Southern Ocean Science
Faculty
Dr. Kristen Buck
Research in the Buck lab is geared toward investigating the biogeochemical cycling
of trace metals in the oceans and, in particular, the role of organic ligands in the
bioavailability and cycling of the bioactive trace metals iron and copper. Buck鈥檚
research in the Southern Ocean is directed primarily at improving understanding of
the chemistry of iron, which serves as a limiting nutrient to phytoplankton in these
waters. An ongoing collaboration with Bethany Jenkins (URI) and Dreux Chappell (ODU)
is designed to investigate the feedback interactions between phytoplankton communities,
nutrient conditions, and the physicochemical speciation of iron in the open waters
of the Antarctic Circumpolar Current, as compared to the coastal waters of the West
Antarctic Peninsula. This current work is funded by the National Science Foundation
and employs a combination of field sampling, shipboard incubation experiments, and
laboratory-based manipulation experiments. Contact Dr. Kristen Buck
Dr. Don Chambers
Dr. Chambers, his students, and research staff study several aspects of the changing
physical state of the Southern Ocean and Antarctica, including: sea level contribution
from Antarctica ice sheet melting, changes in the circulation of the Antarctic Circumpolar
Current over time-periods of several years to a decade or longer, long-term changes
in the eddy kinetic energy throughout the Southern Ocean, and identification of fronts
and jets in the Southern Ocean. They mainly use satellite data (altimetry, gravity,
winds, and sea surface temperature), but also use data from in situ observations including
the Argo array, CTDs, tide gauges, and bottom pressure sensors. Contact Dr. Don Chambers
Dr. Tim Conway
Research in Tim Conway鈥檚 group aims to understand the geochemistry of trace metals
in the marine and earth system, and the role they play as micronutrients and/or toxins
in marine biogeochemical cycles, with effects on the global carbon cycle. Researchers
working with Dr. Conway employ isotopic techniques including measurement of trace
metal (Fe, Zn, Ni, Cd, Cu) isotope ratios by multi-collector HR-ICPMS in a range of
materials including aerosol dust, rocks, sediments rain, seawater, ice-cores, marine
particles and biological materials. We work closely with national and international
collaborators as part of the International GEOTRACES program, working on seawater
and other samples collected from all over the world. Our current Southern Ocean work
focuses on the importance of margin and hydrothermal sources in supplying Fe to the
vast Fe-limited Southern Ocean, and also how biological processes, mixing and physical
upwelling in the region impart distinctive preformed signatures on the trace metals
isotope signatures to newly formed water masses such as Antarctic Surface Water and
Antarctic Intermediate Water. These water masses then carry these signatures north
to the low-latitude oceans. We have recently participated in the Swiss-led Antarctic
Circumnavigation Expedition and also Japanese GEOTRACES cruise GP19. Contact Dr. Tim Conway
Dr. Kendra Daly
Dr. Daly has investigated questions related to polar marine ecosystems for more than
three decades. Her group seeks to improve understanding of the ecology and physiology
of polar marine organisms, including their role in biogeochemical cycles, their interactions
within the marine food web, and community dynamics in relation to their environment.
For example, studies include the overwintering physiology and survivorship of Antarctic
krill in relation to sea ice and the role of bottom-up and top-down forcing on the
marine food web in McMurdo Sound, which is one of the few places on the planet with
relatively undisturbed top predator populations. These investigations have addressed
questions related to the response of Antarctic ecosystems to human activity and climate
change in the Scotia-Weddell seas, Antarctic Peninsula, Bellingshausen Sea, Ross Sea,
and McMurdo Sound using a variety of ship-based, shore-based, and remote sensing technologies,
such as satellites, acoustic and camera imaging systems, and remotely operated vehicles
(ROVs). Contact Dr. Kendra Daly
Dr. Brad Rosenheim
Dr. Rosenheim is a geochemist with interest in improving Antarctic sediment chronology
and developing cold-water paleothermometers. He has developed a pyrolysis separation
method to more accurately date organic matter in sediments of the last deglaciation,
enabling a regional approach to chronicling the last deglaciation. Prior to the development
of the Ramped PyrOx approach, cores were primarily dated using seldom present carbonates,
in Antarctic margin sediments. By developing a method that dates the organic matter
in the sediment by separating old, contaminant organic matter, researchers can now
make better use of cores that contain the glacial-deglacial sequence of sediment facies
even if they do not contain calcium carbonate microfossils to date. Dr. Rosenheim
recently led an effort to retrieve sediments from Mercer Subglacial Lake, 1100 m beneath
the Mercer Ice Stream draining both East and West Antarctica. The expertise of his
group is being used to constrain the carbon cycle and ice cover history of this unique
environment. Contact Dr. Brad Rosenheim
Dr. Amelia Shevenell
Ongoing interdisciplinary geochemical research in the Shevenell laboratory seeks to
understand oceanic drivers of Antarctic ice dynamics on decadal to million year timescales,
using marine sediment archives from both the deep Southern Ocean (ice-distal) and
from Antarctica鈥檚 continental margins (ice-proximal). Our group employs inorganic
and organic geochemical and micropaleontologic (foraminifera) paleoceanographic proxies
for ocean temperature, ice volume, bottom water oxygen, and nutrients to determine
both the evolution of the Southern Ocean system and to track the past influence of
warm, nutrient-rich Circumpolar Deep Water on Antarctica鈥檚 marine terminating ice
sheets during climatic warmings (e.g. the Miocene Climatic Optimum, the last deglaciation,
and during the Holocene). Our work demonstrates a persistent link between Southern
Ocean temperatures and Antarctic ice mass balance on geologic timescales. We are particularly
interested in understanding the influence of the Southern Hemisphere Westerly Winds
and tropical Pacific Ocean-Antarctic climate teleconnections on the rapid retreat
of West and East Antarctic ice streams during the last deglaciation. Contact Dr. Amelia Shevenell
Courtesy Faculty
Dr. Alastair Graham
Dr. Graham is a marine scientist, studying the link between ice sheets and the geological
record. His research interests are focused on uncovering the histories, mechanisms,
and drivers of past glacial and environmental change as recorded by high-latitude
ocean floors and marine sedimentary records, as well as improving knowledge of the
physical processes that govern the evolution of glacial and marine environments. Working
from the glacier front to the deep sea, Dr Graham鈥檚 current research agenda is motivated
by a set of questions steered towards the grand challenges faced by environmental
and Antarctic science in the 21st century: how quickly, by how much, through what
processes, and in response to what triggers do ice sheets and glaciers change over
timescales not captured by observational records? An ongoing major objective of his
work is to produce records of past ice鈥恠heet change at the poles that are significantly
longer than satellite observations, providing the critical centennial to millennial
context for changes to our warming planet and rising seas. Another key aspect is to
study the processes of glacial environments using geophysical and geological tools
to provide insight into modern and future ice-sheet behaviour. Dr Graham works routinely
with glaciologists, oceanographers, and biologists to connect modern and palaeo processes
in ice-sheet settings and increasingly looks to bridge ancient and contemporary systems
in his research. Contact Dr. Alastair Graham
Dr. Xinfeng Liang
As a physical oceanographer, Dr. Liang is interested in using a combination of observations,
numerical models and theory to understand how the ocean works and how the ocean is
affected by and responds to the changing climate. In particular, Dr. Liang is interested
in how the heat, salt, carbon and other biogeochemical tracers are transported in
the global ocean. Another of Dr. Liang鈥檚 current research interests is the dynamic
processes that can supply energy to ocean mixing, and these processes mainly include
internal tides, near-inertial oscillations and mesoscale eddies. Dr. Liang has extensive
seagoing experience, primarily in acquiring and processing data from Lowered/Vessel-mounted
Acoustic Doppler Current Profiler (ADCP). Furthermore, he is familiar with the system
of ocean state estimation (e.g. ECCO), which is powerful and has huge potential in
addressing fundamental oceanographic questions.