Is the Western US ENSO teleconnection stationary in a warming world?
Abstract
El Niño-Southern Oscillation (ENSO) is the dominant driver of long-range wintertime precipitation forecast skill over the Western Contiguous United States (WCONUS). The strength of this teleconnection already shows signs of non-stationarity through the observational record, leading some to question its reliability as a predictor in a warming world. To test the strength of the wintertime teleconnection throughout the 21st century, a Canonical Correlation Analysis (CCA) was conducted on the JFM averaged Pacific sea surface temperature (SST) and WCONUS precipitation data from the Community Earth System Model Large Ensemble Community Project (CESM LENS) 40-member ensemble. The CCA method finds linear SST and Precipitation combinations that maximize the correlation between their temporal evolutions, providing a window into the strength of the teleconnection through time. In both the model and observations the leading CCA spatial mode for SST resembles a combination of ENSO and the Pacific Decadal Oscillation. The precipitation pattern reflects a North-South dipole. In the observational record, at the beginning of the 21st century, the correlation between the SST and precipitation first order canonical correlates begins to decrease, highlighting a weakening of the wintertime teleconnection under a warming climate scenario. In the model, a gradual increase of the ensemble mean correlation, from 1950 to the end of the 21st century, paints a picture of a strengthening wintertime teleconnection signal emerging beyond the noise. Model biases and the implications of these results for the future of ENSO-based seasonal prediction are further discussed in the context of these findings.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMOS021..07P
- Keywords:
-
- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSES;
- 1630 Impacts of global change;
- GLOBAL CHANGE;
- 4215 Climate and interannual variability;
- OCEANOGRAPHY: GENERAL;
- 4922 El Nino;
- PALEOCEANOGRAPHY