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NASA’s Perseverance rover’s Mars Environmental Dynamics Analyzer is collecting data at Jezero crater, characterizing the physical processes in the lowest layer of the Martian atmosphere. Here we present measurements from the instrument’s first 250 sols of operation, revealing a spatially and temporally variable meteorology at Jezero. We find that temperature measurements at four heights capture the response of the atmospheric surface layer to multiple phenomena. We observe the transition from a stable night-time thermal inversion to a daytime, highly turbulent convective regime, with large vertical thermal gradients. Measurement of multiple daily optical depths suggests aerosol concentrations are higher in the morning than in the afternoon. Measured wind patterns are driven mainly by local topography, with a small contribution from regional winds. Daily and seasonal variability of relative humidity shows a complex hydrologic cycle. These observations suggest that changes in some local surface properties, such as surface albedo and thermal inertia, play an influential role. On a larger scale, surface pressure measurements show typical signatures of gravity waves and baroclinic eddies in a part of the seasonal cycle previously characterized as low wave activity. These observations, both combined and simultaneous, unveil the diversity of processes driving change on today’s Martian surface at Jezero crater.

Modeling and observations have long demonstrated that Martian dust storms strongly interfere with global circulation patterns and change the diurnal and semidiurnal pressure variability as well as oscillations with periods greater than one sol associated with planetary waves. As of early 2022, five Mars years of pressure data have been collected by the Curiosity Rover in Gale crater with the Rover Environmental Monitoring Station (REMS). A combination of signal filtering techniques is used to search for pressure signatures that might warn large‐scale dust storms reaching Gale. The analysis combines an exploration of changes in both baroclinic waves and thermal tides for the first time to our knowledge. Focusing on the periods preceding local opacity increases as detected by Curiosity's Mastcam observations, the pressure analysis shows changes in the coupling between the diurnal pressure tide and quasi‐diurnal Kelvin wave, as well as in the temporal evolution of baroclinic waves that are harbingers of the larger dust storms. Changes in the phasing between Kelvin waves and diurnal tides are found to be precursors for the growth phase of periods Z (defined here as Ls∼ 120°–160°), A (Ls∼ 190°–240°), and C (Ls∼ 300°–335°) dust storms. Changes in multi‐sol pressure oscillations also help predict the occurrence of A, B (Ls∼ 245°–295°), and C storms. The specific pressure oscillations preceding each storm period are likely to be signatures of the large‐scale circulation patterns that enable the growth and propagation of the storm fronts. There have been many efforts to characterize the impact of large‐scale dust storms on Mars's atmospheric circulation and wave activity. Surface pressure measurements made by the Curiosity Rover's Rover Environmental Monitoring Station (REMS) in Gale crater enable the study of some of these changes in global circulation patterns. Relatedly, numerical modeling and imaging by orbital spacecraft indicate that particular atmospheric circulation patterns—including particular combinations of waves—favor the growth and propagation of dust storms. Such patterns may be identified via their signature in surface pressure prior to the growth of the storm. This work presents several analyses that find equatorial waves preceding the growth of local dust opacity in Gale crater during the so‐called Z‐storm period in late southern winter and changes in baroclinic wave properties preceding the growth of opacity during other storm periods from early southern spring through late summer. Specific surface‐pressure oscillations in Gale crater precede increases in dust opacityDifferent dust seasons have different anticipatory behaviors depending on the dominant wave typeContinual analysis of pressure waves may be used to inform operations of landed craft on Mars Specific surface‐pressure oscillations in Gale crater precede increases in dust opacity Different dust seasons have different anticipatory behaviors depending on the dominant wave type Continual analysis of pressure waves may be used to inform operations of landed craft on Mars

The chemisorption of CO on the atop site of Pt(111) has been simulated by a Pt4cluster model. Ab initio self consistent field (SCF) and complete active space self consistent field (CASSCF) cluster model wave functions have been obtained for the electronic ground state. Likewise, ab initio SCF wavefunctions have been obtained for two other electronic states. The optimum geometry and vibrational frequencies of chemisorbed CO are reported for the three states. The interaction energy and vibrational shift of chemisorbed CO, with respect to free gas phase CO, have been analyzed for the three electronic states. This analysis is carried out by means of the constrained space orbital variation (CSOV) method. In all cases the bond is found to be dominated by σ donation and π back-donation, known as Blyholder's mechanism. This mechanism is further supported by SCF calculations on a larger, Pt13, cluster model. For both clusters, the CSOV analysis of the vibrational frequency definitely shows that, contrary to previous recent studies, a major contribution to the experimentally observed vibrational shift comes from the π back-donation mechanism. However, we found that, contrary to common belief, σ donation also acts to lower the CO frequency and not to increase it. Physical reasons for such unexpected behaviour are given.