How are winters classified in terms of ENSO strength? Below are a few examples. In these examples, I'm using the following scale: +0.5 to +0.9 SST Anomaly for weak El Nino, +1.0 to +1.4 for moderate El Nino, and +1.5 & above for strong El Nino. Also, I'm using the latest ONI from the CPC.
1. Winter 1951-1952...the El Nino peaked in Sept/Oct/Nov at +1.2, then fell to +0.6 in DJF and +0.4 in JFM. Does this winter get categorized as moderate because it peaked at +1.2, or is it considered weak since the value fell down into the weak range during the winter months?
2. Winter 1987-1988...the El Nino peaked in Aug/Sept/Oct at +1.6, then fell to +0.7 in DJF and +0.5 in JFM. Similarly, does this winter get categorized as strong because it peaked at +1.6 in ASO, weak due to the winter month readings, or some combination of both?
A second question would be regarding the scale used for the strength classification. Above, I've used a 0.5 scale for weak/moderate/strong. I've seen others consider +1.2 as the low threshold for a moderate El Nino. In that case, what is considered the low threshold for a strong El Nino....and which scale is more widely used?
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