Unraveling the circulation and melwater distribution in the Bellingshausen Sea

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Xiyue Zhang in a mountain trek

Xiyue (Sally) Zhang is a PhD student in Environmental Science and Engineering at the California Institute of Technology. She here reporting on some exciting science recently published in the Geophysical Research Letters.


The polar regions have long been fascinating to me, not only for their exoticness, but also their importance to the global climate. My thesis focuses on polar cloud dynamics, and I also worked closely with oceanographers at Caltech to enhance our understanding of ocean/ice shelf interactions in Antarctica.

We started by exploring data from 13 seals that were tagged in 2010. A couple of seals traveled all the way from the tip of the Antarctic Peninsula to the western Bellingshausen Sea shelf break. What really inspired us to focus on the Bellingshausen Sea is the observational study that showed high ice shelf basal melt rates in the region. Therefore, we decided to use all available data in the MEOP consortium in the Bellingshausen Sea (Figure 1). The seal-borne data are advantageous over the limited cruise-based measurements due to the inaccessible nature of the region: it is geographically hard to reach, and hampered by seasonal sea ice cover.


Figure 1: The Bellingshausen Sea region with dots showing the MEOP profiles. Contours show bottom bathymetry. The big black box highlights the main canyon Belgica Trough (BT). For more information, see Zhang et al. (2016).

Using the temperature, salinity, and pressure data collected by 80 seals in the Bellingshausen Sea region from 2007 to 2014, Zhang et al. 2016 analyzed the three-dimensional water masses distribution at the continental shelf break and on the shelf. The Bellingshausen Sea hosts 6 ice shelves that have thinned rapidly over recent decades. A cyclonic circulation within the Belgica Trough, the main shelf canyon, is identified based on the meltwater distribution. This circulation brings water at least 3 degrees Celsius warmer than the freezing temperature towards the coast on the eastern boundary. Water is modified to be colder and fresher as it exits the Belgica Trough via the western boundary. Furthermore, a westward slope current is implied west of the trough. Our findings support the high basal melt rate and thinning of ice shelves in the region detected by satellite observations. We plan to continue using data from the MEOP consortium to improve our understanding of shelf circulation in Antarctica.    

Find out more in the press, on The Washington Post and (in German) in the Klimaretter.

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