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Refer the to THIS SITE to learn about this key driver of Australian climate.
Refer the to THIS SITE to learn about this key driver of Australian climate.
Add the diagrams below to your notes and add explanations for each of them.
Add the diagrams below to your notes and add explanations for each of them.
IMPORTANT: When the Indian and Pacific oceans work together
IMPORTANT: When the Indian and Pacific oceans work together
The El Niño–Southern Oscillation (ENSO) is the major climate driver in the Pacific Ocean and can have a strong impact on Australia's climate. El Niño years are typically warmer and drier over eastern Australia and La Niña years tend to be cooler and wetter over much of the country.
The El Niño–Southern Oscillation (ENSO) is the major climate driver in the Pacific Ocean and can have a strong impact on Australia's climate. El Niño years are typically warmer and drier over eastern Australia and La Niña years tend to be cooler and wetter over much of the country.
When El Niño coincides with a positive IOD, the two phenomena can reinforce their dry impacts. Likewise, when La Niña coincides with a negative IOD, the chance of above-average winter–spring rainfall typically increases.
When El Niño coincides with a positive IOD, the two phenomena can reinforce their dry impacts. Likewise, when La Niña coincides with a negative IOD, the chance of above-average winter–spring rainfall typically increases.
Drying influence expands
Drying influence expands
Some positive IOD events, but not all, occur during the same year as an El Niño. The relationship between El Niño and the IOD is complicated, with the level of dependence between the two an area of active research. The map shows the mean rainfall deciles for total winter-spring rainfall for the six positive IOD events that coincided with El Niño since 1960.
Some positive IOD events, but not all, occur during the same year as an El Niño. The relationship between El Niño and the IOD is complicated, with the level of dependence between the two an area of active research. The map shows the mean rainfall deciles for total winter-spring rainfall for the six positive IOD events that coincided with El Niño since 1960.
Wetting influence expands
Wetting influence expands
Some negative IOD events occur at the same time as La Niña. However, negative IOD events rarely coincide with El Niño. The relationship between La Niña and the IOD is complicated, with the level of dependence between the two an area of active research. The map shows mean rainfall deciles for winter-spring rainfall for the five negative IOD events that coincided with La Niña since 1960.
NOTE: The Indian Ocean Dipole has strengthened significantly over the past month. The latest weekly value of +2.15 °C is the strongest positive weekly value since at least 2001 (when the Bureau's weekly dataset commenced)
NOTE: The Indian Ocean Dipole has strengthened significantly over the past month. The latest weekly value of +2.15 °C is the strongest positive weekly value since at least 2001 (when the Bureau's weekly dataset commenced)
However, international climate models surveyed by the Bureau indicate the positive IOD is unlikely to persist far into summer. IOD breakdown occurs when the monsoon trough moves into the southern hemisphere in early December. With the monsoon trough having a record-late retreat from India this year, the shift into the southern hemisphere may also be later than usual.
However, international climate models surveyed by the Bureau indicate the positive IOD is unlikely to persist far into summer. IOD breakdown occurs when the monsoon trough moves into the southern hemisphere in early December. With the monsoon trough having a record-late retreat from India this year, the shift into the southern hemisphere may also be later than usual.
Typically, a positive IOD brings below average winter–spring rainfall to southern and central Australia, with warmer days for the southern two-thirds of the country. Positive IOD events are often associated with a more severe fire season for southeast Australia.
Typically, a positive IOD brings below average winter–spring rainfall to southern and central Australia, with warmer days for the southern two-thirds of the country. Positive IOD events are often associated with a more severe fire season for southeast Australia.
This is the synoptic chart from 29/10/19, showing the IOD going OFF - low pressure systems forming on Australia's far NW.
This is the synoptic chart from 29/10/19, showing the IOD going OFF - low pressure systems forming on Australia's far NW.
BTW, it also shows the positive SAM - High pressure systems well south, not allowing the cold front to get up the NSW coast.
BTW, it also shows the positive SAM - High pressure systems well south, not allowing the cold front to get up the NSW coast.
This resulted in the below map on 3/11/19 that produced significant rain west of the divide , as far out as bourke.
This resulted in the below map on 3/11/19 that produced significant rain west of the divide , as far out as bourke.
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