Drinkwater ice sheet symposium - tu delft climate inst., 17 oct 2013(1)

“Progress and New Frontiers in
Ice Sheet Remote Sensing”
Mark R. Drinkwater
European Space Agency
ESA-ESTEC
Noordwijk, NL

Contents
 Introduction
 Recent Progress
 New Frontiers
 Summary

Progress and Frontiers in Ice Sheet Remote Sensing | M. Drinkwater | TU Delft Climate Inst., 17 Oct 2013 | Pag. 2

IPY 2007-2008: Satellite Remote Sensing

– The International Polar Year (IPY) provided an
international framework for understanding polar
processes and high-latitude climate
– IPY era spaceborne instrumentation represented a
technological leap beyond the capabilities of the IGY
– Spaceborne technology offered unique capabilities for
obtaining essential data for predictive models
– Unique opportunity to assess current state of art in
remote sensing of polar regions.
2000 Modified Antarctic Mapping Mission ice velocity model.


Collecting satellite polar snapshots

Aircraft and in-situ
Sounders and GPR
Systems

SSMI

MetOp

Aqua &
Terra

DMSP

AMSR-E

MODIS / ASTER

GRACE
ASCAT

AVHRR

Envisat

SMOS

ERS-2

SPOT-4

RADARSAT

HRVIR / VGT

IceSat

ASAR MERIS / A-ATSR

GOCE
ALOS

PALSAR
PRISM / AVNIR-2

wavelength (m)

Frequency (Hz)

M. Drinkwater (ESA)


Cryosphere Satellite Missions
02

03

04

06

05

07

08

09

10

11

12

13

14

PALSAR/ALOS L-band
RA, SAR & Wind Scat/ERS-2

16

15
ALOS-2

RA2 & ASAR/Envisat C-band

RADARSAT-1 C-band

GMES S-1A, B
RCM

RADARSAT-2 C-band
SAR/RISAT C-band

IPY

TerraSAR/Tandem-X X-band

HY-3 WSAR

SAR/COSMO-SKYMED X-band
MetOp -2, -3

ASCAT & AVHRR/MetOp -1
Ku-Scat & MSMR/OCEANSAT-2

Seawinds/QuikSCAT Ku-band
ICESAT

GOCE

WindSat

SMOS

OLS & SSMI/DMSP— AVHRR & AMSU/NOAA
MODIS & AMSR-E/EOS-Aqua
Aster/MODIS/EOS-Terra

AMSR-2/GCOM-W1
VIIRS/NPP

JPSS 1

HY-1B

COCTS/HY-1A

HY-2A
VIRR/FY-1D

MODI & MERSI/FY-3A
Landsat-5, -7
SPOT-4/5

Courtesy: M. Drinkwater

Approved

ICESAT-2
GMES S-3A, B
GRACE-C

CryoSat-2
GRACE

In Orbit

LEO missions

Planned/Pending approval


FY-3B

HY-2B

HY-2B

FY-3C
Landsat DCM
Arctica-M 1 & 2
PCW 1 & 2
HEO missions

Solid = R & D; Hatched = operational mission

Ice Sheet Mass Balance

Ma

Mc

Mm

Mg
Mb

δM / δa ≅ Ma − Mm − Mg
Mass change per year

Accumulation
Rate

Surface
Melt flux


Flux across
grounding
line

Where

Mc
Calving
Flux

Recent Progress:
Quantifying components of
the Mass budget


Assessing Continental Scale
Volume/Mass Changes:



Greenland: Elevation (Volume)/
Mass Change
Envisat

m/yr

IceSat

m/yr


GRACE

mm/yr water eq.

Courtesy R. Forsberg et al. (ESA, CCI Project)

Antarctica: Elevation(Volume)/Mass Change
IceSAT (2003-08)

GRACE (2003-06)

m/yr

Envisat (2003-2012)

Courtesy T. Flament, LEGOS(2013)

•

•
•

Pritchard et al. (2009)

Velicogna (2009)

Envisat RA2 limited latitude (<82o) but all-weather; firn densification and isostatic
adjustment models needed to convert from elevation change (volume) to mass
change
IceSAT limited by cloud and discontinuous temporal sampling, and density of
cross-overs; firn densification model needed to convert to mass
GRACE – low res.; of limited use in Ant. Peninsula; Considerable residual
uncertainty due to Glacial Isostatic Adjustment (GIA)

ESA’s CryoSat Ice Mission: Basic Facts
– Instruments:






SIRAL (SAR/Interferometric Radar
Altimeter)
Star trackers
DORIS (Doppler Orbit and Radio
Positioning Integration by Satellite)
receiver
Laser retro-reflector

– High inclination orbit - 88°latitude
– Non sun-synchronous orbit
– SARIn mode improves across track resolution
designed for rugged ice-sheet terrain
– 369 day repeat (30 day sub cycle) gives dense
across track sampling and captures temporal
changes

Launched: April 8th 2010

http://earth.esa.int/cryosat

Antarctica: CryoSat ice sheet topography
CryoSAT ice-sheet elevation models
•

1 km grid spacing

•

LRM & SARIn

•

Greenland & Antarctica

•

Validation in progress

Progress and Frontiers in Ice Sheet Remote
© CPOM/UCL/ESA/Planetaryvisions Sensing | M. Drinkwater | TU Delft Climate Inst., 17 Oct 2013 | Pag. 12

CryoSat ice sheet topography & BEDMAP-2
Former limit of altimetry coverage (ERS/Envisat)
CryoSat coverage to 2 deg. off pole

CryoSat Topography & BEDMAP basal
boundary conditions – key properties governing
ice flow
© CPOM/UCL/ESA/Planetaryvisions


Continental Scale Melt Flux:

& Key Surface Radiative Quantities


Passive Microwave: daily melt products

July 30, 2013

–

Extreme July 2012 melt, and extensive melting in 2013

–

Strong southeasterly winds across the western coast

–

Record warmest temperature of 25.9 degrees Celsius
in Maniitsoq

Weather map courtesy - DMI.

Ice Sheet Reflectivity (Albedo) & Melting

Before melt


After melt

Mass Flux across Grounding Line:

& Ice shelf Calving Flux


SAR: IPY Pole-to-Coast Ice Velocity Mapping

Satellite InSAR data

Adapted from Rignot et al, Science


Courtesy: Schuechl, UCI

ERS-2: Kangerdlussuaq Tidewater Glacier
Calving and Retreat

Bevan et al. (2013)

• ERS-2 placed in 3d repeat orbit before deorbiting.
• Images focus on Greenland outlet glaciers (March-May 2011)
• Comparison of ERS-1, ERS-2, T-SAR-X indicate 20 year changes

Ice Sheet/Shelf Grounding Line
The Grounding Line is the
boundary
between
the
grounded ice and the
floating ice

It is important for:
a) the ice sheet and the ice shelves
mass budget calculation
b) numerical modelling of ice sheet
dynamics
c) Ice-ocean interactions
Grounding zone

d) oceanic tides
e) Sub-glacial environments


CryoSat: Ice shelf Grounding Line (GL)
Location & GL Ice Thickness

Courtesy, ENVEO

metres

University of Leeds (UK), of CryoSat+ GLITter consortium


27 metres ice shelf freeboard translates to ~220 m ice thickness.

Petermann Glacier: 1992 – 2011
Grounding Line Retreat & Thinning

2011

2911

Courtesy N. Gourmelen (Univ. Edinburgh)

Recent Progress:
Gravimetry –
**Covered by P. Ditmar


New Frontier:
Better resolution of timespace variability, and process
understanding


CryoSat: Basin-resolved rates of Ice
Sheet Elevation/Volume Change
2 years of CryoSat-2 data

m/yr

5½ years of ICESat data

ESA/University of Leeds


CryoSat: Sub-glacial Lakes & Basal
Hydrologic conditions
– CryoSat features a unique
capability to map changes in
Antarctica’s sub-glacial lakes in 3D.
– Sub-glacial lakes interesting in
terms of water transport and ice
dynamics beneath the surface.
– The crater shown was formed when
6 km3 of lake water drained

Malcolm McMillan et al – GRL (2013)

CryoSat: across-track swath elevations

• Standard CryoSat
level 2 SARIn height
product is from point
of closest approach
(POCA)
• Over sloping terrain,
SARIn echo maps a
wide swath across the
ground track, beyond
the POCA
• Swath SARIn mode
returns valid in range
0.5 to 2.0 degrees
• Elevations retrieved
where good coherence


Swath topographic mapping with CryoSat

Source: Noel Gourmelen and CryoSat+ CryoTop team (ESA STSE Study)

New Frontier:
Seeing beneath the surface


SMOS: Polar Ice Sheet Data

– Ice sheets used as natural, uniform
stable calibration reference site
(Dome C)
– But subtle variability observed in
signatures
– Absorption in ice is very low at Lband
– Thermal microwave emission could
originate from up to kilometres
depth.
– Potential for microwave
thermometry? (i.e. in-ice
temperature sounding)
– Lowest temperatures correspond
with subglacial lake basins


AMSR-E
C-band
v-pol

SMOS
L-band
v-pol

Courtesy L. Kaleschke
U. Hamburg

DomeCAir: L-band airborne Campaign Results

Tb Cold = Deep basins (counterintuitive)

Why? Normally warmer at
depth

New Frontier:
Remaining Challenges


Remaining Challenges

– Measure continental snow accumulation directly by remote
sensing
– Unify models for converting volume to mass (firn compaction)
in context of Surface Mass Balance efforts
– Direct, routine measurement of ice thickness at grounding
lines (P-band?)
– Tomography of in-ice layering properties using P-band (ESA
Biomass)
– Sub-surface sounding of ice profile properties (L-band and
UHF frequency range)
– Push temporal resolution of observations to sub-daily (i.e.
diurnal/tidally forced processes) at suitable spatial scales.

POLARIS: P-band coherent radar sounding in
Greenland


Summary

– IPY allow documenting state-of-art in satellite remote sensing of high
latitude regions and the cryosphere
– Satellites provide global perspective on the ice sheet processes on a range of
space and time scales (daily – decadal)
– Huge progress made in study of the mass balance (since early 1990s)
– Space observing system capabilities never better for investigating
cryosphere in a changing climate
– Legacy satellite datasets (ERS, Envisat) and the sustained met satellite
measurements support ice sheet climate research
– ESA’s new satellite missions (CryoSat, GOCE and SMOS) deliver new data
products with exciting potential
– Benefits of long satellite data time series self evident:
–

ESA’s Climate Change Initiative helping to construct fundamental
climate data records and Ice Sheet Essential Climate Variables

– ESA/EC Copernicus Sentinels coming in 2014 to sustain some capabilities

Additional Spare Slides


Accessing ESA Data Products

http://earth.esa.int

Drinkwater ice sheet symposium - tu delft climate inst., 17 oct 2013(1)

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