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The Mars2020 Perseverance Rover landed successfully on the Martian surface on the Jezero Crater floor (18.44°N, 77.45°E) at Martian solar longitude, Ls, ∼5° in February 2021. Since then, it has produced highly valuable environmental measurements with a versatile scientific payload including the MEDA (Mars Environmental Dynamics Analyzer) suite of environmental sensors. One of the MEDA systems is the PS pressure sensor system, which weighs 40 g and has an estimated absolute accuracy of better than 3.5 Pa and a resolution of 0.13 Pa. We present initial results from the first 414 sols of Martian atmospheric surface pressure observations by the PS, whose performance was found to meet its specifications. Observed sol‐averaged atmospheric pressures follow an anticipated pattern of pressure variation in the course of the advancing season and are consistent with data from other landing missions. The observed daily pressure amplitude varies by ∼2%–5 % of the sol‐averaged pressure, with absolute amplitude 10–35 Pa in an approximately direct relationship with airborne dust. During a regional dust storm, which began at Ls ∼ 135°, the daily pressure amplitude roughly doubled. The daily pressure variations were found to be remarkably sensitive to the seasonal evolution of the atmosphere. In particular, analysis of the daily pressure signature revealed diagnostic information likely related to the regional scale structure of the atmosphere. Comparison of Perseverance pressure observations with data from other landers reveals the global scale seasonal behavior of Mars' atmosphere. Plain Language Summary: Mars2020 Perseverance Rover successfully arrived on Mars in February 2021. It landed in an early Martian spring afternoon in a crater north of Mars' equator called Jezero crater. The rover is equipped with meteorological instruments that have so far produced extensive and valuable data for understanding the Martian atmosphere. One of the meteorological instruments is an accurate and precise pressure sensor. The pressure sensor has revealed large changes in the pressure over the seasons that are related to large changes in the actual mass of the Martian atmosphere. This is in line with seasonal pressure changes measured during previous Mars missions and can be explained as the condensation of the atmosphere onto the Martian poles and its subsequent sublimation. On a shorter time scale, the pressure sensor revealed complex pressure changes over a Martian day. These variations are thought to be related to atmospheric dust, whose ubiquitous nature is known to have a strong influence on the Martian climate. As the seasons progressed, the daily pressure variations morphed to exhibit different patterns likely related to the large‐scale regional changes in the atmosphere. Comparison of Perseverance pressure observations with other landers revealed the global nature of the atmosphere. Key Points: The atmospheric pressure observations by Perseverance Rover have proved to be of excellent quality fulfilling expectationsJezero crater pressure exhibits significant differences to other Martian areas likely due to varying regional geography and solar forcingOverall, the diurnal and seasonal atmospheric pressure cycles at Jezero Crater follow an anticipated pattern of pressure variation [ABSTRACT FROM AUTHOR]

Martian global dust storms (GDS) can significantly affect the water cycle in the lower atmosphere (0−40 km). We compare the evolution of water vapor abundances, dust opacity and surface temperatures in the Southern Polar Region (SPR) during GDS years of MY25, MY28, and MY34 relative to years without GDS. During all GDS years, the vapor abundances decrease in the lower atmosphere in the SPR following the storm. Our results suggest that this decrease could be the result of disruption of the southward transport of vapor by atmospheric circulation. Alternatively, the decrease in vapor abundances could be caused by decreased desorption of vapor from the subsurface. Plain Language Summary: This work presents comprehensive analysis of how water vapor in the Martian polar atmosphere reacts to large dust storms in different years. Measurements of water vapor, atmospheric dust, and surface temperatures collected by different spacecraft instruments in years with and without large dust storms are compared. These comparisons inform our understanding of how Martian water vapor is transported through the atmosphere and how it interacts with the surface. Large dust storms decrease the amount of water vapor in the southern polar region. This may indicate that the transport of vapor to the pole is reduced by the storms, or that dusty atmosphere cools the surface and reduces the amount of vapor released from the subsurface. Key Points: Water vapor abundances over the Southern Polar Region of Mars are reduced following a global dust storm (GDS)The decrease in water vapor abundances could be caused by disruption of southward vapor transport by a GDSAlternatively, the decrease could be caused by changes in the surface‐atmosphere vapor exchange [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2010.06.043 Byline: Alexey A. Pankine (a), Leslie K. Tamppari (a), Michael D. Smith (b) Keywords: Mars; Mars, Atmosphere; Mars, Climate; Mars, Polar caps Abstract: We report on new retrievals of water vapor column abundances from the Mars Global Surveyor (MGS) Thermal Emission Spectrometer (TES) data. The new retrievals are from the TES nadir data taken above the 'cold' surface areas in the North polar region (T.sub.surf Author Affiliation: (a) Jet Propulsion Laboratory/Caltech, MS 183-301, Pasadena, CA 91109, United States (b) NASA Goddard Space Flight Center, MS 693, Greenbelt, MD 20771, United States Article History: Received 17 March 2010; Revised 11 June 2010; Accepted 27 June 2010

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2009.06.009 Byline: Alexey A. Pankine (a), Leslie K. Tamppari (a), Michael D. Smith (b) Keywords: Mars; Mars, atmosphere; Mars, climate; Mars, polar caps Abstract: Atmospheric water vapor abundances in Mars' north polar region (NPR, from 60[degrees] to 90[degrees]N) are mapped as function of latitude and longitude for spring and summer seasons, and their spatial, seasonal, and interannual variability is discussed. Water vapor data are from Mars Global Surveyor (MGS) Thermal Emission Spectrometer (TES) and the Viking Orbiter (VO) Mars Atmospheric Water Detector (MAWD). The data cover three complete northern spring-summer seasons in 1977-1978, 2000-2001 and 2002-2003, and shorter periods of spring-summer seasons during 1975, 1999 and 2004. Long term interannual variability in the averaged NPR abundances may exist, with Viking MAWD observations showing twice as much water vapor during summer as the MGS TES observations more than 10 martian years (MY) later. While the averaged abundances are very similar in TES observations for the same season in different years, the spatial distributions in the early summer season do vary significantly year over year. Spatial and temporal variabilities increase between L.sub.s [approximately equal to]80-140[degrees], which may be related to vapor sublimation from the North Polar Residual Cap (NPRC), or to changes in circulation. Spatial variability is observed on scales of [approximately equal to]100km and temporal variability is observed on scales of Author Affiliation: (a) Jet Propulsion Laboratory/Caltech, MS 183-301, Pasadena, CA 91109, United States (b) NASA Goddard Space Flight Center, MS 693, Greenbelt, MD 20771, United States Article History: Received 26 November 2008; Revised 9 April 2009; Accepted 15 June 2009