Modeling North Pacific Decadal Variations and Their

Teleconnection Patterns

Speaker/ Pei-Ning Kirsten Feng

Advisor/ Yu-Heng Tseng

Outline

• Overview• Motivation • Objective• Data and Model• Ongoing / Future work• Summary

North Pacific Decadal Variations

[Di Lorenzo et al.,2008; Bond et al., 2003]

• The NPGO mode closely tracks the second EOF of North Pacific SSTa, also referred to as the "Victoria Mode”(Bond et al., 2003). The NPGO is distinct from the Pacific Decadal Oscillation (PDO) mode (Mantua et al., 1997), which emerges as the first mode of SSTa and SSHa in the Northeast Pacific. However the NPGO is the dominant mode for salinity and nutrients.

Pacific Decadal Variations

[Di Lorenzo et al., 2008]

PDO AREA

North Pacific – AL/PDO

• The Pacific Decadal Oscillation (PDO) Index is defined as the leading principal component of North Pacific monthly sea surface temperature (SST) variability (poleward of 20N).

[Mantua et al., 1997]

Warm Phase Cool Phase

North Pacific – AL/PDO

-300 -250 -200 -150 -100-40

-20

0

20

40

60

SLP 1 (27.7905%)

-1 -0.5 0 0.5 1

-300 -250 -200 -150 -100

-30

-20

-10

0

10

20

30

40

50

60

SST 1 (27.7905%)

-0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8

VIMONT et al., 2003

PC1, ENSO, PDO Index

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000-3

-2

-1

0

1

2

3

4

SST+SLP & SST (R=0.981)

SST+SLP & Nino 3.4 index (R=0.898)

SST & Nino 3.4 index (R=0.898)

SST PC1 (Combined EOF)SST PC1 (SST Only)Nino 3.4 Index

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000-3

-2

-1

0

1

2

3

4

SST+SLP & SST (R=0.981)

SST+SLP & PDO index (R=0.593)

SST & PDO index (R=0.587)

SST+SLP & SST (R=0.981)

SST+SLP & PDO index (R=0.593)

SST & PDO index (R=0.587)

SST PC1 (Combined EOF)SST PC1 (SST Only)PDO Index

Why NPGO index

• Recently it is found that PDO index can’t explain those variations in the ocean. However NPGO pattern is even more similar with them.

Di Lorenzo et al., 2008

North Pacific – NPO/NPGO

• North Pacific Gyre Oscillation, NPGO:

• The NPGO is defined as the second dominant mode of SSHa variability in the Northeast Pacific [180°–110°W; 25°N–62°N] and is correlated with the second mode of North Pacific SSTa.

[Di Lorenzo et al., 2008]

North Pacific – NPO/NPGO

• The NPGO leads decadal variations in the strength of the Kuroshio-Oyashio connecting California and Japan.

Di Lorenzo et al., 2008

NPO and ENSO Modoki

• The dynamics that link ENSO to PDO are referred to as the ‘atmospheric bridge’12, whereby atmospheric teleconnections to the extratropics excited by ENSO project onto the atmospheric variability of the Aleutian Low, which then drives the ocean PDO pattern.

Di Lorenzo et al., 2010

1900-2009 Combined EOF

-260 -240 -220 -200 -180 -160 -140 -120 -100 -80 -60-40

-20

0

20

40

60

SLP 1 (28.1137%)

-1.5 -1 -0.5 0 0.5 1 1.5

-260 -240 -220 -200 -180 -160 -140 -120 -100 -80-40

-20

0

20

40

60

SST 1 (28.1137%)

-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5

-260 -240 -220 -200 -180 -160 -140 -120 -100 -80 -60-40

-20

0

20

40

60

SLP 2 (6.6139%)

-1.5 -1 -0.5 0 0.5 1 1.5

-260 -240 -220 -200 -180 -160 -140 -120 -100 -80-40

-20

0

20

40

60

SST 2 (6.6139%)

-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5

1900-2009 EOF Time Series

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000-3

-2

-1

0

1

2

3

4

SST+SLP & SST (R=0.981)

SST+SLP & Nino 3.4 index (R=0.898)

SST & Nino 3.4 index (R=0.898)

SST PC1 (Combined EOF)SST PC1 (SST Only)Nino 3.4 Index

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000-5

-4

-3

-2

-1

0

1

2

3

4

5

SST+SLP & SST (R=0.517)SST+SLP & NPGO Index (R=0.486)SST & NPGO index (R=0.498)

SST PC2 (Combined EOF)SST PC3 (SST Only)NPGO Index

Atmosphere-Ocean Interaction

[Di Lorenzo et al., 2010]

Teleconnection

• Atlantic Patterns• Pacific Patterns• Global Patterns• Discussion

Atlantic Pattern -- NAO

• The NAO is the dominant mode of winter climate variability in the North Atlantic region ranging from central North America to Europe and much into Northern Asia. The NAO is a large scale seesaw in atmospheric mass between the subtropical high and the polar low.

75oW 50oW 25oW 0o 25oE

30oN

45oN

60oN

75oN

90oN

SLP EOF 1 (51.0839%)

-2 -1 0 1 2 3 4

Pacific Pattern – NPO/WP

• Orthogonally rotated principle component analysis(RPCA) of Northern Hemisphere 1-month mean 700 mb height is used.

• The cold season West Pacific Oscillation has a strong center over or somewhat east of Kamchatka at 50-60°N, 160°E-170°W.

[Barnston and Livezey, 1987]

Pacific Pattern – WP

• The western pacific pattern (WP) is the SLP EOF2 pattern during DJFM in the region of 20~85N, 120E~120W.

125oE 150oE 175oE 160oW 135oW

36oN

48oN

60oN

72oN

84oN

500hPa Height EOF 3 (11.5935%)

-4

-3

-2

-1

0

1

2

3

4

Global Pattern -- AO

• The AO is the dominant pattern of non-seasonal sea-level pressure (SLP) variations north of 20N, and it is characterized by SLP anomalies of one sign in the Arctic and anomalies of opposite sign centered about 37-45N.

[Todd Mitchell , 2004 ]

Global Pattern -- AO

• The loading pattern of AO is defined as the first leading mode from the EOF analysis of monthly mean height anomalies at 1000-hPa (NH). Year-round monthly mean anomaly data has been used to obtain the leading patterns.

Global Pattern and Teleconnection

• AO

• AL ←→ PDO

• ENSO / EPW• WP • CPW

• NAO• NPO ←→ NPGO

• KOE

• PNA

• How these oscillations play roles in the long term climate?

Motivation

• Low-frequency oscillations are not known well.

• Why there are so many decadal variations with similar patterns on time series? Are the related?

• What might be the possible mechanism for those oscillations?

Objective

• First we want to summarize the oscillations and determine their relations, especially stressed on the Pacific area.

• We want to compare the model simulation to the observations and see if those oscillations are shown in the resolutions.

Methods and Model

- Data Source- Model - Methods

Data source

• Hadley SST– 1º x 1º HadISST1 from 1900 to 2009.

• Hadley SLP– 5º x 5º HadSLP2 from 1900 to 2009

• NCEP/NCAR Reanalysis 1– 2.5º x 2.5º Reanalysis 500 Height from 1950 to 2009

ECHAM (AGCM) 19 levels T31

DIECAST (OGCM) 31 Levels (2 deg)

SIT

(Air/S

now/Ice/T

hermocline)

2snow+

2ice+41 w

ater levels

Model ( ECHAM5 / SIT / DIECAST )

ECHAM5 – AGCM, running at various resolutions.

SIT – a one-columnsnow/ice/ocean model with 41-level ocean+ 2-level ice + 2-level snow.

DIECAST – OGCM with 2 degree in the equator, covering from 60°S to 60°N, with 31 levels.

Year: 1871 to 2008

Ongoing / Future Work

- Ongoing Work- Future Work

Ongoing / Future Work

• Analysis of the model resolution

Summary

Summary

……つづく