Abstract
AbstractPonds that form on sea ice can cause it to thin or break-up, which can promote calving from an adjacent ice shelf. Studies of sea ice ponds have predominantly focused on Arctic ponds formed by in situ melting/ponding. Our study documents another mechanism for the formation of sea ice ponds. Using Landsat 8 and Sentinel-2 images from the 2015–16 to 2018–19 austral summers, we analyze the evolution of sea ice ponds that form adjacent to the McMurdo Ice Shelf, Antarctica. We find that each summer, meltwater flows from the ice shelf onto the sea ice and forms large (up to 9 km2) ponds. These ponds decrease the sea ice's albedo, thinning it. We suggest the added mass of runoff causes the ice to flex, potentially promoting sea-ice instability by the ice-shelf front. As surface melting on ice shelves increases, we suggest that ice-shelf surface hydrology will have a greater effect on sea-ice stability.
Highlights
Ponds that form on sea ice are important for the energy balance of the sea ice and the polar oceans
In the Antarctic, ponds may form on the sea ice when snow weighs it down and causes seawater to flood its surface (NSIDC, 2019), scientists have rarely observed the presence of ponds formed from meltwater (Andreas and Ackley, 1981; Perovich, 1996) because there is minimal surface melt on Antarctic sea ice (Vihma and others, 2009)
We show that meltwater from the McMurdo Ice Shelf (McMIS) flows off the ice shelf and onto the adjacent sea ice, forming sea ice ponds that we suggest may affect the stability of the sea ice
Summary
Ponds that form on sea ice are important for the energy balance of the sea ice and the polar oceans. We document and analyze the formation and evolution of sea ice ponds in McMurdo Sound, adjacent to the McMIS, over the austral summers of 2015–16 to 2018–19 We do this qualitatively, by analyzing satellite image data over the period, and quantitatively, by using a water-identification algorithm to measure the evolution of the ponded area. We acquired a time series of completely or partially cloud-free Landsat 8 and Sentinel-2 images over the study site (Fig. 1) for the period from 29 November 2015 to 24 January 2019 (Table S1) This period covers the entire lifecycle of the McMurdo Sound multi-year sea ice that formed in 2016 and broke-out in 2019, and the sea ice that only lasted for the 2015–16 season. Substantial gaps in the availability of quality images during the study period prevent the calculation of ponded area for some stretches of the study period, limiting the temporal resolution of the study and introducing uncertainty about the timing and magnitude of ponding
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