Constraints on water vapor vertical distribution at the Phoenix landing site during summer from MGS TES day and night observations

Pankine, A.; Tamppari, L. K.

doi:10.1016/j.icarus.2015.01.008

Cited by 20 publications

(11 citation statements)

References 54 publications

(122 reference statements)

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“…However, Phoenix measurements showed no significant difference in H 2 O abundance between 9 h and 16 h (Smith et al, 2009b). Moreover, recent remote-sensing studies by MEX/SPICAM and MGS/TES show that local time variation of total H 2 O column is small at this season (e.g., Pankine and Tamppari, 2015;Trokhimovskiy et al, 2015). The systematic error in the HDO/H 2 O ratio can be estimated to be less than $10%.…”

Section: Latitude [Degrees]mentioning

confidence: 83%

Seasonal variation of the HDO/H2O ratio in the atmosphere of Mars at the middle of northern spring and beginning of northern summer

Aoki

Nakagawa

Sagawa

et al. 2015

Icarus

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Section: Latitude [Degrees]mentioning

confidence: 83%

Seasonal variation of the HDO/H2O ratio in the atmosphere of Mars at the middle of northern spring and beginning of northern summer

Aoki

Nakagawa

Sagawa

et al. 2015

Icarus

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“…He concluded that in northern summer, the mixing ratio was 150 ppm and that the column was well mixed, stating specifically that water confined to the lowest 1–2 km was inconsistent with his data. Savijärvi [], also modeling the VL1 site in summertime, found that the column was well mixed to at least 3 km as late as 22:00 h. Tamppari et al [] and Pankine and Tamppari [] both conclude that water vapor is progressively concentrated near the base of the atmosphere as northern summer wanes.…”

Section: Discussionmentioning

confidence: 99%

A revised calibration function and results for the Phoenix mission TECP relative humidity sensor

Zent

Hecht²,

Hudson

et al. 2016

JGR Planets

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A new calibration function for the humidity sensor in the Thermal and Electrical Conductivity Probe (TECP) on the Phoenix (PHX) Mars mission has been developed. Two changes are incorporated: (1) it is now cast in terms of frost point (T f ) rather than relative humidity (RH), and (2) flight data, taken when the atmosphere is independently known to be saturated, are included in the calibration data set. Daytime (6:00 h-19:00 h) frost points ranged from 194 K to 209 K; the nighttime frost point ranged from 179 K to 206 K. The response of the sensor was smooth and continuous throughout. Daytime humidity exhibited large, high-frequency variance driven by turbulence, whereas nighttime humidity varied smoothly with the temperature of the atmosphere. Nighttime saturation of the atmosphere begins at L s 101°, (Martian solar day (sol) 55), which is earlier than reported by either Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) or solid-state imager (SSI). Early mornings are the most humid part of the sol after L s 113°(sol 80), due to sublimation of surface ice that precipitates overnight. H 2 O is removed from the atmosphere into the regolith, mostly during the late afternoon, although this continues into the evening. The ground ice exposed by Phoenix operations masks the naturally occurring process in the early evening and may cause the atmosphere immediately around the lander to saturate somewhat earlier in the evening than it otherwise would have. The average H 2 O vapor density is close to the summertime value expected for equilibrium with ground ice. A discrepancy between the H 2 O column calculated from TECP data and the column measured by CRISM and SSI is likely due to comparable timescales between turbulent mixing through the planetary boundary layer and adsorptive drawdown of H 2 O. We find that RH is mostly < 5% (daytime) or > 95% (nighttime), and the transition between the two extremes is extremely rapid. TECP Humidity MeasurementsThe TECP H 2 O measurement was based on a General Electric Panametrics MiniCap 2 polymer capacitive humidity sensor. The flight sensor was one of four, each mounted in one of the four flight model TECPs that were built and calibrated. The flight instrument was selected from among them based on performance and stability over all six measurement types during calibration. The humidity sensor was mounted internally, on ZENT ET AL.PHOENIX HUMIDITY RESULTS 626 PUBLICATIONS

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“…Therefore, we have chosen the simplest approximation: that there is no diurnal variation. A diurnal variation of 10-20%, as in (Pankine and Tamppari, 2015) would not change any of the main findings of this work, including the location and seasonality of the "humid zones". If we look at GCM derived column water vapor, the change from day to night is indeed small (less than 10%).…”

Section: Validation Of Tes Calculationsmentioning

confidence: 62%

Global seasonal variations of the near-surface relative humidity levels on present-day Mars

Pál¹,

Keresztúri²,

Forget³

et al. 2019

Icarus

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We investigate the global seasonal variations of near-surface relative humidity and relevant attributes, like temperature and water vapor volume mixing ratio on Mars using calculations from modelled and measurement data. We focus on 2 am local time snapshots to eliminate daily effects related to differences in insolation, and to be able to compare calculations based on modelling data from the Laboratoire de Météorologie Dynamique Mars General Circulation Model with the observations of Mars Global Surveyor Thermal Emission Spectrometer. We study the seasonal effects by examining four specific dates in the Martian year, the northern spring equinox, summer solstice, autumn equinox and winter solstice. We identify three specific zones, where the near-surface relative humidity levels are systematically higher than in their vicinity regardless of season. We find that these areas coincide with low thermal inertia features, which control surface temperatures on the planet, and are most likely covered with unconsolidated fine dust with grain sizes less than ∼ 40µm. By comparing the data of relative humidity, temperature and water vapor volume mixing ratio at two different heights (near-surface, ∼ 23 m above the surface), we demonstrate that the thermal inertia could play an important role in determining near-surface humidity levels. We also notice that during the night the water vapor levels drop at ∼ 4 m above the surface. This, together with the temperature and thermal inertia values, shows that water vapor likely condenses in the near-surface atmosphere and on the ground during the night at the three aforementioned regions. This condensation may be in the form of brines, wettening of the fine grains or deliquescence. This study specifies areas of interest on the surface of present day Mars for the proposed condensation, which may be examined by in-situ measurements in the future.

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Constraints on water vapor vertical distribution at the Phoenix landing site during summer from MGS TES day and night observations

Cited by 20 publications

References 54 publications

Seasonal variation of the HDO/H2O ratio in the atmosphere of Mars at the middle of northern spring and beginning of northern summer

Seasonal variation of the HDO/H2O ratio in the atmosphere of Mars at the middle of northern spring and beginning of northern summer

A revised calibration function and results for the Phoenix mission TECP relative humidity sensor

Global seasonal variations of the near-surface relative humidity levels on present-day Mars

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