A Warm Layer in the Nightside Mesosphere of Mars

Nakagawa, Hiromu; Jain, Sonal; Schneider, Nicholas M.; Montmessin, Franck; Yelle, R. V.; Jiang, Fayu; Verdier, Loïc; Kuroda, Takeshi; Yoshida, Nao; Fujiwara, Hitoshi; Imamura, Takeshi; Terada, Naoki; Terada, K.; Seki, K.; Gröller, H.; Deighan, Justin

doi:10.1029/2019gl085646

Cited by 11 publications

(27 citation statements)

References 54 publications

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“…The vertical mixing induced by the turbulent layer can influence the homopause and thereby the thermospheric composition. Although we do not have an explanation for such a distinct layer of warm air in the 10.1029/2020JE006481 mesosphere in the summer night, Nakagawa et al (2020) suggests evidence of wave-3 structures of warm layer with significant amplitudes that have been interpreted as a signature of diurnal, semidiurnal, and/or stationary planetary waves. This requires future work.…”

Section: Latitudinal-altitude Cross-section Of Wavesmentioning

confidence: 65%

“…Meanwhile, the observed enhancement at low latitudes in the northern summer hemisphere was not expected, because the nightside of the Martian mesosphere is presumably cold. This is associated with a strong temperature inversion due to the unexpected warm layer which was recently discovered by Nakagawa et al (2020). This also can be considered as an unstable layer in the mesosphere.…”

Section: Latitudinal-altitude Cross-section Of Wavesmentioning

confidence: 79%

“…For example, a uniform 10 K warmer atmosphere causes a doubling of the radiative damping rate at these altitudes (Eckermann et al, 2011). The unexpected warm layer at altitudes from 60-80 km reported by Nakagawa et al (2020) may have an impact on the rates.…”

Section: Discussionmentioning

confidence: 92%

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Vertical Propagation of Wave Perturbations in the Middle Atmosphere on Mars by MAVEN/IUVS

et al. 2020

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This work offers the first in‐depth study of the global characteristics of wave perturbations in temperature profiles at 20–140 km altitudes derived from the Imaging Ultraviolet Spectrograph (IUVS) onboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft. The peak amplitudes of waves seen in temperature profiles exceed 20% of the mean background, especially on the nightside, which is larger than those in Earth's mesosphere and thermosphere. The wave perturbations generate an instability layer around 70–100 km on the nightside, which potentially causes wave‐breaking and turbulences. Our results highlighted a seasonal variation in the latitudinal distribution of nightside perturbations. Amplitudes of wave perturbations were found to be large in the northern low‐latitude region and the southern polar region during the first half of the year (Ls = 0–180°). An increase of waves in the spectral density was found in southern low‐latitude regions in the latter half of the year (Ls = 180–360°). Vertical wavenumber spectral density in the Martian middle atmosphere shows a power‐law dependence with a logarithmic spectral slope of −3, similar to the features seen in the Earth's atmosphere. The derived spectral power density suggests the longer waves growing with height while the effective dissipation of shorter waves occurs. The strong CO2 15‐micron band cooling can effectively dissipate shorter waves. In contrast, the spectral power density at longer waves suggests an amplitude growth with height of unsaturated waves up to the lower thermosphere.

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Section: Latitudinal-altitude Cross-section Of Wavesmentioning

confidence: 65%

Section: Latitudinal-altitude Cross-section Of Wavesmentioning

confidence: 79%

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Vertical Propagation of Wave Perturbations in the Middle Atmosphere on Mars by MAVEN/IUVS

et al. 2020

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“…Recently, analysis of nightside temperature profiles in the UMLT region retrieved from MAVEN/IUVS stellar occultations revealed a surprising enhancement (so‐called “warm layer”) of up to 90 K above the previous model predictions at altitudes ∼80 km (Nakagawa et al., 2020). The high daytime temperature around 80 km observed by NOMAD/UVIS could suggest that such a warm layer might be present in daytime.…”

Section: Retrieval Of Density and Temperaturementioning

confidence: 95%

Density and Temperature of the Upper Mesosphere and Lower Thermosphere of Mars Retrieved From the OI 557.7 nm Dayglow Measured by TGO/NOMAD

et al. 2022

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The upper mesosphere and lower thermosphere of Mars (70–150 km) is of high interest because it is a region affected by climatological/meteorological events in the lower atmosphere and external solar forcing. However, only a few measurements are available at this altitude range. OI 557.7 nm dayglow emission has been detected at these altitudes by the limb observations with Nadir and Occultation for Mars Discovery (NOMAD) aboard the ExoMars Trace Gas Orbiter (TGO). We develop an inversion method to retrieve density and temperature at these altitudes from the OI 557.7 nm dayglow limb profiles. We demonstrate that the atmospheric density around 90 and 140 km and temperature around 80 km during the daytime can be retrieved from the TGO/NOMAD limb measurements. The retrieved densities show a large seasonal variation both around 90 and 140 km and reach maximum values around perihelion period. This can be explained by temperature variation in the lower atmosphere driven by the dust content and Sun‐Mars distance. Temperature around 80 km is higher than predicted by general circulation models, which is tentatively consistent with the warm atmospheric layer recently discovered in nighttime. The temperature retrieval relies on the temperature dependence of the quenching coefficient of 1S oxygen by CO2. Further validation of this coefficient in the range of the Mars upper atmosphere is needed for the verification of the retrieved high temperature.

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“…The difference between the morning and evening temperatures reveal seasonal warm layers at low‐middle latitudes in the mesosphere, 60–100 km. That might be due to the effect of diurnal thermal tides, which is also observed by IUVS/MAVEN on the night side (Nakagawa et al., 2020).…”

Section: Discussionmentioning

confidence: 72%

Thermal Structure of the Middle and Upper Atmosphere of Mars From ACS/TGO CO₂Spectroscopy

et al. 2022

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Temperature and density in the upper Martian atmosphere, above ∼100 km, are key diagnostic parameters to study processes of the species' escape, investigate the impact of solar activity, model the atmospheric circulation, and plan spacecraft descent or aerobraking maneuvers. In this paper, we report vertical profiling of carbon dioxide (CO2) density and temperature from the Atmospheric Chemistry Suite (ACS) solar occultations onboard the ExoMars Trace Gas Orbiter. A strong CO2 absorption band near 2.7 μm observed by the middle infrared spectrometric channel (ACS MIR) allows the retrieval of the atmospheric thermal structure in an unprecedentedly large altitude range, from 20 to 180 km. We present the latitudinal and seasonal climatology of the thermal structure for 1.5 Martian years (MYs), from the middle of MY 34 to the end of MY 35. The results show the variability of distinct atmospheric layers, such as a mesopause (derived from 70 to 145 km) and homopause, changing from 90 to 100 km at aphelion to 120–130 km at perihelion. Some short‐term homopause fluctuations are also observed depending on the dust activity.

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A Warm Layer in the Nightside Mesosphere of Mars

Cited by 11 publications

References 54 publications

Vertical Propagation of Wave Perturbations in the Middle Atmosphere on Mars by MAVEN/IUVS

Vertical Propagation of Wave Perturbations in the Middle Atmosphere on Mars by MAVEN/IUVS

Density and Temperature of the Upper Mesosphere and Lower Thermosphere of Mars Retrieved From the OI 557.7 nm Dayglow Measured by TGO/NOMAD

Thermal Structure of the Middle and Upper Atmosphere of Mars From ACS/TGO CO₂Spectroscopy

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A Warm Layer in the Nightside Mesosphere of Mars

Cited by 11 publications

References 54 publications

Vertical Propagation of Wave Perturbations in the Middle Atmosphere on Mars by MAVEN/IUVS

Vertical Propagation of Wave Perturbations in the Middle Atmosphere on Mars by MAVEN/IUVS

Density and Temperature of the Upper Mesosphere and Lower Thermosphere of Mars Retrieved From the OI 557.7 nm Dayglow Measured by TGO/NOMAD

Thermal Structure of the Middle and Upper Atmosphere of Mars From ACS/TGO CO2Spectroscopy

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Thermal Structure of the Middle and Upper Atmosphere of Mars From ACS/TGO CO₂Spectroscopy