Extended Abstract (260K)P2.11
Upwelling and Coastal Climate Variability in Southern California, 1998-2007: A Return to the Cool Phase of Pacific Decadal Oscillation?
Pedro Ramirez, California State University, Los Angeles, CA; and S. LaDochy and W. C. Patzert
This study examines the relationship of local upwelling indices, sea surface temperatures, precipitation and air temperatures to larger-scaled Pacific oceanic and atmospheric conditions occurring predominantly since the end of the 1997-98 El Niño event. During the past decade record-breaking weather (hot, cold, wet, dry) characterized coastal southern California, while the regional western United States suffered from one of the worst droughts evident in an approximately 500-year combined proxy and historical record. Southern California coastal areas experienced an unusually cool period of five consecutive summers from 1998 to 2002, during which typical “June Gloom” conditions dominated. The cooler summers occurred during a switch of the Pacific Decadal Oscillation (PDO) from a strong positive to negative phase. Mostly hot summers succeeded cooler ones from 2003 through the present. Weak El Niños typify this period. The most recent swings in southern California climate examined in the context of large-scale atmospheric/oceanic patterns such as the PDO, Southern Oscillation Index (SOI), and Northern Oscillation Index suggest a return to the cool phase of the PDO extending over the next decade. Local sea surface temperatures (SST) follow ENSO (El Niño-Southern Oscillation) shifts and negative SOIs with warm SSTs prevailing during El Niño years and cooler SSTs during La Niña years. Recent upwelling indices produce somewhat more variable patterns than SSTs that, overall, are attributable to major atmospheric/oceanographic changes. Trends and shifts since 1998 in local upwelling indices, SSTs, precipitation, and air temperatures, when compared with earlier (1948-present) patterns, appear to be fairly distinct. However, their tendencies favor the appearance of a PDO cool phase. Similarities between this young phase shift and previous negative PDO multi-decadal periods are blurred, as global warming may have significantly impacted conditions since the last cool phase.
Poster Session 2, General Climate Studies: Poster Session
Monday, 21 January 2008, 2:30 PM-4:00 PM, Exhibit Hall B
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