1. Changes in the NAO forcing in the North Atlantic during 2000-2009
ICES/NAFO Decadal Symposium
Santander, Spain
10-12 May, 2011
Changes in the NAO forcing in the North Atlantic during
K. Drinkwater, E. Colbourne, and H. Loeng

2. Outline Introduction to North Atlantic Oscillation
Temporal Variability in NAO Index
Decadal
Spatial Variability in SSP patterns
Effects on Composite Climate Index (SSTs, SSSs, Sea Ice)
NW Atlantic-Norwegian/Barents Sea
Conclusions

3. Phases of the NAO Positive Phase of NAO Negative Phase of NAO
deeper Low over Iceland, stronger High over the Azores
more northerly storm track
Colder, dryer in NW Atlantic
Warmer, wetter in Europe
Negative Phase of NAO
weaker Low over Iceland, weaker High over the Azores
weaker storms, move southerly
Warmer, wetter in NW Atlantic
Colder dryer in Europe

4. NAO linked to variability in SSTs, SSSs, subsurface SSTs, convection, strength of ocean currents, heat advection, etc.
C.G. Fletcher

5. A few Biological Correlates with NAO

6. NAO in

7. Hurrell NAO Index
Winter (DJFM) NAO index using difference of normalized sea level pressure (SLP) between Lisbon, Portugal and Stykkisholmur/Reykjavik, Iceland since The SLP anomalies at each station were normalized by division of each seasonal mean pressure by the long-term mean ( ) standard deviation.
Hurrell website

8. NAO Time Series – Decadal Variability
In postive index but declined from high in 1990s, still 4th highest decade on record; within decade variance 4th lowest out of 14.

9. Sea Level Pressure Anomalies (Relative to 1968-1996)
2001
2002
2000
2003
2004

10. Sea Level Pressure Anomalies (Relative to 1968-1996)
2005
2006
2007
2008
2009

11. 2000-09 Mean SLP and Anomalies
Sea Level Pressure
Sea Level Pressure Anomalies
There were weak SLP anomalies with the largest variability in the NE Atlantic. Little difference in NW.

13. NAO relationships with environmental variables

14. Positive SST anomalies throughout the North Atlantic.
In contrast, earlier decades tend to show out of phase between NW and NE Atlantic.

16. Normalized CLIMATE ANOMALIES
Torshavn AT
0.79
-0.53
-1.10
1.92
-0.16
-0.34
0.03
0.22
2.11
1.54
0.98
-0.72
-0.91
0.60
1.35
-2.04
-1.29
0.41
1.73
-1.48
2.30
0.65
1.89
1.26
Jan Mayen AT
-0.15
0.97
0.30
-0.60
1.20
0.19
1.76
0.64
-0.04
-0.37
-0.71
-1.05
-1.50
-1.72
-3.64
-2.51
-1.84
0.52
1.31
-0.94
0.86
0.07
-1.16
-0.49
-0.26
1.09
1.65
2.32
1.87
1.99
1.37
Bergen AT
0.25
0.05
-1.79
-0.22
-1.03
-1.19
-0.19
-0.66
0.99
0.33
0.59
-1.39
-0.97
-1.08
-1.59
-0.59
-1.24
-0.03
-0.68
1.22
0.56
-0.64
-0.61
-0.83
-2.37
-0.28
-1.41
0.62
0.47
-1.31
1.68
0.43
1.06
-0.41
-1.23
0.87
-0.30
1.29
1.64
1.53
1.25
0.89
2.46
Bodø AT
-0.77
-1.53
0.29
-2.90
-1.38
-0.47
0.74
0.14
-2.75
-0.17
-0.62
-0.32
-0.93
-1.99
0.44
-1.68
1.05
1.50
1.46
Nor Sea Air T ER40
-0.08
2.10
1.16
0.77
-1.28
-1.27
-0.12
-1.33
-0.57
2.20
-0.73
1.80
-0.58
0.42
-1.13
-1.37
-0.29
-1.56
-0.05
-1.11
-0.42
0.13
1.81
0.96
0.75
-0.21
-0.80
0.78
1.12
0.06
Bear Island AT
-0.20
0.48
1.00
0.40
-0.11
-2.08
-2.50
-1.74
-3.19
1.85
0.91
-0.88
-0.63
1.51
1.34
-0.54
-0.46
2.45
BSW AT ER40
-1.14
0.76
0.35
0.61
-1.42
-1.01
-2.03
-0.09
-3.21
-0.55
1.57
-1.98
-0.81
-1.52
-0.13
-1.35
1.79
0.94
0.70
0.39
-0.39
1.30
0.66
BSN AT ER40
-1.45
0.38
-2.18
0.84
-0.87
-3.59
-0.65
-1.22
0.08
0.92
-0.40
1.13
-0.79
1.33
-0.99
-1.20
2.28
0.21
-2.02
0.12
1.59
0.32
0.36
-0.18
0.34
0.82
0.24
-0.45
1.75
2.13
BSE AT ER40
-1.60
-0.98
0.23
-2.13
0.37
-2.32
-2.26
0.11
0.17
0.93
0.16
-1.77
-1.96
-0.44
-0.56
1.49
-1.07
1.21
0.53
1.66
-2.15
2.06
Murmansk AT
-2.20
-0.33
0.27
-2.88
-2.47
0.63
1.03
-0.51
0.20
-1.51
0.00
2.00
0.80
-1.89
-0.14
1.28
Barents summer open water
1.41
-0.50
-0.48
-0.43
2.80
1.48
-1.25
-0.52
-0.31
-1.06
-0.10
1.86
2.99
-0.86
2.57
3.12
T Svinøy
-0.25
-0.07
-1.66
-0.92
-1.18
0.18
-1.26
0.69
0.02
1.32
1.52
0.73
1.45
T Gimsøy
-1.64
1.71
-0.27
-0.70
2.61
Nor Sea Soda T
3.06
3.15
0.04
1.10
0.10
0.09
1.11
-0.67
-0.82
-1.46
-0.06
-0.01
1.01
0.67
-0.85
3.65
3.41
FUGLØYA - BJØRNØYA T
-2.05
-1.94
-0.69
-1.34
-0.75
1.40
2.23
2.01
VARDØ-N T
-1.67
-1.17
1.15
-0.95
0.57
0.72
0.50
-1.04
-0.84
-0.76
0.83
1.04
2.03
2.59
2.66
Kola T
1.07
0.51
1.70
-0.78
-2.24
0.49
-1.85
-2.11
-1.83
1.27
-0.35
1.91
2.38
2.18
BSW Soda T
-1.12
-1.58
1.39
-1.88
-1.36
-0.24
-1.43
1.58
0.90
1.08
1.24
T Sørkapp
-1.82
-0.02
1.60
1.47
0.15
BSN Soda T
1.19
1.02
1.95
1.36
BSE Soda T
0.45
-1.70
0.55
0.01
1.62
S Svinøy
-2.57
0.28
0.26
-0.38
-1.00
0.46
S Gimsøy
-1.09
-2.72
0.54
1.96
2.54
Nor Sea Soda S
2.17
1.14
1.17
1.77
-1.32
0.81
1.67
FUGLØYA - BJØRNØYA S
-1.75
-2.65
-2.36
2.29
1.90
VARDØ-N S
-1.97
-2.58
-0.89
0.85
0.68
1.18
2.07
Kola S
2.26
1.56
-0.23
2.65
2.56
1.88
3.01
1.83
-1.81
1.63
2.04
BSW Soda S
-1.40
2.44
BSN Soda S
1.72
-0.74
0.31
1.44
0.88
BSE Soda S
0.71
2.15
-1.44
-0.96
Norway
INDEX
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
NUUK
0.80
0.51
1.09
0.43
0.57
1.32
0.18
0.98
1.48
0.72
1.60
0.59
1.41
0.64
1.61
1.17
-0.15
0.63
0.32
-0.37
-1.10
0.46
0.44
0.37
0.10
1.63
0.91
1.07
0.49
-0.93
-1.89
-2.20
1.77
0.41
0.27
0.73
-1.18
-0.54
-0.11
-1.47
-1.68
-0.47
0.03
0.77
0.42
0.61
0.06
0.82
1.33
0.56
1.91
1.10
1.67
1.26
1.04
W. GREENLAND ER40 AT
0.17
1.16
0.69
1.24
0.54
1.37
1.14
-0.31
0.84
0.36
-0.98
0.28
1.30
0.79
1.27
0.75
-1.91
-1.76
-1.07
-1.14
-0.84
0.12
-1.56
-1.16
-0.28
0.22
1.18
0.38
IQUALUIT
0.16
0.78
1.92
-0.03
-0.06
1.02
-0.04
-0.08
-0.36
0.48
1.25
1.06
0.21
0.34
-1.96
0.23
-0.52
-0.60
1.65
0.29
-0.55
-1.27
-0.81
1.64
-0.40
-0.43
-0.79
-0.91
-1.48
-1.54
0.01
1.00
0.58
0.53
1.05
1.31
1.40
1.98
LABRADOR SEA ER40 AT
0.60
0.87
0.83
1.43
1.52
0.08
0.95
0.76
0.26
-0.59
-1.90
0.39
0.02
0.45
1.21
-1.50
-1.69
-1.19
0.70
-0.72
-1.35
-0.45
-1.26
-1.11
-0.05
1.28
0.92
CARTWRIGHT
0.24
1.72
0.81
1.50
0.62
0.97
0.00
0.30
1.80
0.66
0.40
-2.32
0.71
-1.05
-0.51
1.19
-0.63
1.75
-1.01
-0.71
-0.19
-0.58
0.14
-0.16
-0.94
-1.30
-0.17
0.20
1.12
1.23
1.82
1.13
1.22
1.01
1.79
1.59
2.56
LABRADOR SHELF ER40 AT
1.20
-0.10
0.55
0.13
1.03
0.04
-2.46
-0.22
-0.21
0.86
1.74
-1.28
-0.73
0.15
-0.33
-1.33
-1.24
-1.12
0.52
1.44
1.35
1.45
NE NFLD SHELF ER40 AT
-0.96
0.07
1.73
0.93
-2.50
1.36
2.05
-0.35
-0.12
-0.23
-1.06
-1.71
1.47
2.26
ST JOHN'S
-0.42
1.88
0.74
-0.26
-0.18
-0.09
-0.74
-0.41
-1.31
0.33
-0.88
0.35
-0.82
1.53
0.68
-0.07
-1.02
-1.39
-0.69
2.51
1.55
0.88
1.11
2.19
GRAND BANKS ER40 AT
1.08
0.96
2.01
2.00
0.50
2.11
1.39
-0.29
0.67
0.31
2.22
-1.59
0.05
-1.38
-1.98
-1.34
-0.34
0.65
1.29
2.52
0.99
NL SEA ICE
2.16
0.47
-0.65
-1.61
-1.67
0.11
-1.36
-0.85
1.95
ICEBERGS
-0.25
0.94
-1.21
-0.13
-0.92
0.89
-0.87
-2.11
-0.44
-1.77
-1.45
ST. PIERRE BANK BT
-0.46
1.84
-1.99
-1.51
1.34
-0.75
-0.38
2.47
0.85
1.42
2.07
-1.42
-0.78
-1.78
-0.61
-0.53
-0.62
2.91
1.70
-0.70
S27 SURFACE T
-1.73
-0.14
-1.57
-0.20
-1.22
-1.08
-0.86
-0.80
-2.49
-1.40
-1.37
-0.39
1.81
1.15
3.22
S27 BOTTOM T
1.38
4.07
2.32
1.51
-0.56
-1.49
-0.76
-0.95
2.95
2.65
2.70
S27 AGERAGED T
0.90
2.83
0.09
2.73
1.90
1.68
-1.15
0.25
-1.04
3.27
FLEMISH CAP AVG T
1.76
3.10
1.66
-0.77
-0.32
-0.64
-1.58
-2.47
-0.67
2.41
2.60
FLEMISH CAP SURFACE T
0.19
-0.30
-1.65
-0.48
-2.17
-1.66
2.50
-0.66
1.57
2.29
FLEMISH CAP BOTTOM T
3.36
3.30
-0.01
-0.27
-0.89
-2.30
-2.59
1.78
2.28
FLEMISH CAP CIL
1.86
3.08
4.81
1.62
1.49
2.80
-1.44
-1.13
-0.83
2.72
GRAND BANKS SODA T
-1.55
-0.50
1.56
-0.24
-1.09
1.96
-1.80
-2.15
SEAL ISLAND AVG T
1.93
1.69
2.30
3.28
-1.74
-1.64
-1.32
BONAVISTA AVG T
-0.57
-1.94
-0.97
2.48
2.33
SEAL ISLAND CIL
-0.68
2.59
-2.01
1.46
BONAVISTA CIL
-0.02
-2.37
NE NFLD SHELF SODA T
2.03
-2.02
HAMILTON BANK SURFACE T
-3.72
-0.99
-2.63
-2.44
2.82
HAMILTON BANK BOTTOM T
-1.23
2.94
-1.29
1.71
2.25
LABRADOR SHELF SODA T
-2.24
-1.46
2.12
LABRADOR SEA SODA T
-1.17
-0.90
-1.25
-1.20
W. GREENLAND SODA T
2.08
1.85
2.64
S27 SURFACE S
-2.28
-1.85
-1.82
S27 AVERAGED S
-1.41
-1.72
FLEMISH CAP AVG S
2.39
-2.39
GRAND BANKS SODA S
2.38
-2.89
SEAL ISLAND AVG S
2.36
-2.14
3.33
-1.03
BONAVISTA AVG S
2.24
-1.79
2.61
2.49
NE NFLD SHELF SODA S
3.01
LABRADOR SHELF SODA S
1.54
-1.92
LABRADOR SEA SODA S
-2.54
1.58
1.83
2.34
W. GREENLAND SODA S
3.66
2.92
2.04
-3.34
-2.23
-2.53
3.41
Labrador

17. Drinkwater et al., accepted
Composite Climate Indices based on 40 time series of meteorological, sea-ice and oceanographic conditions
Prior to late 1990s out-of-phase relationship, but since then they have been in phase.
Due to changes in atmospheric pressure patterns, weakening of NAO forcing

18. 20-Year Running Mean of Correlation Coefficients of Composite Climate Indices for Labrador Sea and Norwegian/Barents Seas
Last Year of 20-yr time series
Through 2000s negative correlation between 2 regions declining rapidly as both regions warming.

19. Comparison of Composite Climate Indices

20. 20-year Running Mean of Correlation Coefficients of Composite Climate Indices with NAO
Last Year of 20-yr time series
NAO shows significant weakening of correlation with Labrador region although strengthening in NE Atlantic.

21. Conclusions
1. NAO winter anomalies generally positive in , 4th highest decadal anomaly on record (14 decades) but relatively low within decade variability.
2. Mean of the decade shows most of the SLP action in the Northeast Atlantic.
3. Temperatures (salinities and ice) show similarity on both sides of the Atlantic, opposite to usual NAO response.
4. NAO index show weakening correlations with NW Atlantic climate index suggesting weakening of NAO forcing during

22. Thank You for Your Attention!