Freshwater Ice

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Cryosphere Theme
Freshwater Ice
MODIS image of Great Slave Lake taken June 14,
2002
Claude Duguay Department of Geography, University
of Waterloo Canada
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Freshwater Ice

• 1. Rationale for lake and river ice observations
• 2. Status of observations
• 3. Shortcomings of current systems
• 4. Recommendations

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2. Status of observations

• Freeze-up and break-up dates, and duration
• Ice thickness
• Snow depth on ice
• Concentration
• Areal extent
• Shallow lakes and rivers - Areal extent of
  floating and grounded ice
• Open water area
• Cover composition (frazil /congelation) Ice
  types
• Flooding extent
• Bridging/lodgement
• Ice jams
• Aufeis

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Freeze-up and break-up dates, and duration
- In situ observations -
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Historical evolution of the number of lake and
river ice observation sites
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Ice thickness and snow depth on ice (1)
Then (1980s)
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Ice thickness and snow depth on ice (2)
in 2000
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Ice thickness and snow depth on ice (3)
Numerical ice growth model
SAR with optical on shallow lakes and rivers
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Concentration (1)

• Daily
• Multi-source
• Since 1960
• 30-y set (1973-
• 2002) available

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Concentration (2)
Location of 136 lakes in Canadian Ice Service
weekly lake ice cover monitoring program

• AVHRR and RADARSAT
• Visual interpretation
• Once a week
• In tenth
• One value for entire lake
• 1995 (34 lakes) 1998 (136)

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Areal Extent (1)

• Daily
• Global
• Since 2000

500 m
MODIS (MOD10_L2) snow product of a section of
eastern Canada-US Lake ice cyan, open water
pale green, snow white, and clouds purple.
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Areal Extent (2)
2005-07-01
2005-11-26
IMS
Daily Multi-sensor Since 2004 at 4 km NH
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Shallow lakes and rivers - areal extent of
floating and grounded ice
SAR
Water availability in winter Fish overwintering
habitat
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(No Transcript)
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3. Shortcomings of Current Systems - In situ

• Surface-based observations were once the most
  important source of information regarding lake
  and river ice conditions. The erosion of the
  surface-based networks since the mid 1980s has
  left important geographical and temporal gaps for
  several lake and river ice parameters. Some data
  are available in reports and paper archives but
  have not yet been digitized (e.g. Russia - V.
  Vuglinsky).
• Some lake and river ice observations from various
  countries have been compiled into the Global Lake
  and River Ice Phenology Database (GLRID/LIAG) at
  NSIDC. The database contains records for 748
  sites, but again the number of sites reporting
  ice observations has plummeted since the 1980s. A
  similar effort in Canada, the Canadian Ice
  Database (CID), reveals a similar trend. No
  national or international funding is currently
  available to support updating of these databases
  and to reestablish, at least part of, the
  surface-based observational ice networks.

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3. Shortcomings of Current Systems - R.S.

• Satellite remote sensing can provide some of the
  parameters no longer observed in situ. Some
  surface-based measurements, however, are sill
  needed for the validation of remote sensing
  approaches and the refinement of models of
  lake-ice growth and river-ice dynamics.
• Lake ice observations are available via some
  remote sensing derived products (e.g. MODIS snow,
  IMS, CIS). However, the observations are limited
  spatially and/or temporally. Also, important
  climatically and hydrologically relevant
  parameters such as the dates of the first
  appearance of ice, complete freeze-over,
  beginning of thaw, and when the water body
  becomes completely free of ice, are currently not
  available from these products.

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3. Shortcomings of Current Systems - R.S.

• The MODIS 500-m daily snow product is of
  particular interest for lake ice and river ice
  (large rivers) monitoring. However, this product
  has not yet been validated for lakes or rivers.
  Extensive cloud cover and periods of darkness in
  early winter at high latitudes limits its use
  during the freeze-up period at these latitudes.
  Active microwave, SAR and scatterometer data, and
  the higher frequency passive microwave available
  on AMSR-E (89GHz) may help during both the
  freeze-up and break-up periods.
• The spatial resolution of most satellite sensors
  providing high (daily) temporal resolution is
  simply too coarse for the monitoring of the
  majority of river-ice parameters listed in the
  table. Some studies have shown the potential of
  AVHRR and MODIS to monitor break-up dates on very
  large rivers of the Northern Hemisphere. The
  value of higher resolution RADARSAT imagery has
  also been demonstrated for the mapping of river
  ice types. However, the cost associated with the
  acquisition of such imagery has been a major
  impediment to date.
• No satellite mission currently provides lake and
  river ice thickness and snow depth on ice
  measurements.

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4. Recommendations (1)
1) A central international archive (e.g. global
freshwater ice monitoring network) or several
regional archives (part of the network) are
needed. 2) A set of target regions and
lakes/rivers (some of which were part of an
existing historical network) for future long-term
monitoring needs to be identified. This will
first require an international inventory and
digitization of paper records. 3) The
reactivation of existing lake ice or river ice
sites or the addition of new observation sites,
through the establishment of networks of
volunteers and with schools must be encouraged.
Such networks have the advantage of providing a
framework for educating young students and
teachers, as well as the general public,
regarding the importance of freshwater ice
monitoring. Such observational networks have
recently been established in Alaska (Alaska Lake
Ice and Snow Observatory Network or ALISON
http//www.gi.alaska.edu/alison/) and Canada
(IceWatch http//www.naturewatch.ca/english/icewa
tch/).
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4. Recommendations (2)
4) A comparison of conventional (surface-based)
observations of freeze-up and break-up with
satellite-derived time series, starting in the
1970s-1980s with AVHRR data, is needed. This
would ensure some continuity in the transition
between the surface-based and satellite
observations (i.e. post 1980s when many of the
lake/river ice sites were lost). 5) The MODIS
500-m snow product needs to be validated for lake
ice. The development of a composite lake-ice
product from the combination of MODIS Aqua and
Terra data (i.e. increasing the number of MODIS
swaths) should be examined along with the
possible improvements that can be made with the
integration of passive and active microwave
data. 6) It has been shown that SAR can be used
to map ice cover and areas of open water on
rivers and lakes, and to identify areas of
floating and grounded ice. The development of
operational methods based primarily on the use of
high-resolution SAR imagery must be
encouraged. 7) The potential of passive microwave
(and scatterometer) data to map ice cover
(concentration and extent), open water, ice
thickness, and snow depth on ice on large lakes
should be examined.
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Questions?
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1. Rationale for lake and river ice observations
(1)

• Seasonal differences in the ice cover of lakes
  and rivers can have serious impacts on northern
  ecosystems. The changes can alter migration
  patterns and breeding seasons for birds, and food
  supplies for fish and mammals.
• Freshwater ice cover has other wide-ranging
  impacts (e.g. energy, moisture and gas exchanges,
  hydrology, recreation, transportation, safety).
• Ice formation, thickness and break-up are
  important indicators (integrators) of regional
  climate.
• Global Climate Observing System (GCOS) identified
  lake/river freeze-up / break-up as important
  variables for climate monitoring (1 to 2-d
  accuracy).

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1. Rationale for lake and river ice observations
(2)
Consequences of a Reduction in the Duration of an
Annual Ice Cover Experimental Lakes, Ontario,
Canada, 1969-88 (Source Schindler et al., 1990)
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1. Rationale for lake and river ice observations
(3)
Consequences of earlier break-up on the energy
balance of Great Slave Lake, N.W.T., Canada
(Source Rouse et al., 2003)
? Evaporation (mm)
The date of final ice melt in June exerts the
largest single control on the seasonal thermal
and energy regimes of these large northern lakes.
An early thaw greatly enhances the magnitude of
absorbed solar radiation in the high sun season.
This becomes stored heat energy that drives the
large sensible and latent heat fluxes during fall
and early winter. The El Niño year of 1998 had
greatly enhanced evaporation totals compared to
1997 and approached average values comparable to
the lower Laurentian Great Lakes.
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(a)
1. Rationale for lake and river ice observations
(4)
Trends in lake freeze-up and break-up dates, and
0oC isotherms in Canada (Source Duguay et al.,
2006)