This review provides an analysis of activities undertaken by the Mars 2020 Council of Atmospheres (CoA) in support of the entry, descent, and landing (EDL) of the Mars 2020 rover Perseverance in Jezero crater, Mars. The activities of the CoA were designed to evaluate the safety of early-stage landing site candidates and, later, to constrain the range of plausible conditions expected at Jezero crater during the early northern spring season of EDL, following the successful blueprint of similar councils for prior landed Mars missions. The multiyear effort of the CoA involved using a combination of numerical modeling of the local Martian atmosphere with limited-domain mesoscale models and atmospheric reanalysis using data assimilation techniques, along with atmospheric observations from multiple orbiting assets, to generate an atmospheric “forecast” for the day of landing. Here we present an overview of these activities, focusing in greater detail on those elements that depart from prior CoA activities as performed for Mars Phoenix, Mars Science Laboratory, and the InSight lander. Following the successful landing of Perseverance on 2021 February 18, reconstruction and reassessment activities were performed and are presented here, comparing prelanding predictions with actual, as-flown conditions.

Daily, global wide angle imaging of Mars clouds in MARCI (MARs Color Imager, (Malin et al., 2008)) ultraviolet and visible bands reveals the spatial/seasonal distributions and physical characteristics of perihelion cloud trails (PCT); a class of high altitude (40-50 km), horizontally extended (200-1000 km, trending W to WSW) water ice clouds formed over specific southern low-to-mid latitude (5S-40S), mesoscale (~50 km) locations during the Mars perihelion, southern summer season. PCT were first reported in association with rim regions of Valles Marineris (Clancy et al., 2009). The current study employs MARCI 2007-2011 imaging to sample the broader distributions and properties of PCT; and indicates several distinct locations of peak occurrences, including SW Arsia Mons, elevated regions of Syria, Solis, and Thaumasia Planitia, along Valles Marineris margins, and the NE rim of Hellas Basin. PCT are present over Mars solar longitudes (LS ) of 210-310°, in late morning to mid afternoon hours (10am-3pm), and are among the brightest and most distinctive clouds exhibited during the perihelion portion of the Mars orbit. Their locations (i.e., eastern margin origins) correspond to strong local elevation gradients, and their timing to peak solar heating conditions (perihelion, subsolar latitudes and midday local times). They occur approximately on a daily basis among all locations identified (i.e., not daily at a single location). Based on cloud surface shadow analyses, PCT form at 40-50 km aeroid altitudes, where water vapor is generally at near-saturation conditions in this perihelion period (e.g. Millour et al., 2014). They exhibited notable absences during periods of planet encircling and regional dust storm activity in 2007 and 2009, respectively, presumably due to reduced water saturation conditions above 35-40 km altitudes associated with increased dust heating over the vertically extended atmosphere (e.g., Neary et al., 2019). PCT exhibit smaller particle sizes (R eff =0.2-0.5μm) than typically exhibited in the lower atmosphere, and incorporate significant fractions of available water vapor at these altitudes. PCT ice particles are inferred to form continuously (over ~4 hours) at their PCT eastern origins, associated with localized updrafts, and are entrained in upper level zonal/meridional winds (towards W or WSW with ~50 m/sec speeds at 40-50 km altitudes) to create long, linear cloud trails. PCT cloud formation is apparently forced in the lower atmosphere (≤10-15 km) by strong updrafts associated with distinctive topographic gradients, such as simulated in mesoscale studies (e.g., Tyler and Barnes, 2015) and indicated by the surface-specific PCT locations. These lower scale height updrafts are proposed to generate vertically propagating gravity waves (GW), leading to PCT formation above ~40 km altitudes where water vapor saturation conditions promote vigorous cloud ice formation. Recent mapping of GW amplitudes at ~25 km altitudes, from Mars Climate Sounder 15 μm radiance variations (Heavens et al., 2020), in fact demonstrates close correspondences to the detailed spatial distributions of observed PCT, relative to other potential factors such as surface albedo and surface elevation (or related boundary layer depths).

We investigate the behavior of the Martian daytime convective boundary layer (CBL) through a combination of data analysis and modeling. This study relies on two subsets of Mars Express radio occultation (RO) measurements that sounded the atmosphere in northern spring of successive Mars years. Only the first year of observations has been examined previously (Hinson et al., 2008); the second year provides complementary spatial coverage and greatly increases the total number of observations. Analysis of the RO profiles yields basic characteristics of the CBL, such as its depth D and the average potential temperature of the mixed layer theta(m). We also combine RO retrievals of surface pressure with surface temperatures from infrared sounding to characterize the surface forcing, expressing the result as a potential temperature O. These observations are at local times in early afternoon for e s and late afternoon for theta(m) and D, when each parameter is near its diurnal maximum. We use measurements at mid-to-low latitudes, which sample a wide range of theta(s) (227-294 K), to determine the response of the lower atmosphere to spatial variations in surface forcing. The depth of the CBL ranges from less than 3 km in the midlatitude topographic basins to more than 9 km above elevated terrain in the tropics. The dependence of theta(m) on theta(s) is linear, with a characteristic slope of about 0.7 in both years. We gain further insight by performing a simulation with the Oregon State University Mars Mesoscale Model in a region centered on Isidis Planitia, which includes two potential landing sites for the Mars 2020 Rover. As expected from previous modeling of much smaller craters, the arc of steep topography along the western and southern margins of Isidis produces a distinctive, diurnally varying, mesoscale circulation. The simulation captures key features of the observations, such as the wide variations in theta(m) and D - by 34 K and 9 km, respectively - that occur within this region. The model also accounts for peculiar features of RO profiles on the rim of Isidis, where the wind field strongly influences the depth and diurnal evolution of the CBL. Detailed comparisons with the observations validate the general performance of the model and confirm several aspects of the simulated wind field.

The Advanced Metering Infrastructure (AMI) is a major component of the Smart Grid. Researchers have been working to protect its communication by designing protocols that offer security and privacy in various ways to different extents. Simulation testing is a crucial part of any communication protocol development. Current simulation frameworks for power Grid experiments primarily focus on simulating the electrical components and power flow in the Grid. In this paper, we introduce a uniform AMI simulation (AMIsim) framework for evaluating secure and privacy-preserving AMI protocols. AMIsim allows researchers to conduct a performance assessment of their application-layer security protocols that are used for aggregation, privacy-preservation, and confidentiality/integrity protection of smart meter energy data. We report on the empirical results of conducting experiments in AMIsim with an existing AMI secure and privacy-preserving protocol.

In this review, we address the use of numerical computations called Large-Eddy Simulations (LES) to study dust devils, and the more general class of atmospheric phenomena they belong to (convective vortices). We describe the main elements of the LES methodology. We review the properties, statistics, and variability of dust devils and convective vortices resolved by LES in both terrestrial and Martian environments. The current challenges faced by modelers using LES for dust devils are also discussed in detail.

The Mars 2020 (M2020) Council of Atmospheres (CoA) is a joint engineering and science team that is tasked with assessing atmospheric risk associated with entry, descent and landing (EDL). This paper presents the teams, tools, and processes involved in generating the atmospheric data that are used in EDL performance simulations. The overall methodology used by the M2020 CoA is largely the same as the Mars Science Laboratory CoA [1]. Mars Mesoscale Model 5 (MMM5) at Oregon State University and Mars Regional Atmospheric Modeling System (MRAMS) at the Southwest Research Institute are mesoscale models that generate atmospheric parameters, such as wind and density profiles, at the candidate landing sites and at the time of M2020 EDL. Preliminary analysis shows that atmospheric conditions at the candidate landing sites do not significantly affect EDL performance. In fact, simulating EDL with mesoscale winds, instead of generic engineering winds, produces smaller landing ellipses. The M2020 CoA is preparing for the third landing site workshop in January 2017 by evaluating the candidate landing sites at nominal atmospheric conditions, assessing the affects of dust events on EDL performance, and tuning the mesoscale models as more data is received.

Modeling of slope flow circulations in idealized axisymmetric craters is used to understand (1) the large surface pressure amplitude observed in Gale Crater by the Rover Environmental Monitoring Station and (2) the shallow convective boundary layer (CBL) suggested by Curiosity imagery. Air temperatures vary within craters with greater amplitudes than outside them, becoming warmer/colder during day/night. This crater circulation effect is most significant over the depth of the crater (key parameter). Within the idealized craters, a surface pressure cycle develops (in the real atmosphere it is enhanced). Partially caused by thermal expansion, a “surge” of mass away from the craters develops during daytime. Over crater floors, the CBL depth is inhibited by a capping inversion from the adiabatic warming of widespread daytime subsidence. For a variety of craters (radius, depth, and with or without a central mound), the results are very similar. In real‐atmosphere simulations over canyons or large basins, similar circulations are seen.

For a key season in the annual water cycle (1., 1200) a mesoscale model is used to study atmospheric water vapor and water ice clouds in the northern polar region of Mars. Model results at high-resolution (15 km) allow the examination of various mesoscale aspects of the circulation in this complex (topography, albedo and thermal inertia) region. A simple cloud scheme is used, where only the mean cloud particle size is carried, and nucleation is not explicitly treated. For this study, new high-resolution maps of albedo and thermal inertia were developed (poleward of 60 N), and model ground temperatures are in good agreement with observations at high resolution, typically within 5 K of TES (for ice and non-ice locations at AM and PM times of day). Diurnal mean sublimation rates are greatest along the edges of the polar dome and the largest outliers (-25-50 gm/sol). This is a consequence of widespread stability (atmospheric inversion) over the cold interiors of the largest ice surfaces, as well as strong ventilating winds that are modeled around the polar dome with sufficient spatial resolution. The structure of high latitude atmospheric water vapor is complex, especially so near Phoenix. Dynamically, two factors are responsible: (1) the transient circulations that form in the baroclinic zone around the polar dome and (2) a "storm zone" that forms on the poleward slopes of Alba Patera where there is additional transient activity that has a sizeable effect on the Phoenix region. This "storm zone" forms because of a rapidly evolving aspect of the regional circulation, and it plays a key role in the seasonally recurring annular cloud (that is simulated in this study). Also simulated are observations made during the Phoenix mission that seem to be dynamically related to the appearance of the annular cloud. Together this may signify a seasonal transition in the region. To simulate realistic clouds over the polar region (compared with opacity observations and imagery), a sufficiently realistic circulation appears to be important, and relatively high spatial resolution is needed for this. If a low-resolution run (135 km, no nests) is compared to a highresolution run (two levels of nesting to 15 km in the polar region), we find that the high-resolution case produces ten times less cloud ice over the most polar latitudes. The activation of the first nest (45 km) produces a sufficiently realistic circulation, such that excess vapor and cloud ice are readily ventilated equatorward from polar latitudes. A more sophisticated cloud scheme might serve to reduce the sensitivity seen in this study. However, sufficient spatial resolution is what causes the circulation to become realistic, and in this regard microphysics is not involved. 2014 The Authors. Published by Elsevier Inc.

On August 6, 2012, the Mars Science Laboratory rover, Curiosity, successfully landed on the surface of Mars. The Entry, Descent and Landing (EDL) sequence was designed using atmospheric conditions estimated from mesoscale numerical models. The models, developed by two independent organizations (Oregon State University and the Southwest Research Institute), were validated against obser-vations at Mars from three prior years. In the weeks and days before entry, the MSL “Council of Atmospheres” (CoA), a group of atmospheric scientists and modelers, instrument experts and EDL simulation engineers, evaluated the latest Mars data from orbiting assets including the Mars Reconnaissance Orbiter's Mars Color Imager (MARCI) and Mars Climate Sounder (MCS), as well as Mars Odyssey's Thermal Emission Imaging System (THEMIS). The observa-tions were compared to the mesoscale models developed for EDL performance simulation to determine if a spacecraft parameter update was necessary prior to entry. This paper summarizes the daily atmosphere observations and comparison to the performance simulation atmosphere models. Options to modify the at-mosphere model in the simulation to compensate for atmosphere effects are also presented. Finally, a summary of the CoA decisions and recommendations to the MSL project in the days leading up to EDL is provided.

Background: Atmospheric mesoscale modeling [performed in support of Mars Science Laboratory Entry Descent and Landing (MSL EDL) at Ls=151] is used in a high-resolution investigation of the complex circulation in and near Gale Crater. Model results show that afternoon Convective Boundary Layer depths are dramatically suppressed over the northern crater floor. For nearly the same locations, excursions from the expected surface pressure cycle are large, with daytime lows and nighttime highs that exceed the expected values by ~1.5%. Method: The 20-sol meteorological mean diurnal cycle is constructed for the innermost 4 km nest of the OSU Mars Mesoscale Model (OSU MMM). In examining the mean diurnal cycle, important forcings are identified. Numerous slices of winds and potential temperature are used to describe the circulation. Additionally, a diagnostic surface pressure field (based on the relationship between surface pressure and topography) is constructed to provide a dynamically unmodified surface pressure field. The difference between the actual surface pressure field and the diagnostic field is examined, identifying the locations and amplitudes of surface pressure excursions. The relationship between surface pressure excursions and dynamics is investigated. Conclusion: This study reveals that intra-scale interactions (between the larger-scale slope flows across the dichotomy boundary and those caused by Mt. Sharp and the rim walls of Gale Crater) excite smaller-scale circulations that modify the vertical temperature structure most significantly over the northern crater floor. Analysis shows that these circulations are generally mass-conserving, producing subsidence during the day and upwelling at night, and are largely responsible for modifying the temperature of a deep (~3 km) column of air. The modified vertical temperature profile is seen to correspond better with elevation above the mean regional topography than elevation above local topography (the “typical” case for Mars). Convective Boundary Layer (CBL) depths and surface pressures are significantly affected in response to the modified air temperature. In a constructive interaction between dichotomy boundary and crater slope flows, hydraulic jumps are seen to form late at night in craters near the base of the southern rim walls. In Gale Crater, a vigorous hydraulic jump forms near the southwest rim, and persists through early morning with wind speeds reaching ~35 m/s. With nearly constant periods of heating and cooling near the equator throughout the year, an important role for aeolian processes in Gale and other craters along the dichotomy boundary is likely.

The Mars Science Laboratory mission aims to land a car-sized rover on Mars’ surface and operate it for at least one Mars year in order to assess whether its field area was ever capable of supporting microbial life. Here we describe the approach used to identify, characterize, and assess environmental risks to the landing and rover surface operations. Novel entry, descent, and landing approaches will be used to accurately deliver the 900-kg rover, including the ability to sense and “fly out” deviations from a best-estimate atmospheric state. A joint engineering and science team developed methods to estimate the range of potential atmospheric states at the time of arrival and to quantitatively assess the spacecraft’s performance and risk given its particular sensitivities to atmospheric conditions. Numerical models are used to calculate the atmospheric parameters, with observations used to define model cases, tune model parameters, and validate results. This joint program has resulted in a spacecraft capable of accessing, with minimal risk, the four finalist sites chosen for their scientific merit. The capability to operate the landed rover over the latitude range of candidate landing sites, and for all seasons, was verified against an analysis of surface environmental conditions described here. These results, from orbital and model data sets, also drive engineering simulations of the rover’s thermal state that are used to plan surface operations.

Environmental monitoring, data processing, and reporting methods are expensive, labor- and resource-intensive, time-consuming, and often inaccurate. An innovative project management platform was developed for integrating environmental monitoring sensors, telemetry, geographical information systems, models, and geostatistical algorithms for automatically generating contour maps and time-stamped renderings of sensor attributes and multivariate analyses. More specifically, algorithms converting sensor-derived head and solute concentration values allow for automated monitoring of mass flux and discharge to evaluate groundwater remediation system performance and contaminant discharges from aquifers to surface-water receptors. Life-cycle costs and carbon footprints were reduced due to the elimination of energy and labor expenditures associated with transportation, data collection, laboratory efforts, report generation, and information dissemination. A brief summary of two demonstrations of this sensor-based water resources management application is presented. (C) 2011 Wiley Periodicals, Inc.