cycloneye wrote:Historic data of RONI since 1952 has 26 El NIño events and 28 La NIñas.
https://ggweather.com/enso/roni.htm
The table at the top that lists each year by strength seems to follow the old ONI and should be updated as it does not follow the table on the bottom with the indices.
Anyways, some of the most notable changes are: 2023-24 is down to a moderate El Niño, 1991-1992 is now a super/very strong El Niño according to RONI, 1982-1983 is the strongest El Niño measured by RONI (above 97 and 15), and 1972 should be classified as a very strong El Niño now.
1991-1992 stood out to me as the most surprising difference vs regular ONI. An increase from 1.7C in ONI to 2.3C in RONI is quite the jump. Perhaps the global cooling due to Mount Pinatubo gave RONI a significant boost as such cooling may be expected to have a larger effect on tropical surface water temperature than on the equatorial subsurface waters relevant for ENSO dynamics. This would also explain the boost that 1982 got from 3rd strongest to 1st, as volcanic cooling (from El Chichon) was also present during that event.
That 2023 fell so much compared to other El Niño events strongly suggests/confirms that globally warm tropics were indeed the mechanism behind the discrepancy between the very high raw ONI observed that year and the lack of robustness of atmospheric coupling observed.