Expanded Understanding of the Western Antarctic Peninsula Sea-Ice Environment Through Local and Regional Observations at Palmer Station

The Western Antarctic Peninsula (WAP) has been experiencing rapid regional warming since at least the 1950s, however, the impacts of this warming at the local scale are variable and nuanced. Previous studies that have linked sea-ice variability to biogeochemical cycles and food web dynamics often combine local-scale biogeochemical data with coarse-resolution regional satellite sea-ice data, which may not adequately capture local sea-ice conditions. In this study, we analyzed local-scale in situ sea-ice observations collected as part of a 28-year record (1992–2020) from the Palmer Long-Term Ecological Research site at Anvers Island, mid-WAP, in conjunction with isotopically-derived sea-ice meltwater (SIM) fractions and satellite-derived sea-ice motion and concentration, to quantify the variability and long-term trends in local sea-ice behavior. In situ sea ice observations at Palmer Station displayed higher variability than satellite observations and showed no significant declines over this time, despite region-wide declines identified in prior studies. Higher spring SIM fractions were attributed to strong northward sea-ice motion throughout the winter. Applying these local-scale sea-ice insights to similarly scaled stratification and chlorophyll-a measurements, we found that a longer-lasting, more consistent sea-ice pack led to greater water column stratification following the spring sea-ice retreat. Greater sea-ice persistence and stronger stratification led to larger peaks in chlorophyll-a, though sea-ice metrics did not explain the positive temporal trends in either stratification strength or chlorophyll-a. Through this study, we identify how local sea-ice observations and meltwater data can enhance satellite data to build an understanding of the intricate connections between ice, water column dynamics, and phytoplankton.

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