to investigate the comThis paper is dedicated to the memory of M. Allen, V. Formisano, and J. McConnell. position of Mars' atmosphere, with a particular focus on trace gases, clouds and dust. The detection sensitivity for trace gases is considerably improved compared to previous Mars missions, compliant with the science objectives of the TGO mission. This will allow for a major leap in our knowledge and understanding of the Martian atmospheric composition and the related physical and chemical processes. The instrument is a combination of three spectrometers, covering a spectral range from the UV to the mid-IR, and can perform solar occultation, nadir and limb observations. In this paper, we present the science objectives of the instrument and explain the technical principles of the three spectrometers. We also discuss the expected performance of the instrument in terms of spatial and temporal coverage and detection sensitivity.

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Cloud Reflection Observations: Results from the Mars Orbiter Laser Altimeter

Cited by 49 publications

References 19 publications

Atmospheric and surface retrievals in the Mars polar regions from the Thermal Emission Spectrometer measurements

Atmospheric and surface retrievals in the Mars polar regions from the Thermal Emission Spectrometer measurements

PFS/MEX observations of the condensing CO2 south polar cap of Mars

NOMAD, an Integrated Suite of Three Spectrometers for the ExoMars Trace Gas Mission: Technical Description, Science Objectives and Expected Performance

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