Sea Surface Height Anomalies of the Arctic Ocean From ICESat‐2: A First Examination and Comparisons With CryoSat‐2

Abstract

Routine and accurate profiling of the sea surface height (SSH) in the Arctic is needed to continue these crucial time series and provide more detailed insights into these changes. While we can reliably monitor the SSH of the open oceans at lowto-mid latitudes using satellite altimetry data (IPCC, 2019), continuous and widespread measurements at high-latitude ice-covered seas have remained limited. The main challenges are the reduced coverage due to the low inclination orbit of most satellite altimeters, sea surface sampling limited to narrow openings in the sea ice cover, and the need to accurately discriminate between sea ice and ocean surface altimetry returns.

Arctic Freeboard and Snow Depth From Near‐Coincident CryoSat‐2 and ICESat‐2 (CRYO2ICE) Observations: A First Examination of Winter Sea Ice During 2020–2022

“…The weak beams are ∼1/4th of the strong beams, and thus we expect lower precision and longer segment‐lengths of ATL10 when using weak beams (Bagnardi et al., 2021 also noted that preliminary studies of the IS2 Project Science Office have identified range biases across the beams of centimetre‐levels), as the study by Bagnardi et al. (2021) identified an overall a small inter‐beam bias on sea surface height anomalies over the Arctic Ocean between the strong beams of beam‐pair 1 (GT1R) and beam‐pair 3 or 5 (GT3R/GT5R) of ∼3 cm. One could consider using only the strong beams (and potentially only one beam) to limit potential impact on precision, however as we have shown (Figure S1 in Supporting Information ), limited data was available when generating C2I tracks when considering small search radii (by excluding beam‐pairs far away), and when using only strong beams (not shown).…”

“…When considering systematic biases of IS2, its worthy to consider the impact on precision there is from including all six beams in the binning of IS2 observations. While studies have investigated the overall precision of IS2's weak and strong beams in the Arctic (Ricker et al., 2023) along with inter‐beam discrepancies (Bagnardi et al., 2021), it is not clear exactly what the impact is on derived freeboards over sea ice. The weak beams are ∼1/4th of the strong beams, and thus we expect lower precision and longer segment‐lengths of ATL10 when using weak beams (Bagnardi et al., 2021 also noted that preliminary studies of the IS2 Project Science Office have identified range biases across the beams of centimetre‐levels), as the study by Bagnardi et al.…”

“…We are likely to require a radius for binning the observations that is larger than the radius of the theoretical CS2 pulse‐limited footprint (∼850 m, as was used in Bagnardi et al. (2021)), since observations from the two sensors are rarely coinciding at this radius (not shown). Since IS2 observations closest to the CS2 observation should be more representative of the surface observed by CS2, we assign a higher priority to these observations.…”

“…While studies have investigated the overall precision of IS2's weak and strong beams in the Arctic (Ricker et al, 2023) along with inter-beam discrepancies (Bagnardi et al, 2021), it is not clear exactly what the impact is on derived freeboards over sea ice. The weak beams are ∼1/ 4th of the strong beams, and thus we expect lower precision and longer segment-lengths of ATL10 when using weak beams (Bagnardi et al, 2021 also noted that preliminary studies of the IS2 Project Science Office have identified range biases across the beams of centimetre-levels), as the study by Bagnardi et al (2021) identified an overall a small inter-beam bias on sea surface height anomalies over the Arctic Ocean between the strong beams of beam-pair 1 (GT1R) and beam-pair 3 or 5 (GT3R/GT5R) of ∼3 cm. One could consider using only the strong beams (and potentially only one beam) to limit potential impact on precision, however as we have shown (Figure S1 in Supporting Information S1), limited data was available when generating C2I tracks when considering small search radii (by excluding beam-pairs far away), and when using only strong beams (not shown).…”

Consolidating ICESat-2 Ocean Wave Characteristics with CryoSat-2 during the CRYO2ICE Campaign

“…This is especially useful when observing the ocean's surface topography due to its high variability. By 1 August 2021, one year of passes had been collected, so that there were enough data to compare the two altimeter systems [13].…”