A Cabled Observatory in Barrow, Alaska

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A Cabled Observatory in Barrow, Alaska in the
Context of SBI Results

Jackie M. Grebmeier
University of Tennessee Knoxville,
TN, USA Barrow, Alaska 8 February 2005
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The Western Arctic Shelf-Basin Interactions (SBI)
Project
Studies as part of the SBI global change project
are investigating the 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, as a prelude to understanding the
impacts of a potential warming of the Arctic
http//sbi.utk.edu
courtesy Leif Anderson
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2003
1979
Sea ice extent in the Arctic-past, current, and
future
2010-2030
2040-2060
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• ICARP II WG5 Arctic Margins and Gateway
• Draft Science Plan-Feb. 2005 (Paris, France)
• a. Background
• Arctic change reduction sea ice extent and
  thickness
• freshwater balance, est. increase precipitation
  and river runoff
• timing biological production, est. earlier
• cascading effects to higher trophics, change
  ecosystem dynamics
• b. Strategic Area of Interest
• continental margins transformation zone between
  shelf and deep basin regions and gateways for
  inflow/outflow of Pacific and Atlantic waters and
  freshwater (Bering, Fram, Canadian Archipelago,
  St. Anna Trough)
• boundary for cross shelf-basin exchange
• important ventilation deep basins via brine
  transport with POC/DIC/DOC
• upwelling warm, nutrient-rich Atlantic waters up
  slope
• margins area for boundary currents, large scale
  ocean circulation transport heat, salt,
  freshwater, biogeochemical properties and
  sediments around arctic ocean
• model past, present, future impacts Arctic
  ecosystems and global connections

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Figure and caption courtesy Eddy Carmack,
IOS/Canada

• Pacific Inflow Shelf/Gateway/Margin Complex
• focus shelves northern Bering and Chukchi seas
• gateways Bering, plus Anadyr Shpanberg
  straits
• shelf-basin exchange (on- and off-shore)
• canyon connectivity to Arctic Basin Herald
  Canyon, Barrow Canyon, Hanna Canyon
• interactions with East Siberian sea and Beaufort
  sea

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GATEWAYS
MARGINS
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ICARP2 WG5 version, modified Feb. 2005 from E.
Carmack
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Proposed Barrow Cabled Observatory
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Red spring 2002 process cruise Magenta summer
2002 process cruise Green summer 2003 survey
cruise
Joint Office for Science Support (JOSS) Products
for SBI see http//www.joss.ucar.edu/sbi/catalog/
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Seasonal cycle in the Arctic Ocean
JUNE
JULY
MAY
APRIL
AUG
Snow
Snow
SEPT
Ice algae
Sea ice
Sea ice
Zooplankton
Phytoplankton bloom
Grazing
Vertical flux
Wassman et al. 2004
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Ice algae important in spring vs water column
production in summer
Possible ice algal carbon contributes 10-25 of
the particulate organic carbon pool over the
seasonally ice-covered Arctic shelves during the
spring bloom important food for arctic cod
courtesy Gay Sheffield
Ice algae slower rates of decay compared to
temperate diatoms allows more labile
material to fuel benthic production in shelf
regions
courtesy Rolf Gradinger
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Integrated chlorophyll (mg/l), compiled over the
period 1975-1996
Dunton et al. in revision
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modified from L. Codispoti
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High sediment load in the ice, enough to affect
the melting of the ice as well as primary
production in the ice layers and the water
underneath. Very rough numbers (on the order of
10 million tons of terrigenous sediment entrained
in 2001/02) it appears that at least in some
years this can be quite significant.
Eicken
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Chukchi/Beaufort Slope waters Sediment,
chlorophyll, and nutrient-enriched Chukchi shelf
winter water
courtesy Tom Weingartner 2003
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BC
EHS
EHS
BC
Ammonium and silicate sections from East Hanna
Shoal (EHS) And Barrow Canyon (BC) in summer 2002
Codispoti et al.-SBI Hydro Team
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MODEL RESULTS
Phosphate (µM)
Nutrientrich waters lie off the shelf break
The continued retreat of the summer ice cover
exposes more and more of the shelf- break for
longer and longer periods of time to upwelling
favorable winds
From Carmack Chapman, GRL, 2003
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Sea surface temperature-SBI Study area, 23 August
2004
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East Barrow Line (HLY-04-03)
photo by Ev Sherr
Cooper et al.,Science, in prep
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Arctic, Subarctic and Bering Sea dominant
copepods All sketches drawn at same
magnification all scale bars represent 1mm
Arctic Ocean
Arctic Copepods Calanus hyperboreus C.
glacialis Metridia longa
Canada Basin
Chukchi Sea
Beaufort Sea
Shelf Copepods Pseudocalanus sp. Oithona sp.
Russia
Bering Sea Copepods Neocalanus cristatus
N. flemingeri Calanus marshallae
Alaska
Bering Sea Basin
courtesy Sharon Smith
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Vertical Section Along Barrow Canyon, Summer 2002
!?

• Intriguing elevation in particle concentration in
  cold water near shelf-break
• We need data at higher spatial resolution to
  adequately describe this feature

courtesy C. Ashjian
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POC Export Flux 2002 Results
Spring
Summer
Moran et al. in press
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Circulation Superimposed on the Distribution of
Benthic Biomass 1970-1990
Dunton, Schonberg, Maidment, and Grebmeier ,
submitted DSR 2004
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Faunal Benthic Biomass-Color Symbols Amphipod
(pink), Bivalve (brown), Foraminifera (red), Sand
dollar (green), Polychaete (yellow), Other (blue).
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Sediment oxygen uptake (carbon supply) spring vs.
summer 2002
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• NSF Workshop Seafloor Cabled Observatory on the
  Beaufort Shelf (Sue Moore,
  NOAA/UW)
• Integrated acoustic systems that include
  navigation, communication and acoustical
  oceanography
• Since 1999, NOAA has deployed a series of
  autonomous recorders offshore Alaska to (1)
  detect the calls of endangered whales over
  unprecedented spatial and temporal scales (2)
  identify components of anthropogenic noise and
  (3) record variability in ambient noise fields in
  marine mammal habitats
• Specifically, two recorders were successfully
  deployed northeast of Barrow, as part of the
  2003-04 NSF/Shelf Basin Interaction program, to
  detect calls from bowhead whales (Balaena
  mysticetus), walruses (Odobenus rosmarus),
  bearded seals (Erignathus barbatus) and ringed
  seals (Phoca hispida).
• Each of these species is important to the
  Alaskan Native community as sources of nutrition
  and cultural heritage. When considered in
  combination, these top predators can track how
  on-going climate change is affecting the Arctic
  ecosystem, a key objective of the Study of
  Environmental Arctic Change (SEARCH) program.
• Of note, the Study of the North Alaskan Coastal
  System (SNACS), a NSF contribution to SEARCH,
  includes research focused on oceanographic
  variability in bowhead whale feeding habitats
  northeast of Barrow (Ashjian, et al., 2004) and
  it is hoped that acoustic capability can be
  integrated to that program.
• Our scientific interest lies in integrating
  acoustic observing capability into the Seafloor
  Cabled Observatory, planned as part of the Barrow
  Global Climate Change Research Facility (BGCCRF).
  In this way acoustic observations can be made in
  real time for the community of Barrow and for the
  broader science objectives related to
  understanding the effects of climate change on
  the Arctic ecosystem.

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• Scientific Objective for a Cabled Observatory
• Comparison of observations made in Pacific water
  within the surface layer of Barrow Canyon (e.g.
  temperature, salinity, nutrients, chlorophyll,
  stable oxygen isotopes, particle load) with
  coincident upstream measurements in the Bering
  Strait
• Mounting of instruments, such as microcats for
  T/S, upward looking sonar for ice thickness, and
  nutrient, chlorophyll and turbidity sensors
• Time series comparisons would allow both
  seasonal and annual estimation of carbon
  transformation occurring over the northern Bering
  and Chukchi shelves that are so intimately
  connected to marine system further to the north
  near Barrow and into the Arctic Basin
• Additional sensor deployment in the Atlantic
  water layer deeper in Barrow Canyon would track
  these same measurements for compare/contrast
  evaluation of changes in these physical and
  biochemical tracers to evaluate status and trends
  in the physical forcing and ecosystem health of
  the region
• SBI data indicate high levels of silicate and
  ammonium effluxing from Chukchi shelf sediments,
  which are entrained in the northward moving water
  that form plumes of nutrients extending offshore
  at the halocline depth into the Arctic basin

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• Scientific Objective for a Cabled Observatory
  (cont.)
• Other measurements, e.g. dissolved organic
  carbon measured indirectly via CDOM fluorescence
  sensor technology, plankton recorders, benthic
  video recorders, and acoustic devices mounted on
  a cabled network to trace carbon cycle
• Continuous, long-term, measurements of physical
  and biogeochemical parameters using a cabled
  observatory infrastructure could be extremely
  valuable for tracking environmental change at
  various time scales in the region.