1 2 3 Northeast Pacific California Current Gulf of Alaska - - PowerPoint PPT Presentation

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EOF2 SSH

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EOF1 SSH PDO mode

California Current CalCOFI Observations

PDO

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NO3 Chl-a

std

NPGO Salinity

North Pacific Gyre Oscillation (NPGO) Pacific Decadal Oscillation (PDO)

NPGO NPGO

NPGO Mode

explains

CalCOFI SSTa

1970 1980 1990 2000

Northeast Pacific

Physical-Biological Variability

Line P

CalCOFI

Line P

CalCOFI

1970 1980 1990 2000 & $ &

Line P Salinity Line P NO3

NPGO NPGO

& ! $ ! &

Line P SSTa

Gulf of Alaska Line P Observations

psu

!mol m-3

°C

PDO

1 2 3

year

explains

Di Lorenzo et al., GRL 2008.

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EOF1 SSSa (A) (B)

NPGO Index

Line P SSSa CalCOFI SSSa

(C)

1970 1980 1990 2000

PC1 SSSa

year

35.5 32 +5.5

• 5.5

!mol m-3 !mol m-3

longitude latitude latitude

Mean SSSa

Line P

CalCOFI

Line P

CalCOFI

Di Lorenzo et al., in prep.

Coherent variations of salinity in the Northeast Pacific (spatial maps is from ROMS model hindcast)

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EOF1 NO3 Mean NO3 (A) (B)

NPGO Index !"#$ !"%$ !""$ &$$$ !& $ &

Line P NO3

!' !& $ & '

CalCOFI NO3

(C)

1970 1980 1990 2000

PC1 NO3

year

30 1.7 +5.5

• 5.5

!mol m-3 !mol m-3

longitude latitude latitude

Line P

CalCOFI

Line P

CalCOFI

Di Lorenzo et al., in prep.

Coherent variations of nutrients in the Northeast Pacific (spatial maps is from ROMS model hindcast)

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20 40 60 200 150 100 20 40 60

!"# !$#

G4-H,68./

Sea Level Pressure and Wind Vector Anomalies during PDO positive phase Sea Level Pressure and Wind Vector Anomaly during NPGO positive phase

Upwelling depth index

positive indicates shallow upwelling cell

Upwelling depth index

negative indicates shallow upwelling cell

The atmospheric forcing of the PDO and NPGO drive dierent responses in coastal upwelling

Chhak and Di Lorenzo, 2007 Chhak and Di Lorenzo, in prep.

1 2

PDO Forcing pattern NPGO Forcing pattern

3 4

std std

60 40 20 60 40 20

• 200
• 150
• 100

PDO Index Upwelling depth index NPGO Index Upwelling depth index

140W 130W 120W 30N 35N 40N 45N 50N 140W 130W 120W 30N 35N 40N 45N 50N

negative PDO

we find more water coming from the south

+PDO ensemble mean QUESTION: where do the upwelled water at the coast come from during different phases of PDO?

An inverse approach to track changes in upwelling during the negative and positive phase of PDO

positive PDO

we find more water coming from the north and offshore

METHOD: inject passive tracer at the upwelling location and track it backwards in time with ROMS-Adjoint

2 1

• PDO ensemble mean

adjoint passive tracer map at 50m

Chhak and Di Lorenzo, 2007

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CalCOFI SSTa CalCOFI SSSa °C

psu

Model SSTa Model SSSa

R=0.42 R=0.6

nutrients

(nitrate + ammonium)

zooplankton

• t

h e r m

• r

t a l i t y excretion remineralization sinking

uptake/ growth

egestion

detritus phytoplankton

mortality/ higher predation

total grazing

net growth

ROMS NPZD “simplistic” model

sketch courtesy of Neil Banas

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CalCOFI NO3 CalCOFI Chl-a

!mol m-3

std R=0.5 R=0.55

ROMS physical- biological modeling framework

1 2

Model Hindcast of the CalCOFI Observations

Di Lorenzo et al., 2008, GRL

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R=0.47 NPGO Index PC2 Pacific SSTa

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!#&' !#&( !#&$ # #&$ #&( #&'

Corr(SSHa, NPGO)

North Pacific Gyre Oscillation (NPGO) pattern in Satellite SSHa

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EOF2

NPGO Mode

SSHa

defined: as 2nd EOF of SSHa in the Northeast Pacific

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NPGO pattern in Global SSTa

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NPGO pattern in Global SSTa NPGO pattern in SeaWiFS CHL-a

!'"( !'"& !'"$ ' '"$ '"& '"(

Corr(CHL-a, NPGO)

Large-scale climate mode in the PHYSICS

• f climate mode

ECOSYSTEM footprint

1 2

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Phase lag response in the Western Boundary

Changes in strength of the Kuroshio lag changes in the Eastern Boundary

Plotted is KOE Zonal Mode (red) lagged by 3 years (Taguchi et al. 2007)

year NPGO Index KOE Zonal Mode

3

Di Lorenzo et al., in prep.

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NPGOrec(t +1) = NPGOrec(t) + NPO(t)dt

North Pacific Oscillation Index (NPO) North Pacific Gyre Oscillation Index (NPGO) Strength of Kuroshio Index (KOE Index)Taghucci et

• al. (2007)

Atmosphere forces the ocean SSHa Central/Eastern North Pacific SSHa mode Western North Pacific SSHa mode Sea Level Pressure mode

NPGO NPGOrec KOE NPO NPGO

• cean westward propagation
• f SSHa affect western boundary

1 2 3

KOE index lagged by 3 years 3-4 years later Di Lorenzo and Schneider, in prep. CENTRAL/WESTERN North Pacific WESTERN North Pacific

NPO NPGO

EXTRA-TROPICS TROPICS North Pacific Gyre Oscillation (Di Lorenzo, Schneider et al. 2007)

• cean

North Pacific Oscillation (Walker and Bliss, 1932)

atmosphere

KOE Zonal Mode

Strength of KOE (Taguchi et al. 2007)

• cean

S S H a R

• s

s b y W a v e s

ENSO

• cean - atmosphere

SSTa footprinting

(Vimont et al. 2003)

Stochastic Forcing

?

Precursor of NPO in tropical western Pacific SLPa

(Schneider and Di Lorenzo, in prep.)

Di Lorenzo and Schneider, in prep.