Detecting Change in the Detecting Change in the Bering Sea EcosystemBering Sea Ecosystem

Sergei RodionovSergei Rodionov11, James E. Overland, James E. Overland22, Nicholas A. , Nicholas A. BondBond11

11JISAO, University of Washington, Seattle, WA.JISAO, University of Washington, Seattle, WA.

22PMEL, NOAA, Seattle, WA.PMEL, NOAA, Seattle, WA.

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1900 1905 1910 1915 1920 1925 19301910

5% significance level

0

0.1

0.2

0.3

0.4

0.5

0.6

RSI

1910

The SARS Method

January PDO

Searching for the first regime shift

SARS – Sequential Analysis of Regime ShiftsRSI – Regime Shift Index

l = 10

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

1900 1905 1910 1915 1920 1925 1930

5% significance level0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

RSI1910

1912

1914

1922

Searching for the next regime shift

January PDO

l = 10

-3

-2

-1

0

1

2

3

std

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 20000

0.2

0.4

0.6

0.8

l = 10

0.05p = 0.1

The North Pacific Index (Nov-Mar)1899-2003

RSI

1924

1948

1977

1924

1948

1977

19581989

2003

-3

-2

-1

0

1

2

3

1951 1956 1961 1966 1971 1976 1981 1986 1991 1996 2001

p = 0.05

l =

Arctic Oscillation, 1951-2003

1075

1989

1994

1996

1972

1977

www.Beringclimate.noaa.gov

0

0.05

0.1

0.15

0.2

0.25

0.3

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

RSI

1943

1934 1989

1998

1976

1977

PDOaPDOwPDOs

PDOaPDOs

PDOaPDOs

PDOwALPINPINCAR

PNA

NPICPCNPINCAR

PDOwAO

EPI PDOsEPI

AI

NPICPC

Regime Shifts in Climatic Indices

p = 10l = 0.1

The 1989 Shift Winter (DJF) Surface Air Temperature

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

-4

-2

0

2

4

ST

Dl = 10p = 0.1

1989

Arctic Oscillation, Winter (DJF)

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

-3

-2

-1

0

1

2S

TD

1989

l = 10p = 0.1

Pacific Decadal Oscillation, Winter (DJF)

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

-3

-2

-1

0

1

2S

TD

The North Pacific Index, Winter (NDJFM)

l = 10p = 0.1

1989

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

-2

-1

0

1

2

ST

D

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

-2

-1

0

1

2S

TD

EPI

NPICPC

R = -0.26Data: 1950-2003

1990

1998

19901998

R = -0.70Data: 1980-2003

l = 10p = 0.1

East Pacific Index (AMJJ)

Correlations with SLP1950-2003

North Pacific Index (AMJJ)

Regime Shifts in Atmospheric Indices

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 20000

0.05

0.1

0.15

0.2

0.25

RS

I

l = 10p = 0.1

19291938 1997

19691959

1977

1989

SLPw

SATaSATa BSPI

BSPI

SATw

SATa

SLPw

OWSMIX

SATa – Annual surface air temperature, St. Paul.SATw – Winter surface air temperature, St. PaulSLPw – Winter SLP over the Bering SeaBSPI – Bering Sea pressure indexOWS – Optimal wind speed for larval feeding, Mooring 2MIX – Summer wind mixing, Mooring 2

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000996

1000

1004

1008

1012

1016

199819891977194719241911

Mean Winter (NDJFM) SLP over the Bering Sea

1915 1925 1935 1945 1955 1965 1975 1985 1995 2005-4

-2

0

2

4

19981989197719471924 1940

Mean Winter (DJFM) SAT at St. Paul

1950 1960 1970 1980 1990 20000

0.04

0.08

0.12

0.16

0.2

RS

I

Regime Shifts in Oceanic Indices

1965

19771983

2000SSTPrib

SSTPrib

SSTM2

ICI

SSTPrib

IRI

SATPrib – Winter SST near the Pribilof IslandsSATM2 – Winter SST at Mooring 2ICI – Ice Cover IndexIRI – Ice Retreat Index

l = 10p = 0.1

SSTM2

1988

-3

-2

-1

0

1

2

Std

1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

256

260

264

268

272

276

De

gre

es

Ke

lvin

1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Ice Cover Index and Surface Temperature at Mooring 2

ICI

Temperature

l = 10p = 0.1

1978

19881977

1950 1960 1970 1980 1990 20000

0.04

0.08

0.12

0.16

RS

I

Regime Shifts in Biological Indices

l = 10p = 0.1

1977

1966

1981

1984

1992

-2

0

2

Std

1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

1955 1960 1965 1970 1975 1980 1985 1990 1995 20000

20

40

60

80

Bill

ion

s

0

2 0

4 0

6 0

8 0

Mill

ion

s

Time Series of Fish Stocks

Herringyear-classstrength

Pollockrecruitmentat age 1

Bristol Bay sockeye salmon runs

1977

1989

1979

1997

1978 1989

1985 2001

l = 10p = 0.1

l = 5p = 0.1

l = 10p = 0.1

ConclusionsConclusions

• Characteristics of the SARS method:Characteristics of the SARS method:– Automatic detection of regime shifts,Automatic detection of regime shifts,– Improved performance at the ends of time series,Improved performance at the ends of time series,– Can be tuned up to detect regimes of different Can be tuned up to detect regimes of different

scales,scales,– Can handle the incoming data regardless of Can handle the incoming data regardless of

whether they are presented in the form of whether they are presented in the form of anomalies or absolute values,anomalies or absolute values,

– Works well with the time series containing a trend,Works well with the time series containing a trend,– Can be applied to a large set of variables.Can be applied to a large set of variables.

Conclusions (continued)Conclusions (continued)• An application of SARS to the Bering Sea An application of SARS to the Bering Sea

ecosystem demonstrated thatecosystem demonstrated that– The shift of 1977 was the strongest one in the The shift of 1977 was the strongest one in the

last 50 years;last 50 years;– A number of indices experienced a regime shift A number of indices experienced a regime shift

around 1989 (AO, PDOaround 1989 (AO, PDOww, temperature at Mooring , temperature at Mooring 2, herring), 1998 (PDO2, herring), 1998 (PDOss, salmon), or both (NPI, salmon), or both (NPICPCCPC, , EPI, winter SLP, flathead sole);EPI, winter SLP, flathead sole);

– The regime of 1989-1997 was characterized by a The regime of 1989-1997 was characterized by a relative winter cooling and reduced cyclonic relative winter cooling and reduced cyclonic activity;activity;

– Regime shifts in biological indices are not Regime shifts in biological indices are not concentrated around certain, dominant years. concentrated around certain, dominant years. The RSI values are rather evenly distributed The RSI values are rather evenly distributed between 1977 and 1992.between 1977 and 1992.