Joseph Michael Battalio

Atmospheric rivers (ARs) play a crucial role in the global hydrological cycle, yet how the intrinsic midlatitude atmospheric variability modulates their activity on subseasonal timescales remains poorly understood. Here, we show that AR frequency and landfall in both hemispheres vary strongly with the strength and phase of the Baroclinic Annular Mode (BAM). During its positive phase, BAM increases AR occurrence by up to ∼50% and AR‐driven precipitation extremes by up to ∼40% relative to climatology. Stronger and more frequent ARs during the positive phase of the BAM are primarily driven by enhanced potential‐to‐kinetic energy conversion, which favors AR growth and intensification, particularly in the storm‐track regions. This response is consistent with dynamically enhanced poleward moisture transport due to a more baroclinically unstable and stormier environment. The results underscore the importance of BAM‐related intrinsic midlatitude storm‐track variability in modulating global AR activity and its potential to improve extended‐range AR prediction on subseasonal timescales.

Dust is a crucial parameter for planetary atmospheres, particularly for Mars. These mineral micrometre-sized particles absorb and diffuse incoming sun rays, which heat the atmosphere locally. Dust also affects many atmospheric processes, such as the circulation, the water cycle, the atmospheric escape, and the CO2 cycle. In this work, we will present a novel catalogue of local dust storms on Mars. Here, we consider the following dust storm definition: a large and optically thick dust cloud [1]. The dust storms reach different stages during their lifetime: formation, growth/evolution, and dissipation/sedimentation. These storms can be classified by their spatial extension, called local storms (< 1.6 106 km2), regional storms (> 1.6 106 km2) and planetary (global) storms [2]. Questions remain about the storm formation and growth mechanisms, which are relevant to storm forecasting.While many studies dedicated to dust storms are focused on regional storms [3, 4, 5], studying dust activity at a local scale is key to better understanding the first stages of storm formation and growth. Here, we present our work on detecting dust storms in the OMEGA/Mars Express (near-IR imaging spectrometer) dataset, chosen for its high spatial resolution (0.36-4.8 km/pixel), allowing the detection of small storms. We developed a method to detect automatically storms from dust optical depth data (see Figure 1) computed at 0.9 µm [6] available from late Martian Year 26 to mid MY 30. The storm detections have been confirmed manually and compiled into the OMEGA Dust Storm Catalogue (ODSC) [7]. This catalogue is composed of 448 storm detections, from which ~81% are local storms and ~19% regional ones.Figure 1: Automatic detections of two dust storms in an OMEGA/Mars Express observation. [Left] and [right] correspond respectively to the dust optical depth map of the observation derived by [6] and the storm detection mask number. Adapted from [8].Using this catalogue, we studied the spatial, time and diurnal distribution of the detections [8], and we present here a summary of the results. The local storm activity is widespread on Mars (see Figure 2), with favoured areas such as southern polar cap edges, flushing dust storm channels, or Hellas Planitia and Valles Marineris [8]. Most of the storm detections have been made between 10:00 and 18:00, reaching a maximum at 14:00-16:00 [8]. The storm growth mechanisms seem to be less efficient during particular periods of the Martian year, as during the northern solstitial pause (Ls ~240-270°), when we are still detecting many local storms, while the regional storm activity is low. Regional storm detections are mostly concentrated during MY 29 and MY 28, more specifically during the early formation stage of the Global Dust Storm (Ls~265-270°) [8]. This suggests that the lifting and transport processes were stronger and more effective during this period.Figure 2: Spatial distribution of the OMEGA Dust Storm Catalogue detections [top] and OMEGA/Mars Express observations [bottom] from MY 26 to 30 without the MY 28 Global Dust Storm period (Ls~265-305°). For [top], the circles and hexagons symbolised respectively local and regional storms. Extracted from [8].This new local and regional storm catalogue will also be useful for preparing observations of future missions such as the Martian Moons eXploration (MMX, JAXA), which will also study the Martian atmosphere [9] from 2027. Due to its equatorial orbit, MMX and its instrumental payload, especially the MMX InfraRed Spectrometer (MIRS, [10]), will give the opportunity to study diurnal variations of the storms, and therefore to constrain the storm formation and growth mechanisms. The ODSC, among other catalogues [3, 4, 5], is notably used to schedule Martian dust storm observations.References:[1] Kahre M. A. et al. (2017), Cambridge Univ. Press, The Atmosphere and Climate of Mars, 295-337. [2] Cantor, B. A et al. (2001) JGR, 106(E10), 23653–23687. [3] Battalio M. & Wang H. (2021) Icarus, 354, 114059. [4] Guha B. K. et al. (2024) JGR Planets, 129, e2023JE008156. [5] Lombard T. & Montabone L. (2024), 10th International Conference on Mars, abstract #3041. [6] Leseigneur Y. and Vincendon M. (2023) Icarus, 392, 115366. [7] Leseigneur Y. et al. (2025) Zenodo, 10.5281/zenodo.17380018. [8] Leseigneur Y. et al. (2026) JGR: Planets, 131, e2025JE009502. [9] Ogohara K. et al. (2021) Earth, Plan. and Space, 74, 1. [10] Barucci M. A. et al. (2021) Earth, Plan. and Space, 73, 211.

This paper describes the OMEGA Dust Storm Catalogue (ODSC), built over almost 4 Martian Years (end of MY 26 to mid MY 30d) from OMEGA/Mars Express hyperspectral observations. A storm detection method has been developed based on a pixel clustering algorithm applied to the OMEGA dust optical depth retrievals made at 0.9 m. The storm detections have been validated, both automatically and manually. This led to a total of 448 dust storms, of which 364 (∼81%) are local storms and 84 (∼19%) are regional ones. Some of these local dust storms are flagged as “dust lifting”, which corresponds to detections of strong atmospheric dust activities spatially localized above craters. A large increase of local dust storm activity has been noticed in MY 27 during the northern “solstitial pause” ( 240–270) from high southern latitudes to mid northern latitudes (“B”‐storm season). Another active local storm season is during the “C” regional storm season ( 305–330) in MY 27 and 29. In general, most of the dust storm detections have been made between 10:00 and 18:00, with a detection peak from 14:00 to 16:00. These regional storms are concentrated on MY 29 ( 210–360) and on MY 28 ( 210–240), with only a few detections during the northern solstitial pause in both years. Many of these detections were made during the MY 28 Global Dust Storms formation period ( 265–270) in both hemispheres, showing stronger and/or more efficient dust lifting and transport processes compared to other years.

Dust, composed of mineral micrometre-size particles, is omnipresent on Mars and has its own cycle: uplift from the surface and injection into the atmosphere, transport and formation of dust storms, and dissipation (grain sedimentation). Atmospheric dust, and thus dust storms, absorbs and diffuses incoming sunlight, strongly affecting the atmosphere by modifying its thermal structure [1] and enhancing global atmospheric circulation [2]. The intensity of these impacts depends on storm sizes, which are usually classified as local or regional storms (≥ 1.6×106 km2, [3]). Regional storms have been well studied (e.g., [4,5,6]) and characterised in opposition to local ones. This work focuses on local dust storms to better understand the storm evolution mechanisms (local to regional) that are still not well constrained. We developed a method to detect dust storms [a] in the OMEGA IR dataset (2004-2010, Martian Years 26-30), the visible and near-IR imaging spectrometer of Mars Express (ESA). This method is based on a pixel clustering algorithm that is applied to the dust optical depth map [7] of each OMEGA observation. Then, we generate a mask that corresponds to the storm, from which we extract information, after confirming the presence of the storm, such as its size, position, local time, etc. We compiled about 440 new detections into the OMEGA/Mars Express Dust Storm Catalogue (ODSC), mainly composed of local storms (~81%). We identified a peak of local storms, notably in MY 27, during the northern “solstitial pause” (solar longitude, Ls~240-270°), which corresponds to a period of lower regional storm activity due to lower wave activity (e.g., [8,9]). Therefore, this decrease in regional storm detections is not due to a strong decrease in local storm formation, but to a decrease in the growth process efficiency to regional size [a]. Local storms are also very active during the “C-regional storm season” (Ls~305-330°) and widespread on Mars. We found some privileged areas: high southern latitudes (polar cap edges) and close to strong topographic gradients, as inside topographic channels (e.g., Chryse, Acidalia, Arcadia; [4]), Hellas, Valles Marineris, Olympus and Elysium Mons [a]. This suggests that topographic winds contribute to the formation of dust storms during this period. We also noticed a similar diurnal pattern between local storms detected with OMEGA (MY 26-30) and regional ones detected with EXI/EMM (MY 36, [5]).References:[a] Leseigneur, Y., et al. (in revision), JGR:Planets, “OMEGA/MEx Dust Storm Catalogue”.[1] Kass, D. M., et al. (2016), GRL, 43, 6111-6118.[2] Barnes, J. R., et al. (2017), Cambridge Univ. Press, The atmosphere and Climate of Mars, 229-294.[3] Cantor, B. A., et al. (2001), JGR:Planets, 106, 23653-23687.[4] Battalio, M. J., Wang., H. (2021), Icarus, 354, 114059.[5] Guha, B. K., et al. (2024), JGR:Planets, 129, e2023JE008156.[6] Lombard, T., Montabone, L. (2024), EPSC2024, abs.#1334.[7] Leseigneur, Y., Vincendon, M. (2023), Icarus, 392, 115366.[8] Lewis, S. R., et al. (2016), Icarus, 264, 456-464.[9] Battalio, M. J. (2022), JAS, 79, 361-382.

Martian dust storms are valuable to study both for atmospheric science and for characterizing risks for future exploration missions. While dust plays an outsized role in the atmospheric of Mars, we lack a firm characterization of how dust storms initiate, grow, dissipate, and perturb the atmosphere over their lifecycles. Small (local) dust storms on Mars are particularly difficult to study; hundreds to thousands occur each Mars year, but their limited spatial extent and lifetime means we have relatively little to no atmospheric observations for each event. To investigate these local storms, we identified atmospheric measurements from the Mars Climate Sounder that coincide with recently mapped small storm boundaries from Mars Color Imager observations spanning Mars years 28-34 during the northern spring and summer. Using data science techniques to identify and aggregate these coincident observations, we extracted dust and temperature changes aligned with dust storm initiation across ~1350 events. Generally, we found that atmospheric perturbations are strong but short lived in the south, while northern local dust storms are weak. Our findings provide new insights into the atmospheric changes within small dust storms, which can inform future modeling studies and mission planning for exploring Mars.

Dust storms near Mars' South Pole during the perihelion and summer solstice seasons ( L _s ∼ 250–290°) are phenomenologically distinct from martian dust storms in other locations and seasons. While they have previously been observed to increase atmospheric dust loading and warm the south polar atmosphere, they have no notable impact on the middle latitudes, tropics, or northern hemisphere. Here, we use a combination of multiple remote sensing instruments, atmosphere reanalyses, and general circulation modeling to study the evolution of dust storms near the Martian South Pole during Mars Year 30 (a prototypical year for such storms). Dust lifting preferentially occurs in the eastern hemisphere (180°–320°E) and follows the retreating seasonal CO ₂ polar cap to higher latitudes as the season progresses—implicating the strong cap edge thermal forcing and katabatic flows as well as surface dust availability in driving dust lifting. Dust remains confined to the high southern latitudes during this season with strong diurnal variability in both latitudinal and vertical extents. Dust is entrained in the southern circumpolar jet stream, creating filamentation and longitudinal mixing and controlling the flow of dust back onto the polar cap. The diurnally varying atmospheric circulation limits the mixing of dust to lower latitudes and prevents a global thermal response.

Introduction: We have captured Martian dust and weather over 25 years of continuous satellite observations. Using thermal infrared (IR) data from instruments like TES (Mars Global Surveyor), THEMIS (Mars Odyssey), MCS (Mars Reconnaissance Orbiter), and EMIRS (Emirates Mars Mission), we have produced diurnal maps of column dust optical depth (CDOD) covering 13 Martian years (MY 24–37) [1–5]. Two types of maps are available: gridded maps (incomplete) and kriged maps (complete). These maps, normalized to 610 Pa or expressed as total CDOD, are mainly used as “dust scenarios” in the Mars Climate Database [6] and are publicly available (see the links to the datasets in the acknowledgments section). While they have helped study dust seasonality and large-scale storms, their use in multi-annual and daily-scale analyses remains limited.Latest advances: Starting from retrievals provided by the TES, MCS, and EMIRS science teams, we use two processing chains (gridding and kriging) to produce daily quasi-complete gridded CDOD maps and fully complete kriged CDOD maps. These chains were technically improved and scientifically enhanced with the following changes:1. We have used a new tool for Earth – Mars datetime conversion [13] to define a sol of the year for each daily map using a sol-based Mars calendar, as described in [1, Appendix A].2. We have changed the computation of the total CDOD (defined in [1]) by using a lookup table of surface pressure extracted from the MCD v5.3, interpolated at the required time and location.3. We have improved the gridding of retrievals by implementing an automatic method to detect data gaps (when instruments are inactive for several sols or weeks) and dynamically extend the time window (see [1] for details about the time window). This enables continuous generation of daily maps, even if sparse – essential inputs for the kriging process.4. We have used data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM, onboard Mars Reconnaissance Orbiter) to validate CDOD maps together with rover/lander data as in [1]. This might correct a recurring bias, especially during the Low Dust Loading Season (LS = 10°-140°; see [14]), where earlier CDOD maps underestimate dust opacity level. This also might aid in merging data from different instruments.5. We have analyzed the differences between MCS- and EMIRS-based maps, as both instruments observed Mars quasi-simultaneously during MY 36 and 37 – except for a few periods when one of the instruments was not functioning nominally. Despite differences in spatial and temporal coverage, we have attempted to properly integrate CDOD data from MCS and EMIRS to produce combined daily maps for MY 36 and 37 and to deliver a single dataset for each year that reflects the contributions of one or more instruments.Applications: To support characterization of the Martian atmosphere for the ExoMars rover’s Entry, Descent, and Landing (EDL), we have used daily CDOD maps to assess dust opacity risks. Figure 1 presents predicted dust opacity levels for both EDL and surface operations during the nominal (LS = 62°-76°) and backup (LS = 5°-21°) seasons, based on criteria from [17].From daily CDOD maps, it is also possible to identify large-scale dust events (“storms”) that reach regional or planetary scales, track their evolution and key characteristics (trajectory, area, optical depth), and build statistics comparable to dust storm statistics from visible images (e.g. [12, 15]), which are also useful for CDOD maps validation. Due to the volume of daily maps and the lack of prior systematic CDOD maps analysis, a new method is in development to detect and track large-scale dust events using unsupervised machine learning algorithms [9]. A key outcome is the production of a catalog of historic large-scale dust events, which can be routinely updated with new events as new dust maps become available.Finally, the mid-term to long-term objective is to establish a real-time processing chain that spans from receiving the retrievals to producing and processing CDOD maps. Real-time capability is currently hindered by the time required for data downlink and the availability of quasi real-time retrievals. The goal is to develop an early warning meteorological tool capable of daily monitoring of atmospheric dust and issuing alerts if dust levels are rising, potentially signaling the onset of a dust storm. We consider, as an illustrative case, the unexpected early dust storm during MY 35 around LS ≈ 35°. Let us assume that daily data acquisition and processing are feasible between SOY 70 and 75. In this context, if we imagine that ExoMars has successfully landed at Oxia Planum during MY 41, LS ≈ 35°, we could then monitor the daily dust levels near the landing site and issue warnings if a large-scale or regional dust storm emerges nearby (see Figure 2). Following this example, from SOY 73, a warning would have been raised because the mean of the dust core (see [9]) exceeds 0.7 (see [17]). This would allow the mission operations team to take appropriate actions such as suspending scientific activities or entering safe mode (see [17]). Acknowledgments: TM, LM, and VG acknowledge support from CNES and ESA MCD project. BKG was supported by UAE University Grant G00003407. Work at the Jet Propulsion Laboratory, California Institute of Technology, is supported by NASA. The multi-annual dataset of daily gridded and kriged maps v2.x for MY24 through MY36 is available on the MCD webpage (NetCDF format) at https://www-mars.lmd.jussieu.fr/mars/dust_climatology/ and on the VESPA repository (FITS format) at https://bit.ly/3QMFfIf (shortened link). The latest v3.0 of the daily gridded maps for MY24 through part of MY27, together with corresponding TES CDOD retrievals in the infrared and in the visible, are available on the NASA PDS (atmosphere node) at:...

Five years of surface pressure data collected by the Mars rover Curiosity’s Environmental Monitoring Station experienced a recurrent short-lived drop of the daily pressure means, unrelated to dust activity, sudden temperature anomalies, or to pressure signatures of Mars polar CO2 cycle. This drop coincides with the time where models predict Mars Meridional Circulation to split into two cells as it switches from the northward to the southward direction. The pressure drop happened at Gale crater and at the locations of two other Mars stations, InSight and Perseverance. The different sols where the pressure drops occurred at each location follow a latitudinal time sequence consistent with the propagation of the upwelling branch for the Meridional Circulation split predicted by models and with changes in composition trends observed for atmospheric CH4, Ar, O2, and H2O. These pressure drops provide a unique surface observation to track year-to-year differences in Mars meridional atmospheric transport.

We document the propagation of annular modes—zonally symmetric patterns of variability—in Mars's atmosphere using a reanalysis dataset. Mars's Northern Annular Mode (MNAM) sees anomalies of zonal‐mean zonal wind emerge near the subtropics and migrate poleward with a period of 150 days, similarly to Earth's Southern Annular Mode. The mechanism of propagation involves the interaction of the two leading empirical orthogonal functions that define the MNAM. Moreover, the propagation encourages alternating bands of surface wind stress to migrate polewards with a 150‐day period. In addition, a 150‐day periodicity in anomalous column dust optical depth most likely emerges in response to extrema of the MNAM. The combination of the impact of the MNAM's internally forced periodicity on the surface wind stress and the seasonal cycle may contribute to the inter‐annual variability of global dust events, as suggested by a Monte Carlo estimate that correctly approximates the observed incidence of global dust events.