Old teak trees help predict Indonesia drought

SINGAPORE (Reuters) - A group of scientists are developing more accurate drought and harvest forecasts for Indonesia using tree rings, historic rice production figures and sea surface temperature data.

Indonesia is one of the world's most populous nations and a major producer of rice, cocoa, coffee and tobacco.

But the country is regularly at risk of drought caused by the El Nino phenomenon in which the eastern Pacific ocean heats up, with wet wetter moving toward the east and leaving drier weather in west around Southeast Asia and Australia.

U.S. scientist Rosanne D'Arrigo and her colleague Robert Wilson are working on simplified statistical models that can predict drought ahead of the main September-December rice planting season and how severe the drought might be.

The models focus on Java, one of the world's most densely populated islands with 120 million people.

"We're trying to develop simple, predictive model of drought and crop productivity on Java. There are complex models out there but you need to have a local type of analysis and something simple for local people to use," said D'Arrigo of the Lamont-Doherty Earth Observatory of the United States.

She was speaking to Reuters from Dalat in southern Vietnam where she was presenting her team's work at a climate change conference this week. Wilson is from Scotland's University of St. Andrews.

A key part of the model is using sea surface temperature data from the tropical Pacific and from the Indian Ocean. A separate phenomenon called the Indian Ocean Dipole can also cause drought in Australia and affect rainfall in Indonesia.

Other data such as sea-level pressure and wind indexes are also used. The data are examined several months before the usual onset of the monsoon to try to accurately predict likely rainfall patterns over Indonesia.