Week 9: Climate Variability and Hydrologic Change

Question 1

Climate Mode

Answer 1

The state of the climate, natural variability.

Question 2

ENSO

El Nino Southern Oscillation

Answer 2

• ~3-5 years
• Pacific region phenomenon that impacts strongly on eastern Australia and western America.
• A periodical climate change caused by variations in sea surface temperatures over the tropical eastern pacific ocean.
• El Nino: Warmer sea surface temperatures. Rainfall in Eastern Australia decreases, temperature in southern Australia increases

Question 3

IOD

Indian Ocean Dipole

Answer 3

• ~every 6 years
• Oscillation of sea-surface temperatures in which the western Indian Ocean becomes alternately warmer then colder than the eastern part of the ocean.
• Positive IOD: cooler than normal water in the tropical eastern Indian ocean. Decrease rainfall over central and southern Australia.
• Negative IOD: warmer than normal water in tropical eastern Indian ocean. Increase in rainfall over southern Australia.

Question 4

SOI

Southern Oscillation Index

Answer 4

• Measured as the difference in barometric pressure between Tahiti and Darwin.
• Gives an indication of the intensity of ENSO.
• High pressure Darwin: El Nino.
• Lower pressure Darwin: La Nina

Question 5

Non-stationarity

Answer 5

Statistical properties are not constant over time.