ROSETTA-Ice

Description/Abstract

        The Ross Ice Shelf is the largest existing ice shelf in Antarctica, and is currently stabilizing significant portions of the land ice atop the Antarctic continent. An ice shelf begins where the land ice goes afloat on the ocean, and as such, the Ross Ice Shelf interacts with the ocean and seafloor below, and the land ice behind. Currently, the Ross Ice Shelf slows down, or buttresses, the fast flowing ice streams of the West Antarctic Ice Sheet (WAIS), a marine-based ice sheet, which if melted, would raise global sea level by 3-4 meters. The Ross Ice Shelf average ice thickness is approximately 350 meters, and it covers approximately 487,000 square kilometers, an area slightly larger than the state of California. The Ross Ice Shelf has disappeared during prior interglacial periods, suggesting in the future it may disappear again. Understanding the dynamics, stability and future of the West Antarctic Ice Sheet therefore requires in-depth knowledge of the Ross Ice Shelf. The ROSETTA-ICE project brings together scientists from 4 US institutions and from the Institute of Geological and Nuclear Sciences Limited, known as GNS Science, New Zealand. The ROSETTA-ICE data on the ice shelf, the water beneath the ice shelf, and the underlying rocks, will allow better predictions of how the Ross Ice Shelf will respond to changing climate, and therefore how the WAIS will behave in the future. The interdisciplinary ROSETTA-ICE team will train undergraduate and high school students in cutting edge research techniques, and will also work to educate the public via a series of vignettes integrating ROSETTA-ICE science with the scientific and human history of Antarctic research.

        The ROSETTA-ICE survey will acquire gravity and magnetics data to determine the water depth beneath the ice shelf. Radar, LIDAR and imagery systems will be used to map the Ross Ice Shelf thickness and fine structure, crevasses, channels, debris, surface accumulation and distribution of marine ice. The high resolution aerogeophysical data over the Ross Ice Shelf region in Antarctica will be acquired using the IcePod sensor suite mounted externally on an LC-130 aircraft operating from McMurdo Station, Antarctica. Field activities will include ~36 flights on LC-130 aircraft over two field seasons in Antarctica. The IcePod instrument suite leverages the unique experience of the New York Air National Guard operating in Antarctica for NSF scientific research as well as infrastructure and logistics. The project will answer questions about the stability of the Ross Ice Shelf in future climate, and the geotectonic evolution of the Ross Ice Shelf Region, a key component of the West Antarctic Rift system. The comprehensive benchmark data sets acquired will enable broad, interdisciplinary analyses and modeling, which will also be performed as part of the project. ROSETTA-ICE will illuminate Ross ice sheet-ice shelf-ocean dynamics as the system nears a critical juncture but still is intact. Through interacting with an online data visualization tool, and comparing the ROSETTA-ICE data and results from earlier studies, we will engage students and young investigators, equipping them with new capabilities for the study of critical earth systems that influence global climate.

ROSETTA:Decoding ice, ocean and tectonic mysteries of the Ross Ice Shelf

GISTool_sm

The Ross Ice Shelf is a massive apron of ice stretching to an area of 487,000 sq. km (188,000 sq. mi) and a thickness of a few hundred meters. The edge of the ice shelf along the Ross Sea is a wall of ice towering above the water by as much as 50 m (~160 ft). However, ice shelves, like icebergs, are mainly below the waterline. This means that the majority of the shelf is not visible without the use of instruments. Our measurements tell us that at its thickest, back away from the floating edge where it is frozen to the ground below, the shelf is close to 1200 m (~4000 ft) thick. Closer to the Ross Sea where it has gone afloat it thins to less than 300 m (~1000 ft). This incredible ice feature is about the same size as the country of France and is being fed a constant flow of ice from glaciers draining from both the East and West Antarctic Ice Sheets. As new ice is added existing ice is being removed through melting at the base and ice calving at the front. Ross Ice Shelf plays a critical roll in stabilizing the Antarctic ice sheet, buttressing the ice that is constantly moving over the land surface. Studying how the ice, ocean and underlying land interact will inform us of potential change in the ice shelf from projected climate change.

Project Summary

ROSSETTA is a large multi-disciplinary and multi-institutional project with several major goals focused on different parts of the full ice shelf system. The project main goals include a focus on:

The Ice - Ice moves into and across the shelf at a range of speeds from 200-1000 m/yr, taking between 500 and 1000 years to travel from where it first goes afloat to where it ends at the calving edge. However evidence collected suggests that the shelf is sensitive to atmospheric and ocean variability, and can change dramatically on short time scales. Understanding this more fully is a project goal.

The Underlying Bed - The bed structure underneath the ice shelf influences ocean circulation below. Through time pre-glacial coastal erosion followed by glacial scouring has carved deepened trenches in the sediment, while the overlying ice has flattened the tops of bedrock ridges. The bed features influence the ocean circulation beneath the ice.

The Ocean - General ocean circulation, tidal currents and the overall mixing in the Ross Sea embayment, including beneath the ice shelf, are sensitive to the geology below as well as changes in the ice shelf extent and ice thickness below the ice surface.

The coupled system of ice, underlying bed and ocean interaction that is the focus of this project requires involvement from an interdisciplinary team of oceanographers, geologists, geophysicists and instrumentation engineers. The project partners include an integrated airborne team from Lamont-Doherty Earth Observatory, glaciologists from Scripps, geologists from Colorado College and oceanogrpahers from ESR. In the field we have gravimeter support from GNS and Dynamic Gravity Systems, geophysical support from U.S.G.S., air support from the New York Air National Guard and LCL productions filming the technology and airborne science.

The platform to be used in data collection is the icepod imaging system designed to collect a fully integrated dataset of ice thickness and accumulation (radar), ice surface (lidar and surface imagery). In addition two gravimeters and a magnetometer have been added to the instrument suite to identify the geology and the depth of th Ross embayment below the ice shelf.