http://sbi.utk.edu

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The Western Arctic Shelf-Basin Interactions (SBI)
Project-Highlights 2006

• SBI Arctic / global change project 2002-2004 map
• intensive field studies during the record summer
  sea ice retreat
• investigating production, transformation and
  fate of carbon at the shelf-slope interface in
  the northern Chukchi and Beaufort Seas
• downstream of the productive shallow western
  Arctic shelves
• prelude to understanding the impacts of a
  potential warming of the Arctic

http//sbi.utk.edu
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• Overview Statement
• Pacific Water entering through the Bering Strait
  Gateway and across shelf and northward into the
  Arctic Basin
• is the most productive region in the Arctic
• is undergoing the most significant environmental
  change (maximum ice retreat, potential ecosystem
  restructuring)
• critical physical, biogeochemical and biological
  fluxes interact in this region, with ramification
  to the global system
• the ice retreat and oceanic heat flux are
  unprecedented in the modern observational record
  being driven by both local and remote forcing
• biologically-mediated carbon-transformation
  processes are critical to the regional carbon
  cycling and ultimately, to both regional and
  global carbon flux dynamics

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Examples of linkages between Shelf Basin
Interactions and the Arctic System
Atmospheric Forcing
Land-hydrology-sea interface
Sea Ice Cover
Bering Strait Inflow
Shelf Carbon Cycle
Shelf-Basin Exchange
Carbon Storage
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Observed September sea ice extent 1979-2005
Significant and accelerated decrease in sea ice
extent in the late 1990s and 2000s. Note that
largest changes are at inflows of Pacific /
Atlantic water into the Arctic Ocean and during
SBI field programs.

• Rate of decline
• 1979-2001 6.5 per decade
• 1979-2005 8 per decade

96-05 trend 21 per decade?
09/87
09/05
09/02

• ARCSS relevant issues related to warming in the
  western Arctic Ocean
• ecosystem change, including whale migration /
  feeding habit change
• human aspects native community subsistence and
  culture
• increased human presence new transportation
  routes, natural resource exploration
• - potential global consequences of freshwater
  export from the Arctic Ocean

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Increased freshening of Pacific Inflow
Woodgate and Aagaard, GRL 2005

• moorings at Bering Strait
• decrease salinity and increase freshwater flux
• revised Bering Strait FW influx upwards from
  1989
• shelf-basin transport via advection, eddy
  formation, canyon transport

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Bering/Chukchi/Beaufort SeaMarginal Ice Zone
System
Fluxes of heat, salt, freshwater, nutrients
through Bering Strait and their seasonal and
inter-annual variability strongly influence the
Western Arctic ecosystem Woodgate et al. 2005
Clement et al. 2005
HV
WHS
EHS
BC
EB
Modeled Sea Surface (0-5 m) Salinity (ppt),
Velocity (cm/s) and Sea Ice Concentration ( -
red contours) - Mean August 1979-1981
courtesy W. Maslowski
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Increased Pacific water heat fluxes into the
Arctic Ocean

• Increased modeled northward heat flux off the
  Chukchi Shelf correlates with the recent ice
  retreat in the Western Arctic
• (cor. coef. 0.7-08)

Courtesy of W. Maslowski
- Heat content of surface waters above 50 m
depth sufficient to melt 0(10-100 cm) thickness
of sea ice - Studies (both field and modeling)
are needed to understand effects of Pacific Water
advection from Bering Strait into the Arctic
Ocean and its effect on the environment
SBI Hydrography Data Team (Codispoti, Swift et
al.)
Courtesy of W. Maslowski
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Sediment-laden Sea Ice
gt100,000 km2 of sediment-laden sea ice (5-8 x
106 t particulate export, highly significant for
shelf budget) Enhanced rafting due to changing
sea-ice regime Impact on ice primary production
and carbon flux?
Distribution of sediment-laden ice (fraction of
total ice area) (data at www.joss.ucar.edu/cgi-bi
n/catalog/sbi_hly-02-01/research/index)
Eicken et al. in 2005
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NCEP reanalysis forwestern Arctic
Atmospheric Linkages Which storms trigger
upwelling?

22 upwelling events between September 2002 and
May 2003!
No upwelling
Upwelling favorable
Diagnosing an upwelling event in the western
Arctic Cross-stream fluxes of mass and
properties R. Pickart et al.
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Primary production and optical findings in the
SBI region

• Barrow Canyon high productivity, reaching 8.8 g C
  m-2 d-1
• High particle export to slope, basin?
• System relevance High levels of colored
  dissolved organic material (CDOM) were observed
  which would increase energy absorption in the
  surface waters by 40 over clearest natural
  waters thus impacting on heating, albedo impact
  and positive feedback to further ice melt

Sea Area (103 km2) Depth (m) PP (gC/m2 yr)
Barents 1512 200 20-200
White 85 56 25
Kara 926 131 30-50
Laptev 498 48 25-40
East Siberian 987 58 25-40
Chukchi 620 80 20-400
Beaufort 178 124 30-70
Lincoln 64 257 20-40
Shelf N. Can. Arc. Archipelago 146 338 20-40
Shelf NE Greenland 30 119 20-40
Shelf NW Svalbard 6 93 20-40
Hill and Cota, 2005
E. Sakshaug 2004
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Organic markers can detail carbon sources to the
Arctic Basin

• Bioavailable DOM is rapidly produced in shelf
  waters during spring  and summer and some of
  this DOM is transported to the basin - Rates of
  utilization of DOM are relatively low in shelf
  waters - Terrigenous DOM is abundant in shelf
  and polar surface waters - Terrigenous DOM
  discharged to the Arctic Ocean by rivers has a 
  modern radiocarbon age

Harvey, Belicka and Macdonald
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Dissolved Organic Carbon (DOC) Cycling in the
Western Arctic
Annual fluxes Tg DOC
CO2
2.7
2.5
Canada Basin
7.3
6.0
1.3
56 Tg DOC
?
Terrestrial DOC
new Marine DOC

• DOC is being lost while circulating in the Arctic
  Ocean and/or
• fluxes of DOC from river sources are being
  underestimated
• DOC in the Arctic Ocean is probably not as
  refractory as previously thought,
• and sediments are a potentially important source
  of DOC to the Arctic Ocean

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Pelagic-benthic coupling SBI I and II results

• Sediment community oxygen consumption (mmol O2
  m-2 d-1) from 1984-2004
• an indicator of carbon supply to the underlying
  benthos, persistent patterns of carbon flux to
  sediments
• yet time series stations in hot spots (black
  box) indicate decline in carbon supply and
  benthic standing stock Grebmeier et al. 2006,
  Science

• Macrofaunal biomass (g C m-2) from 1977-2004
• identify foot prints of high carbon deposition
  and benthic biomass on the shallow continental
  shelves for time series investigations embedded
  in periodic process studies

Data maps from Grebmeier et al. 2006, Prog.
Oceanogr., accepted
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Zooplankton Grazing Impacts

• Zooplankton grazing impacts are primarily
  dependant on zooplankton biomass, which increases
  in summer but is still low compared to other
  Arctic shelf regions
• High primary production combined with low
  zooplankton grazing results in strong
  benthic-pelagic coupling that supports very high
  benthic biomass

Ashjian, Campbell, Plourde
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Large Horizontal Export of POM at BC
Barrow Canyon (BC) section

• Much of the productivity occurring in this region
  of the Chukchi Sea shelf was
• exported laterally, with plumes of suspended POM
  in the upper halocline observed off-shelf
  extending into the Arctic Ocean basin (Bates et
  al., 2005),
• or
• vertically exported to the sea floor (Moran et
  al., 2005).

UHW
LHW
LargePOC
LargePON
Bates et al., 2005a Moran et al. 2005
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SBI Special Issue One - 23 papers
Plan for SBI DSR 2nd volume-deadline fall 2006
(Eds. Grebmeier, Harvey and Stockwell)
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JOSS website statistics
SBI Datasets 228 (45)
Data Type Benthic 54
Hydrography 59 Ice
11 Meteorology 55
Microbiology 8 Mooring
3 Navigation 22 Optics
7 Plankton
10 Production 5 Satellite
23 Service Bottle 21
Service CTD 16 Underway
48 Water Chemistry 20
Cruise 2004 HLY-04-02 12
HLY-04-03 10 HLY-04-04 4
HX-290 1(U) 2003 HLY-03-03
3 NBP03-04a 12 HX-274
1(U) 2003-14 Helo 0 2002
HLY-02-03 65 AWS-02-I 7
HX-260 1(U) HLY-02-01
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Password Protected 9 Phase I 0 Phase
II 9 2002 Data 1 Loaded lt 1 yr 4
CTD/Bottle 7 Ship CD 2
Phase I 47 II 181
www.joss.ucar.edu/sbi
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SBI Phase III Planning Timeline

• Mar. 2005 SBI Phase II and Phase III planning
  presentation made to ARCSS Committee input
  requested (March 2006, Wash. DC)
• Oct. 2005 discussions with NSF and ARCSS
  Committee about SBI Phase III, letter sent to AC
• Nov. 2005 AC responds with support letter for
  SBI Phase III, plus guidance
• Dec. 6, 2005 AGU informal evening meeting SBI
  Phase III planning
• Dec. 19, 2005 SBI PI online meeting, discussions
  SBI II results Phase III planning
• Jan. 19, 2006 ARCSS Committee/SBI AC online
  meeting-Phase III planning
• Jan. 30, 2006 Open Community eTown Hall Meeting
  SBI update/Phase III
• Feb. 9, 2006 letter from AC to SBI AC/PIs
  outlining their guidance for a SBI Phase III
  direction within the new ARCSS format
• Feb. 22, 2006 Open Town Hall Meeting Phase III,
  Oceans Meeting, Honolulu, Hawaii
• Feb. 26-28, 2006 Final SBI Phase II PI meeting
• Mar. 6, 2006 SBI AC and ARCSS program managers
  at NSF
• Mar. 29, 2006 SBI AC presentation to AC on Phase
  III direction, Seattle, WA
• NSF AO ? Separate SBI Phase III or within larger
  ARCSS AO release planned summer 2006, proposal
  deadline fall 2006, funding 2007 during period of
  International Polar Year (IPY) 2007-2009

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ARCSS/SBI Phase IIIIntegration, Synthesis and
Modeling

• ARCTIC CARBON CYCLING AND
• SHELF-BASIN DYNAMICS

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Overarching Themes and Questions

• What are the important linkages between processes
  in the Western Arctic shelf-basin ecosystem(s)
  and the larger Arctic system? What are the
  ramifications for the global ocean and climate?
• How will the large and interconnected changes
  recently observed in the western Arctic margins
  propagate through natural and human systems in
  the Arctic and sub-Arctic? How do these recent
  changes compare to the past?
• 3. How does climate variability over multiple
  time scales influence the coupled physical,
  chemical, and biological processes over arctic
  shelf/basin systems? How do changes in these?

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Subthemes and Questions
1. Although the Western Arctic appears to play a
disproportionately large role in the dynamics of
pan-Arctic system, there is a growing need to
integrate and synthesize data and processes
linking climate forcing, element and heat fluxes
through the Bering Strait gateway, and shelf /
basin carbon cycling in the Western Arctic with
the broader Arctic system. Relevant studies might
include ? Determine the most significant and
critical changes to the Arctic system documented
in the modern data records ? Investigate forcing
connectivity by the atmosphere, land and ocean on
shelf-basin exchange through a range of spatial
and temporal scales ? Evaluate the impacts of
seasonal sea ice extent and its variability on
high productivity ecosystems, circulation, and
shelf-basin interactions, and ? Understand how
shelf-basin and inter-basin exchanges communicate
change over larger Arctic system scales. ? How
will the large and interconnected changes
observed on the western Arctic shelf and margin
affect and propagate through the larger Arctic
and subarctic natural and human environment and
how do they compare to past changes? ? How does
climate variability over decadal to millennial
scales influence oceanographic, biogeochemical,
and biological processes over arctic shelf/basin
systems, and how do these processes influence the
broader arctic system?
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Subthemes and Questions
2. There is a dynamic barrier at the continental
shelf /slope margin, resulting in sharp physical
and biological gradients. Understanding the
influence of the shelf break barrier on physical
and biological processes is crucial for
evaluating past system states and predicting
future change impacts. Relevant studies might
include ? What processes maintain the sharp
gradient between the most productive shelves
adjacent to the least productive basin in the
worlds ocean? ? How are shelf transformation
products (salt, nutrients, carbon, zooplankton)
fluxed across the shelfbreak into the
basin? ? What processes on this productive shelf
are critical for the tight benthic-pelagic
coupling, which supports an incredible biomass of
marine mammals that in turn are dependent upon by
Native populations for their subsistence and
cultural identity? ? How are these processes
similar/different to continental margins in other
arctic regions and/or continental margins in
other regions of the worlds oceans? ? How will
ongoing environmental changes modify the dynamic
barrier between the shelf and basin?
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Subthemes and Questions

• 3. Variation in ice cover and thickness, mediated
  by solar insolation and advected heat flux
  through Bering Strait, initiate a local to
  system-wide cascade of changes in arctic physical
  and biogeochemical processes that are influenced
  strongly by oceanographic and biological
  processes over western Arctic shelves. Predicted
  future Arctic system changes include reduced sea
  ice, increased freshwater fluxes, higher air and
  sea temperatures, longer growing seasons, and
  permafrost thaw. Consequences of such changes
  will impact food web structure, trophic
  efficiency, sediment mineralization/sediment
  oxidation state, benthic biomass, and carbon
  export and sequestration into the Arctic Basin.
  Relevant research topics might include
• ? How will the timing and extent of predicted
  future changes impact carbon cycling of the
  Arctic shelf system?
• ? How will the arctic system respond to ice
  retreat beyond the shelf break?
• ? What is the strength and variability of the
  linkages between important environmental controls
  of the arctic system (climate/physical
  oceanography) and ice cover, ocean biology and
  other elements of the arctic system (other
  dimensions)?
• ? How will these linkages change in the future?
• ? What are the consequences for the Arctic system
  (carbon, climate, human resource use)?
• How will increased natural resource exploitation
  in the region impact shelf and slope ecosystem
  dynamics?
• How will an increased flux of heat through Bering
  Strait influence clathrate erosion?

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Subthemes and Questions
4. Changing climate may alter the dynamics of
pelagic and benthic arctic systems, with possible
mode shifts in their structure and productivity.
Relevant studies might include ? How do changes
in carbon cycling and pelagic-benthic coupling in
the arctic system, driven by environmental
change, influence the structure of arctic food
webs and the population dynamics of important
producer and consumer groups? ? How will these
changes affect Native communities that depend on
the current ecosystem state for their subsistence
and cultural identity? ? How will future climate
warming affect the production and export of
carbon in arctic environments and the dynamics of
arctic biological communities? ? How will
bottom-up versus top-down controls of arctic
biological systems respond to changing arctic ice
and climatic conditions?
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Comments and suggestions?