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

Mark R. Drinkwater European Space Agency ESA-ESTEC Noordwijk, NL

“Progress and New Frontiers in Ice Sheet Remote Sensing”

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

Contents

Introduction

Recent Progress

New Frontiers

Summary


IPY 2007-2008: Satellite Remote Sensing

2000 Modified Antarctic Mapping Mission ice velocity model.

– 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.


Aircraft and in-situ Sounders and GPR Systems

DMSP

IceSat

Collecting satellite polar snapshots

MetOp

GOCE

GRACE SPOT-4

HRVIR / VGT

SMOS

Aqua & Terra

ALOS

RADARSAT

Envisat

ASAR MERIS / A-ATSR

MODIS / ASTER AMSR-E ASCAT

AVHRR SSMI

PALSAR PRISM / AVNIR-2

wavelength (m)

Frequency (Hz)

ERS-2

M. Drinkwater (ESA)


03

02

04

06

08

10

11

12

13

15

16

07

09

05

14

RCM

SAR/COSMO-SKYMED X-band TerraSAR/Tandem-X X-band

ICESAT GMES S-3A, B

RADARSAT-2 C-band RADARSAT-1 C-band

ICESAT-2 CryoSat-2

SAR/RISAT C-band IPY

Ku-Scat & MSMR/OCEANSAT-2

HY-3 WSAR

Seawinds/QuikSCAT Ku-band

GMES S-1A, B

GRACE

SMOS WindSat

AMSR-2/GCOM-W1 OLS & SSMI/DMSP— AVHRR & AMSU/NOAA

GOCE

HY-1B COCTS/HY-1A JPSS 1 VIIRS/NPP

Courtesy: M. Drinkwater Arctica-M 1 & 2

HEO missions PCW 1 & 2

MetOp -2, -3

GRACE-C

LEO missions

PALSAR/ALOS L-band

ASCAT & AVHRR/MetOp -1

ALOS-2

Landsat DCM Landsat-5, -7

Aster/MODIS/EOS-Terra

RA2 & ASAR/Envisat C-band RA, SAR & Wind Scat/ERS-2

HY-2B HY-2B HY-2A

MODIS & AMSR-E/EOS-Aqua

Cryosphere Satellite Missions

Planned/Pending approval In Orbit Approved Solid = R & D; Hatched = operational mission

SPOT-4/5

FY-3C FY-3B MODI & MERSI/FY-3A VIRR/FY-1D

http://www.climate-cryosphere.org/images/site-images/logos/ipy_logo.jpg


Ice Sheet Mass Balance

gma MMMδaδM −−≅/

Ma

Mm Mc

Mb

Mass change per year AccumulationRate

Surface Melt flux

Flux across grounding

line

Mg

cMCalving Flux

Where


Recent Progress:

Quantifying components of the Mass budget


Assessing Continental Scale Volume/Mass Changes:



Envisat IceSat GRACE

m/yr m/yr mm/yr water eq.

Greenland: Elevation (Volume)/ Mass Change

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


Antarctica: Elevation(Volume)/Mass Change

Courtesy T. Flament, LEGOS(2013)

m/y

r

Envisat (2003-2012) IceSAT (2003-08)

Pritchard et al. (2009)

GRACE (2003-06)

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

http://earth.esa.int/cryosat

Launched: April 8th 2010

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

Antarctica: CryoSat ice sheet topography

CryoSAT ice-sheet elevation models

• 1 km grid spacing

• LRM & SARIn

• Greenland & Antarctica

• Validation in progress


CryoSat ice sheet topography & BEDMAP-2

© CPOM/UCL/ESA/Planetaryvisions

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


Continental Scale Melt Flux:

& Key Surface Radiative Quantities



– 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

Passive Microwave: daily melt products

Weather map courtesy - DMI.

July 30, 2013


Ice Sheet Reflectivity (Albedo) & Melting

Before melt After melt


gma MMMδaδM −−≅/Mass Flux across Grounding Line: & Ice shelf Calving Flux


SAR: IPY Pole-to-Coast Ice Velocity Mapping

Adapted from Rignot et al, Science Courtesy: Schuechl, UCI

Satellite InSAR data


ERS-2: Kangerdlussuaq Tidewater Glacier Calving and Retreat

• 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

Bevan et al. (2013)


The Grounding Line is the boundary between the grounded ice and the floating ice

Ice Sheet/Shelf Grounding Line

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

d)oceanic tides

e)Sub-glacial environments

Grounding zone


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

University of Leeds (UK), of CryoSat+ GLITter consortium 27 metres ice shelf freeboard translates to ~220 m ice thickness.

Courtesy, ENVEO

metres


Petermann Glacier: 1992 – 2011 Grounding Line Retreat & Thinning

2911

2011

Courtesy N. Gourmelen (Univ. Edinburgh)


Recent Progress:

Gravimetry – **Covered by P. Ditmar


New Frontier:

Better resolution of time-space variability, and process understanding


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

m/

yr

5½ years of ICESat data 2 years of CryoSat-2 data

ESA/University of Leeds


– 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: Sub-glacial Lakes & Basal Hydrologic conditions


• 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

CryoSat: across-track swath elevations


Swath topographic mapping with CryoSat

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


New Frontier:

Seeing beneath the surface


AMSR-E C-band v-pol

SMOS L-band v-pol

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 L-band

– 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

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


– 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.

Remaining Challenges


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

http://earth.esa.int/

Date post:	11-May-2015
Category:	Technology
Upload:	tu-delft-climate-institute
View:	852 times
Download:	0 times

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

Technology