Volume changes 2000 – 2011/2012 of glaciers in the Patagonia Icefields from TanDEM‐X and SRTM data

Wael Abdel Jaber1, Dana Floricioiu1, Helmut Rott2, Björn Sass³

1) German Aerospace Center (DLR), Remote Sensing Technology Institute (IMF), Oberpfaffenhofen, Germany 2) Institute for Meteorology and Geophysics, University of Innsbruck, Austria 3) Friedrich‐Alexander‐Universität, Erlangen, Germany

TanDEM‐X Science Team Meeting, Oberpfaffenhofen, Germany, 12 –14 June 2013 The South Patagonia Icefield (SPI)

North Patagonia . SPI extension: 350 km N‐S. Mean width: 35 km. Icefield (NPI) Lat: 73°35’ W NPI . First glacier inventory by Aniya et al. (1996): Lon: 46°20’ to 47°40’ S • 48 major outlet glaciers (see map) Area: 4,200 km² South Patagonia • 100+ small cirque and valley glaciers Icefield (SPI) SPI . Most major glaciers calving into: Lat: 73°30’ W Lon: 48°20′ to 51°30′ S GCN • freshwater lakes Area: 13,000 km2 • Pacific ocean fjords . Most of major glaciers exhibit strong mass loss CD trends over the last decades, except Pio XI and Perito Moreno. . Confirmed by low resolution mass trends obtained by GRACE gravity fields analysis [1].

[1] Jacob T. et al, „Recent contributions of glaciers and ice caps to sea level rise“, Nature, 2012 www.glaciologia.cl

Remote Sensing Technology Institute 2

Aniya et al., 1996 Source: SRTM & TanDEM‐X data

. Well suited multitemporal elevation dataset for mass balance estimation: • Both DEM from SAR bistatic interferometry • Both DEMs acquired in a relatively short time span • Temporal baseline: 11‐12 years  allows detecting slower changes in elevation . SRTM • Acquisition: 11 ‐ 22 February 2000 • C‐band DEM: USGS release 2.0 calibrated with ICESat altitude tie points (DFD) [1] . TanDEM‐X • Integrated TanDEM‐X Processor (ITP): CoSSC data  RawDEMs • 19 RawDEMs (of which 4 with dual baseline phase unwrapping) (17 desc., 2 asc.) ‐ 2011: 8 scenes in austral summer + 2 scenes in winter ‐ Early 2012: 9 scenes in summer . Issues: • Accurate coregistration of both DEMs • Possible biases in DEM difference due to different DEM spatial resolution • Radar signal penetration in ice/snow related to: ‐ physical parameters of snow and ice (liquid water content, ice compactness, …) ‐ system parameters (radar frequency, incidence angle) [1] Felbier A., “Ausgleichung langwelliger Höhenfehler in SRTM mit Kugelflächenfunktionen Remote Sensing Technology Institute auf Basis ausgewählter ICESat‐Daten”, TUM, 20093 Ice and snow surface conditions During SRTM During TanDEM‐X

QuikSCAT: Ku‐band backscattering (σ0) SIR products*: Active channel of bistatic acquisition: 0 X‐band backscattering (σ0) SPI ‐5 P. Moreno Gl.

‐10

‐15 [dB] 0 σ

‐20

‐25

‐30 10‐13 Feb. 2000 14‐17 Feb. 2000 18‐21 Feb. 2000 17 Feb. 2011 (winter scene) Feb. 2000 (summer): ‐10 < σ0 < ‐20 dB  wet glacier surface σ0 < ‐7 dB on glacier plateau

(θi= 39°)  wet glacier surface TDM acquisitions mostly in summer, only 2 acquisitions in winter

SRTM and TanDEM‐X acquired with wet conditions on the firn area  penetration depth is negligible

* Courtesy Matthias Reif, IMGI, Univ. of Innsbruck Remote Sensing Technology Institute 4 Applied procedure for dh/dt derivation

TDM scene CoSSC pair

ITP

Coregistered TDM RawDEM SRTM DEM

- SRTM on ice free areas RawDEM - ICESat GLAS tracks (2003-2009) validation - Overlapping TDM scenes

no new APO OK? estimation

yes

TDM RawDEM

∆h ∆h/∆t ITP: Integrated TanDEM‐X Processor APO: Absolute Phase Offset - RawDEM Flag Mask (FLM) PU error - Thresholding ∆h image PU: Phase Unwrapping masking - Manual selection

Mosaicking

Remote Sensing Technology Institute 5 N SPI: ice elevation change rate 2000 – 2011/2012 Jorge Montt . Most glacier termini (0 – 1400m) display a significant thinning trend

Occidental . Exceptions: Pio XI and Perito Moreno O‘ Higgins . On the plateau (1400 – 3600 m): thinning signal in the N‐E part

Pio XI and equilibrium on West side and South sector

Viedma

Upsala

+8 Ameghino

P. Moreno +4

0m a‐1 Grey

‐4 Tyndall

0 25 50 ‐8 Remote Sensing Technology Institute 6 km Perito Moreno and Ameghino: ice elevation change 2000 ‐ 2011 Perito Moreno (area: 258 km²) N . front stable with periodical damming events . no significant elevation changes Ameghino (area: 76 km²) ∆h=‐70 m . Front in retreat ‐1 Ameghino Gl. • ‐0.8 km (72.7 m a ) [2000‐’11] • ‐3.5 km (152 m a‐1) [‘70‐’93] : large proglacial lake ICESat . Significant surface lowering mostly below equilibrium line ∆h=‐20 m • ‐6.4 m a‐1 [2000‐’11] near current front

• ‐2.3 m a‐1 [‘49‐’93] near ‘93 snout (Aniya et al., ‘96) Perito Moreno Gl. +100 P. AmeghinoMoreno

+50 ‐5.3 m a‐1 0m ‐8.5 m a‐1

‐50

‐100

Remote Sensing Technology Institute 7 Pio XI: ice elevation change 2000 ‐ 2012

N . Largest calving glacier of SPI . Area: 1265 km². Length: 64 km.

∆h=+40 m . Tidewater glacier

. Front advance: +1.97 km [2000 ‐ 2012] (180 m a‐1)

. Only main glacier with increased surface elevation trend +100 1.97 km ∆h=+50 m ‐1 Front: Feb. 2000 . ∆h > +50 m (+4.4 ma ) at 4.5 Front: Feb. 2012 +50 km from front ∆h=+15 m . Slight elevation increase on 0m upper part: ∆h = +15 m (+1.25 ma‐1)

‐50 . Average ice thickening on ‐100 ablation area: +2.2 ma‐1 [‘75‐ ’95] (Rivera and Casassa, 1999)

Remote Sensing Technology Institute 8 Jorge Montt Glacier: ice surface thinning and front retreat

. Area: 500 km². Length: 41 km. . Ice thinning up to 18 ma‐1 concentrated below 900 m a.s.l. (near equilibrium line) where the glacier flows in a steep bed and temperatures are higher. Front retreat: 1.9 km (173 ma‐1). . Thinning rate of ‐3.3 ma‐1 (average on whole glacier) and ‐18 ma‐1 at lower elevations [1975 – 2000]. Front retreat: ‐8.5 km (340 ma‐1) (NASA, CECS)

. Front retreat >800 ma‐1 [Feb. 2010 – Jan. 2011] (Rivera et al. [1])

[1] Rivera, A., Koppes, M., Bravo, C., Aravena, J. C., “Little Ice Age advance and retreat of Glaciar Jorge Montt, Chilean Centro de Estudios Cientificos (CECS), Chile Patagonia”, Climate of the Past, 8, pp. 403‐414, 2012.

Remote Sensing Technology Institute 9 Jorge Montt: ice elevation change 2000 ‐ 2011

Front Feb. 2000 A

1.9 km Front May 2011

(3)

N B (2) ∆h=‐120 m H=603 m

+250 (1) ∆h=‐98 m B H=790 m +125

0m (3) ∆h=‐28 m H=1300 m (1) (2)

‐125 ICESat A Remote Sensing Technology Institute Front retreat 1.9 km 10 ‐250 N Glacier mask and Area Elevation Distribution Jorge Montt . SRTM DEM (yr. 2000) used as reference . Glacier mask: improvement of Randolph Glacier Inventory (RGI) with: • LANDSAT 7 ETM (year: 2001‐2003)  NDSI = (b2‐b5)/(b2+b5) Occidental • SRTM DEM (glacier fronts) O‘ Higgins . Glacier area (yr. 2000)  12870 km²

Pio XI

Viedma Area – Elevation Distribution (AED) for SRTM DEM (2000) 1400 1300 AED yr. 2000 AED yr. 2000 for TDM coverage 1200

Upsala 1100 1000 900 800 [km²] 3600 700 Ameghino 600 Area 500 P. Moreno 2700 400 300 200 1800 100 Grey SRTM 0 DEM 900 yr. 2000 Tyndall Bin area > 80 km² Altitude [m]

0 25 50 0 m Remote Sensing Technology Institute 11 km N Glacier mask and Area Elevation Distribution Jorge Montt . SRTM DEM (yr. 2000) used as reference . Glacier mask: improvement of Randolph Glacier Inventory (RGI) with: • LANDSAT 7 ETM (year: 2001‐2003)  NDSI = (b2‐b5)/(b2+b5) Occidental • SRTM DEM (glacier fronts) O‘ Higgins . Glacier area (yr. 2000)  12870 km² . Glacier area covered with TDM data  11940 km² (92.8%)

Pio XI . Glacier area with missing TDM data  930 km² (7.2%)

Viedma Area – ElevationGlacier Distribution area not covered (AED) byfor TDM SRTM (%) DEM (2000) 1400100 1300 GlacierAED area yr. 2000not covered by TDM (%) 90 AED yr. 2000 for TDM coverage 1200 80 Upsala 1100 100070 900 60 800

[km²]

% 70050 Ameghino 600 Area 40 500 P. Moreno 40030 30020 200 10010 Grey 0

Tyndall Bin area > 80 km² Altitude [m]

0 25 50 Remote Sensing Technology Institute 12 km N SPI: mass balance Jorge Montt . Mean dh/dt for each altitude bin (20 m) computed on bin area covered by TDM

Occidental

O‘ Higgins

Pio XI

Viedma Mean Elevation Change Rate (dh/dt) 4 300 Mean Elevation Change Rate 3 Area Elevation Distribution yr. 2000 250 Upsala 2 200 1

+8 0 150 [km²]

Ameghino ‐1 dh/dt [m/yr] P. Moreno 100 Area +4 ‐2 50 0m a‐1 ‐3 Grey ‐4 0 0

‐4 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 3400 3600 Tyndall Altitude [m]

0 25 50 ‐8 Remote Sensing Technology Institute 13 km N SPI: mass balance Jorge Montt . Mean dh/dt for each altitude bin (20 m) computed on bin area covered by TDM . Mean dV/dt = (dh/dt) * (AED of yr 2000)  scaling data up to entire glacier surface

. dM/dt = (dV/dt) * ρice. Ice density  ρice= 900 kg/m³ Occidental . Overall mass balance: O‘ Higgins

Time SPI total area Area covered by Mean dh/dt (area Total dV/dt Total dM/dt period TDM weighted) Pio XI 2000 – 12868.15 km² 11941.78 km² ‐0.902 m/yr ‐11.605 km³/yr ‐10.444 Gt/yr 2011/‘12

Viedma Mean Volume Change Rate (dV/dt) 0,3 Mean Volume Change Rate 0,2 Upsala

0,1

+8 0 Ameghino

P. Moreno dV/dt‐ [km³/yr] 0,1 +4

‐0,2 0m a‐1 Grey ‐0,3 0

‐4 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 3400 3600 Tyndall Altitude [m]

0 25 50 ‐8 Remote Sensing Technology Institute 14 km N SPI: mass balance Jorge Montt . Mean dh/dt for each altitude bin (20 m) computed on bin area covered by TDM . Mean dV/dt = (dh/dt) * (AED of yr 2000)  scaling data up to entire glacier surface

. dM/dt = (dV/dt) * ρice. Ice density  ρice= 900 kg/m³ Occidental . Global mass balance: O‘ Higgins

Time SPI total area Area covered by Mean dh/dt (area Total dV/dt Total dM/dt period TDM weighted) Pio XI 2000 – 12868.15 km² 11941.78 km² ‐0.902 m/yr ‐11.605 km³/yr ‐10.444 Gt/yr 2011/‘12

Viedma Mean Mass Change Rate (dM/dt) 0,25 Mean Mass Change Rate 0,2

0,15 Upsala 0,1

0,05

+8 0 Ameghino ‐0,05 dM/dt [Gt/yr] P. Moreno +4 ‐0,1 ‐0,15

0m a‐1 ‐0,2 Grey ‐0,25 0 200 400 600 800

‐4 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 3400 3600 Tyndall Altitude [m]

0 25 50 ‐8 Remote Sensing Technology Institute 15 km Gran Campo Nevado (53°S): ice elevation change

N Analysis by: Björn Sass, FAU Erlangen

W E . Area GCN Icefield + adjacent glaciers [2007]: 252.6 km² S (Schneider et al, 2007) 1.1 km h . TanDEM‐X: 2 descending scenes, dual baseline processing . Temporal baseline: Feb. 2000 –Feb. 2012 ∆h=‐80 m Noroeste Gl. . Front retreat of Noroeste Glacier: ‐1.1 km (‐91.6 ma‐1) . ∆h = ‐80 m (6.7 ma‐1) near main calving front of Noroeste Glacier (100 m a.s.l.)

Remote Sensing Technology Institute 16 Conclusions

. TanDEM‐X and SRTM data were used to derive temporal trends of ice elevation change in the SPI and GCN for the period 2000 – 2011/’12. . An overall mass balance was derived, necessary for estimating the contribution of the Patagonia Icefields to sea level rise. . Contrasting behavior is observed on different glaciers with respect to changes in ice elevation and front position. This emphasizes the importance of spatially detailed repeated observations in order to understand the complexity of glacier response to climate change. . The method will be applied to the remaining Patagonian icefields (NPI, Cordillera Darwin). . Near future work: • Error budget estimation for the DEM difference • Estimation of ice mass loss due to frontal retreat, including subsurface ice loss

Thank you for your attention!

Remote Sensing Technology Institute 17 Upsala: ice elevation change 2011 ‐ 2000

N . Front retreat: ‐3.4 km [Feb. 2000 – May 2011] (0.3 m a‐1)

. ∆h>‐160 m (14.5 m a‐1) near main calving front . ∆h~‐110 m (10 m a‐1) on tributaries Bertacchi and Cono . ∆h=‐30 to ‐40 m (10 m a‐1) near equilibrium line (1200 m a.s.l) . Dynamic thinning due to acceleration and large calving events. ‐1 Viedma Gl. . Field survey: ‐9.5 to ‐14 m a [‘91 ‐ ‘93] (Naruse et al., 1997)

∆h=‐50 m ICESat ∆h=‐35 m

+160

+80 Cono Gl. Bertacchi Gl. Upsala Gl. 0m Cono Gl.

‐80 ∆h=‐160 m 3.4 km Bertacchi Gl. ‐160 Remote Sensing Technology Institute 18 Grey, Tyndall, Asia, Amalia: ice elevation changes

N . Tyndall Gl.: • ‐6.3 ma‐1 on terminus [2000‐’11] • ‐4.9 ma‐1 average [’93‐’99] (Raymond et al. 2000)

Frias ∆h=‐55 m . Grey Gl.: Asia • ‐5.4 ma‐1 on east terminus ∆h=0 m • ‐3.6 ma‐1 on main terminus ‐1 Amalia Grey • ‐6.5 ma on west terminus ∆h=‐10 m ∆h=‐60 m

HPS 38 +100 ∆h=‐65 m +50 Photo: Dana Floricioiu, DLR Grey Glacier, front. 0m

‐50 HPS 38 ∆h=‐75 m Tyndall ∆h=‐70 m ‐100

Remote Sensing Technology Institute 19 O’ Higgins, Bernardo, Occidental: ice elevation changes

Bernardo N ∆h=‐50 m Bravo ∆h=‐75 m Tempano ∆h=‐50 m

Occidental ∆h=‐55 m

O’ Higgins ∆h=‐25 m +100

Greve +50 ∆h=‐45 m HPS 8 0m ∆h=‐120 m

Chico ‐50 HPS 9 ∆h=‐35 m ∆h=‐30 m ‐100 . O’ Higgins: ‐2.5 ma‐1 on terminus [2000‐’12] . Glacier with strong historical retreat trend: 14.6 km during the period 1896 ‐ 1995 (Casassa et al. , 1997)

Remote Sensing Technology Institute 20 SPI ice elevation and volume change 2000 – 2011/2012

Total SPI area Area covered by Time Volume Mass change [km2] TanDEM‐X [km2] period change rate [Gt yr‐1 ] rate [km3 yr‐1] 12826.39 11354.67 2000 ‐ ‐11.83 ‐10.65 2011/12

Author Data Area Time period Volume Mass change source covered change rate [Gt yr‐1 ] rate [km3 yr‐1] Jacob et al, GRACE SPI and NPI Jan. 2003 ‐ ‐23 ±9 2012 Dec. 2010 Ivins et al, GRACE SPI and NPI Jan. 2003 – ‐26 ±6 2011 Mar. 2009 Rignot et al, DEM diff. SPI 1975 ‐ 2000 ‐13.0 ± 0.8 2003 (cartogra 1995 ‐ 2000 ‐38.7 ± 4.4 phy & SRTM) Willis et al, DEM diff SPI 2000 – 2012 ‐22.2±1.3 ‐20.0 ± 1.17 GRL, 2012 (ASTER & NPI 2000 – 2011 ‐4.9±0.3 ‐4.4 ± 0.27 SRTM)

EO & cryosphere science, ESA ESRIN, Frascati, 13‐16 Nov.2012 21 Perito Moreno and Ameghino: ice velocities

N . Area: Perito Moreno: 258 km², Ameghino: 76 km².  Ice velocity map • 3 May 2011 / 14 May 2011 (11 days) Ameghino Gl. . P. Moreno and Ameghino: • light seasonal variability • constant annual mean velocity (2008‐ 2012)

Perito Moreno Gl. • agreement with GPS and InSAR [1]

6.0

4.5

3.0 m/day

1.5 Photo: H. Steinberg [1] Stuefer, M., H. Rott, and P. Skvarca, “Glaciar Perito Moreno, 0.0 Patagonia: climate sensitivities and glacier characteristics preceding the 2003/04 and 2005/06 damming events,” Journal of Glaciology, 53 (180), pp. 3‐16, 2007.

Remote Sensing Technology Institute 22 Upsala Glacier: ice velocities January 2008 October 2008 May 2009 October 2009 Upsala Glacier area: 902 km²

N

February 2010 July 2010 March 2011 October 2011

10.0

7.5

5.0 m/day

2.5

2.1 km 0.0 Front: Jan. ‘08 Remote Sensing Technology Institute 23 Pio XI: ice velocity

N 5.0 . Largest calving glacier of SPI . Area: 1265 km². Length: 64 km. 3.75 . Tidewater glacier

2.5 m/day  Ice velocity map 1.25 • 3 May 2011 / 14 May 2011 ‐1 0.0 • Velocities from 1 to 5 md at the bend.

Photo: Ralf Rosenau, TU Dresden

Remote Sensing Technology Institute 24 Shuttle Radar Topography Mission (SRTM)

. NASA/DLR mission: semi‐global DEM by means of single pass interferometry . Acquisition: 11 ‐ 22 February 2000 . Coverage: 56°S to 60°N . Bistatic interferometric system: • C‐band: full coverage • X‐band: partial coverage (gaps) . C‐band DEM spatial posting: 3arcsec(90 m) . Nominal vertical accuracy (90% linear point‐to‐point error): • Relative: 10 m / Absolute: 16 m . Nominal horizontal accuracy (90% circular error): • Relative: 15 m / Absolute: 20 m . DEM available at DFD is calibrated with ICESat altitude tie points  increased accuracy

. ICESat (Ice, Cloud, and land Elevation Satellite)  NASA mission 2003 ‐ 2009 • Geoscience Laser Altimeter System (GLAS) space borne LIDAR altimeter • Footprint: 65 m of diameter. Sampling distance: 170 m.

Remote Sensing Technology Institute 25 TanDEM‐X and ITP

. Objective: global DEM by means of single pass interferometry . Bistatic interferometric system in X‐band . Launch: June 2010 . Nominal relative vertical accuracy (90% linear point‐to‐point error): 2 m (less than 20% slopes), 4 m (more than 20% slopes) . Nominal relative horizontal accuracy (90% circular error): 4 m . Integrated TanDEM‐X Processor (ITP) used to generate RawDEMs from CoSSC data . RawDEM mean asbolute vertical error globally below 3 m . 19 RawDEMs processedwithITP (acquired: 2011 and early 2012) • 4 RawDEMs  dual baseline phase unwrapping

2100 m

TanDEM‐X DEM: O’ Higgins Glacier (SPI) 300 m

Remote Sensing Technology Institute 26