An assessment of the impact of local processes on dust lifting in martian climate models

Simulation of the lifting of dust from the planetary surface is of substantially greater importance on Mars than on Earth, due to the fundamental role that atmospheric dust plays in the former’s climate, yet the dust emission parameterisations used to date in martian global climate models (MGCMs) lag, understandably, behind their terrestrial counterparts in terms of sophistication. Recent developments in estimating surface roughness length over all martian terrains and in modelling atmospheric circulations at regional to local scales (less than O(100 km)) presents an opportunity to formulate an improved wind stress lifting parameterisation. We have upgraded the conventional scheme by including the spatially varying roughness length in the lifting parameterisation in a fully consistent manner (thereby correcting a possible underestimation of the true threshold level for wind stress lifting), and used a modification to account for deviations from neutral stability in the surface layer. Following these improvements, it is found that wind speeds at typical MGCM resolution never reach the lifting threshold at most gridpoints: winds fall particularly short in the southern midlatitudes, where mean roughness is large. Sub-grid scale variability, manifested in both the near-surface wind field and the surface roughness, is then considered, and is found to be a crucial means of bridging the gap between model winds and thresholds. Both forms of small-scale variability contribute to the formation of dust emission ‘hotspots’: areas within the model gridbox with particularly favourable conditions for lifting, namely a smooth surface combined with strong near-surface gusts. Such small-scale emission could in fact be particularly influential on Mars, due both to the intense positive radiative feedbacks that can drive storm growth and a strong hysteresis effect on saltation. By modelling this variability, dust lifting is predicted at the locations at which dust storms are frequently observed, including the flushing storm sources of Chryse and Utopia, and southern midlatitude areas from which larger storms tend to initiate, such as Hellas and Solis Planum. The seasonal cycle of emission, which includes a double-peaked structure in northern autumn and winter, also appears realistic. Significant increases to lifting rates are produced for any sensible choices of parameters controlling the sub-grid distributions used, but results are sensitive to the smallest scale of variability considered, which high-resolution modelling suggests should be O(1 km) or less. Use of such models in future will permit the use of a diagnosed (rather than prescribed) variable gustiness intensity, which should further enhance dust lifting in the southern hemisphere in particular

Using dense seismo-acoustic network to provide timely warning of the 2019 paroxysmal Stromboli eruptions

Stromboli Volcano is well known for its persistent explosive activity. On July 3rd and August 28th 2019, two paroxysmal explosions occurred, generating an eruptive column that quickly rose up to 5 km above sea level. Both events were detected by advanced local monitoring networks operated by Istituto Nazionale di Geofisica e Vulcanologia (INGV) and Laboratorio di Geofisica Sperimentale of the University of Firenze (LGS-UNIFI). Signals were also recorded by the Italian national seismic network at a range of hundreds of kilometres and by infrasonic arrays up to distances of 3700 km. Using state-of-the-art propagation modeling, we identify the various seismic and infrasound phases that are used for precise timing of the eruptions. We highlight the advantage of dense regional seismo-acoustic networks to enhance volcanic signal detection in poorly monitored regions, to provide timely warning of eruptions and reliable source amplitude estimate to Volcanic Ash Advisory Centres (VAAC)

Troposphere-to-mesosphere microphysics of carbon dioxide ice clouds in a Mars Global Climate Model

We have implemented full CO ice cloud microphysics into the LMD Mars Global Climate Model (MGCM) and we have conducted the first global simulations. The microphysical model implementation follows the modal scheme used for water ice cloud microphysics in the MGCM, but includes specific aspects that need to be accounted for when dealing with CO ice clouds. These include nucleation of CO on water ice crystals and CO condensation theory adapted for the Martian conditions. The model results are compared to available observations globally, and separately for polar regions and equatorial mesosphere. The observed seasonal and latitudinal variability of the CO ice clouds is in general reproduced. The polar regions are covered by CO ice clouds during the winter as observed. Instead of forming only in the lowest 10–15 km of the atmosphere, they extend up to several tens of kilometers above the surface in the model, dictated by the modeled temperature structure. We have also quantified the contribution of the cloud microphysics to the surface CO ice deposits. Snowfall from these clouds contributes up to 10% of the atmosphere–surface ice flux in the polar regions in our simulations, in the range that has been indirectly deduced from observations. In the mesosphere, notable amounts of CO ice clouds form only when water ice crystals are used as condensation nuclei in addition to dust particles, and their spatial distribution is in agreement with observations. The mesospheric temperature structure, dominated by tides, dictates the longitudinal and seasonal distribution of these clouds. The seasonal and local time variations of the clouds are not fully reproduced by the model. There is a long pause in CO ice cloud formation in the model around the aphelion season, but clouds have been observed during this period, although with a lower apparition frequency. Modeled mesospheric clouds form mainly during the night and in the morning, whereas during the daytime, when most of the cloud observations have been made, the model rarely predicts clouds. These discrepancies could be explained by the strong dependence of the cloud formation process on mesospheric temperatures that are themselves challenging to reproduce and sensitive to the MGCM processes and parameters. The rare possibilities for nighttime observations might also bias the observational climatologies towards daytime detections. Future developments of the model consist in the inclusion of a possible exogenous condensation nucleus source in the mesosphere and the radiative effect of CO ice clouds. © 2022 Elsevier Inc. All rights reserved.This paper presents the results of ten years of development that has been supported by funding from several sources. We thank the Agence National de la Recherche for funding (project MECCOM, ANR-18-CE31-0013). We are also grateful for the financial support by the LabEx (Laboratoire d’Excellence) ESEP, by the French space agency CNES and the European Space Agency ESA. We acknowledge the support of the French national planetology programme (PNP) as well. F.G.-G. is funded by the Spanish Ministerio de Ciencia, Innovación y Universidades, the Agencia Estatal de Investigación and EC FEDER funds under project RTI2018-100920-J-I00, and acknowledges financial support from the State Agency for Research of the Spanish MCIU through the Center of Excellence Severo Ochoa” award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709). This work was performed using HPC computing resources from GENCI-CINES (Grant 2021-A0100110391), and resources at the ESPRI mesocentre of the IPSL institute .Peer reviewe

Sub-grid Scale Processes: towards a Next-Generation Dust Lifting Scheme for Martian GCMs

International audienceA realistic spatio-temporal variability in atmospheric dust loading is essential to accurately simulate the Martian climate, yet dust lifting in Mars Global Climate Models (MGCMs) is still in relative infancy. We detail several improvements can be made to lifting schemes, following recent developments in observational data and MGCM physics, and taking inspiration from terrestrial dust emission work. The impacts of these additions are found to be significant, though they act in somewhat opposite directions – which perhaps allowed earlier dust-lifting MGCMs to perform as well as they have

SPICAM Aerosol Vertical Distribution Climatology from UV Occultations

We present observations from MEx/SPICAM solar and stellar occultations in the ultraviolet that allow the retrieval of vertical profiles of aerosols with a good coverage over four martian years

SPICAM Climatology of Aerosol Vertical Distribution through UV Occultations

The four Martian years of data of SPICAM occultations show that the seasonal behavior of the hazetop follows closely the seasonal variations of the temperature. The highest hazetops are observed at the warm season around the southern summer solstice. Observations during the MY28 dust storm reveal very high hazetops and detached layers. The high northern latitudes in the autumn give the opposite example of very calm vertical distribution with a low hazetop. These data show that the assumption of a well-mixed dust in the lowest atmosphere is not the only option, but that the martian dust vertical distribution is very variable. We observed detached layers in more than half of the analyzed orbits (accounting for both solar and stellar occultations). The highest detached layers are observed during the global dust storm of MY28, but evident single and multiple layers are observed also during other seasons.The solar occultation dataset can be accessed through the Supplementary Material of the article [1] and the Europlanet IDIS atmospheres node that can be found at http://www.bdap.ipsl.fr/idis/

Jag vill bara vara som alla andra : En kvalitativ studie om könsskillnader mellan barn i förskolan i behov av stöd med adhd

Denna studie syftar till att undersöka om det finns en skillnad mellan könen i bedömning av barn som påvisar hyperaktivitet, sociala svårigheter och aggressivt beteende på förskolan. Det som intresserade författaren till att göra studien var författarens egen erfarenhet inom ämnet samt ett intresse för att veta mer om ämnet. Studien är gjord med kvalitativa intervjuer hos rektorer och förskollärare, sedan har materialet bearbetats och analyserats med en genusteoretisk utgångspunkt. I studiens resultat framgår rektorernas roll kring barn i behov av stöd med adhd symptom, samt hur det påverkar förskollärarnas ansvar i verksamheten. Även hur detta påverkar verksamhetens möjlighet till extra stöd, vilket framkommer i studien och har en påverkan på utbildningen. Studiens resultat visar även att det görs en skillnad mellan pojkar och flickor gällande adhd. Avslutningsvis, visar studien även hur vårdnadshavare väljer att inte se att deras barn möjligen har behov av stöd