Latitude of the Gulf Stream and the Gulf Stream north wall index
Encyclopedia
The Gulf Stream
separates from the US coast near Cape Hatteras
(33oN, 75oW) and then travels eastwards across the North Atlantic, becoming the North Atlantic current
at about 55oW. In the region between 75oW and 55oW it is subject to meanders and is frequently accompanied by eddies. The northern edge of the current is marked by a sharp fall in temperature. This is also the case at much greater depths, so that the warm current is pressed up against a wall of cold water, called the ‘north wall’. Monthly charts of the path of the north wall of the Gulf Stream have been available from surface, aircraft and satellite observations since 1966 and these have been used in several studies of the path’s variability.
at six longitudes between 79oW and 65oW, a series of data that continues to the present day. There have been other subsequent studies. In 1994, Drinkwater et al. examined the latitude of the north wall from the 1970s to 1992 at each degree of longitude from 50 to 75oW, and Miller analysed the onshore/offshore position of the north wall at 10 cross-isobath transects equally spaced between 75 and 80oW from 1976 to 1988. Gangopadhyay et al. have derived a ten-year time series of the latitude of the separation of the Gulf Stream from the 1970s to the 1980s. By applying empirical orthogonal function analysis to temperatures at 200m, Joyce et al. in 2001 constructed a similar index to the GSNW index extending back to the 1950s.
The latitude of the north wall was read from each chart at each of the six longitudes: 79, 75, 72, 70, 67 and 65oW. Principal components analysis
was then used to find the pattern of variation common to the six longitudes. This is preferable to simple averaging of the six latitude estimates which would emphasise the eastern longitudes where the north-south movements are largest, and possibly obscure smaller but coherent north-south shifts further west. Correlation coefficients are calculated between the six time-series and the principal components are the eigenvectors of the resulting correlation matrix. (Empirical orthogonal function analysis proceeds instead from the variance-covariance matrix which again is biased to the eastern longitudes.)
Each principal component is calculated as a weighted average of the standardised latitude series using weightings that can be expressed as correlation coefficients between the components and the original series. The first principal component of the position of the north wall has positive correlation coefficients of about 0.5 with the latitude of the north wall at each of the six longitudes from 79oW to 65oW, respectively, and therefore represents displacements of this whole section of the Gulf Stream. Seasonal changes in the position are relatively small and so this principal component is virtually indistinguishable from that obtained if the annual cycle is removed beforehand.
Because each monthly chart gives the path of the current on one particular day, the monthly positions are strongly influenced by short period meandering of the Stream. Only annual values of the index which average out this variability can be meaningfully used to look at long-term changes.
The latitude of the north wall in any year, as described in the GSNW index, is a delayed response to atmospheric changes over the North Atlantic Ocean, and especially to the North Atlantic Oscillation
(NAO). Gangopadhyay ‘’et al’’. found that the point of separation of the Gulf Stream from the US coast was determined by the wind patterns across the ocean two or three years earlier, which they attributed to the passage of Rossby waves across the ocean. The GSNW index has been observed to follow the North Atlantic Oscillation with a lag of two years which is in agreement with (but Joyce ‘’et al’’. reported a shorter delay). Hameed and Piontkovski have shown the index seems to be most sensitive to the Iceland Low. Taylor and Gangopadhyay have used a simple model developed by Behringer, Regier and Stommel to predict the latitude of the Gulf Stream on the basis of the NAO (see Fig. 1). This model has also been tested using data from a coupled ocean-atmosphere model. The latitude of the Gulf Stream is also affected by the El Nino-Southern Oscillation
in the equatorial Pacific Ocean.
(Figure in preparation)
Fig. 1 Latitude at which the Gulf Stream leaves the US coast as predicted by the Behringer, Regier and Stommel model compared with observations over 40 years (The graphs are in standardised units).
Survey, now run by the Sir Alister Hardy Foundation for Ocean Science in Plymouth, UK, has monitored the plankton
in the surface waters of the North Sea and NE Atlantic for more than half a century. Over most of this time many of the zooplankton
in these regions have gone up and down in abundance as the Gulf Stream has shifted north or south, and, a relationship that has been seen most clearly in the abundance of copepods. The link with the current has also been reported in the zooplankton off the Northumberland coast of the UK studied by the Dove Marine Laboratory
of Newcastle University. Interactions between the individual constituents of the ecosystem appear to have been bringing out a signal weakly expressed throughout the meteorological variables. This process which has been reproduced using an ecosystem model
. Further afield, the GSNW index has been used to forecast temperatures in the Barents Sea
.
This effect has also been seen in non-marine ecosystems. The numbers Daphnia
in two lakes of the English Lake District, Windermere
and Esthwaite Water
, have observed to go down when the Gulf Stream is northward (and up when it is southward),. This is the reverse of the marine relationship, a difference that can be attributed the influence of the timing and intensity of thermal lake stratification
on the seasonal dynamics of the zooplankton. The relationship of thermal stratification to the GSNW index has been replicated in a model. Jennings and Allott have reported a positive relationship between winter nitrate concentrations in two lakes in SW Ireland and the latitudinal position of the Gulf Stream in the previous spring. The long-distance association with the position of the Gulf Stream has also been reported in a long-running series of observations of wild plants along a roadside in the English Cotswolds
.
1966 0.71 -1.52 -0.45 -1.25 -0.69 0.83 3.08 1.14 4.60 -0.16 0.62 0.92 0.65
1967 -0.88 -0.55 -1.48 -1.03 -1.09 -0.87 2.00 -0.59 -0.45 -1.02 2.46 1.14 -0.39
1968 -1.03 1.24 -0.41 -2.13 2.01 0.06 -1.74 -1.10 0.50 1.07 2.09 3.06 0.30
1969 0.94 0.52 1.29 -0.79 0.19 -1.03 -1.05 -2.49 -3.01 -0.33 -2.38 0.13 -0.69
1970 -2.07 -2.72 -1.73 -0.17 -0.02 1.79 -0.42 -2.33 -2.30 -1.24 -1.14 0.36 -1.06
1971 -0.94 -1.51 -1.76 -2.29 -1.28 0.01 -5.19 -3.14 -1.86 -1.79 -2.03 0.79 -1.88
1972 -0.14 -1.30 -0.33 -2.15 -2.15 -2.63 0.12 -1.85 -2.21 -2.90 -0.11 0.02 -1.31
1973 -2.16 -1.32 -1.31 -0.72 -3.33 -2.06 -2.13 -0.28 -0.28 -0.61 0.24 0.16 -1.18
1974 0.79 -3.00 -1.25 0.25 0.03 -0.69 -1.41 -1.27 0.46 -0.23 -1.03 0.16 -0.63
1975 0.22 -0.94 0.99 1.08 -1.24 -0.98 1.62 3.12 -0.45 -1.03 -2.47 0.13 0.00
1976 -0.38 -2.09 -4.31 -0.74 -0.21 0.37 -0.70 -1.01 -1.30 0.92 0.07 0.84 -0.71
1977 2.12 -0.40 1.79 0.92 -2.22 0.51 -0.78 -0.76 0.04 -0.26 -0.71 0.27 0.04
1978 0.04 -2.48 0.82 0.32 -2.61 -3.00 0.06 -1.42 -0.44 -0.21 -0.65 1.18 -0.89
1979 -3.40 -2.60 -2.64 -1.65 -1.48 0.38 -0.45 -1.92 -0.25 -1.99 -2.02 0.25 -1.52
1980 -0.63 0.86 1.41 -1.40 -0.48 -1.94 1.09 -2.56 0.80 1.87 -0.44 1.68 -0.26
1981 -1.93 0.40 -1.05 -2.68 -0.33 -0.73 0.22 -0.44 -0.04 2.52 -1.39 1.34 -0.57
1982 0.58 -1.77 -1.19 -2.75 -1.36 -1.42 -1.87 -0.37 -2.42 0.05 0.40 1.26 -1.12
1983 -0.52 -1.38 0.31 -0.67 -1.50 -1.15 -0.95 3.40 1.00 -0.41 0.72 1.25 0.01
1984 0.81 1.10 0.79 0.69 -0.42 -1.15 -2.36 3.03 -0.23 1.58 1.84 1.85 0.63
1985 1.45 0.63 -0.27 1.79 3.22 1.28 1.09 0.70 1.47 4.54 0.30 0.28 1.37
1986 2.82 -1.14 -1.64 -0.75 -0.95 0.63 -0.02 -1.81 -0.77 1.16 1.30 0.20 -0.08
1987 -2.36 -0.97 -2.73 -1.88 -0.63 -0.44 0.29 0.93 1.59 0.83 0.17 0.74 -0.49
1988 -1.37 1.56 0.21 -0.32 -0.99 -1.18 0.38 -0.22 1.98 0.59 0.40 0.08 0.09
1989 -1.04 0.17 0.65 1.14 1.35 0.80 -0.17 -1.64 -0.13 0.57 1.58 2.37 0.47
1990 1.95 1.31 0.39 0.75 0.40 -1.23 -0.30 1.12 0.98 0.83 1.13 0.90 0.69
1991 0.41 0.33 -0.23 0.38 1.63 2.18 1.54 1.77 2.83 2.31 0.99 1.52 1.31
1992 2.13 0.75 1.35 0.57 1.05 0.06 0.46 0.63 1.00 0.53 0.72 3.23 1.04
1993 -0.60 0.95 -2.49 -0.02 1.03 1.06 0.00 1.31 1.97 1.76 2.36 1.31 0.72
1994 2.54 2.10 1.90 1.09 0.65 2.24 1.19 0.81 0.24 0.28 -0.66 4.64 1.42
1995 4.87 2.93 1.60 0.92 0.75 2.37 1.79 2.94 2.69 2.61 2.32 0.04 2.15
1996 2.42 0.43 1.93 -0.41 -1.04 -1.17 -0.48 -1.13 0.54 -0.03 -0.85 1.94 -0.14
1997 -0.34 -0.50 -1.46 -0.37 0.64 -0.49 0.84 -0.55 -0.71 -0.48 -1.20 0.34 -0.36
1998 1.01 0.18 0.33 -3.33 -2.39 -0.81 -1.02 -0.84 0.58 0.29 -2.05 0.10 -0.68
1999 -0.27 -0.45 -0.74 -0.66 0.81 0.34 -1.99 -0.66 -0.86 1.92 0.65 0.52 -0.11
2000 -0.05 1.33 2.21 -0.01 0.30 0.91 1.26 0.93 2.19 2.84 2.95 2.29 1.43
2001 2.16 1.74 3.85 2.40 1.51 -0.07 0.80 1.09 1.15 -0.49 1.38 1.60 1.43
2002 0.09 0.77 0.36 0.04 0.17 -0.56 5.08 2.22 1.85 1.22 0.57 0.60 0.93
2003 1.02 0.08 2.15 0.18 -1.38 -1.26 1.14 -1.15 -0.40 -0.55 -0.32 0.62 0.01
2004 -1.66 -1.07 -1.27 -2.18 -1.32 -1.84 -1.68 -0.04 -1.44 0.84 0.12 1.26 -0.86
2005 0.83 0.32 -0.78 0.02 0.51 -2.03 -2.59 -0.95 0.31 0.68 0.06 0.17 -0.29
2006 -0.66 -0.54 1.78 -2.76 -0.80 -0.20 -0.37 0.31 1.32 3.82 2.31 1.97 0.52
2007 0.79 0.00 1.03 1.23 0.68 0.95 -0.69 0.29 0.67 0.49 0.37 0.51 0.44
2008 -0.66 2.63 0.97 -0.67 -2.82 -0.67 1.16 -1.04 -0.27 0.96 0.24 3.33 -0.29
2009 1.99 -0.45 -2.45 -0.68 -1.35 0.27 -0.14 0.81 1.38 0.82 0.67 0.53 0.12
2010 0.69 1.12 -1.17 -0.49 -2.22 0.49 0.68 0.79 -0.49 -1.09 -0.25 1.19 -0.26
Gulf Stream
The Gulf Stream, together with its northern extension towards Europe, the North Atlantic Drift, is a powerful, warm, and swift Atlantic ocean current that originates at the tip of Florida, and follows the eastern coastlines of the United States and Newfoundland before crossing the Atlantic Ocean...
separates from the US coast near Cape Hatteras
Cape Hatteras
Cape Hatteras is a cape on the coast of North Carolina. It is the point that protrudes the farthest to the southeast along the northeast-to-southwest line of the Atlantic coast of North America...
(33oN, 75oW) and then travels eastwards across the North Atlantic, becoming the North Atlantic current
North Atlantic Current
The North Atlantic Current is a powerful warm ocean current that continues the Gulf Stream northeast. West of Ireland it splits in two; one branch, the Canary Current, goes south, while the other continues north along the coast of northwestern Europe...
at about 55oW. In the region between 75oW and 55oW it is subject to meanders and is frequently accompanied by eddies. The northern edge of the current is marked by a sharp fall in temperature. This is also the case at much greater depths, so that the warm current is pressed up against a wall of cold water, called the ‘north wall’. Monthly charts of the path of the north wall of the Gulf Stream have been available from surface, aircraft and satellite observations since 1966 and these have been used in several studies of the path’s variability.
History
In 1980, Taylor and Stephens [2] constructed a measure of the latitude of the current, the Gulf Stream north wall (GSNW) index by extracting and analysing time-series of the latitudeLatitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
at six longitudes between 79oW and 65oW, a series of data that continues to the present day. There have been other subsequent studies. In 1994, Drinkwater et al. examined the latitude of the north wall from the 1970s to 1992 at each degree of longitude from 50 to 75oW, and Miller analysed the onshore/offshore position of the north wall at 10 cross-isobath transects equally spaced between 75 and 80oW from 1976 to 1988. Gangopadhyay et al. have derived a ten-year time series of the latitude of the separation of the Gulf Stream from the 1970s to the 1980s. By applying empirical orthogonal function analysis to temperatures at 200m, Joyce et al. in 2001 constructed a similar index to the GSNW index extending back to the 1950s.
Construction of the index
Monthly charts of the Gulf Stream have been published by the US Naval Oceanographic in ‘’Gulf Stream Monthly Summary’’ from 1966 to 1974, and by the US National Oceanic and Atmospheric Administration in ‘’Gulf Stream’’ from 1975 to 1980 and ‘’Oceanographic Monthly Summary’’ from 1981 until 1994. Later charts have been obtained from the US Navy. Each chart gives a snap-shot of the currents path at the end of the month. The monthly charts were analysed by the procedure described in,.The latitude of the north wall was read from each chart at each of the six longitudes: 79, 75, 72, 70, 67 and 65oW. Principal components analysis
Principal components analysis
Principal component analysis is a mathematical procedure that uses an orthogonal transformation to convert a set of observations of possibly correlated variables into a set of values of uncorrelated variables called principal components. The number of principal components is less than or equal to...
was then used to find the pattern of variation common to the six longitudes. This is preferable to simple averaging of the six latitude estimates which would emphasise the eastern longitudes where the north-south movements are largest, and possibly obscure smaller but coherent north-south shifts further west. Correlation coefficients are calculated between the six time-series and the principal components are the eigenvectors of the resulting correlation matrix. (Empirical orthogonal function analysis proceeds instead from the variance-covariance matrix which again is biased to the eastern longitudes.)
Each principal component is calculated as a weighted average of the standardised latitude series using weightings that can be expressed as correlation coefficients between the components and the original series. The first principal component of the position of the north wall has positive correlation coefficients of about 0.5 with the latitude of the north wall at each of the six longitudes from 79oW to 65oW, respectively, and therefore represents displacements of this whole section of the Gulf Stream. Seasonal changes in the position are relatively small and so this principal component is virtually indistinguishable from that obtained if the annual cycle is removed beforehand.
Because each monthly chart gives the path of the current on one particular day, the monthly positions are strongly influenced by short period meandering of the Stream. Only annual values of the index which average out this variability can be meaningfully used to look at long-term changes.
Interpretation of the index
Curry et al. have used the potential energy anomaly difference between the Labrador Sea and Bermuda as a measure of the transport of the Gulf Stream system. Curry and McCartney have pointed out their index correlates well with the latitude of the north wall. The GSNW index is therefore a measure of changes in the large-scale ocean currents.The latitude of the north wall in any year, as described in the GSNW index, is a delayed response to atmospheric changes over the North Atlantic Ocean, and especially to the North Atlantic Oscillation
North Atlantic oscillation
The North Atlantic oscillation is a climatic phenomenon in the North Atlantic Ocean of fluctuations in the difference of atmospheric pressure at sea level between the Icelandic low and the Azores high. Through east-west oscillation motions of the Icelandic low and the Azores high, it controls the...
(NAO). Gangopadhyay ‘’et al’’. found that the point of separation of the Gulf Stream from the US coast was determined by the wind patterns across the ocean two or three years earlier, which they attributed to the passage of Rossby waves across the ocean. The GSNW index has been observed to follow the North Atlantic Oscillation with a lag of two years which is in agreement with (but Joyce ‘’et al’’. reported a shorter delay). Hameed and Piontkovski have shown the index seems to be most sensitive to the Iceland Low. Taylor and Gangopadhyay have used a simple model developed by Behringer, Regier and Stommel to predict the latitude of the Gulf Stream on the basis of the NAO (see Fig. 1). This model has also been tested using data from a coupled ocean-atmosphere model. The latitude of the Gulf Stream is also affected by the El Nino-Southern Oscillation
El Niño-Southern Oscillation
El Niño/La Niña-Southern Oscillation, or ENSO, is a quasiperiodic climate pattern that occurs across the tropical Pacific Ocean roughly every five years...
in the equatorial Pacific Ocean.
(Figure in preparation)
Fig. 1 Latitude at which the Gulf Stream leaves the US coast as predicted by the Behringer, Regier and Stommel model compared with observations over 40 years (The graphs are in standardised units).
Teleconnections across the North Atlantic
The latitude of the north wall has been linked via the atmospheric circulation with a variety of changes at the other side of the North Atlantic Ocean [17], [19], [20], and. The Continuous Plankton RecorderContinuous Plankton Recorder
The Continuous Plankton Recorder survey is one of the longest running marine biological monitoring programmes in the world. Started in 1931 by Sir Alister Hardy, the CPR has provided marine scientists with their only measure of plankton communities on a pan-oceanic scale...
Survey, now run by the Sir Alister Hardy Foundation for Ocean Science in Plymouth, UK, has monitored the plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
in the surface waters of the North Sea and NE Atlantic for more than half a century. Over most of this time many of the zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
in these regions have gone up and down in abundance as the Gulf Stream has shifted north or south, and, a relationship that has been seen most clearly in the abundance of copepods. The link with the current has also been reported in the zooplankton off the Northumberland coast of the UK studied by the Dove Marine Laboratory
Dove Marine Laboratory
The Dove Marine Laboratory is a research and teaching laboratory which forms part of the School of Marine Science and Technology within Newcastle University in the United Kingdom.- History :The original Laboratory was established in October 1897...
of Newcastle University. Interactions between the individual constituents of the ecosystem appear to have been bringing out a signal weakly expressed throughout the meteorological variables. This process which has been reproduced using an ecosystem model
Ecosystem model
An ecosystem model is an abstract, usually mathematical, representation of an ecological system , which is studied to gain a deeper understanding of the real system.Ecosystem models are formed by combining known ecological relations An ecosystem model is an abstract, usually mathematical,...
. Further afield, the GSNW index has been used to forecast temperatures in the Barents Sea
Barents Sea
The Barents Sea is a marginal sea of the Arctic Ocean, located north of Norway and Russia. Known in the Middle Ages as the Murman Sea, the sea takes its current name from the Dutch navigator Willem Barents...
.
This effect has also been seen in non-marine ecosystems. The numbers Daphnia
Daphnia
Daphnia are small, planktonic crustaceans, between 0.2 and 5 mm in length. Daphnia are members of the order Cladocera, and are one of the several small aquatic crustaceans commonly called water fleas because of their saltatory swimming style...
in two lakes of the English Lake District, Windermere
Windermere
Windermere is the largest natural lake of England. It is also a name used in a number of places, including:-Australia:* Lake Windermere , a reservoir, Australian Capital Territory * Lake Windermere...
and Esthwaite Water
Esthwaite Water
Esthwaite Water is one of the smaller and lesser known lakes in the Lake District national park in northern England. It is situated between the much larger lakes of Windermere and Coniston Water, in the traditional county of Lancashire; since 1974 in the administrative county of Cumbria...
, have observed to go down when the Gulf Stream is northward (and up when it is southward),. This is the reverse of the marine relationship, a difference that can be attributed the influence of the timing and intensity of thermal lake stratification
Lake stratification
Lake stratification is the separation of lakes into three layers:# Epilimnion - top of the lake.# Metalimnion - middle layer that may change depth throughout the day.# Hypolimnion - the bottom layer....
on the seasonal dynamics of the zooplankton. The relationship of thermal stratification to the GSNW index has been replicated in a model. Jennings and Allott have reported a positive relationship between winter nitrate concentrations in two lakes in SW Ireland and the latitudinal position of the Gulf Stream in the previous spring. The long-distance association with the position of the Gulf Stream has also been reported in a long-running series of observations of wild plants along a roadside in the English Cotswolds
Cotswolds
The Cotswolds are a range of hills in west-central England, sometimes called the Heart of England, an area across and long. The area has been designated as the Cotswold Area of Outstanding Natural Beauty...
.
Table 1: GSNW index data
Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann1966 0.71 -1.52 -0.45 -1.25 -0.69 0.83 3.08 1.14 4.60 -0.16 0.62 0.92 0.65
1967 -0.88 -0.55 -1.48 -1.03 -1.09 -0.87 2.00 -0.59 -0.45 -1.02 2.46 1.14 -0.39
1968 -1.03 1.24 -0.41 -2.13 2.01 0.06 -1.74 -1.10 0.50 1.07 2.09 3.06 0.30
1969 0.94 0.52 1.29 -0.79 0.19 -1.03 -1.05 -2.49 -3.01 -0.33 -2.38 0.13 -0.69
1970 -2.07 -2.72 -1.73 -0.17 -0.02 1.79 -0.42 -2.33 -2.30 -1.24 -1.14 0.36 -1.06
1971 -0.94 -1.51 -1.76 -2.29 -1.28 0.01 -5.19 -3.14 -1.86 -1.79 -2.03 0.79 -1.88
1972 -0.14 -1.30 -0.33 -2.15 -2.15 -2.63 0.12 -1.85 -2.21 -2.90 -0.11 0.02 -1.31
1973 -2.16 -1.32 -1.31 -0.72 -3.33 -2.06 -2.13 -0.28 -0.28 -0.61 0.24 0.16 -1.18
1974 0.79 -3.00 -1.25 0.25 0.03 -0.69 -1.41 -1.27 0.46 -0.23 -1.03 0.16 -0.63
1975 0.22 -0.94 0.99 1.08 -1.24 -0.98 1.62 3.12 -0.45 -1.03 -2.47 0.13 0.00
1976 -0.38 -2.09 -4.31 -0.74 -0.21 0.37 -0.70 -1.01 -1.30 0.92 0.07 0.84 -0.71
1977 2.12 -0.40 1.79 0.92 -2.22 0.51 -0.78 -0.76 0.04 -0.26 -0.71 0.27 0.04
1978 0.04 -2.48 0.82 0.32 -2.61 -3.00 0.06 -1.42 -0.44 -0.21 -0.65 1.18 -0.89
1979 -3.40 -2.60 -2.64 -1.65 -1.48 0.38 -0.45 -1.92 -0.25 -1.99 -2.02 0.25 -1.52
1980 -0.63 0.86 1.41 -1.40 -0.48 -1.94 1.09 -2.56 0.80 1.87 -0.44 1.68 -0.26
1981 -1.93 0.40 -1.05 -2.68 -0.33 -0.73 0.22 -0.44 -0.04 2.52 -1.39 1.34 -0.57
1982 0.58 -1.77 -1.19 -2.75 -1.36 -1.42 -1.87 -0.37 -2.42 0.05 0.40 1.26 -1.12
1983 -0.52 -1.38 0.31 -0.67 -1.50 -1.15 -0.95 3.40 1.00 -0.41 0.72 1.25 0.01
1984 0.81 1.10 0.79 0.69 -0.42 -1.15 -2.36 3.03 -0.23 1.58 1.84 1.85 0.63
1985 1.45 0.63 -0.27 1.79 3.22 1.28 1.09 0.70 1.47 4.54 0.30 0.28 1.37
1986 2.82 -1.14 -1.64 -0.75 -0.95 0.63 -0.02 -1.81 -0.77 1.16 1.30 0.20 -0.08
1987 -2.36 -0.97 -2.73 -1.88 -0.63 -0.44 0.29 0.93 1.59 0.83 0.17 0.74 -0.49
1988 -1.37 1.56 0.21 -0.32 -0.99 -1.18 0.38 -0.22 1.98 0.59 0.40 0.08 0.09
1989 -1.04 0.17 0.65 1.14 1.35 0.80 -0.17 -1.64 -0.13 0.57 1.58 2.37 0.47
1990 1.95 1.31 0.39 0.75 0.40 -1.23 -0.30 1.12 0.98 0.83 1.13 0.90 0.69
1991 0.41 0.33 -0.23 0.38 1.63 2.18 1.54 1.77 2.83 2.31 0.99 1.52 1.31
1992 2.13 0.75 1.35 0.57 1.05 0.06 0.46 0.63 1.00 0.53 0.72 3.23 1.04
1993 -0.60 0.95 -2.49 -0.02 1.03 1.06 0.00 1.31 1.97 1.76 2.36 1.31 0.72
1994 2.54 2.10 1.90 1.09 0.65 2.24 1.19 0.81 0.24 0.28 -0.66 4.64 1.42
1995 4.87 2.93 1.60 0.92 0.75 2.37 1.79 2.94 2.69 2.61 2.32 0.04 2.15
1996 2.42 0.43 1.93 -0.41 -1.04 -1.17 -0.48 -1.13 0.54 -0.03 -0.85 1.94 -0.14
1997 -0.34 -0.50 -1.46 -0.37 0.64 -0.49 0.84 -0.55 -0.71 -0.48 -1.20 0.34 -0.36
1998 1.01 0.18 0.33 -3.33 -2.39 -0.81 -1.02 -0.84 0.58 0.29 -2.05 0.10 -0.68
1999 -0.27 -0.45 -0.74 -0.66 0.81 0.34 -1.99 -0.66 -0.86 1.92 0.65 0.52 -0.11
2000 -0.05 1.33 2.21 -0.01 0.30 0.91 1.26 0.93 2.19 2.84 2.95 2.29 1.43
2001 2.16 1.74 3.85 2.40 1.51 -0.07 0.80 1.09 1.15 -0.49 1.38 1.60 1.43
2002 0.09 0.77 0.36 0.04 0.17 -0.56 5.08 2.22 1.85 1.22 0.57 0.60 0.93
2003 1.02 0.08 2.15 0.18 -1.38 -1.26 1.14 -1.15 -0.40 -0.55 -0.32 0.62 0.01
2004 -1.66 -1.07 -1.27 -2.18 -1.32 -1.84 -1.68 -0.04 -1.44 0.84 0.12 1.26 -0.86
2005 0.83 0.32 -0.78 0.02 0.51 -2.03 -2.59 -0.95 0.31 0.68 0.06 0.17 -0.29
2006 -0.66 -0.54 1.78 -2.76 -0.80 -0.20 -0.37 0.31 1.32 3.82 2.31 1.97 0.52
2007 0.79 0.00 1.03 1.23 0.68 0.95 -0.69 0.29 0.67 0.49 0.37 0.51 0.44
2008 -0.66 2.63 0.97 -0.67 -2.82 -0.67 1.16 -1.04 -0.27 0.96 0.24 3.33 -0.29
2009 1.99 -0.45 -2.45 -0.68 -1.35 0.27 -0.14 0.81 1.38 0.82 0.67 0.53 0.12
2010 0.69 1.12 -1.17 -0.49 -2.22 0.49 0.68 0.79 -0.49 -1.09 -0.25 1.19 -0.26