Ice Sheet Phase 1 Status and Plans

Ice_sheets_CCI:
Status and plans
R Forsberg, L Sørensen, R Meister, J Levinsen,
J Dall, A Kusk (DTU-Space, Denmark)
T Nagler, K Scharrer (ENVEO, Austria)
D Evansberget, C Ås (S&T, Norway)
K Khvorostovsky (NERSC, Norway)
A Shephard, A Hogg (U Leeds, UK)
S Andersen, M Langer (GEUS, Denmark)
C Hvidberg (NBI, Denmark), S Svendsen (DMI, Denmark)
CCI Products overview
Coverage of ECVs, based on user requirements
ECV
Product
Surface
Elevation
Change
(SEC)
Ice Velocity
(IV)
Calving
Front
Location
(CFL)
Grounding
Line
Location
(GLL)
Spatial
resolution
5 km grid
Temporal
resolution
4 per year
Period
Spatial and temporal
coverage, phase 1
1991present
All ice sheet, 19912012
5-year running means
500 m grid
1 per year*
1991present
Coastal margin
(1995/96 and 2008)
Timeseries select
glaciers
Greenland interior north
250 m
shapefile
4 per year
1991present
Major outlet glaciers
250 m
shapefile
* CCI phase 2
1 per year
1991present
All major floating
glaciers
Ice velocities from
SAR interometry (Joughin)
+ main CCI validation areas
Phase 1 ECV processing + Sentinels
Coverage areas for SAR interferometry
Phase: All ice sheet – Sentinel-1
ECV prototype products
Example: Ice Velocity from SAR
• Ice velocity and grounding lines determined
by SAR feature tracking and interferometry
• Three methods - complementary error
characteristics:
- Speckle tracking
- D-InSAR
- MAI (multi-aperture interferometry)
Speckle tracking implemented in DTUSUSIE
Area
Ice
sheet
interior
79-fjord IV from speckle tracking (GEUS/DTU)
Ice
sheet
margin
Accu
-racy
Sensors
Method
<10
m/y
ERS SAR
Calibration with balance
velocities
D-InSAR and MAI
techniques
10 to
30
m/yr
ERS
SAR,
ASAR,
PALSAR
Calibration with stationary
control points on bedrock.
Speckle-tracking (highest
accuracy) and featuretracking (lowest accuracy)
ECV prototype products
More examples:
Petermann Glacier IV
(ERS, 1995/96)
ECV prototype products
Petermann Glacier
Grounding Line
Location
(ERS, 1995/96)
ECV prototype products
Jakobshavn
Glacier
Grounding
Lines
(ASAR-summer)
Surface Elevation Changes
Two algorithms for ENVISAT 2002-12: cross-over (XO) and repeat track (RT)
XO
(Nersc)
RT
(DTU)
Colour
Scales
-0.8 -> 0.2 m/yr
SEC errors
XO
Error characteristics as a function of
Ice sheet slope .. different characteristics
ECV combined algorithm:
– least-squares collocation with errors
RT
Ice sheet
Slopes
(scale 0 -> 3 )
SEC merged product
SEC
Envisat
2002-10
(m/yr)
Trend
error
(m/yr)
Envisat vs IceSat
Jakobshavn sector
of icesheet - example
Envisat 2002-12
CCI RT+XO algorithm
(preliminary)
ICESat 2003-9
(colour scale -4 to 1 m)
Envisat - IceSat - GRACE
Envisat
IceSat
m/yr
GRACE
m/yr
mm/yr water eq.
Trends in Greenland ice sheet
Example: 5-year running means of Envisat
2003-7
2004-8
-1
-0.5
2005-9
0
0.5
2006-10
1 m/yr
Trends: Mass loss - GRACE
Masscons
2010
2012
Greenland -228 GT/yr*
*) coincident estimation with
Canadian ice caps, no C-1 terms
IMBIE
main
trend
results
SEC Validation data
Validation of Surface Elevation Change:
NASA IceBridge and ESA CryoVEx
DTU
CryoVEx /
Promice
NASA
Parca /
IceBridge
IV and CFL validation data
Validation data …. GPS velocity (IV) and Landsat (CFL)
Landsat data coverage for
Calving Front validation
Envisat ASAR summer 2008
(ECV production data)
In-situ GPS data from PROMICE
and various outlet glacier projects
Current CCI status
• Greenland CCI project started Jan 1, 2012
• First prototype products to be released
• ECV production ongoing till medio spring 2014:
- ERS altimetry (awaits REAPER reprocessing)
- SAR ice velocities (awaits new ESA RadarSat campaign 2013)
- Grounding lines and calving from locations of all major glaciers
• Validation and usefulness for ice sheet and climate modelling
• New CCI project extension:
- SAR software and methodology preparation – Sentinel-1
- CryoSat-2 (fill-in between EnviSat and Sentinel-3)
- Antarctica scoping exersize – online user requirements
and data documents - completed
New Antarctica-CCI to start 2014 (to include GRACE)
• Data web site:
www.esa-icesheets-cci.org
Auxillary data generated for CCI
Improved DEM of Greenland from digital mapping, ASTER, ERS/ICESat and CryoSat
• Reference for SEC and IV .. resolution 200 m-1 km, polar stereographic or UTM
• Land/ice masks … including outlying glaciers and ice caps
Ice_Sheets_CCI Phase 2
• Two CCI projects: Greenland_ice_sheet_CCI and Antarctica_CCI
• Antarctica CCI ECV’s: SEC, IV (margin areas), CFL, Mass balance
• Complete Greenland IV mapping – Sentinel-1 processing focus
• Seamless processing of altimetry SEC time series 1991-2018 (ERS-1, ERS-2,
Envisat, CryoSat-2, Sentinel-3 … challenges i referencesystem and radar types)t
• GRACE mass balance to be added as new CCI (Antarctica + Greenland?)
Seamless altimetry missions for SEC
RadarSat ESA SAR acquisition 2013
Ice_Sheets_CCI Phase 2
Example of possible new Greenland mass-balance GCOS product …
CCI Envisat trends + GRACE – merged … masscon + firn compaction model
Low weight to Envisat => GRACE (mm w.eq./yr)
”Optimal” combination (same mass loss)
Thanks for your attention
SE-Greenland calving front, Køge Bugt

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