Recent rainfall cycle in the Intermountain Region as a quadrature amplitude modulation from the Pacific decadal oscillation
Article first published online: 24 JAN 2009
Copyright 2009 by the American Geophysical Union.
Geophysical Research Letters
Volume 36, Issue 2, January 2009
How to Cite
2009), Recent rainfall cycle in the Intermountain Region as a quadrature amplitude modulation from the Pacific decadal oscillation, Geophys. Res. Lett., 36, L02705, doi:10.1029/2008GL036329., , , and (
- Issue published online: 24 JAN 2009
- Article first published online: 24 JAN 2009
- Manuscript Accepted: 19 DEC 2008
- Manuscript Revised: 10 DEC 2008
- Manuscript Received: 14 OCT 2008
 Precipitation in the Intermountain Region has experienced a pronounced 10–20 yr cycle during the last four decades. We present evidence of a quadrature phase coupling of these 10–20 yr cycles between the Pacific Decadal Oscillation (PDO) and the Intermountain rainfall. The PDO has been linked to precipitation anomalies in the Northwest and Southwest U.S., while the Intermountain Region remains marginal. During the transition phase of a 10–20 yr cycle in the PDO, an anomalous circulation dipole over the Gulf of Alaska is formed. This circulation dipole modulates the synoptic activity that produces rainfall in the Intermountain Region. As a result, the Intermountain rainfall cycle has repeatedly lagged the PDO cycle by a quarter phase, amounting to about 3 to 4 years. Future understanding of the 10–20 yr cycle embedded in the PDO and its quadrature phase modulation may help predict the Intermountain climate.