92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Tuesday, 24 January 2012
Connecting the Pacific to Regional Climate for Decadal Prediction: A Successful Case in the Western U.S.
Hall E (New Orleans Convention Center )
Shih-Yu Wang, Utah State University, Logan, UT; and R. Gillies and L. E. Hipps

The strong connection of decadal climate variabilities between the Pacific and the US Intermountain West (IMW) has been documented by numerous studies. It was suggested that constructive and destructive superposition between ENSO and the Pacific Decadal Oscillation can respectively strengthen and weaken the ENSO-induced North American dipole. But to date, how these different scales of natural variability interact and how such interactions influence climate of the IMW remains unclear. Recent studies focusing on the decadal-scale climate variability have turned attention to the Great Salt Lake (GSL), a large closed-basin lake located in the heart of the IMW. As a pluvial lake, the GSL integrates hydrological forcings over a substantial watershed which, when coupled with the lake's shallowness, results in extensive fluctuations in elevation. The large drainage area that constitutes the GSL tends to dampen out the interannual variability and so, has a tendency to be more responsive to climatic variabilities at longer timescales. As a result, the change in the GSL elevation reflects the recurrent wet/dry periods that have characterized the IMW, since any abrupt and prolonged downtrends (uptrends) of the GSL elevation are usually reflective of drought (pluvial) conditions. In particular, a multi-decadal (~30 year) and a quasi-decadal (~12 year) frequency bands stand out significant in the GSL elevation spectrum. We have found that the hydrological factors controlling the GSL elevation variation respond to a particular teleconnection that is induced at the transition point of the so-called Pacific Inter-Decadal Oscillation (IPO) the transition that lies approximately half-way between the warmest and coldest SST anomalies in the tropical central Pacific. Such circumstance in process creates consistent time lags between the IPO and the GSL elevation; this leads to a phase lag of 6-10 years in the multi-decadal frequency and a phase lag of ~3 years in the quasi-decadal frequency. Such phase lags result from a distinctive teleconnection pattern that develops during the transition points between the IPO's warm and cool phases. These processes provide a plausible explanation for the observed phase lags in the occurrence of local droughts/pluvials over the IMW to the IPO cycle. A statistical model derived from this hypothesis has successfully predicted the record-high precipitation and snow in the IMW that occurred in early 2010.

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