Centre Toulousain d'Histoire du Droit et des Idées Politiques

Abstract. Sea ice volume's significant interannual variability requires long-term series of observations to identify trends in its evolution. Despite improvements in sea ice thickness estimations from altimetry during the past few years thanks to CryoSat-2 and ICESat-2, former ESA radar altimetry missions such as the Environmental Satellite (Envisat) and especially the European Remote-Sensing Satellite (ERS-1 and ERS-2) have remained under-exploited so far. Although solutions have already been proposed to ensure continuity of measurements between CryoSat-2 and Envisat, there is no time series integrating ERS. The purpose of this study is to extend the Arctic radar freeboard time series back to 1995. The difficulty in handling ERS measurements comes from a technical issue known as the pulse blurring effect, altering the radar echoes over sea ice and the resulting surface height estimates. Here we present and apply a correction for this pulse blurring effect. To ensure consistency of the CryoSat-2, Envisat and ERS-2 time series, a multiparameter neural-network-based method to calibrate Envisat against CryoSat-2 and ERS-2 against Envisat is presented. The calibration is trained on the discrepancies observed between the altimeter measurements during the mission-overlap periods and a set of parameters characterizing the sea ice state. Monthly radar freeboards are provided with uncertainty estimations based on a Monte Carlo approach to propagate the uncertainties all along the processing chain, including the neural network. Comparisons of corrected radar freeboards during overlap periods reveal good agreement between the missions, with a mean bias of 0.30 cm and a standard deviation of 9.7 cm for Envisat and CryoSat-2 and a 0.20 cm bias and a standard deviation of 3.8 cm for ERS-2 and Envisat. The monthly corrected radar freeboards obtained from Envisat and ERS-2 are then validated by comparison with several independent datasets such as airborne, mooring, direct-measurement and other altimeter products. Except for two datasets, comparisons lead to correlations ranging from 0.41 to 0.94 for Envisat and from 0.60 to 0.74 for ERS-2. The study finally provides radar freeboard estimation for winters from 1995 to 2021 (from the ERS-2 mission to CryoSat-2).

The relatively stable conditions of the sea ice cover in the Antarctic, observed for almost 40 years, seem to be changing recently. Therefore, it is essential to provide sea ice thickness (SIT) and volume (SIV) estimates in order to anticipate potential multi-scale changes in the Antarctic sea ice. For that purpose, the main objectives of this work are: (1) to assess a new sea ice freeboard, thickness and volume altimetry dataset over 2003–2020 and (2) to identify first order impacts of the sea ice recent conditions. To produce these series, we use a neuronal network to calibrate Envisat radar freeboards onto CryoSat-2 (CS2). This method addresses the impacts of surface roughness on Low Resolution Mode (LRM) measurements. During the 2011 common flight period, we found a mean deviation between Envisat and CryoSat-2 radar freeboards by about 0.5 cm. Using the Advanced Microwave Scanning Radiometer (AMSR) and the dual-frequency Altimetric Snow Depth (ASD) data, our solutions are compared with the Upward looking sonar (ULS) draft data, some in-situ measurement of the SIMBA campaign, the total freeboards of 6 Operation Ice Bridge (OIB) missions and ICESat-2 total freeboards. Over 2003–2020, the global mean radar freeboard decreased by about −14% per decade and the SIT and SIV by about −10% per decade (considering a snow depth climatology). This is marked by a slight increase through 2015, which is directly followed by a strong decrease in 2016. Thereafter, freeboards generally remained low and even continued to decrease in some regions such as the Weddell sea. Considering the 2013–2020 period, for which the ASD data are available, radar freeboards and SIT decreased by about −40% per decade. The SIV decreased by about −60% per decade. After 2016, the low SIT values contrast with the sea ice extent that has rather increased again, reaching near-average values in winter 2020. The regional analysis underlines that such thinning (from 2016) occurs in all regions except the Amundsen-Bellingshausen sea sector. Meanwhile, we observed a reversal of the main regional trends from 2016, which may be the signature of significant ongoing changes in the Antarctic sea ice.

Beginning in the twelfth century, taxation increasingly became an essential component of medieval society in most parts of Europe. The state-building process and relations between princes and their subject cities or between citizens and their rulers were deeply shaped by fiscal practices. Although medieval taxation has produced many publications over the past decades there remains no synthesis of this important subject.
\nThis volume provides a comprehensive overview on a European scale and suggests new paths of inquiry. It examines the fiscal systems and practices of medieval Europe, including essen- tial themes such as medieval fiscal theory and the power to tax; royal and urban taxation; and Church taxation. It goes on to survey the entire European continent, as well as including com- parative chapters on the non-European medieval world, exploring questions on how taxation developed and functioned; what kinds of problems authorities encountered assessing their fiscal power; and the circulation of fiscal cultures and practices across cities and kingdoms. The book also provides a glossary of the most important types of medieval taxes, giving an essential def- inition of key terms cited in the chapters.
\nThe Routledge Handbook of Public Taxation in Medieval Europe will appeal to a large audience, from seasoned scholars who need a comprehensive synthesis, to students and younger scholars in search of an overview of this critical subject.

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Texte rédigé dans le cadre de la journée d'études (8 décembre 2022) organisée à la Faculté de droit de Toulouse à l'occasion du Cinquième centenaire de la naissance de Jacques Cujas. 
\nL'étude relate les festivités et les discours prononcés en 1922 pour le centenaire précédent.

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Pour qu’une jurisprudence « fasse jurisprudence », il faut un dépassement du simple cadre concret de l’affaire. C’est ce que nous indique la doctrine contemporaine, semblant ainsi exclure a priori cette donnée de l’ancien droit. Or, nous constatons que très tôt la jurisprudence a pris place parmi les sources du droit. L’existence même d’une doctrine, à travers notamment les arrêtistes, a permis à la jurisprudence ce dépassement casuistique et même une anticipation sur l’avenir. Elle a directement participé au mouvement vers l’unification du droit sous notre ancien droit et à une adaptation aux besoins sociétaux contemporains malgré l’omnipotence de la loi souhaitée à la Révolution.

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