On the definition of the marginal ice zone: a case study with SAR and passive microwave data

Abstract

Widening and increasing extent of the marginal ice zone (MIZ), a transitional area between the open ocean and the pack ice, underscores the scientific significance of observing the MIZ. In the present study, we employed passive microwave (PM) and synthetic aperture radar (SAR) sea ice concentration (SIC) in the Greenland Sea and Beaufort Sea in November 2021 to detect the MIZ using two different MIZ definitions: SIC threshold-based (MIZ _t ) and SIC anomaly-based (MIZ _σ ). This study is the first to compare the SIC threshold-based with SIC anomaly-based MIZ definition using two different sources of SIC data. Our findings reveal that the SIC anomaly-based definition delineates a spatially extensive MIZ, capturing SIC variation attributed to sea ice growth. We also found that SAR data, compared to PM data, consistently identifies a broader MIZ region and is less sensitive to the threshold for the SIC anomaly standard deviation, underscoring the importance of selecting the appropriate MIZ definition.

Keywords

• Arctic
• convolutional neural network
• marginal ice zone
• passive microwave
• synthetic aperture radar
• sea ice concentration