A new look at Antarctic coastal polynya variability and trends

Authors: Jason Ward*, UCLA Geography, Marilyn Raphael, University of California, Los Angeles
Topics: Polar Regions, Coastal and Marine, Climatology and Meteorology
Keywords: Antarctic, polynyas, coast, cryosphere, sea ice
Session Type: Paper
Day: 4/4/2019
Start / End Time: 3:05 PM / 4:45 PM
Room: Taylor, Marriott, Mezzanine Level
Presentation File: No File Uploaded

Every year, the Antarctic sea ice field expands, which significantly reduces gas, heat, and mass transfers. However, situated in the pack ice and along the coastal regions, are areas of open water and reduced ice cover called polynyas, which continually allow the ocean-atmosphere transfers. To fully understand polynyas, researchers must understand their temporally dynamic nature at various scales.

In past studies, polynya variability is most frequently analyzed at daily, monthly, and inter-annual scales. However, analyses of seasonal scale variability and multiyear monthly trends are missing. This study analyzes the size and variability of the 25 largest and most frequently occurring Antarctic coastal polynyas to better understand the temporal scales at which their variability occurs and how their trends change over time.

The cumulative circumpolar system of polynyas experiences total variability at the daily, seasonal, monthly, and annual scales, in descending order of percent contribution to total cumulative variability. Total Antarctic system area has a statistically significant positive trend throughout the study period. 5 individual polynya systems experience significant long-term trends – 3 negative and 2 positive. While significant trends seldom occur at the annual scale, they are much more frequent at the monthly level.

The 4 historically largest and most productive polynyas decreased in areal extent, and thus ice production, throughout the study period. The next 3 largest producers of coastal sea ice each experienced increases in areal extent. Thus, the greatest contributors to polynya area and ice production may change relatively soon as current tendencies persist.

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