Manfred Stein - Academia.edu (original) (raw)
Papers by Manfred Stein
Warmes Wasser und Eisschmelze bei Grönland
Antarctic environment - physical oceanography: the Antarctic Peninsula and Southwest Atlantic region of the Southern Ocean
Journal of Northwest Atlantic Fishery Science, Mar 17, 2010
This paper examines the variability in the hydrographic conditions in the waters off West Greenla... more This paper examines the variability in the hydrographic conditions in the waters off West Greenland with a focus on the influence of the Polar Water off East Greenland and its associated sea ice or "Storis". During the mid-1970s, mid-1980s and early-1990s, maxima of Polar Water were observed in the upper water layers off Fyllas Bank, West Greenland. At a station located on the offshore bank slope in about 900 m of water, the upper 75 m of the water column are primarily influenced by the Polar Water and the "Storis". There, monthly mean temperatures are maximum and salinities a minimum during August-September. In years of larger than usual amounts of "Storis", cold diluted surface waters appear along the west coast of Greenland. Observations of sea surface temperature anomalies off Fyllas Bank during July indicate strong warming from 1989 to 2008, going from what appears to be the coldest year to close to the warmest. Warm anomalies were actually re-established in 1996. Warmer-than-normal sub-surface conditions peaked in 2003, a year with no "Storis". From 2002 onwards, a phenomenon is observed which seems to indicate a new structure in the distribution of SST anomalies: a band of colder-than-normal waters on the shelves off East and West Greenland. It is assumed that the continuous warming has led to massive sea ice melt off East Greenland, and the ice drifts with the East Greenland Current along the shelves off East and West Greenland, strongly influencing the temperature and salinity characteristics of the surface waters.
Journal of Northwest Atlantic Fishery Science, Oct 28, 2005
Sea-surface temperature anomalies in the North Atlantic Subpolar Gyre indicate cold conditions in... more Sea-surface temperature anomalies in the North Atlantic Subpolar Gyre indicate cold conditions in the 1980s and warming from the mid-1990s onwards, with maximum temperatures observed during October 2003. The latter is consistent with air temperatures at Nuuk, Greenland, which document that 2003 was the warmest year since 1950. Ocean temperatures off West Greenland show a significant upward trend (0.096°C y-1 in 0-300 m layer during 1983-2004), which is considerably higher than that for the North Atlantic Basin over the period 1955-2003. Long-term (1964-2004) observations from Fyllas Bank off West Greenland also reveal warm conditions during the 1960s, although the highest temperatures on record are from the recent years of the present century. Geostrophic transports estimated from autumn 2004 hydrographic data suggest increased northward transport of the West Greenland Current. Ocean properties at this time were more saline and up to 2°C warmer-than-normal. Volume transports were + 2.4 Sv in the core of the West Greenland Current, + 0.5 Sv on the West Greenland shelf, and-1.9 Sv in the Baffin Island Current. While the northward (+) transport figures are in the range of the mean October and November transport values (+ 1.6 Sv to + 3.0 Sv), the southward (-) transport figure is considerably smaller than earlier published values (-3.1 Sv to-4.6 Sv).
Journal of Northwest Atlantic Fishery Science, Sep 1, 1989
The observations and changes in the hydrographic parameters temperature, salinity and oxygen duri... more The observations and changes in the hydrographic parameters temperature, salinity and oxygen during the 1980s off West Greenland are described and discussed in the light of a climatic cooling, which occupied the Davis Strait area during the period 1982-84. The analysis which includes time-series data from 1963 has revealed great negative anomalies in the temperaturesalinity characteristic due to the atmospheric influence, which has led to changes in the circulation pattern as well as the sea ice distribution in the Davis Strait.
[Fish biological and oceanographic studies during two voyages on the exploratory boat "Anton Dohrn" 1980 and 1981 towards the western Barents Sea and to the Spitzbergen islands]
Recent climatic models are considered in terms of their accuracy, errors and assumptions. Matched... more Recent climatic models are considered in terms of their accuracy, errors and assumptions. Matched with observed trends in the world oceans and atmosphere, a latitude dependent global warming is predicted with strong warming trends in the northern latitudes. Models project global sea level rises and reduced ocean circulation in the North Atlantic Ocean. The CO2 transport at the ocean-atmosphere interface, the stability of ocean strata and potential storm activities are discussed in relation 'to the possible consequences to the fisheries in the North Atlantic.
Based on recent studies which highlight the dominating influence of the North Atlantic Oscillatio... more Based on recent studies which highlight the dominating influence of the North Atlantic Oscillation (NAO) on climatic changes in the North Atlantic Ocean, and their potential influences on biotic processes in the ocean, the paper analyses existing time series of recruitment of cod (Gadus morhua) off Greenland, air temperatures of Nuuk/West Greenland, subsurface ocean temperature on Fylla Bank, and the winter (December to February) NAO Index. As a first objective the paper outlines a causal nexus from NAO to recruitment of cod. It is shown how the increasing complexity of the system when moving from the NAO Index to the water temperature and recruitment through the air temperatures might complicate the existence of a direct relationship between the first and the last step of the system, which leads to a decreasing correlation from the top (NAO index) to the bottom (recruitment). The second objective of the paper is to reveal by means of the example of Greenland cod recruitment, Water temperatures in June on Fylla Rank, air temperatures at West Greenland, and the winter NAG index that a causal nexus can explain how Environmental Variability Effects (EVE) act on marine fisheries. Future fisheries management considerations should realise that the. EVE aspect has to be incorporated in models and management decisions.
Journal of Northwest Atlantic Fishery Science, Dec 1, 2001
Statistical methods were used to describe and forecast monthly mean air and bottom water temperat... more Statistical methods were used to describe and forecast monthly mean air and bottom water temperatures from 3 sites in the Northwest Atlantic region, up to one year in advance. ARIMA (Auto-Regressive-Integrated-Moving-Average) models were developed that accounted for 92% of the total variability in the long-term time series of monthly means of air temperature and 80% for bottom water temperatures. These models were then used to forecast conditions in 1999, with results showing good agreement between the predicted and observed values of both air and bottom water temperatures. Intervention analysis that models events as step-like features was also carried out. While this provided a better model fit to the observed data series, such events can not be predicted. Since nearly all fitted interventions appeared during winter (DecemberMarch), prediction of temperatures during these months must be viewed with caution. Results showed that the use of ARIMA models yields better forecasts for highly variable time series than simple models based upon averages of previous monthly averages alone.
Lowest cod fish stock in front of Western Greenland since 1982
Informationen fuer die Fischwirtschaft (Germany), 1992
[Lowest cod fish stock in front of Western Greenland since 1982]. [German]
Hydrography, Krill and Fish and Their Possible Relationships Around Elephant Island
Antarctic Ocean and Resources Variability, 1988
Krill, fish, and hydrological conditions around Elephant Island were studied with a station grid ... more Krill, fish, and hydrological conditions around Elephant Island were studied with a station grid program (Elephant Island box) between the 1975/76 and 1985/86 seasons on an almost annual basis. During the nine times of observation krill distribution and abundance was assessed by standard hauls with the RMT 1+8- nets, that of fish by commercial-sized bottom trawsl, both supplemented by vertical CTD profiles. The area north of Elephant Island was found to be characterized by the confluence of Scotia Sea and Weddell Sea waters. The dynamic topography elucidated the nature of a stationary meander in the vicinity of Elephant Island. Krill and fish abundances were related to the different water masses. Median krill abundances varied between 15 individuals/1000 m3 in November 1983 as a maximum to x = 0 in May 1986, showing the normal seasonal cycle but no clear interannual trend within this time series, pointing to a more stable situation than around South Georgia. Also krill distribution appeared in a persistent spatial pattern along seasons and years. Total fish biomass was found to be generally higher (up to more than 100 times) in krill-rich areas than in krill-poor areas. Analysis is aggravated by the observed remarkable changes in biomass and population structure of the most dominant fish species between 1977/78 and 1980/81 due to heavy fishing activities.
Journal of Northwest Atlantic Fishery Science, 2004
Based on climatological data on air temperatures, sea ice cover, as well as on subsurface oceanog... more Based on climatological data on air temperatures, sea ice cover, as well as on subsurface oceanographic time series and historic data from World Ocean Data Centre A (WDC-A), this paper analyses the climatic conditions off West Greenland during the decade of the 1990s and compares them with previous decades. The 1990s was a decade of extremes. The North Atlantic Oscillation (NAO) index flipped from one of its most positive values in winter 1995 to one of its most negative the following winter and reached a high level again during the last winter of the decade. Air temperatures at Nuuk tended to follow these extremes, e.g. during the high NAO Index in the early-1990s, there were very cold air temperatures at West Greenland. Approximately 50% of the variance in winter temperatures at Nuuk can be explained by air pressure changes over the North Atlantic. Nuuk air temperatures are shown to be representative of the climatic variability over the west coast of West Greenland from Cape Farewell in the south to Egedesminde in the Disko Bight area. There is significant correlation between the area-weighted mean bottom water temperature index for the German groundfish survey area off East and West Greenland and the autumn time series data from Fyllas Bank station 4 for the corresponding depth layers 0-200 m and 200-400 m. Accordingly, the subsurface oceanic variability measured at this slope station can be used as proxy for subsurface ocean variability off West Greenland. Surface layer cooling during the early-1990s was accompanied by decreasing salinities in the upper 400 m at the slope of Fyllas Bank, perhaps due to the heavy sea-ice conditions during 1992-93. There is evidence of low surface salinities (<33.0) during summer and autumn at Fyllas Bank station 4. These low salinities are not found during spring. This low saline water during summer and autumn off West Greenland is possibly derived from the Arctic freshwater supply that passes along East Greenland. The presence of Irminger Water (4°C < θ <6°C, 34.95 <S <35.1) at the slope off Fyllas Bank is mapped using WDC-A data from 1946 to 1999. It is shown that this water mass, mostly found at depths between 400 and 800 m, arrives in pulses and was present during several years in the second half of the 20 th century. There were, however, major periods (1955-62 and 1973-81) when Irminger Water was not observed at Fyllas Bank station 4.
Memoirs of National Institute of Polar Research. Special issue, 1983
Zur Veränderlichkeit des Ausstromes aus der Grönlandsee durch die Dänemarkstraße
Krill and hydrographic conditions off the Antarctic Peninsula
Meeresforschung; 25; 1-22; ISSN 0341-6836, 1978
Der Kabeljau und das Klima – Das grönländische Beispiel
Physical oceanography during Walther Herwig III cruise WH211
Water temperature profiles from 67 XBT drops along the track of POLARSTERN cruise ANT-III/2
Warmes Wasser und Eisschmelze bei Grönland
Antarctic environment - physical oceanography: the Antarctic Peninsula and Southwest Atlantic region of the Southern Ocean
Journal of Northwest Atlantic Fishery Science, Mar 17, 2010
This paper examines the variability in the hydrographic conditions in the waters off West Greenla... more This paper examines the variability in the hydrographic conditions in the waters off West Greenland with a focus on the influence of the Polar Water off East Greenland and its associated sea ice or "Storis". During the mid-1970s, mid-1980s and early-1990s, maxima of Polar Water were observed in the upper water layers off Fyllas Bank, West Greenland. At a station located on the offshore bank slope in about 900 m of water, the upper 75 m of the water column are primarily influenced by the Polar Water and the "Storis". There, monthly mean temperatures are maximum and salinities a minimum during August-September. In years of larger than usual amounts of "Storis", cold diluted surface waters appear along the west coast of Greenland. Observations of sea surface temperature anomalies off Fyllas Bank during July indicate strong warming from 1989 to 2008, going from what appears to be the coldest year to close to the warmest. Warm anomalies were actually re-established in 1996. Warmer-than-normal sub-surface conditions peaked in 2003, a year with no "Storis". From 2002 onwards, a phenomenon is observed which seems to indicate a new structure in the distribution of SST anomalies: a band of colder-than-normal waters on the shelves off East and West Greenland. It is assumed that the continuous warming has led to massive sea ice melt off East Greenland, and the ice drifts with the East Greenland Current along the shelves off East and West Greenland, strongly influencing the temperature and salinity characteristics of the surface waters.
Journal of Northwest Atlantic Fishery Science, Oct 28, 2005
Sea-surface temperature anomalies in the North Atlantic Subpolar Gyre indicate cold conditions in... more Sea-surface temperature anomalies in the North Atlantic Subpolar Gyre indicate cold conditions in the 1980s and warming from the mid-1990s onwards, with maximum temperatures observed during October 2003. The latter is consistent with air temperatures at Nuuk, Greenland, which document that 2003 was the warmest year since 1950. Ocean temperatures off West Greenland show a significant upward trend (0.096°C y-1 in 0-300 m layer during 1983-2004), which is considerably higher than that for the North Atlantic Basin over the period 1955-2003. Long-term (1964-2004) observations from Fyllas Bank off West Greenland also reveal warm conditions during the 1960s, although the highest temperatures on record are from the recent years of the present century. Geostrophic transports estimated from autumn 2004 hydrographic data suggest increased northward transport of the West Greenland Current. Ocean properties at this time were more saline and up to 2°C warmer-than-normal. Volume transports were + 2.4 Sv in the core of the West Greenland Current, + 0.5 Sv on the West Greenland shelf, and-1.9 Sv in the Baffin Island Current. While the northward (+) transport figures are in the range of the mean October and November transport values (+ 1.6 Sv to + 3.0 Sv), the southward (-) transport figure is considerably smaller than earlier published values (-3.1 Sv to-4.6 Sv).
Journal of Northwest Atlantic Fishery Science, Sep 1, 1989
The observations and changes in the hydrographic parameters temperature, salinity and oxygen duri... more The observations and changes in the hydrographic parameters temperature, salinity and oxygen during the 1980s off West Greenland are described and discussed in the light of a climatic cooling, which occupied the Davis Strait area during the period 1982-84. The analysis which includes time-series data from 1963 has revealed great negative anomalies in the temperaturesalinity characteristic due to the atmospheric influence, which has led to changes in the circulation pattern as well as the sea ice distribution in the Davis Strait.
[Fish biological and oceanographic studies during two voyages on the exploratory boat "Anton Dohrn" 1980 and 1981 towards the western Barents Sea and to the Spitzbergen islands]
Recent climatic models are considered in terms of their accuracy, errors and assumptions. Matched... more Recent climatic models are considered in terms of their accuracy, errors and assumptions. Matched with observed trends in the world oceans and atmosphere, a latitude dependent global warming is predicted with strong warming trends in the northern latitudes. Models project global sea level rises and reduced ocean circulation in the North Atlantic Ocean. The CO2 transport at the ocean-atmosphere interface, the stability of ocean strata and potential storm activities are discussed in relation 'to the possible consequences to the fisheries in the North Atlantic.
Based on recent studies which highlight the dominating influence of the North Atlantic Oscillatio... more Based on recent studies which highlight the dominating influence of the North Atlantic Oscillation (NAO) on climatic changes in the North Atlantic Ocean, and their potential influences on biotic processes in the ocean, the paper analyses existing time series of recruitment of cod (Gadus morhua) off Greenland, air temperatures of Nuuk/West Greenland, subsurface ocean temperature on Fylla Bank, and the winter (December to February) NAO Index. As a first objective the paper outlines a causal nexus from NAO to recruitment of cod. It is shown how the increasing complexity of the system when moving from the NAO Index to the water temperature and recruitment through the air temperatures might complicate the existence of a direct relationship between the first and the last step of the system, which leads to a decreasing correlation from the top (NAO index) to the bottom (recruitment). The second objective of the paper is to reveal by means of the example of Greenland cod recruitment, Water temperatures in June on Fylla Rank, air temperatures at West Greenland, and the winter NAG index that a causal nexus can explain how Environmental Variability Effects (EVE) act on marine fisheries. Future fisheries management considerations should realise that the. EVE aspect has to be incorporated in models and management decisions.
Journal of Northwest Atlantic Fishery Science, Dec 1, 2001
Statistical methods were used to describe and forecast monthly mean air and bottom water temperat... more Statistical methods were used to describe and forecast monthly mean air and bottom water temperatures from 3 sites in the Northwest Atlantic region, up to one year in advance. ARIMA (Auto-Regressive-Integrated-Moving-Average) models were developed that accounted for 92% of the total variability in the long-term time series of monthly means of air temperature and 80% for bottom water temperatures. These models were then used to forecast conditions in 1999, with results showing good agreement between the predicted and observed values of both air and bottom water temperatures. Intervention analysis that models events as step-like features was also carried out. While this provided a better model fit to the observed data series, such events can not be predicted. Since nearly all fitted interventions appeared during winter (DecemberMarch), prediction of temperatures during these months must be viewed with caution. Results showed that the use of ARIMA models yields better forecasts for highly variable time series than simple models based upon averages of previous monthly averages alone.
Lowest cod fish stock in front of Western Greenland since 1982
Informationen fuer die Fischwirtschaft (Germany), 1992
[Lowest cod fish stock in front of Western Greenland since 1982]. [German]
Hydrography, Krill and Fish and Their Possible Relationships Around Elephant Island
Antarctic Ocean and Resources Variability, 1988
Krill, fish, and hydrological conditions around Elephant Island were studied with a station grid ... more Krill, fish, and hydrological conditions around Elephant Island were studied with a station grid program (Elephant Island box) between the 1975/76 and 1985/86 seasons on an almost annual basis. During the nine times of observation krill distribution and abundance was assessed by standard hauls with the RMT 1+8- nets, that of fish by commercial-sized bottom trawsl, both supplemented by vertical CTD profiles. The area north of Elephant Island was found to be characterized by the confluence of Scotia Sea and Weddell Sea waters. The dynamic topography elucidated the nature of a stationary meander in the vicinity of Elephant Island. Krill and fish abundances were related to the different water masses. Median krill abundances varied between 15 individuals/1000 m3 in November 1983 as a maximum to x = 0 in May 1986, showing the normal seasonal cycle but no clear interannual trend within this time series, pointing to a more stable situation than around South Georgia. Also krill distribution appeared in a persistent spatial pattern along seasons and years. Total fish biomass was found to be generally higher (up to more than 100 times) in krill-rich areas than in krill-poor areas. Analysis is aggravated by the observed remarkable changes in biomass and population structure of the most dominant fish species between 1977/78 and 1980/81 due to heavy fishing activities.
Journal of Northwest Atlantic Fishery Science, 2004
Based on climatological data on air temperatures, sea ice cover, as well as on subsurface oceanog... more Based on climatological data on air temperatures, sea ice cover, as well as on subsurface oceanographic time series and historic data from World Ocean Data Centre A (WDC-A), this paper analyses the climatic conditions off West Greenland during the decade of the 1990s and compares them with previous decades. The 1990s was a decade of extremes. The North Atlantic Oscillation (NAO) index flipped from one of its most positive values in winter 1995 to one of its most negative the following winter and reached a high level again during the last winter of the decade. Air temperatures at Nuuk tended to follow these extremes, e.g. during the high NAO Index in the early-1990s, there were very cold air temperatures at West Greenland. Approximately 50% of the variance in winter temperatures at Nuuk can be explained by air pressure changes over the North Atlantic. Nuuk air temperatures are shown to be representative of the climatic variability over the west coast of West Greenland from Cape Farewell in the south to Egedesminde in the Disko Bight area. There is significant correlation between the area-weighted mean bottom water temperature index for the German groundfish survey area off East and West Greenland and the autumn time series data from Fyllas Bank station 4 for the corresponding depth layers 0-200 m and 200-400 m. Accordingly, the subsurface oceanic variability measured at this slope station can be used as proxy for subsurface ocean variability off West Greenland. Surface layer cooling during the early-1990s was accompanied by decreasing salinities in the upper 400 m at the slope of Fyllas Bank, perhaps due to the heavy sea-ice conditions during 1992-93. There is evidence of low surface salinities (<33.0) during summer and autumn at Fyllas Bank station 4. These low salinities are not found during spring. This low saline water during summer and autumn off West Greenland is possibly derived from the Arctic freshwater supply that passes along East Greenland. The presence of Irminger Water (4°C < θ <6°C, 34.95 <S <35.1) at the slope off Fyllas Bank is mapped using WDC-A data from 1946 to 1999. It is shown that this water mass, mostly found at depths between 400 and 800 m, arrives in pulses and was present during several years in the second half of the 20 th century. There were, however, major periods (1955-62 and 1973-81) when Irminger Water was not observed at Fyllas Bank station 4.
Memoirs of National Institute of Polar Research. Special issue, 1983
Zur Veränderlichkeit des Ausstromes aus der Grönlandsee durch die Dänemarkstraße
Krill and hydrographic conditions off the Antarctic Peninsula
Meeresforschung; 25; 1-22; ISSN 0341-6836, 1978
Der Kabeljau und das Klima – Das grönländische Beispiel
Physical oceanography during Walther Herwig III cruise WH211
Water temperature profiles from 67 XBT drops along the track of POLARSTERN cruise ANT-III/2