The Oceanic Nino Index (ONI) is widely recognized as the standard measure used to assess and quantify the strength of El Nino and La Nina events. It is specifically designed to monitor sea-surface temperature anomalies in the equatorial Pacific Ocean, which are indicative of El Nino or La Nina conditions. The ONI is regularly updated and provides a consistent measure for scientists and researchers to track the intensity and duration of El Nino and La Nina phenomena.