Predicting ENSO devastation

Sandhya Sekar in SciDev.net:A new computer model can help forecast the socio-economic devastation caused by rainfall and floods triggered by the El Nino-Southern Oscillation (ENSO) phenomena.  Philip Ward from VU University, Amsterdam, who with his colleagues created the ‘cascade’ modelling framework, says that it is capable of predicting the effect of ENSO on floods at the global and regional scales.

“During El Niño years, the risk is higher than average in north-eastern India, the findings suggest,” says Ward in an interview with SciDev.Net. “On the other hand, some basins in eastern India show lower than average damage during La Niña years.”

ENSO refers to the effects of anomalous sea surface temperatures off the western coast of South America that cause climatic changes across the tropics and subtropics. Southern Oscillation refers to temperature variations on the surface of the tropical eastern Pacific Ocean (warming and cooling known as El Niño and La Niña, respectively) and in  surface  air pressure in the tropical western Pacific.

Ward’s approach, published in September in the Proceedings of the National Academy of Sciences, combines three different models that predict rainfall, water drainage patterns and also the socio-economic impacts of floods, including on GDP.

The models found abnormal flood volumes across more than a third of the earth’s surface during El Nino years when the oceans were warmer than usual, and also during La Nina years when the oceans were colder.  “Our models and results are already at a resolution of one square kilometre which we have found to be very useful for many users of the data in practical applications,” Ward tells SciDev.Net....

Sunrise over the South Pacific, NASA image from the International Space Station