Sea ice, hydrological, and biological processes in …CEOSCEOS Sea ice, hydrological, and biological...
Transcript of Sea ice, hydrological, and biological processes in …CEOSCEOS Sea ice, hydrological, and biological...
CEOSCEOSCEOS
Sea ice, hydrological, and biological processes in the Churchill River estuary region,
Hudson Bay
Freshwater Institute, Fisheries & Oceans Canada, Winnipeg, MBCentre for Earth Observation Science, University of Manitoba
Institute of Ocean Sciences, Fisheries & Oceans Canada, Sidney, BCUniversity of Calgary Centre for Alpine and Arctic
Climate Research
Z.A. Kuzyk, R.W. Macdonald, M.A. Granskog, R.K. Scharien, R.J. Galley, C. Michel, D. Barber, and G. Stern
Introduction
Chesterfield Inlet
Nelson R.
Haye
s R.
Sever
n R.
Wini
skR.
Thelon R.
Kazan R.
Tha-anne R.Thlewiaza R.
Churchill R.
Seal R.
Grande Riviere de la Baleine
Nastapoca R.
Innuksuac R.
Povingnituk R.
Hudson Bay
La Grande R.
• Estuaries– Near-shore regions
where river water and sea water meet
– Prominent features of Hudson Bay
• Interface for transfer– River water– Heat– Dissolved and
particulate materials• Affect how and when
materials delivered and may alter properties.
• Potential sites of biological production.
Lepage and Ingram 1988
Great Whale River
Ingram and Prinsenberg, 1998
La Grande and Eastmain
• Ice cover alters the character of estuaries.– Prevents direct wind and
wave mixing– Sometimes allows larger
plumes• Sea ice complicates
the freshwater budget.– Melt –freshwater source– Grows - salt (brine)
• Western Hudson Bay• Winter-spring transition
– March to May 2005
• Data sources• Hydrological and meteorological
data– Environment Canada, Manitoba
Hydro• Physical observations of ice cover• Measurements of salinity, oxygen
isotopes (δ18O), nutrients and suspended particulate material
• Simple models of ice growth• Budgets for heat and freshwater
Churchill River Estuary Region
EstuaryButton Bay (marine site)
(b) MODIS image, Jan 1, 2005
Landfast ice
Mobile ice offshore
Flaw leadRubble ice
Landfast ice, lead in the distance
Rubble ice at outer edge of landfast ice
WINTER PRE-MELT
EARLYMELT FRESHET
BREAK UP
Winter
Pre-melt
Early melt
Freshet
Break up
PERIOD
0
1
2
3
Chl
orop
hyll
a(m
g m
-3)
EstuaryButton Bay
River
Changes in Surface Water Chlorophyll a Concentrations
0 10 20 30 40SALINITY
0
1
2
3
4
5
6
Nitr
ate
(uM
)
Salinity0 10 20 30 40
0
10
20
30
40
50
Salinity
Early melt & freshetWinter & pre-melt
Changes in Nutrient Distributions
Sili
cic
acid
(uM
)Seawater
River water
Conceptual Model: Physical Evolution of Estuary
Churchill River Discharge
Over-flooding of river water along edge of rubble zone
Button Bay
Breach in rubble and gap in landfast ice
Quickbird RGB Composite, May 27, 2005
Great Whale River• Stable, wide landfast ice cover and
large plume• Smooth gradients in salinity and
nutrients• Phytoplankton distributed along
gradients
Nelson River• Narrow, unstable landfast ice
cover if any at all• Well mixed, probably nutrient
rich• Plume flowing directly into
lead
Contrast with other Estuaries in Hudson Bay
CEOSCEOSCEOS
Conclusions and Implications• Wide spectrum of conditions for frozen
estuaries– Highly variable seasonally– Dependent on sea ice and river discharge– Inter-annual variability?– Variability and potentially instability may
pose challenge for predicting sensitivity and responses of estuaries to change.
CEOSCEOSCEOS
Conclusions and Implications• Freshwater budget allows estimate of region’s
sea ice growth.– Water column in Button Bay reflects more
ice growth than can be accounted for in the landfast ice
• Influence of ice growth in flaw lead, maybe polynya in NW• Comparison with satellite observations• Modelling context
– Ice growth as source of cold, saline bottom water for all of Hudson Bay
– In Arctic Ocean, estuary structure and distribution of river water are important controls on this process.
CEOSCEOSCEOS
Acknowledgements• ArcticNet• Fisheries and Oceans (FWI and IOS)• Churchill Northern Studies Centre, Port of
Churchill, community of Churchill• North/South Consultants Inc., Manitoba Hydro,
Environment Canada• Natural Sciences and Engineering Research
Council of Canada (NSERC)• Northern Scientific Training Program (Indian
and Northern Affairs)• Academy of Finland• Field team including M. Pazerniuk, A. Hare,
E. Braekevelt, J. Ehn, R. Hodgson, B. LeBlanc, P. Fitzpatrick, R. Bougie, J. Batstone