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The Tropical Cloud Oscillation (TCO) in the Martian atmosphere is a shift of clouds in the northern spring and summer tropical cloud belt between the eastern and western hemispheres on an intra‐seasonal timescale of about 10–40 sols. The TCO is a significant intraseasonal variation and may strongly affect the Martian general circulation, water cycle, and dust cycle. We examine TCOs using multiple data sets with a focus on the clouds observed in Mars Daily Global Maps during Mars Year (MY) 29–35. One or more TCO cycles are observed in each MY and the phenomenon is most prominent during Ls = 135°–185°. Space‐time spectral analysis shows a variety of waves which appear to follow the theoretical dispersion relationships of equatorial waves, such as Kelvin waves, Rossby waves, and Mixed Rossby Gravity waves. The TCO appears to be controlled by zonal wavenumber one traveling waves with Kelvin and Rossby wave characteristics and exhibits a fine‐scale latitudinal structure that requires modeling with sufficient resolution. Issues with current data assimilation products for use in studies of Martian equatorial waves due to this fine‐scale structure are discussed. Plain Language Summary: During martian northern spring and summer, a relatively thick water ice cloud belt is observed in the tropics (approximately 25°S–25°N), which modifies large‐scale circulation, global water transport and the atmospheric dust cycle. We report on a Tropical Cloud Oscillation (TCO) that is a periodic shift in the thickness of this cloud belt between the eastern and western hemispheres on timescales (about 10–40 Mars days) longer than that of weather but shorter than that of seasons. Since the TCO involves changes in clouds and implies changes in circulation, it may also modulate the dust and water cycles. We examine TCOs using image data for Mars Year 29–35 (late 2007 through early 2021). One or more TCO cycles are observed in each Mars Year and the phenomenon is most prominent in late northern summer. A wide variety of atmospheric waves are found during TCOs; however, the most important are equatorial waves traveling eastward and westward with one peak and one trough around the planet. These waves have narrow latitudinal length scales and thus require high resolution numerical models to simulate and properly represent in data assimilation products. Key Points: The Martian tropical cloud belt exhibits eastern—western zonal oscillations that are most prominent in late northern summerTropical Cloud Oscillations are controlled by large‐scale low frequency equatorial Kelvin and Rossby wavesEquatorial wave dynamics may have an important effect on the Martian water and dust cycles [ABSTRACT FROM AUTHOR]

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]

We describe the model‐independent analysis technique of Mars Science Laboratory (MSL) pressure and Mars Climate Sounder (MCS) data in de la Torre Juárez et al. (2019, https://doi.org/10.22541/essoar.169945479.90436599/v1) that compared multiple years of surface pressures on Gale before, during, and after the Global Dust Storm of Mars Year 34. The analysis found (a) representative pressure scale heights over Gale; (b) that the storm was followed by a pressure deficit at Gale; (c) the following C storms did not eliminate the deficit; (d) changes in the duration of the polar caps condensation seasons, with an early start of the North Polar (NP) ice cap growing season the year before the Great Dust Storm (GDS) and a late signature of the end of the expansion season thereafter, changes consistent with a larger growth phase of the NP cap; (e) MCS observed a larger than usual NP cap; and (f) cold temperature anomalies over the NP and warm over the Southern Pole after the storm. We also show that the analysis of observed MSL pressure data alone filters out effects on the pressure signal that are attributable to dynamical and orographic processes in a recent model analysis that makes similar interpretations as our 2019 study. One additional Mars year of observations is included to eliminate early concerns about sensor drifts. Noting that a similar NP anomaly was observed with MCS data after the last early GDS in MY25, and not the later GDS of MY27, the results suggest a possible unique effect of early GDSs. Plain Language Summary: In 2018, Mars Year 34, Mars experienced a dust storm that encircled the whole planet and darkened its skies more than most storms in the recent past. Already in 2019 an analysis reported surface pressures below the climatological values observed over the previous 3 years in Gale Crater. The pressure deficit persisted into Mars Year 35 long after the end of the storm and dust over Gale had returned to levels from previous years. The storm coincided with a longer duration of the condensation season of the North Polar ice cap and a subsequent increase in its maximum amount of ice volume. We perform here a full analysis of five Mars Years of data showing how the duration of the polar caps sublimation/condensation seasons changed around the time of the storm, that the extension of the polar caps changed, and that the atmosphere above the North Pole was slightly colder than in years before the storm. Key Points: A technique to measure representative pressure scale heights at Gale enables tracking signatures of changes in the polar ice capsREMS surface pressure with Mars Climate Sounder observations are used to describe the polar processes after the great storm of Mars Year 34Multiannual pressure data show a short Southern Polar Cap growth season before the storm followed by a long Northern Polar Cap growth season [ABSTRACT FROM AUTHOR]

Martian dust lifting is believed to occur through two primary mechanisms: dust devils and wind stress forced dust lifting. Gale Crater's varied terrain and meteorology provide a unique in situ perspective on Martian dust lifting, with the Mars Science Laboratory Curiosity rover passing through both conditions and locations detrimental to dust lifting (e.g., the crater floor) and those with active sand motion and frequent dust lifting (e.g., the Bagnold Dunes). Between Ls = 248° in Mars Year 33 and Ls = 51° in Mars Year 37, over ∼3.5 Mars years and 2,300 sols, the rover's Navigation Cameras took 1,260 dedicated image sequences to search for dust lifting. Approximately 42.7% of all sequences, and 9.5% of the total images have shown active dust lifting, both dust devils and linear/straight‐line wind stress dust lifting. 79% of dust lifting events are classified as dust devils, while ∼16% are linear wind stress dust lifting and the remainder are of an indeterminate type. We analyze this large catalog of dust lifting events to provide ground truth on theoretical and model expectations of dust lifting and show that dust lifting in Gale Crater occurs throughout the Martian year, is strongly peaked in frequency near solar noon (even after accounting for observational biases), and that dust lifting shows an affinity for sand‐covered surfaces which highlights the importance of saltating sand grains for Martian dust lifting in both dust devils and wind stress forced lifting. Plain Language Summary: Airborne dust is an important control on the modern Martian climate. Dust is lifted into the air by two primary mechanisms: dust devils (rotating columns of air that are also common in dry areas on Earth) and the force of straight‐line winds acting on dust‐covered surfaces. The Mars Science Laboratory Curiosity rover Navigation Cameras have taken regular movies to search for dust lifting in the Gale Crater. Approximately 42.7% of all sequences, and 9.5% of the total images have shown active dust lifting and we analyze this large catalog of events to better understand the mechanisms and conditions that lift dust into the air on Mars. We find that dust lifting in Gale Crater is more strongly clustered near solar noon than previously expected from analyses of air pressure and that dust lifting often occurs on sand‐covered terrains, suggesting that the motion of sand grains across the surface supports dust lifting. Key Points: The Mars Science Laboratory Navigation Cameras have taken 1,260 dedicated image sequences searching for dust liftingApproximately 42.7% of all sequences and 9.5% of all images show active dust liftingDust lifting in the Gale Crater most frequently occurs on sand‐covered surfaces [ABSTRACT FROM AUTHOR]

The Mars 2020 Perseverance rover landed in Jezero crater on 18 February 2021. After a 100‐sol period of commissioning and the Ingenuity Helicopter technology demonstration, Perseverance began its first science campaign to explore the enigmatic Jezero crater floor, whose igneous or sedimentary origins have been much debated in the scientific community. This paper describes the campaign plan developed to explore the crater floor's Máaz and Séítah formations and summarizes the results of the campaign between sols 100–379. By the end of the campaign, Perseverance had traversed more than 5 km, created seven abrasion patches, and sealed nine samples and a witness tube. Analysis of remote and proximity science observations show that the Máaz and Séítah formations are igneous in origin and composed of five and two geologic members, respectively. The Séítah formation represents the olivine‐rich cumulate formed from differentiation of a slowly cooling melt or magma body, and the Máaz formation likely represents a separate series of lava flows emplaced after Séítah. The Máaz and Séítah rocks also preserve evidence of multiple episodes of aqueous alteration in secondary minerals like carbonate, Fe/Mg phyllosilicates, sulfates, and perchlorate, and surficial coatings. Post‐emplacement processes tilted the rocks near the Máaz‐Séítah contact and substantial erosion modified the crater floor rocks to their present‐day expressions. Results from this crater floor campaign, including those obtained upon return of the collected samples, will help to build the geologic history of events that occurred in Jezero crater and provide time constraints on the formation of the Jezero delta. Plain Language Summary: The Mars 2020 Perseverance rover, along with the Ingenuity Helicopter technology demonstration, landed in Jezero crater, Mars on 18 February 2021. Here, we detail results from the first science campaign of the mission, the purpose of which was to explore the enigmatic Jezero crater floor. By the end of the campaign, Perseverance traversed more than 5 km, created seven abrasion patches, and sealed a total of nine samples and a witness tube for return to Earth. Analysis of the rocks in the crater floor revealed two distinct geologic formations, named the Máaz and Séítah formations. Both formations were determined to be igneous in origin, the former likely from a series of lava flows and the latter formed from a slowly cooling melt or magma body. The composition of the Máaz and Séítah formation rocks also indicate that they experienced significant alteration from water in the past, consistent with Jezero crater having once been filled with water. Results from Perseverance's Jezero crater floor campaign, including those obtained upon return of the collected samples to Earth, will help build the geologic history of Jezero crater and reveal its past habitability. Key Points: The Máaz and Séítah formations are igneous, with Séítah representing olivine‐rich cumulates and Máaz representing separate lava flowsCrater floor rocks have been variably altered to produce carbonates and other alteration minerals during multiple aqueous episodesPost‐emplacement processes tilted these rocks near the Máaz‐Séítah contact, and erosion produced varied textures and olivine‐rich regolith [ABSTRACT FROM AUTHOR]

We utilize SuperCam's Mars microphone to provide information on wind speed and turbulence at high frequencies on Mars. To do so, we first demonstrate the sensitivity of the microphone signal level to wind speed, yielding a power law dependence. We then show the relationship between the microphone signal level and pressure, air and ground temperatures. A calibration function is constructed using Gaussian process regression (a machine learning technique) taking the microphone signal and air temperature as inputs to produce an estimate of the wind speed. This provides a high rate wind speed estimate on Mars, with a sample every 0.01 s. As a result, we determine the fast fluctuations of the wind at Jezero crater which highlights the nature of wind gusts over the Martian day. To analyze the turbulent behavior of this wind speed estimate, we calculate its normalized standard deviation, known as gustiness. To characterize the behavior of this high frequency turbulent intensity at Jezero crater, correlations are shown between the evaluated gustiness statistic and pressure drop rates/sizes, temperature and energy fluxes. This has implications for future atmospheric models on Mars, taking into account turbulence at the finest scales. Plain Language Summary: The NASA Perseverance mission sent microphones to the surface of Mars. This microphone has recorded signals due to the wind. We examine how these recorded signals vary with other sensor data from Perseverance, which shows a link between the microphone signal, the dedicated wind speed sensor and air temperature. Based on this finding, we develop a way to predict the wind speed from the microphone data using a machine learning technique. The microphone records data at a very high rate compared with sensors so far sent to Mars. This means that the wind speed predicted from the microphone data can be used to study the chaotic and variable wind behavior on Mars to a level never seen before. We show that this chaotic and variable behavior has links to temperature and the number of whirlwinds observed. This will lead us to better weather models for Mars. Key Points: Wind‐induced noise is observed by the SuperCam Mars microphone on PerseveranceMicrophone and air temperature data are used to estimate the wind speed at high frequencies, using a machine learning modelThe wind speed estimate is used to examine the relationships between turbulent intensity, pressure drops, temperature, and energy flux [ABSTRACT FROM AUTHOR]

Using Perseverance (Mars 2020) and Mars Science Laboratory (MSL) measurements, we obtain planetary waves with a period of 1.5–30 sols in the 1.5 m temperature, winds (Mars 2020), surface pressure, and relative humidity. Planetary waves emerge and propagate latitudinally across all variables. Short‐period waves peak at periods of ∼2, 3, and 4.5 sols, confirming previous detections of waves, and wave amplitudes agree at Mars 2020 and MSL for all variables. The simultaneous detection of waves within Gale and Jezero craters in multiple variables indicates that planetary‐scale dynamics influences many facets of local weather throughout the year. Multiple waves are correlated or anti‐correlated between MSL and Mars 2020, suggesting waves originate in both hemispheres. Further, waves at one site do not always lead the other, suggesting a combination of baroclinic and barotropic processes as wave sources, determined from the phasing of the temperature and winds in Jezero compared to the Ensemble Mars Atmospheric Reanalysis System. Plain Language Summary: Atmospheric waves on Mars can initiate large dust storms, so understanding their properties is critical for the safety of missions. The surface pressure, temperature, relative humidity, and winds of Gale and Jezero craters are analyzed by Mars Science Laboratory (MSL) and Mars 2020 to quantify the signal of planetary waves over the first few months of the Mars 2020 mission. Mars 2020 and MSL detect waves in all variables with frequencies similar to observations from orbit and elsewhere on the surface. Comparing waves from Mars 2020, MSL, and orbit will provide needed context for these waves to enable predictions of dust storms. Key Points: Both rovers observe 1.5–30 sol waves in multiple variables during northern spring with amplitudes agreeing with a reanalysisMars Science Laboratory (MSL) and Mars 2020 observations alternatively correlate and anti‐correlate, pointing to planetary waves originating in different hemispheresNorth‐south propagating waves vacillate between first occurring at MSL or Mars 2020, suggesting waves grow from multiple types of instabilities [ABSTRACT FROM AUTHOR]

Acoustics is new on Mars: it allows the characterization of turbulence at smaller scales than previously possible within the lowest part of the Planetary Boundary Layer. Sound speed measurements, by the SuperCam instrument and its microphone onboard the NASA Perseverance rover, allow the retrieval of atmospheric temperatures at 0.77 m above the ground, at 3 Hz, with a ∼10 ms response time that is 20–100 times shorter than for typical thermocouple sensors used on Mars. Here we report on the first measurements of the sound speed‐derived temperature and its fluctuations near the surface. Data highlight large and rapid fluctuations up to ±7 K/s, whose amplitude over such a timescale has never been reported, nor predicted by atmospheric models. These fluctuations follow the daytime pattern of the turbulence and highlight occasional high amplitude events that are likely due to the conjunction of low thermal inertia and strong winds. Plain Language Summary: The atmospheric surface layer of Mars, is prone to various interactions between the surface and the atmosphere, which control most of the climate and the weather of the red planet. There, large temperature gradients generate an intense turbulence during the daytime. Hence, the measurement of the air temperature variations close to the surface is important to understand the spatial and temporal scales of this turbulence. The SuperCam instrument onboard the NASA Perseverance rover enables the retrieval of the near‐surface atmospheric temperatures, and their fluctuations, at an unprecedented short timescale. Sound speed‐derived temperatures, also call sonic temperatures, collected over the Northern spring and summer of Martian Year 36 reveal large and rapid thermal fluctuations up to ±7 K/s, whose amplitude over such a timescale is not reported by any weather station sensors, nor predicted by models that simulate small‐scale eddies. These fluctuations follow the daytime pattern of the turbulence with a maximum amplitude early afternoon. Some occasional high temperature fluctuation events are observed, suggesting a complex effect of ground properties and local meteorological conditions on the turbulence. Overall, acoustics is a new and promising technique that records a unique view of atmospheric temperature variations near the surface of Mars. Key Points: Sound speed derived temperature is used to study the microscale turbulence at an unprecedented short response timeAir temperature experiences fluctuations as high as ±7 K/s, which has never been reported in situ, nor resolved by mesoscale atmospheric modelsSonic temperature fluctuations follow the daytime turbulence pattern and find their origin in complex surface‐atmosphere interactions [ABSTRACT FROM AUTHOR]

Gale crater, the field site for NASA's Mars Science Laboratory Curiosity rover, contains a diverse and extensive record of aeolian deposition and erosion. This study focuses on a series of regularly spaced, curvilinear, and sometimes branching bedrock ridges that occur within the Glen Torridon region on the lower northwest flank of Aeolis Mons, the central mound within Gale crater. During Curiosity's exploration of Glen Torridon between sols ∼2300–3080, the rover drove through this field of ridges, providing the opportunity for in situ observation of these features. This study uses orbiter and rover data to characterize ridge morphology, spatial distribution, compositional and material properties, and association with other aeolian features in the area. Based on these observations, we find that the Glen Torridon ridges are consistent with an origin as wind‐eroded bedrock ridges, carved during the exhumation of Mount Sharp. Erosional features like the Glen Torridon ridges observed elsewhere on Mars, termed periodic bedrock ridges (PBRs), have been interpreted to form transverse to the dominant wind direction. The size and morphology of the Glen Torridon PBRs are consistent with transverse formative winds, but the orientation of nearby aeolian bedforms and bedrock erosional features raise the possibility of PBR formation by a net northeasterly wind regime. Although several formation models for the Glen Torridon PBRs are still under consideration, and questions persist about the nature of PBR‐forming paleowinds, the presence of PBRs at this site provides important constraints on the depositional and erosional history of Gale crater. Plain Language Summary: Wind has played a major role in sculpting the surface of Mars. Gale crater, the field site for NASA's Mars Science Laboratory Curiosity rover since it landed there in 2012, contains a vast and varied record of deposition and erosion by the wind. This study focuses on a series of regularly spaced, generally straight bedrock ridges that occur within the clay‐bearing Glen Torridon region of Aeolis Mons (informally named Mount Sharp) in Gale crater. During Curiosity's exploration of the Glen Torridon region between sols ∼2300–3080 of the mission, the rover drove through this field of ridges, acquiring images and compositional observations along the way. This study characterizes the Glen Torridon ridges using orbiter and rover data to determine their shape, size, occurrence, and relationship to other wind‐formed features in the area. We find that the Glen Torridon ridges were carved by wind into the bedrock of Mount Sharp. Questions remain about the winds that formed these ridges, but this study provides important information about the history and environment of Gale crater and reports the first rover observations of this type of erosional feature on Mars. Key Points: Decameter‐long, regularly spaced bedrock ridges oriented northeast‐southwest occur throughout the Glen Torridon region of Aeolis MonsGlen Torridon ridges cross‐cut elevation contours and bedding, exhibit bifurcations, and are disrupted by small impact cratersGlen Torridon ridges are erosional periodic bedrock ridges whose formation places erosional and depositional constraints on Aeolis Mons [ABSTRACT FROM AUTHOR]

A suite of high resolution cameras onboard the Mars Science Laboratory (MSL) Curiosity rover have provided an unparalleled look at active aeolian processes on Mars, including within the first active dune field explored on another planet, the Bagnold Dunes. Here we present results from a subset of MSL's repeat imaging ("change detection") experiments with temporal resolutions sufficient to probe the diurnal variability in winds within Gale crater. Images reveal that saltation is a near‐daily phenomenon during southern summer, with repeatable diurnal circulation patterns producing steady impact ripple migration toward the west/southwest. Nighttime fluxes are inferred to be ∼four times larger than daytime fluxes, consistent with predictions from the MarsWRF model of multiple periods of enhanced wind between sunset and sunrise. Multiple factors are likely facilitating saltation at this time: (a) time‐averaged nighttime winds have a higher degree of variance (i.e., higher peak friction speeds) than daytime winds, (b) interactions between regional Hadley flows and local, thermally driven slope winds cause increased turbulence at night, and (c) relatively higher atmospheric density produces correspondingly higher shear stresses and decreases critical thresholds. Observations of sand transport at a range of spatiotemporal scales (down to scale of individual particles moving on the timescale of seconds) support the idea that bedform migration is driven by intermittent, low‐flux saltation events when winds fluctuate between canonical impact and fluid thresholds. Yet, whereas gustiness may play a role in initiating transport, saltation is found to be highly predictable on diurnal timescales and is only stochastic on the shortest timescales characteristic of turbulent fluctuations in wind. Plain Language Summary: Repeat "change detection" imaging experiments performed using cameras onboard the Mars Science Laboratory Curiosity rover have provided a rare look at active wind‐blown sand movement on Mars. Rover images acquired during local summer reveal near‐daily migration of sand ripples toward the west/southwest. Ripple migration is inferred to occur predominately between sunset and sunrise each sol, based on the observation of ∼four times more sand transport at night than during the day. In lieu of in situ meteorological data, predictions from the MarsWRF atmospheric model are used to interpret the circulation patterns responsible for sand transport. Close comparison between the model and observations suggests that dunes and ripples in the vicinity of the rover's traverse are being shaped by a unique combination of regional circulation patterns and local slope winds. Close examination of sand movement (down to the scale of individual sand grains) helps shed light on the physics of sand transport under natural Martian conditions and decipher possible differences between wind‐driven landscape modification on Earth and Mars. Key Points: Curiosity rover images have enabled the examination of aeolian transport on smaller spatiotemporal scales than achieved previously on MarsRecurring nighttime circulation patterns generate near‐daily impact ripple migration along the rover's traverse during local summerRipple morphodynamics are consistent with intermittent, low‐flux saltation driven by winds between traditional impact and fluid thresholds [ABSTRACT FROM AUTHOR]

We present interannual, seasonal, and regional variations in the daytime Martian convective boundary layer (CBL). Martian CBL meteorology is driven both by the effect of diurnal and seasonal cycles as well as complex Martian topography. One of the most important components of the Martian atmosphere is its dust cycle. Here, we develop a novel semi‐interactive dust transport model within the MarsWRF framework, in which the dust is lifted, advected by model winds, mixed, and allowed to sediment, but is then scaled to match two‐dimensional maps of the observed daily column‐integrated dust opacity. This allows the vertical dust distribution and associated dust radiative heating to be controlled by model processes, while the horizontal dust distribution is constrained to follow observations. We report the impact of the dust cycle on Martian boundary layer meteorology. Enhanced dust transport lowers the global net surface heating rates, decreasing the turbulent mixing in CBL to virtually zero (within the dust storm season) and, enhances the wind shear on average by almost 50%. As a superposition of both impacts, during global dust storms (GDS) in Mars Year (MY) 25 and 34, we find that long‐lasting extremely shallow daytime boundary layers can globally form as shallow as 0.5 km (but not for the less intense GDS in MY 28), unlike the 9 km deep and highly turbulent CBL formation at GDS onset and decay. Based on our GCM results, strong CBL suppression lasts as long as approximately 67 and 57 sols during GDS events in MY 25 and 34. Plain Language Summary: In recent years, thanks to the ongoing lander and rover missions, in situ observations of Martian surface processes (water, dust, and methane transport) have been attracting more attention, especially to search for the signatures of the planet's habitability. From this emerges the significance of planetary boundary layer dynamics, which is the key governor of surface exchange processes in the lowermost portion of the atmosphere. Although the current knowledge has been advancing by observing diurnal characteristics for specific locations, seasonal and year‐to‐year variations on a global scale are still less well comprehended. Here, we examine year‐to‐year, seasonal, and regional variabilities of the Martian daytime planetary boundary layer (so‐called convective boundary layer governed by daytime radiative heating), assessing a decade‐long general circulation model (GCM) simulation from Mars Year 24–34. Our results show that global dust storms in Mars Years 25 and 34 have profound impacts on the convective boundary layer, causing a severe surface cooling as a long‐term global‐darkness state, thus resulting in a global weakening in convective activity. We find that deep and highly turbulent convective boundary layers (with a depth of 9 km) convert into extremely shallow (0.5 km) boundary layers even during the daytime, as a consequence of global dust storms. Key Points: A novel semi‐interactive dust transport model is developed within the MarsWRF general circulation model (GCM) frameworkWe report strong interannual, seasonal, and regional variations in the Martian convective boundary layer (CBL)Our GCM results show a long‐lasting extremely shallow daytime boundary layer during global dust storms [ABSTRACT FROM AUTHOR]

Large eddy simulation (LES) of the Martian convective boundary layer (CBL) with a Mars‐adapted version of the Weather Research and Forecasting model is used to examine the impact of aerosol dust radiative‐dynamical feedbacks on turbulent mixing. The LES is validated against spacecraft observations and prior modeling. To study dust redistribution by coherent dynamical structures within the CBL, two radiatively active dust distribution scenarios are used: one in which the dust distribution remains fixed and another in which dust is freely transported by CBL motions. In the fixed dust scenario, increasing atmospheric dust loading shades the surface from sunlight and weakens convection. However, a competing effect emerges in the free dust scenario, resulting from the lateral concentration of dust in updrafts. The resulting enhancement of dust radiative heating in upwelling plumes both generates horizontal thermal contrasts in the CBL and increases buoyancy production, jointly enhancing CBL convection. We define a dust inhomogeneity index (DII) to quantify how much dust is concentrated in upwelling plumes. If the DII is large enough, the destabilizing effect of lateral heating contrasts can exceed the stabilizing effect of surface shading such that the CBL depth increases with increasing dust optical depth. Thus, under certain combinations of total dust optical depth and the lateral inhomogeneity of dust, a positive feedback exists between dust optical depth, the vigor and depth of CBL mixing, and—to the extent that dust lifting is controlled by the depth and vigor of CBL mixing—the further lifting of dust from the surface. Plain Language Summary: We use a very high‐resolution atmospheric model (Mars‐adapted version of the Weather Research and Forecasting model) to study the interaction between dust and turbulent motions at the bottom of the Martian atmosphere. The model is validated against satellite observations and previously validated model results. Two types of experiment are conducted to test the effect of the horizontal dust distribution. With horizontally uniform dust levels, increasing the total dust amount reduces solar heating reaching the surface and thus cools the surface and weakens upward motions. However, if the dust is allowed to move horizontally in the region, upward‐moving air tends to concentrate the dust and these plumes hence become dustier than average. Dust contained in the upward plumes is then heated by the Sun, increasing the speed of upward motion. Thus, the stronger temperature differences may result in faster upward plumes as the amount of atmospheric dust increases. Stronger vertical plumes require stronger horizontal motions at the surface, due to mass conservation within a convection cell. These stronger surface winds may lead to greater dust lifting, and thus this study suggests that dust storms on Mars may grow in their early stages through a natural positive feedback between dust inhomogeneity, radiative heating, and accelerated winds. Key Points: Dust radiative‐dynamical feedback upon turbulent mixing in the Martian convective boundary layer is demonstrated by Large Eddy SimulationThe destabilizing effect of dust lateral heating contrasts is found to augment convection and deepen the boundary layerUnder some circumstances a positive feedback may exist between dust radiative heating, the intensity of boundary layer mixing, and dust lifting [ABSTRACT FROM AUTHOR]

Surface pressure measurements on Mars have revealed a wide variety of atmospheric phenomena. The Mars Science Laboratory Rover Environmental Monitoring Station pressure sensor data set is now the longest duration record of surface pressure on Mars. We use the first 2580 Martian sols, nearly 4 Mars years, of measurements to identify atmospheric pressure waves with periods of tens of minutes to hours using wavelet analysis on residual pressure after the tidal harmonics are removed. We find these waves have a clear diurnal cycle with strongest activity in the early morning and late evening and a seasonal cycle with the strongest waves in the second half of the martian year (Ls = 180–360°). The strongest such waves of the entire mission occurred during the Mars Year 34 global dust storm. Comparable atmospheric waves are identified using atmospheric modeling with the MarsWRF general circulation model in a "nested" high spatial resolution mode. With the support of the modeling, we find these waves best fit the expected properties of inertia‐gravity waves with horizontal wavelengths of O(100s) of km. Plain Language Summary: Measuring air pressure from the surface of Mars has revealed a wide variety of atmospheric phenomena. The Curiosity rover's record or surface air pressure is now the longest yet made on Mars. We use the first ∼8 years of Curiosity's pressure observations to look for atmospheric waves with periods of tens of minutes to hours. We find these waves have a clear pattern in their daily behavior with the strongest activity in the early morning and late evening and a seasonal cycle with the strongest waves in the second half of the Martian year (Northern hemisphere fall and winter). The strongest of such waves occurred in 2018 during a global dust storm. We find comparable waves in atmospheric modeling. With the support of modeling, we find these waves best fit the expected properties of buoyancy waves forced by airflow over topography with horizontal wavelengths of 100–1,000 km. Key Points: We detect atmospheric pressure waves with periods of tens of minutes to 3 h with Mars Science Laboratory Rover Environmental Monitoring Station observationsWe find comparable waves in mesoscale atmospheric simulations with the MarsWRF general circulation modelBased on their characteristics, we interpret waves with periods greater than 1 h as topographically forced inertia‐gravity waves [ABSTRACT FROM AUTHOR]

The Mars Science Laboratory rover (Curiosity) has monitored the line‐of‐sight extinction within Gale Crater since mission sol 100 (16 November 2012, MY 31 Ls 208°) with Navcam and since mission sol 1,187 (8 December 2015, MY 33 Ls 79°) with the color imager, Mastcam. This work reports 1,375 sols (>2 MYs) of line‐of‐sight extinction monitoring within Gale Crater with Mastcam and updates the Navcam line‐of‐sight extinction record to sol 2,556 (15 October 2019, MY 35 Ls 93°). A cyclical pattern with one or more peaks in the dusty season (Ls∼180–360°) and a trough in the less‐dusty season (Ls∼0–180°) was observed with both imagers and the results from Mastcam red and Navcam agree well. Green and blue filter Mastcam data show generally lower extinction than in the red filter data. Extinction as a function of azimuth and elevation angle were investigated and the extinction as a function of azimuth was generally found to be smooth and thus the dust well‐mixed horizontally. The extinction as a function of elevation shows increased dust loading at lower elevations during dusty seasons, indicative of dust lifting from the base of the crater. Plain Language Summary: The Curiosity rover has been taking images of the northern rim of Gale Crater, Mars, since 100 Mars days after landing (16 November 2012) with its single‐color Navigational camera and since 1,187 Mars days after landing (8 December 2015) with the Mastcam full‐color camera. Using these images, we can infer how much dust there is between the rover and the edge of the crater. Over the course of the mission, the results from both cameras agree well, showing an increase in dust during the Southern Hemisphere summer and a drop in dust during the Southern Hemisphere winter. Looking at the mixing of dust inside Gale Crater, it appears that the dust is well‐mixed horizontally, but there is evidence of more dust closer to the crater floor in some seasons, which could mean that dust is being lifted off the crater floor. Key Points: 1,375 sols of Mastcam‐derived line‐of‐sight extinction within Gale Crater are presented along with updates to the Navcam extinction recordA cyclical pattern with one or more peaks in the dusty season and a trough in the less‐dusty season was observed with both camerasExtinction suggests increased dust loading at lower elevations during dusty seasons, indicative of lifting or external introduction of dust [ABSTRACT FROM AUTHOR]

The upper bound of 50 parts per trillion by volume for Mars methane above 5 km established by the ExoMars Trace Gas Orbiter, substantially lower than the 410 parts per trillion by volume average measured overnight by the Curiosity Rover, places a strong constraint on the daytime methane flux at the Gale crater. We propose that these measurements may be largely reconciled by the inhibition of mixing near the surface overnight, whereby methane emitted from the subsurface accumulates within meters of the surface before being mixed below detection limits at dawn. A model of this scenario allows the first precise calculation of microseepage fluxes at Gale to be derived, consistent with a constant 1.5 × 10−10 kg·m−2·sol−1 (5.4 × 10−5 tonnes·km−2·year−1) source at depth. Under this scenario, only 2.7 × 104 km2 of Mars's surface may be emitting methane, unless a fast destruction mechanism exists. Plain Language Summary: The ExoMars Trace Gas Orbiter and the Curiosity Rover have recorded different amounts of methane in the atmosphere on Mars. The Trace Gas Orbiter measured very little methane (<50 parts per trillion by volume) above 5 km in the sunlit atmosphere, while Curiosity measured substantially more (410 parts per trillion by volume) near the surface at night. In this paper we describe a framework which explains both measurements by suggesting that a small amount of methane seeps out of the ground constantly. During the day, this small amount of methane is rapidly mixed and diluted by vigorous convection, leading to low overall levels within the atmosphere. During the night, convection lessens, allowing methane to build up near the surface. At dawn, convection intensifies and the near‐surface methane is mixed and diluted with much more atmosphere. Using this model and methane concentrations from both approaches, we are able—for the first time—to place a single number on the rate of seepage of methane at Gale crater which we find equivalent to 2.8 kg per Martian day. Future spacecraft measuring methane near the surface of Mars could determine how much methane seeps out of the ground in different locations, providing insight into what processes create that methane in the subsurface. Key Points: Nighttime SAM‐TLS seasonal cycle enrichment measurements and TGO sunset/sunrise measurements are not in oppositionMicroseepage fluxes must be local to Gale, range from 0.82 to 4.6 kg/sol, and are consistent with a constant source at depthLittle of Mars experiences microseepage unless a fast destruction mechanism exists or Gale is very unusual [ABSTRACT FROM AUTHOR]

Abstract: Orbiter‐based observations have demonstrated that active aeolian environments are ubiquitous across Mars. Here we examine one such environment, the Bagnold Dune Field in Gale crater, with repeat imaging campaigns conducted from Curiosity during southern summer. Images reveal widespread migration of aeolian impact ripples (up to 2.8 cm/sol), which is in stark contrast to the inactivity of similar bedforms during southern winter. The winds responsible for steady southwestward migration of ripples are consistent with predictions of regional‐scale flows that enter the crater from the north and interact with the topography of Mount Sharp but are not fully representative of all dune‐forming winds. Inferred friction speeds of 1.5 m/s needed to explain mobilization of bedforms are likely not being achieved, and thus, a majority of sediment transport may be taking place at subthreshold conditions. This hypothesis is further supported by sand flux estimates that suggest a low saltation flux environment within the dune field. [ABSTRACT FROM AUTHOR]

A cationic bis-imidazolium-based amphiphile was used to form thermoreversible nanostructured supramolecular hydrogels incorporating neutral and cationic drugs for the topical treatment of rosacea. The concentration of the gelator and the type and concentration of the drug incorporated were found to be factors that strongly influenced the gelling temperature, gel-formation period, and overall stability and morphology. The incorporation of brimonidine tartrate resulted in the formation of the most homogeneous material of the three drugs explored, whereas the incorporation of betamethasone resulted in a gel with a completely different morphology comprising linked particles. NMR spectroscopy studies proved that these gels kept the drug not only at the interstitial space but also within the fibers. Due to the design of the gelator, drug release was up to 10 times faster and retention of the drug within the skin was up to 20 times more effective than that observed for commercial products. Experiments in vivo demonstrated the rapid efficacy of these gels in reducing erythema, especially in the case of the gel with brimonidine. The lack of coulombic attraction between the gelator-host and the guest-drug seemed particularly important in highly effective release, and the intermolecular interactions operating between them were found to lie at the root of the excellent properties of the materials for topical delivery and treatment of rosacea. [ABSTRACT FROM AUTHOR]

Aim A Delphi survey was undertaken to refine the position description of a registered nurse working in a forensic hospital, in New South Wales, Australia. Background Prior to commencing operation in 2008, position descriptions were developed from a review of legislation, as well as policies and procedures used by existing forensic mental health services in Australia. With an established workforce and an evolving model of care, a review of the initial registered nurse position description was required. Method An online Delphi survey was undertaken. Eight executive (88.9%) and 12 (58.3%) senior nursing staff participated in the first survey round. A total of four survey rounds were completed. Results At the final round, there was consensus (70%) that the revised position description was either very or somewhat suitable. There were a total of nine statements, from 31 originally produced in round 1, that did not reach consensus. Conclusions The Delphi survey enabled a process for refining the Forensic Hospital registered nurse position description. Implications for nursing management Methods that facilitate executive and senior nursing staff consensus in the development and review of position descriptions should be considered in nursing management. [ABSTRACT FROM AUTHOR]

Aim This study evaluated a framework for nursing managers which entailed supporting and challenging participants to critically analyse the effectiveness of their workplace behaviours in facilitated discussion groups using context-laden real-life scenarios. Background Leadership development in nursing managers has been shown to reduce burnout and promote workplace satisfaction. Method Ninety per cent of nursing managers ( n = 63) employed in the organisation participated in the study. Data relating to burnout, workplace satisfaction and leadership practices were collected prior to and after participation in the support and challenge framework. Qualitative feedback was sought through a survey administered at follow-up. Result Nursing Unit Managers were significantly less satisfied in their intrinsic domain of workplace satisfaction at follow-up. Qualitative feedback indicated that participants experienced benefits related to networking, personal development and role development. Conclusion The experience of critiquing and challenging leadership when shared with peers who practice in a similar context was qualitatively reported as beneficial and valuable, in spite of a decrease in workplace satisfaction. Implications for nursing management Nursing manager's leadership development is a continuous process. Supporting and challenging nursing managers is likely to generate uncertainty related to self and role. The sharing and testing of this uncertainty with peers is welcomed and warrants further exploration. [ABSTRACT FROM AUTHOR]

TOPIC: The next iteration of the Diagnostic and Statistical Manual of Mental Disorders is due for release in May 2013. The current diagnostic criteria for autism are based on a behavioral triad of impairment, which has been helpful for diagnosis and identifying the need for intervention, but is not useful with regard to developing interventions. Revised diagnostic criteria are needed to better inform research and therapeutic intervention. PURPOSE: This article examines the research underpinning the behavioral triad of impairment to consider alternative explanations and a more useful framing for diagnosis and intervention. SOURCES: Contemporary research and literature on autism were used in this study. CONCLUSIONS: It is proposed that the cognitive processing triad of impaired abstraction, impaired theory of mind, and impaired linguistic processing become the triad of impairment for autism in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders. These are investigable at the diagnostic level and can usefully inform intervention. Further, in addressing the debate on whether restrictive and repetitive behavior should remain central to diagnosis or be replaced by a deficit in imagination, the authors argue that both behavioral manifestations are underpinned by impaired abstraction. [ABSTRACT FROM AUTHOR]

There is a paucity of research in the area of nurse engagement in the process of practice development. Little is published about the sequencing of engagement with consent and pre-measures in a research project. It has, however, been recognized that without engagement, development of one's practice, and subsequently health service change, would be minimal. This article reports on nurse engagement in the first six weeks of the implementation of a new model of care in two correctional service health care settings. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]