Research in Physical Oceanography and Climate

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Animated image shows evolution of Pacific sea surface temperature, illustrating variations in the equatorial “Cold Tongue” due to Tropical Instability Waves; courtesy of Climate Dynamics PhD student Bala Narapusetty.

Introduction

Physical properties of the ocean are a key part of the climate system. For instance, the ocean transports a significant amount of heat, especially in the tropics, and so ocean currents help the atmosphere redistribute energy from the sun, warming and cooling different parts of the atmosphere in the process. Compared to the atmosphere, the ocean has a large heat capacity and takes a long time to propagate disturbances in currents and temperature. This means that the ocean has a much longer “memory” than the atmosphere, and may hold the key to predicting some aspects of climate months or even years in the future. The importance of the ocean to climate is on display in the El Nino Southern Oscillation phenomenon, in which coupled ocean-atmosphere changes in the equatorial Pacific affect weather across the globe. George Mason and COLA scientists have made important contributions to understanding El Nino as well as other aspects of physical oceanography important to climate.

Physical oceanography plays a role in much of the climate dynamics research in AOES. This page describes some of the work of faculty most focussed on physical oceanography.

Bohua Huang

Dr. Huang’s research is concentrated on understanding the climate influence of the tropical oceans. He has used ocean general circulation models to simulate the upper ocean circulation of the tropical Atlantic and Pacific Oceans and to study the oceanic responses to the atmospheric forcing on seasonal and interannual time scales. These processes are important for us to understand the mechanisms of the anomalous phenomena in the tropical oceans, such as the El Niño events in the Pacific and the fluctuations of the meridional gradient of the sea surface temperature (SST) in the tropical Atlantic Ocean, which has significant impact on the climate conditions of the Atlantic Sector. Currently, Dr. Huang conducts numerical experiments using state-of-the-art coupled ocean-atmosphere general circulation models to understand the mechanisms of the ocean-atmosphere interactions and their effects on global climate variability. One emphasis is on the relative roles played by remote forcing from the El Niño/Southern Oscillation and the regional air-sea feedback in both the tropical Atlantic and Indian Oceans in determining the anomalous sea surface temperature (SST) patterns in these ocean basins that are important for regional climate. He has been using coupled models to examine the multi-decadal variability of the Atlantic overturning circulation and its climate effects.

Dr. Huang also conducts researches aimed at improving the coupled models. One of his major interests is to find the sources of the systematic bias of current climate models in the tropical ocean/atmosphere and their influences on the quality of the model simulations and predictions. He had participated in the seasonal forecast research and operational monthly predictions in the Center for Ocean-Land-Atmosphere Studies (COLA) in Maryland and had conducted long-term ocean data assimilation analysis to provide realistic oceanic initial conditions for the model forecast. Besides modeling, Dr. Huang also conducts extensive diagnostic studies using comprehensive ocean-atmosphere datasets to analyze historical climate variations.

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Barry Klinger

After his early work on coastal eddy formation and oceanic deep convection, Dr. Klinger’s work has centered on various overturning circulations of the ocean. Overturning occurs when currents at one depth feed currents at another depth through upwelling or downwelling. Overturning is an important mechanism for the ocean to exchange heat and chemical properties with the ocean.

The most famous overturning system is the global network of cells known as the “conveyer belt”. Dr. Klinger has used ocean general circulation models to better understand what drives conveyer belt circulations. Recently, working with Climate Dynamics graduate student Carlos Cruz, he has looked at how these circulations may change over years to decades due to changes in atmospheric forcing. Current work includes analyzing how global warming may change the overturning and (with graduate student Oluwayemi Garuba) comparing decadal variability of overturning among different climate models.

Dr. Klinger has also studied more shallow overturning systems known as the Subtropical Cells. These cells link the subtropics with the equator. Current work, in collaboration with fellow AOES faculty member Paul Schopf and Matthew Harrison of NOAA Geophysical Fluid Dynamics Laboratory, is studying how a similar overturning cell cools the Pacific ocean off the coast of South America. While the South American upwelling, an important process for fisheries, has been studied for a long time, climate models have trouble reproducing the cold surface temperatures. Dr. Klinger seeks to understand the ways in which the coastal upwelling is connected to the general circulation of the Pacific.

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Edwin Schneider

Dr. Schneider is carrying out experiments using coupled climate models to isolate and understand the role of ocean dynamics in low frequency internal climate variability and in externally forced climate change. He has also diagnosed the magnitude and distribution of tracer mixing in the world ocean.

Paul Schopf

Dr. Schopf is an international expert on the theory and oceanography of El Nino, having developed the “delayed oscillator” theory in the early 1980’s with his collaborator, Max Suarez. This theory remains at the core of our understanding of the quasi-periodicity of El Nino and La Nina. Dr. Schopf has recently been intrigued with the question of how El Nino interacts with the long-term coupled climate system, and whether feedback processes exist which might explain why El Nino appears quite stable over the historical record. This has strong implications for how we look at how global warming might affect El Nino. Most recently, this has led to a collaboration with Dr. Klinger of AOES and Matthew Harrison of the NOAA Geophysical Fluid Dynamics Laboratory in a study of coastal upwelling in the South Pacific and its impact on climate.

Along the way of studying El Nino, Dr. Schopf has developed numerical ocean circulation models, including the Poseidon model, used at NASA and COLA, and teaches courses in numerical methods for climate modeling. His students have obtained positions at the NOAA Geophysical Fluid Dynamics Laboratory, the University of Miami, and the NASA Goddard Space Flight Center.
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