el niño- southern oscillation enso. el niño- southern oscillation 1.enso events 2.normal...
TRANSCRIPT
![Page 1: El Niño- Southern Oscillation ENSO. El Niño- Southern Oscillation 1.ENSO events 2.Normal conditions 3.ENSO conditions 4.Cause of ENSO events Unit 3 Lecture](https://reader035.vdocuments.mx/reader035/viewer/2022062404/551918c855034642428b4a01/html5/thumbnails/1.jpg)
El Niño- Southern Oscillation‘ENSO’
![Page 2: El Niño- Southern Oscillation ENSO. El Niño- Southern Oscillation 1.ENSO events 2.Normal conditions 3.ENSO conditions 4.Cause of ENSO events Unit 3 Lecture](https://reader035.vdocuments.mx/reader035/viewer/2022062404/551918c855034642428b4a01/html5/thumbnails/2.jpg)
El Niño- Southern Oscillation
1. ENSO events2. Normal conditions3. ENSO conditions4. Cause of ENSO events
Unit 3 Lecture 9
![Page 3: El Niño- Southern Oscillation ENSO. El Niño- Southern Oscillation 1.ENSO events 2.Normal conditions 3.ENSO conditions 4.Cause of ENSO events Unit 3 Lecture](https://reader035.vdocuments.mx/reader035/viewer/2022062404/551918c855034642428b4a01/html5/thumbnails/3.jpg)
• Ocean/atmosphere interaction ~ surface water temperature/ atmospheric pressure
• Occurs on a 3-4 year cycle
• Earliest written records – 1500’s Spanish explorers
• Phenomenon usually observed around Christmas season in waters off Peru and Ecuador
ENSO Events
![Page 4: El Niño- Southern Oscillation ENSO. El Niño- Southern Oscillation 1.ENSO events 2.Normal conditions 3.ENSO conditions 4.Cause of ENSO events Unit 3 Lecture](https://reader035.vdocuments.mx/reader035/viewer/2022062404/551918c855034642428b4a01/html5/thumbnails/4.jpg)
![Page 5: El Niño- Southern Oscillation ENSO. El Niño- Southern Oscillation 1.ENSO events 2.Normal conditions 3.ENSO conditions 4.Cause of ENSO events Unit 3 Lecture](https://reader035.vdocuments.mx/reader035/viewer/2022062404/551918c855034642428b4a01/html5/thumbnails/5.jpg)
Warm surface temp → Low-pressure tropical cyclones (hurricanes or typhoons)
![Page 6: El Niño- Southern Oscillation ENSO. El Niño- Southern Oscillation 1.ENSO events 2.Normal conditions 3.ENSO conditions 4.Cause of ENSO events Unit 3 Lecture](https://reader035.vdocuments.mx/reader035/viewer/2022062404/551918c855034642428b4a01/html5/thumbnails/6.jpg)
![Page 7: El Niño- Southern Oscillation ENSO. El Niño- Southern Oscillation 1.ENSO events 2.Normal conditions 3.ENSO conditions 4.Cause of ENSO events Unit 3 Lecture](https://reader035.vdocuments.mx/reader035/viewer/2022062404/551918c855034642428b4a01/html5/thumbnails/7.jpg)
![Page 8: El Niño- Southern Oscillation ENSO. El Niño- Southern Oscillation 1.ENSO events 2.Normal conditions 3.ENSO conditions 4.Cause of ENSO events Unit 3 Lecture](https://reader035.vdocuments.mx/reader035/viewer/2022062404/551918c855034642428b4a01/html5/thumbnails/8.jpg)
Tradewinds
• Tradewinds ‘push’ surface waters at western edge of basin• Warm water piles up in west “Pacific warm pool” , sea surface 1m higher• Pycnocline found at 100m depth at western edge of basin and only at
30m depth at eastern edge of basin• Coastal winds ‘push’ waters offshore (i.e. via Ekman transport)
~ cold nutrient-rich waters subsurface waters upwelled
Cause of ENSO Events - Normal Conditions
![Page 9: El Niño- Southern Oscillation ENSO. El Niño- Southern Oscillation 1.ENSO events 2.Normal conditions 3.ENSO conditions 4.Cause of ENSO events Unit 3 Lecture](https://reader035.vdocuments.mx/reader035/viewer/2022062404/551918c855034642428b4a01/html5/thumbnails/9.jpg)
• Cool, nutrient-rich coastal surface waters ~ upwelled waters come from below
the pycnocline
Normal Conditions - Peru and Ecuador
• Major fishery i.e. in the 1970’s 22% of all fish production came from coastal waters off of Peru and Ecuador
OCEAN
NOAA
![Page 10: El Niño- Southern Oscillation ENSO. El Niño- Southern Oscillation 1.ENSO events 2.Normal conditions 3.ENSO conditions 4.Cause of ENSO events Unit 3 Lecture](https://reader035.vdocuments.mx/reader035/viewer/2022062404/551918c855034642428b4a01/html5/thumbnails/10.jpg)
• High pressure system over coastal Peru and Ecuador ~ dry in winter
Normal Conditions - Peru and Ecuador (cont’d)
ATMOSPHERE
NOAA
![Page 11: El Niño- Southern Oscillation ENSO. El Niño- Southern Oscillation 1.ENSO events 2.Normal conditions 3.ENSO conditions 4.Cause of ENSO events Unit 3 Lecture](https://reader035.vdocuments.mx/reader035/viewer/2022062404/551918c855034642428b4a01/html5/thumbnails/11.jpg)
• Warmer than normal, nutrient deplete coastal surface waters ~ upwelled water comes from above
pycnocline
ENSO Conditions - Peru and Ecuador
OCEAN
• Fishery crashes (lower catch, higher prices at fish market)~ causes death of organisms adapted to
cooler, nutrient rich surface waters~ upsets and shifts food web dynamics NOAA
![Page 12: El Niño- Southern Oscillation ENSO. El Niño- Southern Oscillation 1.ENSO events 2.Normal conditions 3.ENSO conditions 4.Cause of ENSO events Unit 3 Lecture](https://reader035.vdocuments.mx/reader035/viewer/2022062404/551918c855034642428b4a01/html5/thumbnails/12.jpg)
Tradewinds Relax or Cease
• Tradewinds no longer ‘push’ surface waters at western edge of basin• Pacific warm pool begins to flow back towards eastern edge of basin
~ via Equatorial Counter Current~ starts to move in Sept., makes it to S. America in Dec. or Jan.
• pycnocline flattens out ~ now found at a greater depth in the east
• Coastal winds still ‘pushing’ waters offshore (i.e. via Ekman transport)~ warm nutrient-deplete surface waters upwelled
Cause of ENSO Events - ENSO Conditions
![Page 13: El Niño- Southern Oscillation ENSO. El Niño- Southern Oscillation 1.ENSO events 2.Normal conditions 3.ENSO conditions 4.Cause of ENSO events Unit 3 Lecture](https://reader035.vdocuments.mx/reader035/viewer/2022062404/551918c855034642428b4a01/html5/thumbnails/13.jpg)
• Low pressure system over coastal Peru and Ecuador ~ wet in winter~ heavy rains cause flooding and landslides on usually dry land
ENSO Conditions - Peru and Ecuador (cont’d)
ATMOSPHERE
NOAA
![Page 14: El Niño- Southern Oscillation ENSO. El Niño- Southern Oscillation 1.ENSO events 2.Normal conditions 3.ENSO conditions 4.Cause of ENSO events Unit 3 Lecture](https://reader035.vdocuments.mx/reader035/viewer/2022062404/551918c855034642428b4a01/html5/thumbnails/14.jpg)
• Flooding in North and South America (low pressure system)~ landslides, erosion
• Droughts in Australia (high pressure system)~ fires
• Switching position of pressure zones effects jet stream flow~ increase in tropical storms in the Pacific~ decrease in tropical storms in the Atlantic
ENSO Conditions - Global
![Page 15: El Niño- Southern Oscillation ENSO. El Niño- Southern Oscillation 1.ENSO events 2.Normal conditions 3.ENSO conditions 4.Cause of ENSO events Unit 3 Lecture](https://reader035.vdocuments.mx/reader035/viewer/2022062404/551918c855034642428b4a01/html5/thumbnails/15.jpg)
![Page 16: El Niño- Southern Oscillation ENSO. El Niño- Southern Oscillation 1.ENSO events 2.Normal conditions 3.ENSO conditions 4.Cause of ENSO events Unit 3 Lecture](https://reader035.vdocuments.mx/reader035/viewer/2022062404/551918c855034642428b4a01/html5/thumbnails/16.jpg)
• More rain• Cooler• Increase in number and strength of
tornadoes ~ only two F4 tornadoes in FL occurred
during strong El Niño years• Less hurricanes
ENSO Conditions - Florida
![Page 17: El Niño- Southern Oscillation ENSO. El Niño- Southern Oscillation 1.ENSO events 2.Normal conditions 3.ENSO conditions 4.Cause of ENSO events Unit 3 Lecture](https://reader035.vdocuments.mx/reader035/viewer/2022062404/551918c855034642428b4a01/html5/thumbnails/17.jpg)
![Page 18: El Niño- Southern Oscillation ENSO. El Niño- Southern Oscillation 1.ENSO events 2.Normal conditions 3.ENSO conditions 4.Cause of ENSO events Unit 3 Lecture](https://reader035.vdocuments.mx/reader035/viewer/2022062404/551918c855034642428b4a01/html5/thumbnails/18.jpg)