The Southwest part of the US has always suffered from drought. The most recent once took place between the period of 2011 to 2017. California has also experienced years of rainfall that are lower than the usual amount that they get in a certain time in a year. The El Nino Phenomenon is known to influence the rainfall in the Southwest part of the US, but it isn't always a perfect match.
The University of Washington and the Woods Hole Oceanographic Institution, is collaborating with new research that explores the ocean conditions and the prolonged drought due to the conditions of the atmosphere in the Southwestern part of the US.
According to the study published in the Journal of Geophysical Research: Atmospheres, on August 6, 2019, the answer to the question is quite complex. This is the journal of the American Geophysical Union.
"What causes the droughts that could last for decades in some of the vulnerable parts of the world, and why do they happen? Is it possible for scientists to make predictions of when such a phenomenon would happen and in what areas?," said Dr. Luke Parsons, a postdoctoral researcher in atmospheric sciences from the University of Washington. He is the primary researcher of the study.
"Our study shows that when you have the El Nino event, it only means that the La Nina event is up and coming. This could only mean the beginning of multiple years of drought in the Southwestern part of the US."
As a rule of thumb, El Nino years can be predicted when the sea surface of the region off the coast o Peru is at least 1 degree warmer than the usual. People in the communities could only expect the conditions to get worse and once the drought sets in, it could last for years. La Nina years, on the other hand, is setting it when the region is 1 degree Celsius cooler than the average. However, this rule of thumb doesn't always hold true.
"People think that the El Nino phenomenon means more rain for the Southwestern part of the country, but it isn't always the case," said Parsons. "An El Nino sometimes brings rain with it, or it could cause it, but frequently that is not the reason why any given year is wet."
The new research is based on the climate model created to explore the relationship between the world's largest ocean and the long-term droughts in the US, including those felt in California, Arizona, and Western Colorado and New Mexico.
A better understanding of the long-term drought experience could help people make better decisions to attend to people's needs to keep the balance in an ecosystem.
