Laboratoire de Sciences de la Terre

<strong class="journal-contentHeaderColor">Abstract.</strong> Inverse methods have been widely used in the field of Earth Sciences, particularly in seismology. Here, we introduce a new application of inversion theory to retrieve Arctic sea ice thickness (SIT) and its overlying snow depth (SD) using freeboard data from Ku-band/Ka-band radar and laser altimeters. We do this using the TransTessellate2D algorithm, a Bayesian trans-dimensional approach that allows us to invert for an unknown number of model parameters. This new inversion method is probabilistic in nature, and can offer a novel understanding of covariances between fields of interest as well as their uncertainties. We use this approach to jointly retrieve SIT and SD in one step, without using a climatology for SD. The inversion results are statistically encouraging when compared to snow and ice evaluation products: for April 2019, we obtain a higher linear correlation coefficient and a slope closer to the one-to-one line than the AWI CryoSat-2 SIT product compared to the Operation Ice Bridge (OIB) SIT product. For the inverted SD, our results exhibit similar statistical properties to the UiT and AMSR2 SD products when regressed against the OIB SD product. The SD is similar in terms of spatial patterns to the AMSR2 product in the 2018&ndash;2021 winter periods. We evaluate the inversion against data from MOSAiC and IceBird missions. These evaluations are also promising, especially for IceBird. Using this approach, we can choose the number of physical variables (SIT, SD and penetration factors) to be inverted for. Thus, we can also invert for the penetration factor, either from one or both satellites (in addition to inverting for SIT and SD at the same time). This paves the way for further research in understanding these penetration factors and their link to SIT and SD retrievals. We obtain values for the penetration factors between 0.5 and 1.2 for CryoSat-2 and around 0 for ICESat-2. Lastly, we investigate the multi-frequency inversion using data from the Ka- and Ku-band radar altimeters, thus preparing for the European Space Agency's planned dual-frequency altimetry mission, CRISTAL.

Abstract. The Quaternary climate is characterized by glacial–interglacial cycles, with the most recent transition from the last glacial maximum to the present interglacial (the last deglaciation) occurring between ∼ 21 and 9 ka. While the deglacial warming at high southern latitudes is mostly in phase with atmospheric CO2 concentrations, some proxy records indicate that the onset of the warming occurred before the CO2 increase. In addition, high southern latitudes exhibit a cooling event in the middle of the deglaciation (15–13 ka) known as the “Antarctic Cold Reversal”. In this study, we analyse transient simulations of the last deglaciation performed with six different climate models as part of the 4th phase of the Paleoclimate Modelling Intercomparison Project (PMIP4) to understand the processes driving high-southern-latitude surface temperature changes. As the protocol of the last deglaciation sets the choice of freshwater forcing as flexible, the freshwater forcing is different in each model, thus complicating the multi-model comparison. While proxy records from West Antarctica and the Pacific sector of the Southern Ocean suggest the presence of an early warming before 18 ka, only half the models show a significant warming at this time (∼ 1 °C or ∼ 10 % of the total deglacial warming). All models simulate a major warming during Heinrich Stadial 1 (18–15 ka), concurrent with the CO2 increase and with a weakening of the Atlantic Meridional Overturning Circulation (AMOC) in some models. However, the simulated Heinrich Stadial 1 warming over Antarctica is smaller than the one suggested from ice core data. During the Antarctic Cold Reversal, simulations with an abrupt AMOC strengthening exhibit a high-southern-latitude cooling of 1 to 2 °C, in relative agreement with proxy records, while simulations with rapid North Atlantic meltwater input exhibit a warming. Using simple models to extract the relative AMOC contribution, we find that all climate models simulate a high-southern-latitude cooling in response to an AMOC increase with a response timescale of several hundred years, suggesting the choice of the North Atlantic meltwater forcing substantially affects high-southern-latitude temperature changes. Thus, further work needs to be carried out to reconcile the deglacial AMOC evolution with the Northern Hemisphere ice sheet disintegration and associated meltwater input. Finally, all simulations exhibit only minimal changes in Southern Hemisphere westerlies and Southern Ocean meridional circulation during the last deglaciation. Improved understanding of the processes impacting Southern Hemisphere atmospheric and oceanic circulation changes accounting for deglacial atmospheric CO2 increase is needed.

Abstract. This paper presents a comprehensive overview of the Coupled Model Intercomparison Project Phase 7 (CMIP7) request for data pertaining to Earth systems science, and provides justification for the resources needed to produce this data. Topics within the CMIP7 Earth system (CMIP7-ES) theme centre around tracking of flows of energy, carbon, water and other fluxes across domains, and constraining feedbacks between these cycles and the climate system. These topics are summarized in this paper as scientific ‘opportunities’ describing specific model intercomparison experiments and use cases for next-generation Earth System Model (ESM) output. These opportunities were submitted by modelling groups and scientific consortia following an extended public consultation process. Contained within each opportunity are requests for groups of Climate &amp;amp; Forecasting (CF) variables, which are bundled into variable groups representing all data required to address the opportunities’ needs. Novel opportunities in CMIP7 compared with previous phases will include running ‘emissions-driven’ simulations that integrate carbon emissions and removal scenarios with updated representations of the global carbon cycle, expanded variable groups needed to model marine trophic interactions and biogeochemistry, and data needed to understand the risk of global tipping points, among others. The production of these variables will close key gaps and uncertainties identified during previous rounds of CMIP, and support the 7th Intergovernmental Panel on Climate Change Assessment Report (AR7). We argue that CMIP7-ES data will be broadly used by scientific, policy, governmental, industry, and other communities that rely on climate model projections for research and decision making. As an author group we also reflect on the evolution of the CMIP7-ES data request as a part of a deliberative process in support of the global CMIP program.

<strong class="journal-contentHeaderColor">Abstract.</strong> Inverse methods have been widely used in the field of Earth Sciences, particularly in seismology. Here, we introduce a new application of inversion theory to retrieve Arctic sea ice thickness (SIT) and its overlying snow depth (SD) using freeboard data from Ku-band/Ka-band radar and laser altimeters. We do this using the TransTessellate2D algorithm, a Bayesian trans-dimensional approach that allows us to invert for an unknown number of model parameters. This new inversion method is probabilistic in nature, and can offer a novel understanding of covariances between fields of interest as well as their uncertainties. We use this approach to jointly retrieve SIT and SD in one step, without using a climatology for SD. The inversion results are statistically encouraging when compared to snow and ice evaluation products: for April 2019, we obtain a higher linear correlation coefficient and a slope closer to the one-to-one line than the AWI CryoSat-2 SIT product compared to the Operation Ice Bridge (OIB) SIT product. For the inverted SD, our results exhibit similar statistical properties to the UiT and AMSR2 SD products when regressed against the OIB SD product. The SD is similar in terms of spatial patterns to the AMSR2 product in the 2018&ndash;2021 winter periods. We evaluate the inversion against data from MOSAiC and IceBird missions. These evaluations are also promising, especially for IceBird. Using this approach, we can choose the number of physical variables (SIT, SD and penetration factors) to be inverted for. Thus, we can also invert for the penetration factor, either from one or both satellites (in addition to inverting for SIT and SD at the same time). This paves the way for further research in understanding these penetration factors and their link to SIT and SD retrievals. We obtain values for the penetration factors between 0.5 and 1.2 for CryoSat-2 and around 0 for ICESat-2. Lastly, we investigate the multi-frequency inversion using data from the Ka- and Ku-band radar altimeters, thus preparing for the European Space Agency's planned dual-frequency altimetry mission, CRISTAL.

L’image cultuelle, l’objet par excellence du rapport des vivants avec les morts, ne fut pas une donnée immédiate, par tous et en tout temps admise. Elle oscilla entre iconomachie et iconodoulie, entre des discours dépréciatifs et des discours de justification, entre des théories et des pratiques souvent contradictoires. Nous essaierons dans le cadre de cet article d’examiner au plus près, grâce aux sources littéraires, les soubresauts que subirent au fil du temps, à partir de l’ère commune, les images en particulier des ancêtres et des maîtres, mêlant ainsi la généalogie biologique et la généalogie spirituelle, le rôle et le type qu’elles accordèrent à la représentation des morts. Nous nous efforcerons dès lors d’analyser de manière transversale lesdites religions chinoises, le confucianisme, le taoïsme et le bouddhisme, afin d’en faire émerger le régime différencié du culte des vivants aux morts.

Giorgio Nardone's evolved model of brief strategic therapy is a psychotherapy that is currently considered to demonstrate high efficacy and efficiency for a variety of emotional disorders. This article presents the history and epistemological foundations of brief strategic therapy, based on systems thinking, cybernetics, general systems theory, and constructivism. The evolution and historical development are analyzed from the opening of the Mental Research Institute in Palo Alto to the creation of the Strategic Therapy Center in Arezzo Italy. The theoretical foundations of brief strategic therapy focused on the present and solutions are presented, starting from the premise that attempts at solution actually maintain the problem and proposing that based on strategic logic the solution always adapts to the problem and its object of study.

En este ensayo pretendo analizar la relación entre Rawls y el derecho concibiendo a Rawls mismo como un filósofo del derecho y, de hecho, como jurista. Si bien Rawls no se per-cibió a sí mismo como filósofo del derecho, y aunque en su obra hay muchas discusiones jurídicas importantes –algunas de las cuales mencionaré realizó sus principales contri-buciones a la teoría jurídica a través de su filosofía política, porque la teoría jurídica hace parte de la filosofía política y Rawls escribió de manera abstracta sobre la disciplina en conjunto. Deseo identificar, pero también evaluar, brevemente aquellos aspectos de la teoría de la justicia de Rawls que se relacionan de forma directa con los asuntos tradicionales de la filosofía del derecho.

Climatic changes weaken lavender and lavandin crops, intensify the effects of dieback and increase their impact on the environment. The impacts of climatic factors were studied through the ecophysiology of the plant, the central issue of assessment; which made it possible to demonstrate a threshold value for the loss of diameter of a branch at which the plant would die; the diameter can be continuously monitored through the use of microdendrometers. Facing this challenge, the value of innovative agroecological cultivation practices, plant cover between rows, has been assessed to increase the resilience of crops to climate and pests. Even if they did not show a direct interest in the face of climate change, the vegetation cover is of undeniable interest in reducing dieback due to Stolbur