Research Letter
Probable causes of the abnormal ridge accompanying the 2013–2014 California drought: ENSO precursor and anthropogenic warming footprint
Article first published online: 2 MAY 2014
DOI: 10.1002/2014GL059748
©2014. American Geophysical Union. All Rights Reserved.
Additional Information
How to Cite
2014), Probable causes of the abnormal ridge accompanying the 2013–2014 California drought: ENSO precursor and anthropogenic warming footprint, Geophys. Res. Lett., 41, 3220–3226, doi:10.1002/2014GL059748.
, , , and (Publication History
- Issue published online: 2 JUN 2014
- Article first published online: 2 MAY 2014
- Accepted manuscript online: 14 APR 2014 09:15AM EST
- Manuscript Accepted: 10 APR 2014
- Manuscript Revised: 7 APR 2014
- Manuscript Received: 27 FEB 2014
Keywords:
- California drought;
- ENSO precursor;
- teleconnection;
- anthropogenic warming
Abstract
The 2013–2014 California drought was initiated by an anomalous high-amplitude ridge system. The anomalous ridge was investigated using reanalysis data and the Community Earth System Model (CESM). It was found that the ridge emerged from continual sources of Rossby wave energy in the western North Pacific starting in late summer and subsequently intensified into winter. The ridge generated a surge of wave energy downwind and deepened further the trough over the northeast U.S., forming a dipole. The dipole and associated circulation pattern is not linked directly with either El Niño–Southern Oscillation (ENSO) or Pacific Decadal Oscillation; instead, it is correlated with a type of ENSO precursor. The connection between the dipole and ENSO precursor has become stronger since the 1970s, and this is attributed to increased greenhouse gas loading as simulated by the CESM. Therefore, there is a traceable anthropogenic warming footprint in the enormous intensity of the anomalous ridge during winter 2013–2014 and the associated drought.