On the assimilation of ice velocity and concentration data into large-scale sea ice models

Data assimilation into sea ice models designed for climate studies has started about 15 years ago. In most of the studies conducted so far, it is assumed that the improvement brought by the assimilation is straightforward. However, some studies suggest this might not be true. In order to elucidate this question and to find an appropriate way to further assimilate sea ice concentration and velocity observations into a global sea ice-ocean model, we analyze here results from a number of twin experiments (i.e. experiments in which the assimilated data are model outputs) carried out with a simplified model of the Arctic sea ice pack. Our objective is to determine to what degree the assimilation of ice velocity and/or concentration data improves the global performance of the model and, more specifically, reduces the error in the computed ice thickness. A simple optimal interpolation scheme is used, and outputs from a control run and from perturbed experiments without and with data assimilation are thoroughly compared. Our results indicate that, under certain conditions depending on the assimilation weights and the type of model error, the assimilation of ice velocity data enhances the model performance. The assimilation of ice concentration data can also help in improving the model behavior, but it has to be handled with care because of the strong connection between ice concentration and ice thickness. This study is first step towards real data assimilation into NEMO-LIM, a global sea ice-ocean model

Au large de Villefranche-sur-Mer – La rade

Tout au long de ce chantier organisé durant le mois de novembre 2015, nous avons travaillé dans des conditions météorologiques exceptionnelles. Du beau temps du début à la fin avec des eaux offrant une température de 20 à 18° fin novembre. Pas de courant, une eau limpide, aucune plongée annulée pour raison météo durant cette nouvelle prospection… Ces conditions météorologiques de fin d’été nous ont posé cependant un problème primordial pour nos fouilles. S’il est préférable de travailler dans..

Au large de Villefranche-sur-Mer – La Rade

Durant cette nouvelle prospection archéologique 2014, les découvertes effectuées lors des immersions ont été, une fois encore, à la hauteur de nos espérances. La météo défavorable à cette période de l’année a bien souvent des effets positifs pour notre prospection car les coups de mer dégagent totalement la partie supérieure du fond marin de la rade. Du coup, le bilan du mobilier sauvegardé lors de cette mission 2014 est exceptionnel. Sauvés des eaux, ces précieux témoignages du passé, minuti..

Optimising the future Belgian offshore wind farm monitoring programme

Six years of monitoring triggered a reflection on how to best continue with the monitoring programme. The basic monitoring has to be rationalised at the level of the likelihood of impact detection, the meaningfulness of impact size and representativeness of the findings. Targeted monitoring should continue to disentangle processes behind the observed impact, for instance the overarching artificial reef effect created by wind farms. The major challenge however remains to achieve a reliable assessment of the cumulative impacts. Continuing consultation and collaboration within the Belgian offshore wind farm monitoring team and with foreign marine scientists and managers will ensure an optimisation of the future monitoring programme