Phoenix and MRO coordinated atmospheric measurements

Abstract

[1] The Phoenix and Mars Reconnaissance Orbiter (MRO) missions collaborated in an unprecedented campaign to observe the northern polar region summer atmosphere throughout the Phoenix mission (25 May to 2 November 2008; L s = 76°-150°) and slightly beyond (∼L s = 158°). Five atmospherically related campaigns were defined a priori and were executed on 37 separate Martian days (sols). Phoenix and MRO observed the atmosphere nearly simultaneously. We describe the observation strategy and history, the participating experiments, and some initial results. We find that there is general agreement between measurements from different instruments and platforms and that complementary measurements provide a consistent picture of the atmosphere. Seasonal water abundance behavior matches with historical measurements. Winds aloft, as measured by cloud motions, showed the same seasonally consistent, diurnal rotation as the winds measured at the lander, during the first part of the mission (L s = 76°-118°). A diurnal cycle recorded from L s ∼ 108.3°-109.1°, in which a dust front was approaching the Phoenix Lander, is examined in detail. Cloud heights measured on subsequent orbits showed that in areas of active lifting, dust can be lofted quite high in the atmosphere, doubling in height over 2 h. The combination of experiments also revealed that there were discrete vertical layers of water ice and dust. Water vapor column abundances compared to near-surface water vapor pressure indicate that water is not well mixed from the surface to a cloud condensation height and that the depth of the layer that exchanges diurnally with the surface is 0.5-1 km.

MGS TES observations of the water vapor above the seasonal and perennial ice caps during northern spring and summer

“…Numerical modeling of the water vapor diurnal behavior (Zent et al, 1993;Pathak et al, 2008), and recent observations by Phoenix Lander Tamppari et al, 2010;Whiteway et al, 2009;Daerden et al, 2010) and orbiting instruments on Mars Express (e.g. Tschimmel et al, 2008) indicate that large proportion of the atmospheric water vapor may be confined to a near-surface layer from 100 m to 1-2 km thick in the afternoon (at the time of TES nadir observations analyzed here) and that cloud formation and precipitation at night may keep water vapor confined to heights below 4-6 km above the surface.…”

The Sample Analysis at Mars Investigation and Instrument Suite

“…Jakosky et al (1997) argued that measurements from the Viking lander indicate that even diurnal cycles cause more than half of the atmospheric water vapor to exchange with the surface implying that seasonal effects should be even more pronounced. Coordinated measurements (Tamppari et al 2010) in 2008 from the Phoenix Lander and the Mars Reconnaissance Orbiter allowed both dust and water vapor variability to be studied over part of a seasonal cycle and the extent of the diurnal atmosphere/surface exchange in the polar region to be determined. CO 2 will also condense on the surface in the winter latitudes and adsorb into the surface at all latitudes.…”

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

“…Our simulations suggest that the high altitude clouds (above 10 km) observed around L s = 90°during the Phoenix mission (Whiteway et al, 2009;Tamppari et al, 2010) could be associated with the high vertical extent ($12-19 km) of vapor during this time.…”

“…Savijärvi and Määttänen (2010) simulations were compared to the Phoenix lander observations of the diurnal cycle of vapor partial pressure and the ice clouds; they did not attempt to match the TES observations. The mixing ratio profiles were constrained by representative daytime water vapor column abundances for the Phoenix location from Tamppari et al (2010).…”