A wet spring: what is a 'negative Indian Ocean Dipole' and why does it mean more rain for Australia's east?

The Bureau of Meteorology recently announced a negative Indian Ocean Dipole event is underway.

But what does that mean and how does it affect Australia’s weather? Will we get a reprieve from the flooding rains of recent months?

For many places across the east coast, the answer is no. Spring won’t bring a clean break from this year’s very wet winter.