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Forests strongly modify the accumulation, metamorphism and melting of snow in mid and high-latitude regions. Recently, snow routines in hydrological and land surface models have been improved to incorporate more accurate representations of forest snow processes, but model inter-comparison projects have identified deficiencies, partly due to incomplete knowledge of the processes controlling snow cover in forests. The Snow Under Forest (SnoUF) project was initiated to enhance knowledge of the complex interactions between snow and vegetation. Two field campaigns, during the winters 2016–17 and 2017–18, were conducted in a coniferous forest bordering the snow study at Col de Porte (1325 m a.s.l, French Alps) to document the snow accumulation and ablation processes. This paper presents the field site, instrumentation, and collection methods. The observations include distributed forest characteristics (tree inventory, LIDAR measurements of forest structure, sub-canopy hemispherical photographs), meteorology (automatic weather station and radiometers array), snow cover and depth (snow poles transect and laser scan), and snow interception by the canopy during precipitation events. The weather station installed under dense canopy during the first campaign has been maintained since then and provides continuous measurements throughout the year since 2018. Data are publicly available from the repository of the Observatoire des Sciences de l’Univers de Grenoble (OSUG) data center at http://dx.doi.org/10.17178/SNOUF.2022 (Sicart et al., 2022).

Pending its full entry into force, the Canada-European Union Comprehensive Economic and Trade Agreement (CETA) is provisionally applied since September 21st, 2017, without the investor-state dispute settlement system it contains. This part of the agreement falls within the area of shared competence between the Union and its many Member States, unlike the "common commercial policy" which is an exclusive competence of the Union. It has been excluded in order to quickly trigger the provisional application of the agreement. The consensus of both Parties on this delimitation has made it possible to implement most of the agreement according to very different procedures in Canada and in the European Union. However, the CETA admits several causes for the premature termination of its provisional application, including the definitive failure of the parliamentary approval and ratification process of any Member State of the Union., En attendant son entrée en vigueur intégrale, l’Accord économique et commercial global entre le Canada et l’Union européenne (AECG/ CETA) est d’application provisoire depuis le 21 septembre 2017, sans le système de règlement des différends entre investisseurs et États qu’il comporte. Cette partie de l’accord relève du domaine de compétence partagée entre l’Union et ses nombreux États membres, à la différence de la «politique commerciale commune » qui est de compétence exclusive de l’Union. Elle a été exclue du champ de l’application provisoire afin de déclencher celle-ci rapidement. Le consensus des deux Parties sur cette délimitation a permis de mettre en application la majeure partie de l’accord selon des procédures très différentes au Canada et au sein de l’Union européenne. L’AECG admet cependant plusieurs causes de fin prématurée de son application provisoire, parmi lesquelles l’échec définitif du processus d’approbation parlementaire et de ratification de n’importe quel État membre de l’Union., En espera de su plena entrada en vigor, el Acuerdo Económico y Comercial General entre el Canadá y la Unión Europea (AECG/CETA) se aplica provisionalmente desde el 21 de septiembre de 2017, sin el sistema de resolución de conflictos entre inversores y Estados que contiene. Esta parte del acuerdo entra en el ámbito de la competencia compartida entre la UE y sus numerosos Estados miembros, a diferencia de la "política comercial común" que es competencia exclusiva de la UE. Se ha excluido a fin de poner en marcha rápidamente la aplicación provisional del acuerdo. El consenso de ambas Partes sobre esta delimitación ha permitido la aplicación de la mayor parte del acuerdo según procedimientos muy diferentes en el Canadá y en la Unión Europea. Sin embargo, el AECG admite varias causas para la terminación prematura de su aplicación provisional, entre ellas el fracaso definitivo del proceso de aprobación parlamentaria y ratificación de cualquier Estado miembro de la Unión., Lejeune Yves. Le régime d'application provisoire de l'AECG entre le Canada et l'Union européenne. In: Revue Québécoise de droit international, Hors-série janvier 2022 – Une passion pour le droit international. Amicorum Discipulorumque Liber : Daniel Turp. pp. 141-166.

The Solid Precipitation Intercomparison Experiment (SPICE) was conducted as an internationally coordinated project, initiated and guided by the Commission for Instruments and Methods of Observation (CIMO) of the World Meteorological Organization (WMO). The SPICE field experiments took place between 2013 and 2015, with a preparatory stage during the winter of 2012/13. SPICE was carried out as a major international effort, and has been remarkable for the diversity of organizations which hosted SPICE tests, contributed with instruments, and were engaged in the data analysis and the derivation of results. In addition to National Meteorological and Hydrological Services, research organizations, academia, and the private sector played active roles and made unique contributions. Field experiments were conducted at twenty sites located in fifteen countries, on all continents except Africa and Antarctica, as outlined in Section 2 of this report. The instrument manufacturing community made a significant contribution to SPICE, as more than twenty instrument manufacturers provided instruments measuring precipitation amount, snow depth, and snow water equivalent. Each instrument model was tested on one or more sites in different climate regimes and over a large range of environmental conditions, providing a solid foundation for the results presented in this report.

International audience; We investigate the problem of balancing model complexity and input data requirements in snow hydrology. For this purpose, we analyze the performance of two models of different complexity in estimating variables of interest in snow hydrology applications. These are snow depth, bulk snow density, snow water equivalent and snowmelt run-off. We quantify the differences between data and model prediction using 18 years of measurements from an experimental site in the French Alps (Col de Porte, 1325 m AMSL). The models involved in this comparison are a one-layer temperature-index model (HyS) and a multilayer model (Crocus). Results show that the expected loss in performance in the one-layer temperature-index model with respect to the multilayer model is low when considering snow depth, snow water equivalent and bulk snow density. As for run-off, the comparison returns less clear indications for identification of a balance. In particular, differences between the models' prediction and data with an hourly resolution are higher when considering the Crocus model than the HyS model. However, Crocus is better at reproducing sub-daily cycles in this variable. In terms of daily run-off, the multilayer physically based model seems to be a better choice, while results in terms of cumulative run-off are comparable. The better reproduction of daily and sub-daily variability of run-off suggests that use of the multilayer model may be preferable for this purpose. Variation in performance is discussed as a function of both the calibration solution chosen and the time of year. Copyright © 2016 John Wiley & Sons, Ltd.