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Characteristics of PDV and the need for a PDV research and monitoring. Nate Mantua JISAO/SMA Climate Impacts Group University of Washington. November-April SLP change: (1977-88) - (1965-76).
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Characteristics of PDV and the need for a PDV research and monitoring Nate Mantua JISAO/SMA Climate Impacts Group University of Washington
Cool season Aleutian Low variability: (Nitta and Yamada 1989, J. Met. Soc. Japan; Trenberth 1990, BAMS) North Pacific winter sea level pressure field (i.e. the Aleutian Low) “shifted” in 1977
The Pacific Decadal Oscillation • an El Niño-like pattern of climate variability • 20 to 30 year periods of persistence in North American and Pacific Basin climate • warm extremes prevailed from 1925-46, and again from 1977-98; a prologed cold era spanned 1947-76 1925 1947 1977 1998? (Mantua, Hare, Zhang, Wallace and Francis 1997, BAMS)
Warm phase PDO and North American climate temperature precipitation Todd Mitchell, UW/JISAO
Minobe (1999 GRL; 2000 Prog. Oceanogr) Wavelet of NPI & PDOI
Some key unanswered questions • How many decadal/interdecadal modes are there in Pacific climate? • What are their dynamics and predictability? • Can we detect phase changes soon after they take place?
Distinct modes of NP SST variability?from a Rotated PC analysis of COADS SST 1945-1993(Nigam et al. 1999, Eos Trans.)
Slowdown of the meridional overturning circulation in the Tropical Pacific~25% decrease in upwelling from 1970’s to 1990’s, rising eq. SSTs and a reduced CO2 flux to the atmosMcPhaden and Zhang, Nature,2002
1 2 1Mantua et al. (1997), 2Lagerloef (1995) OCEANIC AND ATMOSPHERIC EVIDENCE FOR A PACIFIC DECADAL OSCILLATION (PDO) PHASE SHIFT AFTER 1998 Gary S. E. Lagerloef, Earth and Space Research, Seattle, WA, USA Patrick Cummins, Institute of Ocean Sciences, Sidney BC, Canada Jeffrey Polovina, NOAA/NMFS, Honolulu, HI, USA Gary T. Mitchum, University of South Florida, St. Petersburg, FL, USA
Alaska Commercial Salmon Catches 1878-2001 Alaska Department of Fish and Game http://www.state.ak.us/adfg
Ecosystems change 1960’s Bottom trawl surveys in Pavlov Bay, Alaska (source: Botsford et al. 1997 Science) 1970’s 1980’s
Pavlov Bay, Alaska Trawl surveys (Anderson and Piatt 1999, Mar. Ecol. Prog. Ser.)
Pacific Sardines: a history of 20th Century boom and bust cycles(Kawasaki and Omori 1988)
PDV projects: revised outline INTRODUCTION: motivation II. the nature of PDV Instrumental Description of PDV Paleo-reconstructions of PDV III. PDV modeling, mechanisms and predictability PDV observing strategy: past and future mechanisms of PDV in coupled models Prediction and predictability of PDV PDV and land surface feedbacks PDV and global warming IV. PDV impacts: mechanisms and predicting impacts Fisheries/Marine food webs water resources Energy, fire, Human health, Ag?
7. Observations System Simulation Experiments for PDV in coupled models The problem? • Need to design a purposeful monitoring system for PDV modes Why is it important? • Background observing system planned for CLIVAR may not be sufficient for PDV nowcasts or forecast initializations What has been done so far? • nothing What needs to be done? • Simulated predictions (as suggested in item 6) with degraded initial conditions What will be different if it is done? • PDV monitoring needs can be compared with planned and existing capabilities
Feb 2003 PDV workshop • A small two day workshop organized by Ed Sarachik, Nate Mantua, and David Legler to discuss and revise a draft prospectus for a PDV science program http://www.usclivar.org/PDV_0203.html And ftp://ftp.atmos.washington.edu/mantua/PDV