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
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– –1998 was so intense, it disrupted global weather
Normal
Normal Year
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