Beniche M., Vialard Jérôme, Lengaigne Matthieu, Voldoire A., Srinivas G., Hall N. M. J. (2024). A distinct and reproducible teleconnection pattern over North America during extreme El Niño events. Scientific Reports - Nature, 14 (1), p. 2457 [12 p.]. ISSN 2045-2322.
Titre du document
A distinct and reproducible teleconnection pattern over North America during extreme El Niño events
El Nino-Southern Oscillation (ENSO) teleconnections are an important predictability source for extratropical seasonal climate forecasts. Previous studies suggest that the ENSO teleconnection pattern depends on the ENSO phase (El Nino vs. La Nina) and/or Sea Surface Temperature (SST) pattern (central Pacific vs. eastern Pacific El Nino events). Observations and ensemble simulations with the CNRM-CM6.1 atmospheric general circulation model indicate that only extreme El Nino events (e.g. 1982-1983, 1997-1998, 2015-2016) display a statistically significant eastward shift relative to the well-known Pacific-North American teleconnection pattern that occurs during both central and eastern Pacific moderate El Nino or during La Nina. This specific teleconnection pattern emerges when equatorial SST anomalies are both eastward-shifted and sufficiently large to exceed the deep atmospheric convection threshold over most of the eastern Pacific, resulting in a basin-wide reorganization of tropospheric heat sources. It yields> 0.5 std wet conditions over Western United States (74% likelihood) as well as> 0.5 std warm anomalies over Canada and the Northern United States (71% likelihood), with more consistency across events and ensemble members than for any other El Nino or La Nina type. These findings hold important implications for the seasonal forecasting of El Nino's impacts on the North American climate.
Plan de classement
Sciences du milieu [021]
;
Limnologie physique / Océanographie physique [032]
