The answer is once every three to seven years with an average of 5. Take a look at the measured El Nino index as computed by the Climate Prediction Center and the El Nino Episodes really jump out. Then you can decide for your self how to best state it. The index values can be found at;
Answers & Comments
Verified answer
The answer is once every three to seven years with an average of 5. Take a look at the measured El Nino index as computed by the Climate Prediction Center and the El Nino Episodes really jump out. Then you can decide for your self how to best state it. The index values can be found at;
http://www.cpc.noaa.gov/products/analysis_monitori...