Westward Displacement of Atmospheric East-West Circulation Ameliorated Drought-Induced Conditions in Australia and India during the Major 2023-24 and 1997-98 El Nino Events

Based on a compilation of widely available climate analysis products, we show evidence for a significant variation in the spatial pattern of the large-scale vertical zonal atmospheric circulation patterns across the equatorial Indo-Australasian domain of the Eastern Hemisphere during the major 2023-24 El Nino event. The region of large-scale subsidence and its associated teleconnection patterns that are usually centered across Indonesia (the 'Maritime Continent') were displaced to the west over the equatorial Indian Ocean. In the record of El Nino events with readily available online dynamical tropospheric fields (one source from 1947 and the other from 1979), this has only been seen two other times, during the strong 1997-98 El Nino and the weaker 1977-78 event. These three events may well be consistent with internal variability, but at present, the reason for such occurrences has not been established. KEYWORDS: Climate variability; El Nino; ENSO; La Nina
1. Introduction There has been considerable media concern and public consternation that seasonal forecasts of a strong El Nino in 2023-24 failed to result in the suppression of rainfall and [...]