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Measurements of ground and near surface atmospheric temperatures at Jezero obtained during 700 sols by the Mars Environmental Dynamics Analyzer (MEDA) characterize the thermal behavior of the near surface Martian atmosphere during a full Martian Year. The seasonal evolution of MEDA measurements is compared with predictions from the Mars Climate Database and the solar irradiance at the surface. Thermal tides observed in the daily cycle of temperatures follow a seasonal cycle with additional variations greater than 2 K on time‐scales of tens of sols. We also observe sol‐to‐sol variations of about 1 K in mean daily air temperatures in autumn and winter with periodicities of 4–7 sols that might be related to baroclinic disturbances that are frequent in those seasons at high latitudes. We examine the evolution of the vertical thermal gradient and temperature fluctuations without finding a seasonal response to irradiance and dust load. We find that the convective boundary layer becomes isothermal and collapses 1 hr before sunset except during northern hemisphere winter, when the collapse occurs closer to sunset, implying a longer duration of the daytime convective instability. Around this period, the rover was located in the delta front in a location of complex topography where we observed stronger thermal gradients and intense daytime air temperature fluctuations. We also find in this place a nighttime event of gravity waves on near‐surface air temperatures, with amplitudes of 2 K and periods of 10 min. These waves possibly propagate downward through a near isothermal stable layer. The Perseverance rover on Mars is carrying a meteorological station that among other measurements obtains air temperatures at three heights near the surface as well as ground temperatures. We analyze seasonal and local changes in temperatures measured over one Martian year (687 Earth days) in which Perseverance moved several kilometers across Jezero crater, comparing in situ observations with the output from a Global Climate Model of the atmosphere of Mars. Our results show that the diurnal cycle of temperatures is modulated by the solar irradiance on the surface, the amount of dust in the atmosphere, local dynamics and large‐scale weather systems. The temperature difference between the ground and the atmosphere greatly determines the meteorology in the lower atmosphere. Neither this temperature difference, nor temperature fluctuations, which during daytime are a proxy of atmospheric convection driven by the heating of the surface, show seasonal variations in line with the seasonal solar irradiance or dust load. Instead, the rover path toward a more complex topography led to the highest surface‐to‐air temperature difference during the northern hemisphere winter, despite the solar irradiance being minimum at that time. Close to this complex topography, the meteorological station recorded oscillations in near‐surface temperature related to gravity waves. Seasonal variations in irradiance at Mars' surface drive observed daily mean near‐surface air temperatures with some differences from modelsThermal tides and long‐period traveling waves present a clear seasonal cycle with autumn and winter seasons more prone to variabilityAir temperatures underwent non‐seasonal changes near Jezero's delta, with strong daytime convection and nighttime gravity waves Seasonal variations in irradiance at Mars' surface drive observed daily mean near‐surface air temperatures with some differences from models Thermal tides and long‐period traveling waves present a clear seasonal cycle with autumn and winter seasons more prone to variability Air temperatures underwent non‐seasonal changes near Jezero's delta, with strong daytime convection and nighttime gravity waves

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. 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. 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 The atmospheric pressure observations by Perseverance Rover have proved to be of excellent quality fulfilling expectations Jezero crater pressure exhibits significant differences to other Martian areas likely due to varying regional geography and solar forcing Overall, the diurnal and seasonal atmospheric pressure cycles at Jezero Crater follow an anticipated pattern of pressure variation

MarsWRF output combined with thermodynamic theory is used to predict temporal and spatial trends of “dust devil activity” in Gale CraterModeled activity and observed vortex pressure drops are both greatest in local summer, peaking ~13:00‐14:00, and smallest in winterSensible heat flux drives increased activity as MSL climbs, but pressure drop numbers increase faster, unless a threshold activity is used Convective vortices and dust devils have been inferred and observed in Gale Crater, Mars, using Mars Science Laboratory (MSL) meteorological data and camera images. Rennó et al. (1998, https://doi.org/10.1175/1520‐0469(1998)055<3244:asttfd>2.0.co;2) modeled convective vortices as convective heat engines and predicted a “dust devil activity” (DDA) that depends only on local meteorological variables, specifically the sensible heat flux and the vertical thermodynamic efficiency which increases with the pressure thickness of the planetary boundary layer. This work uses output from the MarsWRF General Circulation Model, run with high‐resolution nests over Gale Crater, to predict DDA as a function of location, time of day, and season, and compares these predictions to the record of vortices found in MSL's Rover Environmental Monitoring Station pressure data set. Much of the observed time‐of‐day and seasonal variation of vortex activity is captured, such as maximum (minimum) activity in southern summer (winter), peaking between 11:00 and 14:00. However, while two daily peaks are predicted around both equinoxes, only a late morning peak is observed. An increase in vortex activity is predicted as MSL climbs the northwest slopes of Aeolis Mons, as observed. This is attributed largely to increased sensible heat flux, due to (i) larger daytime surface‐to‐air temperature differences over higher terrain, enhanced by reduced thermal inertia, and (ii) the increase in drag velocity associated with faster daytime upslope winds. However, the observed increase in number of vortex pressure drops is much stronger than the predicted DDA increase, although a better match exists when a threshold DDA is used. The daytime Martian atmosphere produces convective vortices called “dust devils” when they are dust‐filled. Vortices produce rapid pressure drops, which have been detected in Gale Crater by Mars Science Laboratory instruments. Observed vortex pressure drops are compared with vortex activity predicted using a numerical model, MarsWRF. Because vortices are far smaller than MarsWRF's grid spacing, the model can't predict them directly. Instead, the theory of Rennó et al. (1998) is used to calculate “dust devil activity” (DDA) – a measure of vortex activity – based on the large‐scale atmospheric state. Predicted DDA matches the general variation of vortex observations with time of day and season, such as maximum (minimum) activity in southern summer (winter), peaking between 11:00 and 14:00. However, while two daily peaks are predicted around both equinoxes, only a late morning peak is observed. Predicted DDA also increases as Mars Science Laboratory climbs the slopes of Aeolis Mons, as observed. This is attributed to (i) larger daytime surface‐to‐air temperature differences at higher altitudes and (ii) faster daytime upslope winds higher up the slopes. However, the observed increase in number of vortex pressure drops is much stronger than the predicted DDA increase, although they match better when a threshold DDA is used.

The Sample Analysis at Mars (SAM) instrument onboard the Mars Science Laboratory Curiosity rover measures the chemical composition of major atmospheric species (CO2, N2, 40Ar, O2, and CO) through a dedicated atmospheric inlet. We report here measurements of volume mixing ratios in Gale Crater using the SAM quadrupole mass spectrometer, obtained over a period of nearly 5 years (3 Mars years) from landing. The observation period spans the northern summer of MY 31 and solar longitude (LS) of 175° through spring of MY 34, LS= 12°. This work expands upon prior reports of the mixing ratios measured by SAM QMS in the first 105 sols of the mission. The SAM QMS atmospheric measurements were taken periodically, with a cumulative coverage of four or five experiments per season on Mars. Major observations include the seasonal cycle of CO2, N2, and Ar, which lags approximately 20–40° of LSbehind the pressure cycle driven by CO2condensation and sublimation from the winter poles. This seasonal cycle indicates that transport occurs on faster timescales than mixing. The mixing ratio of O2shows significant seasonal and interannual variability, suggesting an unknown atmospheric or surface process at work. The O2measurements are compared to several parameters, including dust optical depth and trace CH4measurements by Curiosity. We derive annual mean volume mixing ratios for the atmosphere in Gale Crater: CO2= 0.951 (±0.003), N2= 0.0259 (±0.0006), 40Ar = 0.0194 (±0.0004), O2= 1.61 (±0.09) x 10‐3, and CO = 5.8 (±0.8) x 10‐4. The atmosphere of Mars is made up of primarily carbon dioxide, and during the Martian year, the barometric pressure is known to cycle up and down substantially as this carbon dioxide freezes out and then is rereleased from polar caps. The Mars Science Laboratory Curiosity rover has now acquired atmospheric composition measurements at the ground over multiple years, capturing the variations in the major gases over several seasonal cycles for the first time. With the Sample Analysis at Mars instrument, the annual average composition in Gale Crater was measured as 95.1% carbon dioxide, 2.59% nitrogen, 1.94% argon, 0.161% oxygen, and 0.058% carbon monoxide. However, the abundances of some of these gases were observed to vary up to 40% throughout the year due to the seasonal cycle. Nitrogen and argon follow the pressure changes but with a delay, indicating that transport of the atmosphere from pole to pole occurs on faster timescales than mixing of the components. Oxygen has been observed to show significant seasonal and year‐to‐year variability, suggesting an unknown atmospheric or surface process at work. These data can be used to better understand how the surface and atmosphere interact as we search for signs of habitability. First multiyear in situ measurements of the major components of the Mars atmosphere have been obtained by the MSL/SAM investigationSeasonal variation of CO2, N2, and Ar reveals differences in atmospheric transport and mixing timescalesOxygen varies seasonally and interannually, independently from Ar and N2, on timescales too fast to be explained by known chemistry

The Rover Environmental Monitoring Station (REMS) instrument is on board NASA's Mars Science Laboratory (MSL) Curiosity rover. REMS has been measuring surface pressure, air, and ground brightness temperature, relative humidity, and ultraviolet (UV) irradiance since MSL's landing in 2012. In Mars Year (MY) 34 (2018) a global dust storm reached Gale Crater at Ls~ 190°. REMS offers a unique opportunity to better understand the impact of a global dust storm on local environmental conditions, which complements previous observations by the Viking landers and Mars Exploration Rovers. All atmospheric variables measured by REMS are strongly affected albeit at different times. During the onset phase, the daily maximum UV radiation decreased by 90% between sols 2075 (opacity ~1) and 2085 (opacity ~8.5). The diurnal range in ground and air temperatures decreased by 35 and 56 K, respectively, with also a diurnal‐average decrease of ~2 and 4 K respectively. The maximum relative humidity, which occurs right before sunrise, decreased to below 5%, compared with prestorm values of up to 29%, due to the warmer air temperatures at night, while the inferred water vapor abundance suggests an increase during the storm. Between sols 2085 and 2130, the typical nighttime stable inversion layer was absent near the surface as ground temperatures remained warmer than near‐surface air temperatures. Finally, the frequency domain behavior of the diurnal pressure cycle shows a strong increase in the strength of the semidiurnal and terdiurnal modes peaking after the local opacity maximum, also suggesting differences in the dust abundance inside and outside Gale. Atmospheric opacity over Gale Crater was increased by more than 8 times and disturbed all the atmospheric variables measured by REMSREMS data suggest that the nighttime near‐surface atmosphere stability was reduced and its water abundance increased during the GDSThe semidiurnal mode peaked after the local opacity maximum, suggesting different dust abundance inside and outside Gale

We analyze 10 years of Mars Express total electron content (TEC) data from the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) instrument. We describe the spatial, seasonal, and solar cycle behavior of the Martian TEC. Due to orbit evolution, data come mainly from the evening, dusk terminator and postdusk nightside. The annual TEC profile shows a peak at Ls= 25–75° which is not related to the solar irradiance variation but instead coincides with an increase in the thermospheric density, possibly linked with variations in the surface pressure produced by atmospheric cycles such as the CO2or water cycles. With the help of numerical modeling, we explore the contribution of the ion species to the TEC and the coupling between the thermosphere and ionosphere. These are the first observations which show that the TEC is a useful parameter, routinely measured by Mars Express, of the dynamics of the lower‐upper atmospheric coupling and can be used as tracer for the behavior of the thermosphere. Ten years of Mars Express total electron content (TEC) data from the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) instrument are analyzed. The TEC is a parameter that gives information of the amount of free electrons within the ionosphere (ionized layer at ~100–200 km). In this study, we describe how the TEC varies along the seasons, planet coverage, and also with the solar activity. We have found that variations in the thermosphere (neutral atmospheric layer between 100 and 200 km) have an effect on the ionosphere, especially notable during spring of the northern hemisphere. With the help of a numerical simulation of the ionosphere‐thermosphere over a Martian year, we have found that Mars' atmospheric cycles can have an effect on the upper atmosphere. The spatial, seasonal, and solar cycle variation of 10 years of Mars' TEC is assessedMars Express routinely measures the dynamic of the thermosphere‐ionosphere couplingThe TEC can be used as a tracer for atmospheric cycles on the upper atmosphere

The Mars Environmental Dynamics Analyzer instrument, on board NASA's Mars 2020 Perseverance rover, includes a number of sensors to characterize the Martian atmosphere. One of these sensors is the Radiation and Dust Sensor (RDS) that measures the solar irradiance at different wavelengths and geometries. We analyzed the RDS observations made during twilight for the period between sol 71 and 492 of the mission (Ls 39°–262°, Mars Year 36) to characterize the clouds over the Perseverance rover site. Using the ratio between the irradiance at zenith at 450 and 750 nm, we inferred that the main constituent of the detected high‐altitude aerosol layers was ice from Ls = 39°–150° (cloudy period), and dust from Ls 150°–262°. A total of 161 twilights were analyzed in the cloudy period using a radiative transfer code and we found: (a) signatures of clouds/hazes in the signals in 58% of the twilights; (b) most of the clouds had altitudes between 40 and 50 km, suggesting water ice composition, and had particle sizes between 0.6 and 2 µm; (c) the cloud activity at sunrise is slightly higher that at sunset, likely due to the differences in temperature; (d) the time period with more cloud detections and with the greatest cloud opacities is during Ls 120°–150°; and (e) a notable decrease in the cloud activity around aphelion, along with lower cloud altitudes and opacities. This decrease in cloud activity indicates lower concentrations of water vapor or cloud condensation nuclei (dust) around this period in the Martian mesosphere. During twilight, ground‐based observations of the irradiance allows the detection and characterization of high‐altitude clouds (above 30–35 km). Because the sun is at or below the horizon, the cloud layers reflect the direct light that only reaches the higher parts of the atmosphere, producing an increase in the sky brightness with respect to the cloud‐free scenario. Moreover, the decrease in the intensity with the solar zenith angle highly depends on the cloud altitude and density. Using observations made by the Radiation and Dust Sensor, part of the instrument Mars Environmental Dynamics Analyzer on board Perseverance rover, we present here a study of the twilight clouds detected at the Perseverance landing site for the first 490 sols of the mission (Mars Year 36). By modeling the irradiance at 450 and 950 nm with radiative transfer simulations, we constrained the cloud altitude, opacity, and particle radius. The number of twilights analyzed allowed us to study the seasonal trend in the cloud activity. During the cloudy period, Ls 39°–150°, we find a significant decrease in the cloud activity above 30–35 km around aphelion (Ls ∼ 70°). This implies that the seasonal distribution of clouds above 30–35 km differs from that observed at lower altitudes. Most of the cloud detected at twilight between sol 71 and 492 of the Mars 2020 mission (Ls 39°–262°) occurred at altitudes between 40 and 50 kmAround aphelion (Ls ∼ 70°) we found the minimum in cloud activity and lower cloud opacitiesThe cloud activity at sunrise is slightly stronger than at sunset and this is likely due to the lower temperatures Most of the cloud detected at twilight between sol 71 and 492 of the Mars 2020 mission (Ls 39°–262°) occurred at altitudes between 40 and 50 km Around aphelion (Ls ∼ 70°) we found the minimum in cloud activity and lower cloud opacities The cloud activity at sunrise is slightly stronger than at sunset and this is likely due to the lower temperatures

We identify temporal variations in surface albedo at Jezero crater using first‐of‐their‐kind high‐cadence in‐situ measurements of reflected shortwave radiation during the first 350 sols of the Mars 2020 mission. Simultaneous Mars Environmental Dynamics Analyzer (MEDA) measurements of pressure, radiative fluxes, winds, and sky brightness indicate that these albedo changes are caused by dust devils under typical conditions and by a dust storm at Ls∼ 155°. The 17% decrease in albedo caused by the dust storm is one order of magnitude larger than the most apparent changes caused during quiescent periods by dust devils. Spectral reflectance measurements from Mastcam‐Z images before and after the storm indicate that the decrease in albedo is mainly caused by dust removal. The occurrence of albedo changes is affected by the intensity and proximity of the convective vortex, and the availability and mobility of small particles at the surface. The probability of observing an albedo change increases with the magnitude of the pressure drop (ΔP): changes were detected in 3.5%, 43%, and 100% of the dust devils with ΔP < 2.5 Pa, ΔP > 2.5 Pa and ΔP > 4.5 Pa, respectively. Albedo changes were associated with peak wind speeds above 15 m·s−1. We discuss dust removal estimates, the observed surface temperature changes coincident with albedo changes, and implications for solar‐powered missions. These results show synergies between multiple instruments (MEDA, Mastcam‐Z, Navcam, and the Supercam microphone) that improve our understanding of aeolian processes on Mars. Small particles at the surface of Mars are lifted and transported through interactions with the atmosphere, modifying the fraction of solar radiation reflected by the surface (albedo). We analyzed the first albedo measurements acquired at 1 Hz and other environmental variables measured at Jezero crater, concluding that albedo changes are caused by dust devils under typical conditions and by a dust storm. The darkening of the surface induced by the storm is around 10 times larger than that caused in the absence of a storm by dust devils. Surface images indicate that this darkening is caused by dust removal. Only a fraction of the dust devils cause an albedo change, depending on their intensity, size and trajectory, and on the features of the small particles at the surface. The combined analysis of environmental variables, images and microphone recordings acquired by the Mars 2020 mission improve our understanding of the processes involved in the lifting and transport of small particles. We identify surface albedo changes using Mars 2020 first‐of‐their‐kind high‐cadence in situ measurements of reflected solar radiationThe most remarkable albedo changes observed within seconds outside dust storm conditions were caused by dust devilsA multi‐instrument analysis showed that the dust storm reduced surface albedo by more than 15%, primarily caused by dust removal We identify surface albedo changes using Mars 2020 first‐of‐their‐kind high‐cadence in situ measurements of reflected solar radiation The most remarkable albedo changes observed within seconds outside dust storm conditions were caused by dust devils A multi‐instrument analysis showed that the dust storm reduced surface albedo by more than 15%, primarily caused by dust removal

The Mars Environmental Dynamics Analyzer instrument on Mars 2020 has five Atmospheric Temperature Sensors at two altitudes (0.84 and 1.45 m) plus a Thermal InfraRed Sensor that measures temperatures on the surface and at ∼40 m. We analyze the measurements from these sensors to describe the evolution of temperatures in Jezero up to mission sol 400 (solar longitude LS= 13°–203°). The diurnal thermal cycle is characterized by a daytime convective period and a nocturnal stable atmosphere with a variable thermal inversion. We find a linear relationship between the daytime temperature fluctuations and the vertical thermal gradient with temperature fluctuations that peak at noon with typical values of 2.5 K at 1.45 m. In the late afternoon (∼17:00 Local True Solar Time), the atmosphere becomes vertically isothermal with vanishing fluctuations. We observe very small seasonal changes in air temperatures during the period analyzed. This is related to small changes in solar irradiation and dust opacity. However, we find significant changes in surface temperatures that are related to the variety of thermal inertias of the terrains explored along the traverse of Perseverance. These changes strongly influence the vertical thermal gradient, breaking the nighttime thermal inversion over terrains of high thermal inertia. We explore possible detections of atmospheric tides on near‐surface temperatures and we examine variations in temperatures over timescales of a few sols that could be indicative of atmospheric waves affecting near‐surface temperatures. We also discuss temperatures during a regional dust storm at LS= 153°–156° that simultaneously warmed the near surface atmosphere while cooling the surface. The Mars Environmental Dynamics Analyzer instrument on the Mars 2020 Perseverance rover records temperatures in Jezero at four altitudes from the surface to 40 m. We describe the evolution of temperatures over the first 400 Martian days of the mission from northern spring to early autumn. Diurnal temperatures show an unstable convective regime during the daytime and a stable atmosphere at night. Daytime convection produces thermal fluctuations that peak at noon with typical values of 2.5 K at 1.45 m. These thermal fluctuations vanish in the late afternoon when an isothermal atmosphere is observed from the surface up to 40 m. We also find a linear relationship between the daytime temperature fluctuations and the thermal gradient between the surface and the atmosphere. We find very little seasonal change in air temperatures. However, the thermal inertia of the terrain affects surface temperatures, and the nighttime thermal inversion breaks over terrains with high thermal inertia. We investigate the possible detection in near surface temperatures of thermal tides and atmospheric waves. Finally, we show the thermal response of the surface and the atmosphere during the passage of a regional dust storm with a simultaneous cooling of the surface and warming of the near‐surface atmosphere. Surface and atmospheric temperatures at Jezero show small seasonal variations from Spring to early Autumn that agree with modelsThe intensity of daytime convective fluctuations is correlated with vertical thermal gradients, which depend on the surface thermal inertiaA dust storm significantly heated the lower atmosphere while cooling the surface indicating strong radiative effects of low altitude dust Surface and atmospheric temperatures at Jezero show small seasonal variations from Spring to early Autumn that agree with models The intensity of daytime convective fluctuations is correlated with vertical thermal gradients, which depend on the surface thermal inertia A dust storm significantly heated the lower atmosphere while cooling the surface indicating strong radiative effects of low altitude dust

The Mars 2020 mission rover “Perseverance”, launched on 30 July 2020 by NASA, landed successfully 18 February 2021 at Jezero Crater, Mars (Lon. E 77.4509° Lat. N 18.4446°). The landing took place at Mars solar longitude Ls = 5.2°, close to start of the northern spring. Perseverance's payload includes the relative humidity sensor MEDA HS (Mars Environmental Dynamics Analyzer Humidity Sensor), which operations, performance, and the first observations from sol 80 to sol 410 (Ls 44°–210°) of Perseverance's operations we describe. The relative humidity measured by MEDA‐HS is reliable from late night hours to few tens of minutes after sunrise when the measured humidity is greater than 2% (referenced to sensor temperature). Data delivered to the Planetary Data System include relative humidity, sensor temperature, uncertainty of relative humidity, and volume mixing ratio (VMR). VMR is calculated using the MEDA‐PS pressure sensor values. According to observations, nighttime absolute humidity follows a seasonal curve in which release of water vapor from the northern cap with advancing northern spring and summer is visible. At ground level, frost conditions may have been reached a few times during this season (Ls 44°–210°). Volume mixing ratio values show a declining diurnal trend from the midnight toward the morning suggesting adsorption of humidity into the ground. Observations are compared with an adsorptive single‐column model, which complies with observations and confirms adsorption. The model allows estimating daytime VMR levels. Short‐term subhour timescales show large temporal fluctuations in humidity, which suggest vertical and spatial advection. The Mars 2020 mission rover “Perseverance” landed successfully on 18 February 2021 at Jezero Crater, Mars. The rover's payload includes a versatile instrument suite which includes a relative humidity sensor, whose observations for the first 410 Martian days are described here. The observations show how the lowest level of atmosphere is generally dry but still exceeding saturation is feasible because of cold nights. Sensor operations and accuracy estimates are presented. Relative humidity together with MEDA pressure and air temperature observations allow calculating absolute water vapor content of air at the sensor level at nighttime. Humidity observations are also compared with models describing water vapor adsorption and desorption into and out from soil. The results show how atmospheric humidity at the rover's site experiences large subhour variability. Humidity observations help to understand interchange of humidity between the soil and the atmosphere. Water is mandatory for life, such as on earth, thus understanding these water cycle processes better are important for evaluating possibilities of past and current habitability of Mars. Perseverance is also collecting samples which maybe returned to Earth one day. Knowledge of the conditions at the times when samples were collected maybe useful. Humidity observations in Mars by M2020 Perseverance rover during the first 410 sols of operation are shown and discussedHumidity sensor MEDA‐HS operations and sensor accuracy are explainedAdsorptive single column model is tested and compared with humidity observations Humidity observations in Mars by M2020 Perseverance rover during the first 410 sols of operation are shown and discussed Humidity sensor MEDA‐HS operations and sensor accuracy are explained Adsorptive single column model is tested and compared with humidity observations

The Mars Environmental Dynamics Analyzer (MEDA) on board Perseverance includes first‐of‐its‐kind sensors measuring the incident and reflected solar flux, the downwelling atmospheric IR flux, and the upwelling IR flux emitted by the surface. We use these measurements for the first 350 sols of the Mars 2020 mission (Ls∼ 6°–174° in Martian Year 36) to determine the surface radiative budget on Mars and to calculate the broadband albedo (0.3–3 μm) as a function of the illumination and viewing geometry. Together with MEDA measurements of ground temperature, we calculate the thermal inertia for homogeneous terrains without the need for numerical thermal models. We found that (a) the observed downwelling atmospheric IR flux is significantly lower than the model predictions. This is likely caused by the strong diurnal variation in aerosol opacity measured by MEDA, which is not accounted for by numerical models. (b) The albedo presents a marked non‐Lambertian behavior, with lowest values near noon and highest values corresponding to low phase angles (i.e., Sun behind the observer). (c) Thermal inertia values ranged between 180 (sand dune) and 605 (bedrock‐dominated material) SI units. (d) Averages of albedo and thermal inertia (spatial resolution of ∼3–4 m2) along Perseverance's traverse are in very good agreement with collocated retrievals of thermal inertia from Thermal Emission Imaging System (spatial resolution of 100 m per pixel) and of bolometric albedo in the 0.25–2.9 μm range from (spatial resolution of ∼300 km2). The results presented here are important to validate model predictions and provide ground‐truth to orbital measurements. We analyzed first‐of‐its‐kind measurements from the weather station on board NASA's Perseverance rover. These include the incident solar radiation and the amount that is reflected by the surface, as well as the thermal atmospheric forcing (greenhouse effect) and the thermal heat released by the surface. These measurements comprise the radiant energy budget, which is fundamental to understanding Mars' weather through its impact on temperatures. From the solar measurements, we obtained the surface reflectance for a variety of illuminating and viewing geometries. We found that the thermal atmospheric forcing is weaker than expected from models, likely because of the strong diurnal variation in atmospheric aerosols observed by the rover, which is not accounted for by models. We also found that the surface reflectance is not uniform from all directions, but that it decreases when the Sun is highest in the sky (near noon) and increases when the Sun is directly behind the observer (sunset and sunrise), and thus the shadows cast by their roughness elements (e.g., pores and pits) are minimized. Because models neither consider diurnal variations in atmospheric aerosols nor in the surface reflectance, the results presented here are important to validate model predictions for future human exploration. Mars Environmental Monitoring Station (MEDA) allows the first in situ determination of the surface radiative budget on Mars, providing key constraints on numerical modelsMEDA allows the direct determination of thermal inertia and albedo, providing ground‐truth to satellite retrievalsAlbedo shows a strong non‐Lambertian behavior, with minimum values at noon and higher values toward sunrise and sunset Mars Environmental Monitoring Station (MEDA) allows the first in situ determination of the surface radiative budget on Mars, providing key constraints on numerical models MEDA allows the direct determination of thermal inertia and albedo, providing ground‐truth to satellite retrievals Albedo shows a strong non‐Lambertian behavior, with minimum values at noon and higher values toward sunrise and sunset

We characterize vortex and dust devils (DDs) at Jezero from pressure and winds obtained with the Mars Environmental Dynamics Analyzer (MEDA) instrument on Mars 2020 over 415 Martian days (sols) (Ls= 6°–213°). Vortices are abundant (4.9 per sol with pressure drops >0.5 Pa correcting from gaps in coverage) and they peak at noon. At least one in every five vortices carries dust, and 75% of all vortices with Δp> 2.0 Pa are dusty. Seasonal variability was small but DDs were abundant during a dust storm (Ls= 152°–156°). Vortices are more frequent and intense over terrains with lower thermal inertia favoring high daytime surface‐to‐air temperature gradients. We fit measurements of winds and pressure during DD encounters to models of vortices. We obtain vortex diameters that range from 5 to 135 m with a mean of 20 m, and from the frequency of close encounters we estimate a DD activity of 2.0–3.0 DDs km−2sol−1. A comparison of MEDA observations with a Large Eddy Simulation of Jezero at Ls= 45° produces a similar result. Three 100‐m size DDs passed within 30 m of the rover from what we estimate that the activity of DDs with diameters >100 m is 0.1 DDs km−2sol−1, implying that dust lifting is dominated by the largest vortices in Jezero. At least one vortex had a central pressure drop of 9.0 Pa and internal winds of 25 ms−1. The MEDA wind sensors were partially damaged during two DD encounters whose characteristics we elaborate in detail. Dust devils (DDs) are whirlwinds of warm air with winds strong enough to lift dust. They are common in Earth deserts and much more abundant on Mars, where they are one of the elements that bring dust to the atmosphere. The Mars 2020 mission landed in Jezero crater on February 2020 and has observed a plethora of DDs that we investigate with the meteorological sensors on the Mars Environmental Dynamics Analyzer (MEDA) instrument. Results for more than 400 Martian days from spring to autumn indicate a high abundance of events with small seasonal variability. Terrains with lower thermal inertia, warming more efficiently at noon, favor the appearance of DDs. We also found an increased DD activity during a short dust storm that covered the region. From modeling MEDA data, we find that DDs at Jezero have diameters from 5.0 to 135 m. We estimate that about 2–3 DDs are formed per km2and Martian day. Large vortices with diameters of 100 m form frequently enough to dominate dust lifting at Jezero. Two DDs damaged part of the hardware of the wind sensors of MEDA and we detail the characteristics of those events. Vortices and dust devils (DDs) are frequent on Jezero. Mars Environmental Dynamics Analyzer detects 5.0 and 1.0 events per sol respectively when correcting from sampling effectsIntense vortices on Jezero tend to be dusty with 75% of all vortices with a pressure drop larger than 2.0 Pa being dustyWe calculate 2.5 and 0.1 DDs km−2sol−1with sizes of 20 and 100 m respectively. The largest events dominate dust lifting Vortices and dust devils (DDs) are frequent on Jezero. Mars Environmental Dynamics Analyzer detects 5.0 and 1.0 events per sol respectively when correcting from sampling effects Intense vortices on Jezero tend to be dusty with 75% of all vortices with a pressure drop larger than 2.0 Pa being dusty We calculate 2.5 and 0.1 DDs km−2sol−1with sizes of 20 and 100 m respectively. The largest events dominate dust lifting

The Mars Environmental Dynamics Analyzer, onboard the Perseverance rover, is a meteorological station that is operating on Mars and includes, among other sensors, the radiometer Radiation and Dust Sensor (RDS). From RDS irradiance observations, a total of 374 dust devils (DDs) were detected for the first 365 sols of the mission (Ls = 6°–182°), which along with wind and pressure measurements, we estimated a DD frequency of formation at Jezero between 1.3 and 3.4 DD km−2sol−1(increasing as we move from spring into summer). This frequency is found to be smaller than that estimated at the Spirit or Pathfinder landing sites but much greater than that derived at InSight landing site. The maximum in DD frequency occurs between 12:00 and 13:00 local true solar time, which is when the convective heat flux and lower planetary boundary layer IR heating are both predicted to peak in Jezero crater. DD diameter, minimum height, and trajectory were studied showing (a) an average diameter of 29 m (or a median of 25 m) and a maximum and minimum diameter of 132 ± 63.4 and 5.6 ± 5.5 m; (b) an average minimum DD height of 231 m and a maximum minimum‐height of 872 m; and (c) the DD migration direction is in agreement with wind measurements. For all the cases, DDs decreased the UV irradiance, while at visible or near‐IR wavelengths both increases and decreases were observed. Contrary to the frequency of formation, these results indicate similar DD characteristics in average for the studied period. Dust devils are dry, dusty convective vortices that play a key role in the dust cycle on Mars by lifting dust from the surface to the atmosphere. Parameters like the dust devil formation frequency or size characteristics are key to constrain their contribution to the planet's dust budget. Using observations made by the Radiation and Dust Sensor of the instrument Mars Environmental Dynamics Analyzer onboard Perseverance rover, we estimated the dust devil (DD) frequency for the full diurnal cycle in Jezero crater, Mars, during the first half of the Martian year. We find that between 1 and 3 DD per km−2form every day, mainly around noon, and they become more frequent as spring advances to summer. The formation frequency is smaller than that estimated at the Spirit landing site but much greater than the values derived at InSight landing site, indicating a high variability in activity depending on location. When the DDs blocked the direct sunlight from reaching the sensor, we estimated their diameters to range between 5 and 130 m with an average of 29 m. In all detections, the presence of DDs resulted in a decrease of the measured UV radiation. A dust devil frequency of occurrence of between 1.3 and 3.4 dust devils km−2sol−1was derived from MEDA‐RDS observations for the first 365 sols, displaying the maximum activity at around noon and increasing as we move from spring into summerWe find an average dust devil diameter of 29 m (or a median diameter of 25 m) and maximum and minimum diameters of 132 ± 63.4 m and 5.6 ± 5.5 mDust devil migration directions are in agreement with the MEDA background wind direction measurements A dust devil frequency of occurrence of between 1.3 and 3.4 dust devils km−2sol−1was derived from MEDA‐RDS observations for the first 365 sols, displaying the maximum activity at around noon and increasing as we move from spring into summer We find an average dust devil diameter of 29 m (or a median diameter of 25 m) and maximum and minimum diameters of 132 ± 63.4 m and 5.6 ± 5.5 m Dust devil migration directions are in agreement with the MEDA background wind direction measurements

The pressure sensors on Mars rover Perseverance measure the pressure field in the Jezero crater on regular hourly basis starting in sol 15 after landing. The present study extends up to sol 460 encompassing the range of solar longitudes from Ls∼ 13°–241° (Martian Year (MY) 36). The data show the changing daily pressure cycle, the sol‐to‐sol seasonal evolution of the mean pressure field driven by the CO2sublimation and deposition cycle at the poles, the characterization of up to six components of the atmospheric tides and their relationship to dust content in the atmosphere. They also show the presence of wave disturbances with periods 2–5 sols, exploring their baroclinic nature, short period oscillations (mainly at night‐time) in the range 8–24 min that we interpret as internal gravity waves, transient pressure drops with duration ∼1–150 s produced by vortices, and rapid turbulent fluctuations. We also analyze the effects on pressure measurements produced by a regional dust storm over Jezero at Ls∼ 155°. Mars rover Perseverance landed on 18 February 2021 on Jezero crater. It carries a weather station that has measured, among other quantities, surface atmospheric pressure. This study covers the first 460 sols or Martian days, a period that comprises a large part of the Martian year, including spring, summer and a part of autumn. Each sol, the pressure has significant changes, and those can be understood as a result of the so‐called thermal tides, oscillations of pressure with periods that are fractions of one sol. The mean value of pressure each sols changes with the season, driven by the CO2sublimation in summer and condensation in winter at both poles. We report oscillations of the mean daily pressure with periods of a few sols, related to waves at distant parts of the planet. Within single sols, we find oscillations of night pressure with periods of tens of minutes, caused by gravity waves. Looking at shorter time intervals, we find the signature of the close passage of vortices such as dust devils, and very rapid daytime turbulent fluctuations. We finally analyze the effects on all these phenomena produced by a regional dust storm that evolved over Jezero in early January 2022. We study the pressure measurements performed on the first 460 sols by the rover Perseverance M2020The daily and seasonal cycles and the evolution of six tidal components and their relationship to dust content are presentedWe characterize long‐period waves (sols), short‐period gravity waves (min.), rapid pressure fluctuations and a regional dust storm impact We study the pressure measurements performed on the first 460 sols by the rover Perseverance M2020 The daily and seasonal cycles and the evolution of six tidal components and their relationship to dust content are presented We characterize long‐period waves (sols), short‐period gravity waves (min.), rapid pressure fluctuations and a regional dust storm impact

Martian atmospheric dust is a major driver of weather, with feedback between atmospheric dust distribution, circulation changes from radiative heating and cooling driven by this dust, and winds that mobilize surface dust and distribute it in the atmosphere. Wind‐driven mobilization of surface dust is a poorly understood process due to significant uncertainty about minimum wind stress and whether the saltation of sand particles is required. This study utilizes video of six Ingenuity helicopter flights to measure dust lifting during helicopter ascents, traverses, and descents. Dust mobilization persisted on takeoff until the helicopter exceeded 3 m altitude, with dust advecting at 4–6 m/s. During landing, dust mobilization initiated at 2.3–3.6 m altitude. Extensive dust mobilization occurred during traverses at 5.1–5.7 m altitude. Dust mobilization threshold friction velocity of rotor‐induced winds during landing is modeled at 0.4–0.6 m/s (factor of two uncertainty in this estimate), with higher winds required when the helicopter was over undisturbed terrain. Modeling dust mobilization from >5 m cruising altitude indicates mobilization by 0.3 m/s winds, suggesting nonsaltation mechanisms such as mobilization and destruction of dust aggregates. No dependence on background winds was seen for the initiation of dust lifting but one case of takeoff in 7 m/s winds created a track of darkened terrain downwind of the helicopter, which may have been a saltation cluster. When the helicopter was cruising at 5–6 m altitude, recirculation was seen in the dust clouds. Mars is a dusty planet with dusty atmosphere, and dust is a major factor in the weather. Weather events, from large storms to small dust devils, raise dust in their winds, but the conditions needed to lift the dust remain elusive. We used video of six flights of the Ingenuityhelicopter, taken by Mastcam‐Z on the Perseverancerover, to document when and where dust lifting occurred. We found that the helicopter sometimes kicked up dust when it was cruising >5 m above the surface, and that it always did so when it was 1.4–3.6 m above the surface as it landed. Some of the dust was likely lifted when the winds moved sand particles, and the sand dislodged the sticky dust, as in some current models. However, some dust lifting happened with lower winds, and likely happened when large aggregates of dust (sometimes called “dust bunnies”) were dislodged and broke up. Six flights of the Ingenuity helicopter were documented with video acquired by Mastcam‐Z on the Perseverance rover in Jezero crater, MarsDust mobilization was expected when the helicopter was below 1‐m altitude but was observed at low wind speeds from >5 m altitudeRecirculating dust clouds unexpectedly formed while the helicopter was at >5 m cruising altitude Six flights of the Ingenuity helicopter were documented with video acquired by Mastcam‐Z on the Perseverance rover in Jezero crater, Mars Dust mobilization was expected when the helicopter was below 1‐m altitude but was observed at low wind speeds from >5 m altitude Recirculating dust clouds unexpectedly formed while the helicopter was at >5 m cruising altitude

We use in situ environmental measurements by the Mars Science Laboratory (MSL) mission to obtain the surface energy budget (SEB) across Curiosity's traverse during the first 2500 sols of the mission. This includes values of the downwelling shortwave solar radiation, the upwelling solar radiation reflected by the surface, the downwelling longwave radiation from the atmosphere, the upwelling longwave radiation emitted by the surface, the sensible heat flux associated with turbulent motions, and the latent heat flux associated with water phase changes. We then analyze their temporal variation on different timescales and relate this to the mechanisms causing these variations. Through its Rover Environmental Monitoring Station, MSL allows for a more accurate determination of the SEB than its predecessors on Mars. Moreover, the unprecedented duration, cadence, and frequency of MSL environmental observations allow for analyses of the SEB from diurnal to interannual timescales. The results presented in this article can be used to evaluate the consistency with predictions from atmospheric numerical models, to validate aerosol radiative properties under a range of dust conditions, to understand the energy available for solar‐powered missions, and to enable comparisons with measurements of the SEB by the Perseverance rover at Jezero crater. The primary energy input at the Martian surface is the solar radiation, which depends on the time of the day and season, geographical location (latitude and altitude), and atmospheric dust and gas abundances. Another energy input is the thermal atmospheric forcing, which depends on the vertical distribution of dust and water ice aerosols as well as CO2and H2O molecules. Together with the reflected solar radiation and the thermal radiation emitted by the surface, these four terms make up the net radiative forcing of the surface. In response to it, energy outputs as turbulent motions and water phase changes emerge to cool down/warm up the ground. The remaining energy is available to control the thermal environment in the surface and shallow subsurface through conduction into the soil. By using first‐of‐their‐kind measurements from the Mars Science Laboratory mission, we calculate the energy inputs and outputs across Curiosity's traverse over the first 2500 Martian days of the mission. We then analyze their temporal variations and relate this to the mechanisms causing such variations. An accurate determination of the surface energy budget is key to preparing for the human exploration of Mars because it contributes to improvements in the predictive capabilities of numerical models. We have calculated each term of the surface energy budget during the first 2500 sols of the Mars Science Laboratory missionWe have analyzed the variation of each term from diurnal to interannual timescales in relation to the mechanisms causing the variationsOur results are important in preparation for the human exploration of Mars to evaluate the consistency with predictions from models We have calculated each term of the surface energy budget during the first 2500 sols of the Mars Science Laboratory mission We have analyzed the variation of each term from diurnal to interannual timescales in relation to the mechanisms causing the variations Our results are important in preparation for the human exploration of Mars to evaluate the consistency with predictions from models