Less pessimism over weather patterns

Neil Barraclough, Meerlieu


AFTER I left school I went beekeeping for a while, and an old timer told me that beekeepers need to be able to think a year ahead, and be able to change their mind in five minutes.

I think weather predicting might be the same.

In a letter to the editor (Gippsland Times 26/3) I preached doom and gloom, but finished off with:

“On a brighter side, the recent massive rains in northern Queensland may fill Lake Eyre, and if so the evaporation from it should give us some relief in showers that we wouldn’t have got otherwise.”

Lake Eyre is the fullest it has been since 1974, and the other very high level in the past 70 years was 1950.

East Sale’s rainfall averages 592mm per year, and it received 719mm in 1950, 868mm in 1951 and its wettest year on record of 1952 with 944mm.

This was the wettest three years in East Sale’s rainfall record starting in 1944.

In 1974, Sale received 843mm and 1975 710mm, another very wet period.

I haven’t been able to find much information on Lake Eyre with Google searches, so a proper analysis of the effect of Lake Eyre having water in it can’t be done yet.

However, Hobart would be less likely to be affected by Lake Eyre, so I checked its rainfall going back to 1880.

Interesting, there appeared to be a level of correlation between our cyclic droughts and Hobart’s.

However, the two occasions Lake Eyre was at its fullest were only average rainfall for Hobart, suggesting that whatever gave Sale its wet periods when Lake Eyre was at its fullest didn’t affect Hobart’s rainfall to any extent.

There has been a lot of research on the albedo (reflectivity) of the land and rain formation.

It is considered likely that increases in the heat reflected from the land reduces rainfall.

The likelihood of evaporation from Lake Eyre increasing rainfall to the east of it has been widely discussed, but little thought given to the changes in albedo-reflectivity from a white salt pan-red earth to water with low heat reflectivity.

On a downside, there are Pacific Islanders who live from the sea, and they have noted that ocean currents change direction about four months before the world’s scientists pick up an emerging El Nio – and they noted these changes perhaps a month ago.

We don’t get an El Nio every time the ocean currents change, but it is far more likely to occur when they do.

There are a lot of what are likely negative factors that have come together at the same time, but with Lake Eyre filling to the level it has, my pessimism rating has dropped from 9.5 to seven.