Oceanography Research at RSES
Introduction to Oceanographic research
The ocean is continuously changing. Changes in the circulation is caused by changes in climate: atmospheric winds and temperatures can both alter the ocean state. Since the circulation transports heat, chemicals, nutrients and salinity around the global ocean, any changes can result in feedbacks to climate. The ocean is also a delicate balance between nutrients, chemicals and ecosystems. These quantities also change -- on short time scales and longer time scales -- and can indicate changes in the circulation or changes in climate. Oceanography research at RSES includes field observations, laboratory studies of ocean processes, chemical investigations, ocean and climate modelling, paleoceanographic studies and satellite based measurements.
Research topics
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Today, Earth's oceans are teaming with life, and even deep marine trenches contain enough oxygen to support complex organisms. However, oceans in Earth's distant past were fundamentally different. In the first half of Earth history, ~4.5 to 2.3 billion years (Ga) ago, the world's oceans and atmosphere were almost entirely devoid of oxygen. |
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The Indian Ocean Dipole is now recognised as a climate system of international importance because of its effect on rainfall in Indonesia, Australia, Asia, and East Africa. Resolving the debate about how the Dipole and ENSO climate systems interact, and how they respond to different background climates, is essential for understanding the nature of drought in southern Australasia. |
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The primary focus of the ocean chemistry group within Earth Environment is on understanding the behaviour of trace elements and isotopes in ocean, their sources and sinks and the role they play in biological systems. Microscopic plankton form the base of the marine food-chain and account for more than half of global primary production, and hence modulate our climate through the ocean's ability to drawdown CO 2 . |
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Radiocarbon is produced in the stratosphere by the collision of nitrogen atoms with thermal neutrons produced naturally by cosmic rays or artificially by atmospheric nuclear bomb testing. Atomic 14 C is rapidly oxidized to 14 CO 2 in the atmosphere and enters plants and animals via photosynthesis and the food chain. When an organism dies the 14 C decays back to Nitrogen 14. The half-life (the time it takes for half of the carbon-14 to decay) is 5730 years. After about 10 half-lives there is essentially no carbon-14 left in a sample. This results in a limit of this technique of 50-60,000 years, after which other radiometric techniques have to be used to age a sample.
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The dynamics of the global ocean depends on the forcing from climate and the physical processes which occur in the ocean. Studies into Ocean Dynamics concentrate on determining the role of physical processes through both laboratory experiments and numerical modelling. Examples include flow through straits such as the Indonesian Throughflow, the East Australian Current and the Antarctic Circumpolar Current in the Southern Ocean. These studies ultimately feed into models of the earth's climate and ecosystem. |