Probable Causes of the Abnormal Ridge Accompanying the 2013-2014 California Drought: ENSO Precursor and Anthropogenic Warming Footprint

Journal Article · Fri May 16 04:00:00 EDT 2014 · Geophysical Research Letters, 41(9):3220–3226

DOI:https://doi.org/10.1002/2014GL059748· OSTI ID:1159014

Wang, S-Y ^[1]; Hipps, Lawrence; Gillies, Robert R.; Yoon, Jin-Ho

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1. Simon

The 2013-14 California drought was accompanied 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 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 GHG loading as simulated by the CESM. Therefore, there is a traceable anthropogenic warming footprint in the enormous intensity of the anomalous ridge during winter 2013-14, the associated drought and its intensity.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1159014
• Report Number(s): PNNL-SA-102345; KP1703020
• Journal Information: Geophysical Research Letters, 41(9):3220–3226, Journal Name: Geophysical Research Letters, 41(9):3220–3226
• Country of Publication: United States
• Language: English

Related Subjects

California drought
ENSO precursor
anomalous ridge
warming effect