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Education: The Effects of Density-Driven Circulation on Climate

Map of global sea surface currents and temperature
STUDENT OUTCOMES
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Explain the influence of ocean salinity on the thermohaline circulation
Describe how changes in the ocean's circulation can produce large changes in climate (NSES,189; NAAEE,54; OLS,12)
Explain how climate variations can induce changes in the global ocean circulation
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How Does Density-Driven Circulation Affect Climate (and Vice Versa)?
Carbon is the basic building block of life, and its compounds form solids, liquids, or gases. Carbon helps form the bodies of living organisms; it dissolves in the ocean; mixes in the atmosphere; and can be stored in the crust of the planet. A carbon atom could spend millions of years moving through this complex cycle. The ocean plays the most critical role in regulating Earth's carbon balance, and understanding how the carbon cycle is changing is key to understanding Earth's changing climate. Excess heat associated with the increase in global temperature during the last century is being absorbed and moved by the ocean. Surface ocean and atmospheric temperature changes may cause evaporation to intensify and, as a result, significantly alter sea surface salinity and ocean circulation patterns.

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Ocean circulation

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FAQs
  • Touching on the practical implications of the mission, how will the information from this and related projects help us to understand the effects of global climate change in both our ocean and atmosphere?

    • If you go to the NASA Website, you will see 15 or 16 satellites already flying which measure different aspects of the Earth's systems: atmospheric, land processes, ice, snow and the ocean. Aquarius is one of the many, yet we are providing this very important piece of information, this missing piece of the puzzle. I couldn't say this is going to be the silver bullet that's going to change everything, right? But this is certainly one of the key pieces of missing information to be added to our database of all known knowledge and to monitor the global changes. The capability of the satellites is global coverage. You don't have to send a thousand ships and all their technicians to the ocean, because every week, the satellite will cover every part of the planet.

      Salinity is affected by precipitation, evaporation, river runoff, ice melting; so anything related to salt and freshwater will give you a signature in salinity. This is part of the water cycle. In other words, if you are melting more of the snow pack in California, where does the snow go? You can't store it in your backyard; it eventually has to go back to the ocean. When the water goes back to the ocean, you will see the salinity becomes fresher. If the ice is melting, you're going to see salinity changes. Salinity is really an indicator of many of these processes. Aquarius will provide information about the global water cycle, and more importantly, will quantify the change. You can use the salinity changes to infer how much the source is changing. In that way, it's a very powerful data set to be added to the so-called knowledge database.
      Yi Chao, Aquarius Project Scientist, NASA Jet Propulsion Laboratory in Ocean Bights Interview with Yi Chao, The Magazine of the Catalina Marine Society (CMS), Vol. 2, No. 2 (Interviewer: Chris Howell).
  • Why does the Atlantic have more evaporation?

    • Mostly due to the land-sea contrast (located between two major continents). It is also smaller than the Pacific.
      Yi Chao, Aquarius Project Scientist, NASA Jet Propulsion Laboratory in Inspire Chat with Yi Chao (Host: Jim Gerard).