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Decades long El Niño-like climate variations: the Pacific Decadal Oscillation and its impacts on marine and terrestrial systems. Nate Mantua Climate Impacts Group University of Washington, Seattle WA October 21, 2003, UC Berkeley. Outline. PDO signatures in Pacific/N. American climate

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slide1

Decades long El Niño-like climate variations: the Pacific Decadal Oscillation and its impacts on marine and terrestrial systems

Nate Mantua

Climate Impacts Group

University of Washington, Seattle WA

October 21, 2003, UC Berkeley

outline

Outline

PDO signatures in Pacific/N. American climate

impacts on forests and marine ecosystems

paleoclimate evidence

mechanisms and predictability

the pacific decadal oscillation
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
  • PDOfingerprints found in records of temperature, precipitation, snow pack, streamflow, and marine ecosystems

1998?

1947

1925

1977

1900 1925 1950 1975 2000

Mantua et al. 1997: A Pacific Interdecadal Climate Oscillation with Impacts on Salmon Production, Bulletin of the American Meteorological Society, Vol 78, p 1069-1079.

pdo research
PDO research ...

Bothclimate and fisheries research are behind this story

  • Ebbesmeyer et al’s “1977 Regime Shift”
    • A step change in 40 environmental parameters in the Pacific (1991)
    • Nitta and Yamata 1989, Tanimoto et al 1993, Graham 1994, Trenberth and Hurrel 1994, Kawamura 1994, Latif and Barnett 1994, Miller et al 1994, Zhang 1996, Zhang et al 1997, Mantua et al 1997, Minobe 1997 ... and many more have followed
1976 step in pacific climate 40 environmental changes ebbesmeyer et al 1991 paclim proceedings
“1976 Step in Pacific Climate: 40 environmental changes …”(Ebbesmeyer et al. 1991, PACLIM proceedings)

Large and local scale climate indices, Canadian geese, NW salmon, dungeness crab, Pacific sea birds numbers, Washington Oyster growth … all folded into a 40-member composite variable.

(see Kerr, Science Vol 255, 1992)

pdo research at the university of washington
PDO research at the University of Washington
  • A product of 3 semi-independent streams of research
      • Hare and Francis (1992), UW Fisheries Research Institute: North Pacific climate and 20-30 year boom/bust cycles in Alaska salmon
      • Zhang and Wallace (1994), UW Atmospheric Sciences: Ocean/Atmos variability in Pacific climate, ENSO vs North Pacific Climate Variations
      • Mantua (1995), UW Climate Impacts Group: Pacific Northwest “climate history”, climate impacts on NW salmon
slide8

Oct-March Sea Level Pressure anomalies during

warm phases of PDO: an intensified Aleutian Low

L

H

H

Contours every .5 mb

slide9

500 mb height anomalies during warm phases

of PDO: the Pacific North America pattern

H

L

H

Contours every 5 meters

slide10

October-March PDO Regression fields

Surface Air Temperature

Precipitation

Figures produced by Todd Mitchell, UW/JISAO

regional indicators for pdo variability mantua et al 1997 bams
Regional Indicators for PDO variability(Mantua et al 1997, BAMS)

Gulf of Alaska winter air temperature

BC Coastal SST

Scripps Pier SST

1925

1947

1977

Kenai River Streamflow

BC/Washington Streamflow

pdo and north american climate
winter and spring time temperatures: relatively warm in northwest North America, and cool in the southeast

winter and spring time precipitation: wet in the southern US and northern Mexico, and dry in the Pacific Northwest and Great Lakes regions

winter and spring time temperatures: relatively cool in northwest North America, and warm in the southeast

winter and spring time precipitation: dry in the southern US and northern Mexico, and wet in the Pacific Northwest and Great Lakes regions

PDO and North American Climate

Warm PDO: 1925-46; 1977-1998(?)

Cool PDO: 1900-1924; 1947-1976;

snowpack pdo and tree growth
Snowpack, PDO and tree growth

Mountain hemlock in the Cascade

and Olympic Mountains

high elevation OR/WA Mt Hemlock and snowpack

Deep snowpack

Low snowpack

low elevation OR/WA Mt Hemlock and pdo

warm/dry

warm/dry

Cool/wet

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

From Peterson and Peterson (2001)

alaska commercial salmon catches 1878 2001
Alaska Commercial Salmon Catches 1878-2001

Alaska Department of Fish and Game http://www.state.ak.us/adfg

slide18

1960’s

Bottom trawl surveys in Pavlov Bay, Alaska

(source: Botsford et al. 1997, Science, 277: 509-515)

1970’s

1980’s

a history of change from a 50 year record of gulf of alaska bottom trawl surveys
A history of change from a 50 year record of Gulf of Alaska bottom trawl surveys

From: Anderson and Piatt (2000) Mar. Ecol. Prog. Ser 189: 117-123.

pacific salmon catch data analysis hare mantua and francis 1999 fisheries
Pacific salmon catch data analysis(Hare, Mantua and Francis 1999, Fisheries)
  • Combine commercial+sport+subsistence catch from 1925-1997
  • assume that catch reflects abundance
  • apply “regional normalization”
  • focus on critical period by shifting each record in time to reflect typical year of ocean entry (chinook & chum 3 years, sockeye 2 years, coho and pink 1 year)
slide21

An Inverse Production Pattern

34% variance

Hare, Mantua, and

Francis 1999, Fisheries Vol 24: 6-14

PC scores

r(pdo) = .73

r(niño34) = .53

why an inverse production response to pdo enso related variability
Why an inverse production response to PDO/ENSO-related variability?

H1: “optimal stability window” and “bottom up” impacts on marine food-webs

Gargett 1997, Fisheries Oceanogr. 6:109-117

Phytoplankton

production

N

S

Stratification or upwelling

slide23

Other coherent patterns in marine ecosystems?

Empirical Evidence for N. Pacific Regime Shifts in 1977 and 1989

Hare and Mantua, Progress in Oceanogr. 2000, 47: 103-145

slide24

1976-77

1988-89

1976-77: PC1

1988-89: PC2

Hare and Mantua, Progress in Oceanogr. 2000, 47: 103-145

tree ring based pdo index reconstructions ex gedalof and smith 2001 geophys res letts 28 1515 1518
Tree-ring based PDO index reconstructions:(ex: Gedalof and Smith 2001, Geophys. Res. Letts. 28: 1515-1518)

Plots courtesy of Torrence and Compo http://paos.colorado.edu/research/wavelets

slide27
Geoducks:

“gooey duck”,

Panopea abrupta

geoduck shells may have the tree-rings of the extratropical seas

slide28

Thin section of geoduck shell from Protection Island

x

warm PDO

cool PDO

1969

1998

1978

Are Strom, 2003 M.Sc., UW School of Fisheries

ocean temperature reconstruction based on protection island geoduck growth rates
Ocean temperature reconstruction based on Protection Island geoduck growth rates

Growing season (March-October) temperatures

x

x

x

Are Strom, 2003 M.Sc., UW School of Aquatic and Fishery Sciences

paleo salmon abundance estimates from lakebed sediment cores finney et al 2000 science 290 795 799
Paleo-salmon abundance estimates from lakebed sediment cores(Finney et al. 2000, Science 290: 795-799)

1700

1800

1900

2000

slide32

ENSO/PDO combined influences on North American

Climate (JFM precipitation)

warm PDO/La Niña

cool PDO/La Niña

Gershunov, Barnett

and Cayan 1999 Eos Transactions

columbia river summer april september streamflow
Columbia River summer (April-September) streamflow

} ~ 20%

change

Alan Hamlet and Dennis Lettenmaier, UW Civil Engineering

pdo predictability
PDO Predictability

PDO mechanisms will define itspredictability

  • best case scenario:
    • slow ocean adjustment+air/sea coupling (like El Niño)
  • Worst case scenario:
    • ocean adjustment to surface fluxes is purely via mixed-layer heat storage -- this would limit predictability to ~ 1 year

atmosphere

ocean

Re-emergence in entraining mixed layers

Deser et al. 2003, J. Climate 16:57-72

enso forced variability of the pdo newman et al j climate letters in press
ENSO-forced variability of the PDO Newman et al. J. Climate Letters (in press)
  • PDO variability reflects a “reddened” response to atmospheric “white noise” and ENSO forcing (at all time scales)
  • The basic model:

“the PDO is simply due to reemergence + ENSO forcing + random atmospheric forcing”

PDOforecastn = *PDOobservedn-1 +*ENSOn + oisen

simple model performance newman compo and alexander in press j climate letters
Simple model performanceNewman, Compo and Alexander (in press) J. Climate Letters

Forecast vs. Observed

Annual PDO (July-June)

  • 1 year lead time hindcasts vs Observed correlations
  • Modeled time series power spectra not as “red” as observed PDO
  • Prediction for July-June 2004? ~ + .6 to +1

1900

1950

2000

Power Spectra

Observed

forecast

Period

now casting
Now-casting
  • assessing the current status of the PDO is difficult:

what should we be tracking????

    • El Niño experience tells us that improved understanding will come with improved measurements, diagnostics and modeling
slide38

Keeping track of El Niño/Southern Oscillation: the TAO/TRITON array

  • The backbone of today’s ENSO Observing Network
  • initiated in 1985, completed in 1994
  • 70 moored buoys provide real-time in-situ surface and subsurface conditions (winds, temperatures, currents)
summary
Summary
  • over the past few centuries PDO has been an important pattern of climate variability at periods comparable to a human’s life time
  • provides insights into the history of water and fishery resources: can we learn from this history?
  • offers another avenue for improving climate predictions at the seasonal and (potentially) multi-year time scales
  • fisheries and climate research communities putting lots of effort into learning more about PDO and its impacts
slide41

upwelling food webs in our coastal ocean: the California Current

http://www.noaa.gov/

Cool water, weak stratification

high nutrients, a productive “subarctic” food-chain with abundant forage fish and few warm water predators

Warm stratified ocean, few

nutrients, low productivity “subtropical” food web, a lack of forage fish and abundant predators

Abundant Krill!

Krill are in short supply

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