Quantifying Upper Layer Circulation using Iceberg GPS Tracking

16 slidesThe Greenland proglacial fjord system, where glaciers from the ice sheet reach the ocean, is an important contributor to sea level rise. When reaching the ocean, these glaciers break off icebergs. These icebergs travel through the fjord and out into the open ocean. All the while, different types of water circulate through the fjord, meeting with the glacier’s terminus and affecting it’s stability. The tidewater glacier, Jakobshavn Isbrae, and it’s fjord, Ilulissat, is of particular interest because it is the most prolific glacial system in Greenland in terms of ice export. Many studies have addressed Jakobshavn's glacial front, but little is known about Ilulissat’s ocean circulation due to the difficulty of collecting field measurements in the ice-choked region. Through our study, we deploy transmitting GPS units on icebergs in Ilulissat Fjord, thereby directly tracking iceberg movement and indirectly detecting the fjord's circulation patterns. Using icebergs as proxies for surface circulation thus provides an alternative to deploying marine instruments that have minimal likelihood for survival in the treacherous fjord environment. Results of our study show that: at a distance of 35km away from the glacier terminus, iceberg movement is no longer dominated by glacial calving events; and that there are eddy circulation patterns at fjord widening locations. This study has the potential to help oceanographers understand more about Ilulissat's circulation dynamics, and can inform glaciologists about how glaciers such as Jakobshavn's acceleration is affected by this type of circulation