New ENSO Identification: Applications for Seasonal Prediction

The industry-standard way to declare the state of the El Nino Southern Oscillation (ENSO) is through the use of the ENSO 3.4 index (Ocean Nino Index; 3-month average of sea-surface temperature anomalies in the ENSO 3.4 domain). The ENSO 3.4 index is a pre-defined box of averaged sea-surface temperature anomalies about the central-eastern equatorial Pacific. It is argued here that ENSO is not a rigid phenomenon that can be classified by only two states (El Nino or La Nina), but rather is a spectrum. Many ENSO states often go unnoticed as the ENSO 3.4 index can on occasion, miss critical information that can be used to make decisions that are based up the seasonal forecast. It is argued that sea-surface temperatures might not be the best variable to monitor with regards to role of ENSO on weather variability in the extra-tropics. Coherent atmospheric standing waves in the tropics often set up during strong ENSO states. It is shown that 200mb Velocity Potential (VP200) is one such field that a tropical atmospheric standing wave can project onto. A case study of the advancement of the Super El Nino of 2015-2016 will be shown. To communicate this complex information to clients trading natural gas futures, we have developed the Atmospheric ENSO Index (AEI) using the discussed VP200 principles. This index is an example of applying research into daily operations. A time-series comparison of the 2015-2016 Super El Nino with other strong El Nino's observed in history will be shown.