El Niño was long considered a reliable tool for predicting future precipitation in the southwestern United States, but its forecasting power has diminished in recent cycles, possibly due to global climate change. In a study published today in Nature Communications, scientists and engineers at the University of California, Irvine demonstrate a new method for projecting wet or dry weather in the winter ahead.
El Niño was long considered a reliable tool for predicting future precipitation in the southwestern United States, but its forecasting power has diminished in recent cycles, possibly due to global climate change. In a study published today in Nature Communications, scientists and engineers at the University of California, Irvine demonstrate a new method for projecting wet or dry weather in the winter ahead.
“The interhemispheric teleconnection that we have discovered promises earlier and more accurate prediction of winter precipitation in California and the southwestern U.S.,” said study co-author Efi Foufoula-Georgiou, UCI Distinguished Professor of civil & environmental engineering. “Knowing how much rain to expect in the coming winter is crucial for the economy, water security and ecosystem management of the region.”
The researchers called the new teleconnection the New Zealand Index, because the sea surface temperature anomaly that triggers it begins in July and August in the southwestern Pacific Ocean, close to New Zealand. As the sea surface temperature in the region cools down or heats up, it causes a change in the southern Hadley cell, an atmospheric convection zone from the equator to about the 30th parallel south.
This prompts a commensurate anomaly east of the Philippine Islands, which, in turn, results in a strengthening or weakening of the jet stream in the Northern Hemisphere, having a direct influence on the amount of rain that falls on California between November and March.
Read more at University of California - Irvine
Image: The water level of the San Luis Reservoir in California's Merced County fluctuates in wet and dry years. UCI research gives resource managers a new tool for predicting winter rainfall months in advance. (Credit: Amir AghaKouchak, UCI)
