Preprints
https://doi.org/10.5194/tc-2021-144
https://doi.org/10.5194/tc-2021-144

  25 May 2021

25 May 2021

Review status: this preprint is currently under review for the journal TC.

Brief communication: lack of agreement in remote sensing detection of cyclonic drift caused by Atlantic weather in Antarctic sea ice

Wayne de Jager1 and Marcello Vichi1,2 Wayne de Jager and Marcello Vichi
  • 1Department of Oceanography, University of Cape Town, Cape Town, 7700, South Africa
  • 2Marine and Antarctic Research Centre for Innovation and Sustainability (MARIS), University of Cape Town, Cape Town, 7700, South Africa

Abstract. Sea-ice extent variability, a measure based on satellite-derived sea ice concentration measurements, has traditionally been used as an essential climate variable to evaluate the impact of climate change on polar regions. However, concentration- based measurements of ice variability do not allow to discriminate the relative contributions made by thermodynamic and dynamic processes, prompting the need to use sea-ice drift products and develop alternative methods to quantify changes in sea ice dynamics that would indicate trends in Antarctic ice characteristics. Here, we present a new method to automate the detection of rotational drift features in Antarctic sea ice at daily timescales using currently available remote sensing ice motion products from EUMETSAT OSI SAF. Results show that there is a large discrepancy in the detection of cyclonic drift features between products, both in terms of intensity and year-to-year distributions, thus diminishing the confidence at which ice drift variability can be further analysed. Product comparisons showed that there was good agreement in detecting anticyclonic drift, and cyclonic drift features were measured to be 1.5–2.2 times more intense than anticyclonic features. The most intense features were detected by the merged product, suggesting that the processing chain used for this product could be injecting additional rotational momentum into the resultant drift vectors. We conclude that it is therefore necessary to better understand why the products lack agreement before further trend analysis of these drift features and their climatic significance can be assessed.

Wayne de Jager and Marcello Vichi

Status: open (until 20 Jul 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Wayne de Jager and Marcello Vichi

Data sets

Global Low Resolution Sea Ice Drift Norwegian Meteorological Institute http://www.osi-saf.org/?q=content/global-low-resolution-sea-ice-drift-c

Wayne de Jager and Marcello Vichi

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Short summary
Ice motion can be used to better understand how weather and climate change effects the ice. Antarctic sea ice extent has shown large variability over the observed period, and dynamical features may also have changed. Our method allows for the quantification of rotational motion caused by wind and ocean currents, and how this may have changed with time. However, available satellite products do not agree on the estimation of cyclonic motion, hampering our ability to detect longer-term trends.