Post on 17-Jan-2018
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Material for Exam 2 starts HERE
Oceanic Currents
• Surface Currents– Cold = high latitude– Warm = low latitude– Gyres: circulate in which directions?
Major Ocean Currents
Figure 6.22
Peru Current
Oceanic Currents
• Deep Currents– Thermohaline circulation– Distributes energy– Effects of global warming?
Deep Currents
Figure 6.23
ENSO events
• ENSO events are a disruption of the ocean-atmosphere system in the tropical Pacific
• El Nino Southern Oscillation– El Nino – ocean– Southern Oscillation – atmosphere
El Niño
• Changes in pressure patterns• Changes in wind patterns• Mainly concentrated in the Pacific Ocean• Measured using Southern Oscillation
Index– Differences in pressure observed in Tahiti
and Darwin, Australia– Combined to form ENSO
• Affects weather globally
Buoys
El Niño
Impacts of ENSO Events
• Marine environments• Atlantic hurricanes• Global precipitation patterns• Wildfires
• Australia-Drought and bush fires • Indonesia, Philippines-Crops fail, starvation follows • India, Sri Lanka-Drought,fresh water shortages • Tahiti-6 tropical cyclones • South America-Fish industry devastated • Across the Pacific-Coral reefs die • Colorado River basin-Flooding, mud slides • Gulf states-Downpours cause death, property damage • Peru, Ecuador-Floods, landslides • Southern Africa-Drought, disease, malnutrition
El Niño
ENSO
• When high and low pressure systems exist in some locations, they not only impact local weather conditions, but also influence the overall size, shape, and position of the entire Rossby wave pattern
• Teleconnections: relationship between weather or climate patterns at two widely separated locations
ENSO
ENSO
Occurs once every 3 to 5 years (but varies)• Is regulated by PDO
– Switch to PDO warm phase in 1999 appears to have dampened ENSO
• Major ENSO events in last 25 years: 1982–1983, 1986–1987, 1991–1993, 1997–1998, 2002–2003
• 1997–1998 was so intense, it disrupted global weather
Normal
Normal Year
ENSO
ENSO
ENSO Year
La Nina
• El Niño = warm phase, La Niña = cool phase
• La Niña brings extreme normal conditions• Not all El Niño events are followed by La
Niña events• La Niña events increase wildfires in the SE
and Atlantic hurricanes
La Nina