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Impacts of El Nino

Impacts of El Nino. Observations Mechanisms for remote impacts. Observations. Growth and Decay of El Nino. A closer look at impacts. http://iri.columbia.edu/climate/ENSO ENSO and CLIMATE Temperature and Precipitation Tropical Cyclones ENSO and SOCIETY Regional impacts

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Impacts of El Nino

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  1. Impacts of El Nino • Observations • Mechanisms for remote impacts

  2. Observations

  3. Growth and Decay of El Nino

  4. A closer look at impacts http://iri.columbia.edu/climate/ENSO ENSO and CLIMATE Temperature and Precipitation Tropical Cyclones ENSO and SOCIETY Regional impacts http://www.pmel.noaa.gov/tao/elnino/impacts.html

  5. Mechanisms for remote impacts • Latent heating associated with tropical precipitation anomalies excites waves in the atmosphere: • Atmospheric equatorial Kelvin and Rossby waves propagate zonally. Associated subsidence warms troposphere and suppresses precipitation • Rossby waves can also propagate into extratropics (especially in winter) causing large-scale circulation anomalies which impact weather. (Note that propagation requires a westerly mean flow and the relevant Rossby waves have an eastward group velocity)

  6. Source: D. Neelin

  7. Source: D. Neelin

  8. Impacts on the North Atlantic Region El Nino – La Nina La Nina El Nino

  9. Impacts on marine ecosystems Yearly average of Chlorophyll concentrations 1997 1998 El Niño low La Niña high Source: A. Timmermann

  10. El Nino Prediction

  11. El Nino research issues • Phase locking to seasonal cycle (onset and termination) • What determines and limits the amplitude of El Nino? • What controls the frequency of El Nino events? • How will El Nino respond to anthropogenic climate change?

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