201
2 The Physics of the Arctic and Subarctic
Oceans in a Changing Climate
Camila Campos
1
and Myriel Horn
1
1
Alfred Wegener Institute (AWI), Helmholtz Centre for
Polar and Marine Research, P.O. Box 120161, 27570
Bremerhaven, Germany
2.1 Call for Abstracts
The Arctic climate system has been drastically impacted by
the changing global climate. While summer sea ice reduced
dramatically/significantly, and the atmospheric warming is
amplified over the Arctic, changes in the ocean are less
obvious due to its higher inertia. However, Arctic and
Subarctic Oceans play a crucial role in modulating mid-latitude and polar climate. Thus, investigating the pathways and
timescales of oceanic and atmospheric dynamics is crucial to
understand major aspects of current climate change. We
invite presentations advancing our understanding of the relevance of Arctic and Subarctic Oceans.
2.2 Abstracts of Oral Presentations
2.2.1 Declining Convection in the North Atlantic
Initiated Through Warming Summers
Marilena Oltmanns
1*
, Johannes Karstensen
1
, Jürgen Fischer
1
1
GEOMAR Helmholtz Centre for Ocean Research Kiel,
Düsternbrooker Weg 20, 24105 Kiel, Germany
*corresponding author: moltmanns@geomar.de
Keywords: Atmosphere-ocean interactions, Subpolar
North Atlantic, Ocean circulation, Atmospheric dynamics,
Climate variability
A shutdown of ocean convection, triggered by
enhanced melting over Greenland, is regarded as potential tipping element in future climate and recent model
studies, reporting that rising meltwater fluxes from
Greenland are already pervading the North Atlantic, have
substantiated the emerging threat. Yet, from an observational viewpoint, the atmospheric forcing is deemed more
important than melting as explicit evidence for an
impending halt in convection is still lacking. Here we
show, based upon a comprehensive set of in situ hydrographic observations, that warm summers – associated
with salient fresh layers, capping the convective region,
increased sea surface temperatures and enhanced melting – evoke reinforcing atmospheric responses, including
heavier precipitation in fall and reduced ocean heat losses
throughout winter, which contribute to maintaining a
strong stratification and coactively shorten the period for
convection. Considering that the summer warming over
the last decades was accompanied by concurrent trends in
the identified feedbacks and is expected to proceed further, we anticipate that the critical threshold for a convective shutdown will be reached faster than estimates,
premised only on melt rates, suggest.
2.2.2 Upper Layer Circulation in the Nordic
Seas – Spatial Distribution Variability of Heat,
Freshwater and Potential Energy
Catherine Drinkorn
1,2*
, Görkan Björk
1
1
Department of Marine Sciences, University of
Gothenburg, Carl Skottsbergsgata 22B, 41319
Gothenburg, Sweden
2
Faculty of Geosciences, University of Bremen,
Klagenfurter Str. 2-4, 28359 Bremen, Germany
*corresponding author: gusdrica@student.gu.se
Keywords: Subarctic, Upper layer circulation, Climate
change, Hydrography, Variability
The Nordic and Subarctic Seas constitute a major region
for the exchange of warm and salty Atlantic water with cool
and fresher Arctic water masses. This modification of
Atlantic and Arctic water masses is the main driver for the
northern deep-water formation branch of the global overturning circulation and hence an important climatic factor. In
order to investigate its stability and robustness against climate warming, contemporary hydrographic data of great
spatial and temporal resolution needs to be persistently
examined and represented in an insightful manner. Therefore,
the aim of this project is to pursue a previous study by Björk
et al. (2001, Polar Res 20: 161–168), who illustrated the
upper layer circulation in the Nordic Seas inferred from spatial distribution of freshwater, heat and potential energy
based on data from numerous hydrographic stations until
1998. It will be investigated whether and to what extent seasonal and decadal cycles or trends occur in the whole picture
by adding hydrographic data from after 1998 to the previous
data set. Furthermore, correlation with known natural cycles,
trends or properties, e.g., the North Atlantic Oscillation
(NAO), Arctic sea ice extent or characteristic topography,
may lead to a better understanding of the possible variability
properties and their causes.
2.2.3 Fram Strait Recirculation and the East
Greenland Current
Maren Richter
1,2*
, Wilken-Jon von Appen
1
1
Alfred-Wegener-Institut, Helmholtz-Zentrum für Polarund Meeresforschung, Am Handelshafen 12, 27570
Bremerhaven, Germany
2
Universität Bremen, Bibliothekstraße 1, 28359 Bremen,
Germany
*corresponding author: mrichter@awi.de
Appendices
2 The Physics of the Arctic and Subarctic
Oceans in a Changing Climate
Camila Campos
1
and Myriel Horn
1
1
Alfred Wegener Institute (AWI), Helmholtz Centre for
Polar and Marine Research, P.O. Box 120161, 27570
Bremerhaven, Germany
2.1 Call for Abstracts
The Arctic climate system has been drastically impacted by
the changing global climate. While summer sea ice reduced
dramatically/significantly, and the atmospheric warming is
amplified over the Arctic, changes in the ocean are less
obvious due to its higher inertia. However, Arctic and
Subarctic Oceans play a crucial role in modulating mid-latitude and polar climate. Thus, investigating the pathways and
timescales of oceanic and atmospheric dynamics is crucial to
understand major aspects of current climate change. We
invite presentations advancing our understanding of the relevance of Arctic and Subarctic Oceans.
2.2 Abstracts of Oral Presentations
2.2.1 Declining Convection in the North Atlantic
Initiated Through Warming Summers
Marilena Oltmanns
1*
, Johannes Karstensen
1
, Jürgen Fischer
1
1
GEOMAR Helmholtz Centre for Ocean Research Kiel,
Düsternbrooker Weg 20, 24105 Kiel, Germany
*corresponding author: moltmanns@geomar.de
Keywords: Atmosphere-ocean interactions, Subpolar
North Atlantic, Ocean circulation, Atmospheric dynamics,
Climate variability
A shutdown of ocean convection, triggered by
enhanced melting over Greenland, is regarded as potential tipping element in future climate and recent model
studies, reporting that rising meltwater fluxes from
Greenland are already pervading the North Atlantic, have
substantiated the emerging threat. Yet, from an observational viewpoint, the atmospheric forcing is deemed more
important than melting as explicit evidence for an
impending halt in convection is still lacking. Here we
show, based upon a comprehensive set of in situ hydrographic observations, that warm summers – associated
with salient fresh layers, capping the convective region,
increased sea surface temperatures and enhanced melting – evoke reinforcing atmospheric responses, including
heavier precipitation in fall and reduced ocean heat losses
throughout winter, which contribute to maintaining a
strong stratification and coactively shorten the period for
convection. Considering that the summer warming over
the last decades was accompanied by concurrent trends in
the identified feedbacks and is expected to proceed further, we anticipate that the critical threshold for a convective shutdown will be reached faster than estimates,
premised only on melt rates, suggest.
2.2.2 Upper Layer Circulation in the Nordic
Seas – Spatial Distribution Variability of Heat,
Freshwater and Potential Energy
Catherine Drinkorn
1,2*
, Görkan Björk
1
1
Department of Marine Sciences, University of
Gothenburg, Carl Skottsbergsgata 22B, 41319
Gothenburg, Sweden
2
Faculty of Geosciences, University of Bremen,
Klagenfurter Str. 2-4, 28359 Bremen, Germany
*corresponding author: gusdrica@student.gu.se
Keywords: Subarctic, Upper layer circulation, Climate
change, Hydrography, Variability
The Nordic and Subarctic Seas constitute a major region
for the exchange of warm and salty Atlantic water with cool
and fresher Arctic water masses. This modification of
Atlantic and Arctic water masses is the main driver for the
northern deep-water formation branch of the global overturning circulation and hence an important climatic factor. In
order to investigate its stability and robustness against climate warming, contemporary hydrographic data of great
spatial and temporal resolution needs to be persistently
examined and represented in an insightful manner. Therefore,
the aim of this project is to pursue a previous study by Björk
et al. (2001, Polar Res 20: 161–168), who illustrated the
upper layer circulation in the Nordic Seas inferred from spatial distribution of freshwater, heat and potential energy
based on data from numerous hydrographic stations until
1998. It will be investigated whether and to what extent seasonal and decadal cycles or trends occur in the whole picture
by adding hydrographic data from after 1998 to the previous
data set. Furthermore, correlation with known natural cycles,
trends or properties, e.g., the North Atlantic Oscillation
(NAO), Arctic sea ice extent or characteristic topography,
may lead to a better understanding of the possible variability
properties and their causes.
2.2.3 Fram Strait Recirculation and the East
Greenland Current
Maren Richter
1,2*
, Wilken-Jon von Appen
1
1
Alfred-Wegener-Institut, Helmholtz-Zentrum für Polarund Meeresforschung, Am Handelshafen 12, 27570
Bremerhaven, Germany
2
Universität Bremen, Bibliothekstraße 1, 28359 Bremen,
Germany
*corresponding author: mrichter@awi.de
Appendices