Impacts of El Nino Observations Mechanisms for remote
Impacts of El Nino • Observations • Mechanisms for remote impacts
Observations What are the impacts?
Growth and Decay of El Nino
A closer look at impacts http: //iri. columbia. edu/climate/ENSO and CLIMATE Temperature and Precipitation Tropical Cyclones ENSO and SOCIETY Regional impacts http: //www. pmel. noaa. gov/tao/elnino/impacts. html
Mechanisms for Remote Impacts How do these impacts occur?
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)
Source: D. Neelin
Source: D. Neelin
El Nino La Nina El Nino – La Nina Impacts on the North Atlantic Region
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?
El Nino Prediction (next lecture)
- Slides: 14