CoAuthors

Andrea Storto (CNR-ISMAR, Italy); Roshin P. Raj (NERSC, Norway); Laurent Bertino (NERSC, Norway); Jiping Xie (NERSC, Norway); Francois Counillon (NERSC, Norway)

The inter-annual changes of the Arctic Ocean features are well-known proxies of the global climate change, affecting the global climate through specific processes (e.g. dense water formation, meridional heat redistribution). The ocean circulation at high latitudes has significantly changed during recent decades, with an enormous impact on the socio-economic activities of the Nordic populations. Monitoring the Arctic environment is however non-trivial: the Arctic observing network is notably lacking the capability to provide a full picture of the changing ocean due to technological and economical limitations to sample the seawater beneath the ice or in the marginal ice zones. This leads to the obvious need of optimizing the exploitation of data from space-borne sensors. Among these, altimetric radars measuring the sea level at millimetric precision have revolutionized our knowledge of the oceanic circulation, for more than 2 decades, at a large spectrum of scales ranging from the mesoscale activity to the slowly varying basin-wide dynamics. Technological solutions are continuously needed and pursued to enhance the spatial resolution of the altimetric signal and enable the solution of the mesoscale dynamics, either in the design of the altimeter itself (e.g. wide-swath altimeters) or in the combined use of altimeter data from multiple bands. Newly reprocessed along-track measurements of Sentinel-3A, CryoSat-2, and SARAL/AltiKa altimetry missions (AVISO/TAPAS), optimized for the Arctic Ocean (retracking) and sampled at 5 Hz, have been recently produced in the framework of CNES AltiDoppler project. This study is devoted to the exploitation of such satellite altimetry data in high-latitude regions. We investigate the benefits of the reprocessed altimetry dataset at 5 Hz with augmented signal resolution in the context of ocean and sea-ice coupled short-range forecasts. In particular, we compare the effectiveness of this dataset to improve the mesoscale details of the forecasts in comparison to the conventional altimetry sampling dataset and to the altimetry-blind experiments, in order to assess the added value of the enhanced altimetry reprocessing in Nordic Seas. This comparison can motivate the assimilation of the high-resolution altimetry data in ocean re-analysis for the Arctic.