Mapping and assessing variability in the Antarctic Marginal Ice Zone, the Pack Ice and coastal Polynyas

• Published in: The Cryosphere
• Main Authors: Stroeve, Julienne, Jenouvrier, Stéphanie, Campbell, Garrett G., Barbraud, Christophe, Delord, Karine
• Other Authors: National Snow and Ice Data Center (NSIDC), University of Colorado Boulder, Center for Polar Observation and Modelling, University College of London London (UCL), Biology Department (WHOI), Woods Hole Oceanographic Institution (WHOI), Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), Institut National de la Recherche Agronomique (INRA)-La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: [SDE]Environmental Sciences; Antarctic; The Antarctic; Antarc*; Sea ice; The Cryosphere; The Cryosphere Discussions
• Online Access: https://hal.science/hal-01329561; https://doi.org/10.5194/tc-10-1823-2016

International audience Sea ice variability within the marginal ice zone(MIZ) and polynyas plays an important role for phytoplanktonproductivity and krill abundance. Therefore, mappingtheir spatial extent as well as seasonal and interannual variabilityis essential for understanding how current and futurechanges in these biologically active regions may impact theAntarctic marine ecosystem. Knowledge of the distributionof MIZ, consolidated pack ice and coastal polynyas in thetotal Antarctic sea ice cover may also help to shed lighton the factors contributing towards recent expansion of theAntarctic ice cover in some regions and contraction in others.The long-term passive microwave satellite data recordprovides the longest and most consistent record for assessingthe proportion of the sea ice cover that is covered by eachof these ice categories. However, estimates of the amount ofMIZ, consolidated pack ice and polynyas depend strongly onwhich sea ice algorithm is used. This study uses two popularpassive microwave sea ice algorithms, the NASA Team andBootstrap, and applies the same thresholds to the sea ice concentrationsto evaluate the distribution and variability in theMIZ, the consolidated pack ice and coastal polynyas. Resultsreveal that the seasonal cycle in the MIZ and pack ice is generallysimilar between both algorithms, yet the NASA Teamalgorithm has on average twice the MIZ and half the consolidatedpack ice area as the Bootstrap algorithm. Trends alsodiffer, with the Bootstrap algorithm suggesting statisticallysignificant trends towards increased pack ice area and no statisticallysignificant trends in the MIZ. The NASA Team algorithmon the other hand indicates statistically significantpositive trends in the MIZ during spring. Potential coastalpolynya area and amount of broken ice within the consolidatedice pack are also larger in the NASA Team algorithm.The timing of maximum polynya area may differ by as muchas 5 months between algorithms. These differences lead todifferent relationships between sea ice ...