Marine X-band Radar Observations of Sea Ice Drift Fields in the Arctic
Abstract
This presentation covers shipboard marine X-band radar (MR) sea ice drift field measurements. They are based on the maximum cross correlation between two sequential MR backscatter images separated ∼1 min in time, a method that is commonly used to estimate sea ice drift from satellite products. The advantage of MR is that images in close temporal proximity are readily available. A typical MR antenna rotation period is ∼1-2 s, whereas satellite revisit times can be on the order of days. The technique is applied to ∼4 weeks of measurements taken from R/V Sikuliaq in the Beaufort Sea in the fall of 2015. The resulting MR sea ice drift fields have ∼500 m and up to ∼5 min resolution, covering a maximum range of ∼4 km. They are validated using the GPS-tracked motion of Surface Wave Instrument Float with Tracking (SWIFT) drifters, wave buoys, and R/V Sikuliaq during ice stations. The comparison between MR and reference sea ice drift measurements yields root-mean-square errors from 0.8 to 5.6 cm s-1. The MR sea ice drift fields near the ice edge reveal strong horizontal gradients and peak speeds > 1 m s-1. The observed submesoscale sea ice drift processes include an eddy with ∼6 km diameter and vorticities <-2 (normalized by the Coriolis frequency) as well as converging and diverging flow with normalized divergences <-2 and >1, respectively. The sea ice drift speed correlates only weakly with the wind speed (r2 = 0.34), which presents a challenge to conventional wisdom.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.C32C..03L
- Keywords:
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- 0750 Sea ice;
- CRYOSPHEREDE: 0758 Remote sensing;
- CRYOSPHEREDE: 1621 Cryospheric change;
- GLOBAL CHANGEDE: 4207 Arctic and Antarctic oceanography;
- OCEANOGRAPHY: GENERAL