Transcript Glaciers - Ensembles

Glaciers_cci
Frank Paul
University of Zurich, Switzerland
The Target: Glaciers
Adequacy of the User requirements
• Is your URD adequate with GCOS/CMUG requirements?
-> Yes of course! (it is based on these documents)
• We analysed the following sources to determine the UR:
•
GCOS: 82, 92, 107; CEOS response, IGOS Cryosphere report
•
feedback and advice from KSB (WGMS, GLIMS, CMUG)
•
questionnaire among CRG and wider glaciological community
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scientific literature
• What did we learn from this analysis?
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there is a strong demand to complete the global inventory (GCOS T2.1)
•
strong support to also investigate elevation changes and velocity fields
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feedback from the community about ongoing work (to avoid overlap)
•
created a new overview of key regions with completeness level
GCOS requirements (satellite specs.)
CMUG requirements (satellite specs.)
Some differences of Glaciers_cci
• Glaciers_cci (the area product) is based on a sensor that is in
orbit since 27 years (Landsat TM)
• follow-up sensors have (ETM+) or will have the same spectral
characteristics (LDCM, Sentinel 2)
• the main product depends on manual digitization by experts
rather than an automated (button press) application
• key to product quality is thus communication and agreement
on methodological standards and advice through tutorials
• we do produce in cooperation with the wider GLIMS
community a one time snapshot of the global ice cover
•
sometimes politically delicate (by location or person)
The Problem: Debris Cover
The Problem: Debris Cover
Selected key regions
Completeness Level (CL)
Did the PSD meet the needs of CRG?
• We are currently working on the PSD ...
•
it will provide an overview of the technical specifications, the error
characteristics and an error budget for all three products
• The short answer is: Yes, they will!
•
the specifications of the input data sets are largely given, whereas the
requirements for the output products (area / elev. ch. / velocity) differ
•
individual CRG members or CMUG require different formats (shape files,
GeoTiff, grid, netCDF, resolution, level of detail, completeness, etc.)
•
depending on the needs (e.g. spatial resolution) the errors will differ
• CRG member Sven Kotlarski (IAC) will give a short overview
on how the glacier area product can be used in RCMs
The integrated perspective
• How is the the integrated perspective on consistency
between the ECVs addressed?
•
we will follow the SoW and other CCIs as close as possible (e.g. website)
•
our deliverables will have a similar structure than for all other CCIs
•
we have a strong commitment to provide products that are relevant for
IPCC AR5 and GTN-G
•
KSB and climate/hydrological model experts are in our CRG
•
we have a direct link to the Landcover_cci (validation data)
•
However, the direct interaction with the other CCIs is weak
• We will be cooperative as best as possible!
Product uncertainties
• at first we will try to assess them (which is not easy)
• a number of round-robin experiments should help to provide
improved guidelines for methodological data consistency
• multiple digitizings of the same glacier will give an internal
accuracy measure
• comparison with independently created products (area)
• validation with higher accuracy products (LIDAR DEMs)
• application of different methods and ground truth data
• get feedback from the community, open for refinements
• we do not need ECMWF data
A Case Study
Using Glacier Inventory Data
in Regional Climate Modelling
Sven Kotlarski
Institute for Atmospheric and Climate Science
ETH Zurich, Switzerland
BACKGROUND (1)
• Interactive role of glaciers in the climate system
• Direct and indirect feedback mechanisms
• Poor representation in today's climate models:
-
Static glacier masks
No changes in ice extent, no feedback to atmosphere
No consideration of water volume stored
No / simplified runoff generation
Exception: Ice sheet models in ESM
BACKGROUND (2)
More sophisticated approach desirable for assessing regional climate change in
glacierized areas and for hydrological analyses in glacierized river basins
• Interactive glacier
scheme for regional
climate modelling
(Kotlarski et al., Clim Dyn, 2010)
• Glacier mass balance
and area changes on
a subgrid scale
TILE APPROACH
•
•
two-layer ice body
V-A-relation
MODEL SETUP
•
•
•
18 km x 18 km
Forcing: ERA40 (model
development and evaluation),
ECHAM5-MPI-OM (scenario)
Glacier inventory data needed for
initialization of glacier areas
(total area per grid cell, areaaltitude distribution) and for model
validation
CHANGE OF GLACIER AREA
Initialisation January 1958
WGI
(collection of national
inventories, scaled to 1958)
End of simulation
(December 2003)
- 23.6 %
So far: no Alpine-wide validation possible!
USING THE 2003 ALPINE GLACIER
INVENTORY (1)
1.) Model validation
USING THE 2003 ALPINE GLACIER
INVENTORY (2)
2.) Initializing glacier cover
(here: regional climate change scenario)
- 47.4 %
Temperature change anomaly [K]
these scenarios are still initialized with
the simulated glacier cover in 2003!
- 74.2 %
Amplification
of warming
ONGOING ...
Application of REMOGLACIER
in Himalayas / Karakorum
(MPI-M Hamburg)
GLIMS inventory
to be completed
Implementation of glacier parameterization
scheme into new Canadian RCM CRCM5
(Environment Canada / UQAM Montréal)
glacier fraction derived from
GlobCover Land Cover product (on 0.05°)
To be updated by
new inventories
SUMMARY
• Interactive description of mountain glaciers in a state-of-the-art
regional climate model
• Glacier inventory data important for both model development and
model application (initialization and evaluation)
• Main requirements: - completeness
(URD)
- temporal consistency (snapshots)
- area-altitude distribution
• Less important: - spatial accuracy and detail
- high temporal resolution
LOOKING FORWARD TO DATA FROM Glaciers_cci …
GRID BOX CROSS SECTION