Reply on EC1

Abstract

Satellite altimetry missions flying over the ice-covered Arctic Ocean have been opening the possibility to further understand recent changes in the surface circulation. The use of these data has been however deferred by the need for dedicated processing, with efforts to generate consistent Arctic-wide datasets ongoing. The aim of this paper is to provide and assess a new gridded dataset of sea surface height anomaly and geostrophic velocity, extending over both the ice-covered and open ocean areas of the Arctic. Data from the Cryosat-2 mission in the period 2011–2020 were gridded at one month intervals, up to 88° N, using the Data-Interpolating Variational Analysis (DIVA) method. To examine the robustness of our results, we compare our dataset to independent satellite and in-situ data. We find that our dataset is well correlated with independent satellite data at monthly time scales and agrees with in-situ observed variability at seasonal to interannual time scales. Our geostrophic velocity fields can resolve the variability of boundary currents wider than about 50 km. We further discuss the seasonal cycle of sea surface height and geostrophic velocity in the context of previous literature. Large scale features emerge: a wintertime Arctic-wide maximum in sea surface height, with the highest amplitude over the shelves, and basin wide seasonal acceleration of Arctic slope currents in winter. We suggest that this dataset can be used to study not only the large scale variability of sea surface height and circulation but also the regionally confined boundary currents.