Sea surface height anomaly and geostrophic velocity from altimetry measurements over the Arctic Ocean (2011–2018)

Abstract

Abstract. In recent decades the decline of the Arctic sea ice has modified vertical momentum fluxes from the atmosphere to the ice and the ocean, thereby affecting the surface circulation. In the past ten years satellite altimetry has contributed to understand these changes. However, data from ice-covered regions require dedicated processing, originating inconsistency between ice-covered and open ocean regions in terms of biases, corrections and data coverage. Thus, efforts to generate consistent Arctic-wide datasets are still required to enable the study of the Arctic Ocean surface circulation at basin-wide scales. Here we provide and assess a monthly gridded dataset of sea surface height anomaly and geostrophic velocity. This dataset is based on Cryosat-2 observations over ice-covered and open ocean areas of the Arctic up to 88° N for the period 2011 to 2018, interpolated using the Data-Interpolating Variational Analysis (DIVA) method. Geostrophic velocity was not available north of 82° N before this study. To examine the robustness of our results, we compare the generated fields to one independent altimetry dataset and independent data of ocean bottom pressure, steric height and near-surface ocean velocity from moorings. Results from the comparison to near-surface ocean velocity show that our geostrophic velocity fields can resolve seasonal to interannual 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, i.e. Arctic-wide maximum sea surface height between October and January, 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 sea surface height and circulation but also the regionally confined boundary currents. The dataset is available in netCDF format from PANGAEA at [data currently under review].

Overview of the MOSAiC expedition: Physical oceanography

“…Our full-depth hydrography data can be used as validation for satellite gravimetry. Combined with satellite altimetry, improved gravimetry would reduce uncertainty in sea-level trends (e.g., Jeon et al, 2018) and allow us to monitor freshwater changes and geostrophic circulation in the Arctic with improved accuracy (e.g., Armitage et al, 2016Armitage et al, , 2017Doglioni et al, 2021).…”

Sea surface height super-resolution using high-resolution sea surface temperature with a subpixel convolutional residual network

“…SSH and SST variables are linked by a hidden physical relation (Leuliette and Wahr, 1999) that we aim to use by combining these multiresolution data to downscale the coarse SSH. This could lead to estimate ocean currents as they are formed by geostrophy from SSH gradient (Doglioni et al, 2021). This is a super resolution (SR) problem applied to oceanography.…”

A new Arctic MSS model derived from combined Cryosat-2 and ICESat observations

“…Prandi et al (2021) presented an Arctic sea level anomaly (SLA) dataset with combined observations from SARAL/AltiKa, Cryosat-2 and Sentinel-3A, exhibiting better performance and temporal resolution than mono-mission datasets. Doglioni et al (2022) also provided monthly SLA products spanning from 2011 to 2020 with Cryosat-2 products. In addition to sea level, some key technologies of sea surface determination in polar oceans were also widely used in sea ice research, especially with ICESat and Cryosat-2 measurements (see e.g.…”