We are interested in the ocean's role in the climate of the Earth. The ocean plays a determining role in the variability of the climate system on inter-annual to millennial timescales. We use global observations and a hierarchy of ocean models together with advanced computational and mathematical techniques to study the ocean. Our current research is directed in three broad areas:

1. the surface-to-surface transport and ventilation of ocean water masses
2. inter-annual to decadal variability of the ocean's wind-driven circulation
3. global ocean biogeochemical cycles

Simulation of the physical, chemical and biological processes that determine atmospheric composition. Development of

1. detailed numerical models of photochemistry and atmospheric radiation, and
2. global chemical transport models that describe ozone and other trace gases.

Studies include the predicted effects of volcanic sulfate aerosols on stratospheric ozone loss, the role of clouds in scattering sunlight and altering photochemistry, and the non-linearities in chemical systems that lead to sudden changes such as the depletion of ozone caused by CFC increases.

Professor Gudrun Magnusdottir is interested in atmospheric and climate dynamics. In her work she uses observations as well as a hierarchy of numerical models to study dynamical processes in the atmosphere, and climate variability.

One focus of her research centers on investigating feedback mechanisms influencing the unprecedented high-latitude trends in several climate variables over recent decades.

Another focus of her research centers on tropical-extratropical as well as troposphere-stratosphere dynamical interactions.

A third focus centers on the Intertropical Convergence Zone (ITCZ), its variability on different timescales, and what controls it in the climate system.

My research primarily involves the use of geochemical variations preserved in cave-calcite deposits (speleothems) to reconstruct time-series of past environmental changes. A major goal of my research is to improve our understanding of what fundamentally controls speleothem stable isotopic composition and trace-element composition at both short and long timescales (seasonal to glacial-interglacial scale). These proxies are primarily controlled by variations in temperature and/or rainfall at a particular study area, but the specific mechanisms are complicated, incorporating a range of atmospheric, hydrologic, biologic, pedologic, kinetic, crystallographic, and thermodynamic controls. To understand these controls, I combine detailed studies of modern cave systems with studies of fossil speleothems, utilizing a wide range of analytical techniques (e.g. microsampling, analytical chemistry, mass spectrometry, laser ablation, etc.) along with laboratory experiments, rigorous data analysis, and geochemical modeling. Speleothem records can be dated much more precisely than most other paleoclimate archives using U-series methods, and therefore, often provide important information about the relative timing and mechanisms of abrupt climate change. The ultimate goal of my research is to obtain precisely dated, high-resolution, quantitative reconstructions of past variations in rainfall and temperature at a wide range of timescales.

Our research focuses on how terrestrial ecosystems work, with an emphasis on what controls the exchanges of gases and energy between land surfaces and the atmosphere. This research is relevant to several environmental problems, including understanding changes in climate and global biogeochemistry. Our approach is interdisciplinary, borrowing techniques and ideas from a range of academic disciplines including plant physiology, community and ecosystem ecology, hydrology, micrometeorology, environmental physics, and biogeochemistry.

The goals of our research are twofold.

First,we seek to understand why the ¹⁴C age of marine dissolved organic carbon (DOC) is thousands of years old, despite evidence that most of it is produced in the surface ocean during photosynthesis. Is black carbon, produced on land, a significant source of old oceanic DOC?

In 2001, ESS/CGECR researchers Ellen Druffel, John Southon and Susan Trumbore were awarded $2 million by the W.M. Keck Foundation for the development of an accelerator mass spectrometry (AMS) facility – the Keck-Carbon Cycle AMS facility - for radiocarbon measurements in support of carbon cycle research at University of California, Irvine.

Related Research Group: Santos Research Group