Another La Niña Event / Australia

The Bureau of Meteorology has officially declared a La Nina weather system is underway in the South Pacific.
Models predict the event, characterized by above average rainfall, will continue until early 2023.
It is expected to peak during spring.

Many communities are still rebuilding after at least 22 people died and more than 25,000 homes and businesses were damaged by floodwaters earlier this year. In the first week of April southern Queensland and northern NSW each received more than a year's rainfall.
This is the third back-to-back La Nina event and the fourth instance of three consecutive events since records began in 1900.
There is already wet soil, high rivers and full dams right across NSW and. with more rain on the horizon, comes the very real possibility of flooding.
According to the Bureau's Climate Driver Update, tropical Pacific sea surface temperatures have been cooling since June and are now at La Nina thresholds. Atmospheric indicators are also displaying patterns typical of the weather event.

Bureau head of long-range forecasts, Dr Andrew Watkins, said that while La Nina criteria had been met, most models forecast it to be weak to moderate in strength.
During La Nina events, waters in the eastern tropical Pacific Ocean are cooler than normal, and waters in the western tropical Pacific Ocean warmer than normal. This causes changes in wind, cloud and pressure patterns over the Pacific.
When this change in the atmosphere combines with changes in ocean temperature, it can influence global weather patterns and climate, including increasing rainfall over large parts of Australia.
There was an 80 per cent chance of above average rainfall for many parts of the eastern half of Australia.

According to the Bureau, a negative Indian Ocean Dipole (IOD) event also continues. A negative IOD is associated with above-average spring rainfall for much of Australia. When a La Nina and negative IOD combine, it further increases the likelihood of above average rainfall over Australia, particularly in the eastern half of the continent. SAM (Southern Annular Mode) is a climate driver that can influence rainfall and temperature in Australia. Full explanation here.
At least you'd hope all this reduces the bush fire threat this summer.

A Wobbly Moon

How interesting is this?

A wobble in the moon’s orbit around Earth affects mangrove cover across Australia and likely contributed to mass tree deaths in the Gulf of Carpentaria, new research suggests.
The moon’s orbit around Earth does not occur in a flat plane.

 “Since the 1720s, people have known that it moves up and down by a few degrees,” said the study’s lead author, Prof Neil Saintilan of Macquarie University. He likened the motion to “when you’re spinning a coin – as it loses momentum, it kind of wobbles”.

Photograph: Jono Searle/AAP

A study published in the journal Scientific Advances has found that an 18.61-year cycle known as the lunar nodal cycle shapes the condition of tidal wetlands
This has affected the mangrove forests in Northern Australia.
Read the whole article here in the Guardian.

The Mangrove forest type occurs in many of Australia’s coastal regions, but has a total area of only 0.9 million hectares, or 0.6% of Australia’s native forest cover. Australian Mangrove forests contain 41 species of mangrove from 19 plant families. More than half of the world’s mangrove species are found in Australia.