FIELD VALIDATION OF ICESAT-2 DATA ALONG CHINARE ROUTE IN EAST ANTARCTICA

Abstract. A field validation of the ICESat-2 elevation data has been conducted along the CHINARE (CHINese Antarctic Research Expedition) route near the Amery Ice Shelf in East Antarctica from December 2019 to February 2020. The study area covers a 520 km traverse from the coastal Zhongshan Station to the inland Taishan Station. We deployed two roof-mounted GNSS receivers to collect elevation data along the traverse and reduced them to the ice surface height with measured boresight parameters. The comparison of the ICESat-2 data (Release 003) with the high-precision ground-based GNSS along the traverse shows that the elevations of ATL06 ice surface products are accurate to 1.5 cm with 9.1 cm precision, and the elevations of ATL03 photon events are accurate to 4.3 cm with 8.5 cm precision. The validation results indicated high accuracy of 1.5–4.3 cm of ICESat-2 data, which provides the potentials to observe and evaluate the low-level mass changes in East Antarctica. The methodology and hardware system can be improved to execute a continuous assessment of ICESat-2 data in the following mission period.

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Assessment of ICESat-2 ice surface elevations over the Chinese Antarctic Research Expedition (CHINARE) route, East Antarctica, based on coordinated multi-sensor observations

The Cryosphere ◽

10.5194/tc-15-3083-2021 ◽

2021 ◽

Vol 15 (7) ◽

pp. 3083-3099

Author(s):

Rongxing Li ◽

Hongwei Li ◽

Tong Hao ◽

Gang Qiao ◽

Haotian Cui ◽

...

Keyword(s):

Satellite System ◽

East Antarctica ◽

Continuous Assessment ◽

Zhongshan Station ◽

Ice Cloud ◽

Ice Surface ◽

Amery Ice Shelf ◽

Gnss Receivers ◽

Antarctic Research ◽

Global Navigation Satellite

Abstract. We present the results of an assessment of ice surface elevation measurements from NASA's Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) along the CHINARE (CHINese Antarctic Research Expedition) route near the Amery Ice Shelf in East Antarctica. The validation campaign was designed and implemented in cooperation with the 36th CHINARE Antarctic expedition from December 2019 to February 2020. The assessment of the ICESat-2 geolocated photon product (ATL03) and land ice elevation product (ATL06) was performed based on coordinated multi-sensor observations using two roof-mounted kinematic global navigation satellite system (GNSS) receivers, two line arrays of corner cube retroreflectors (CCRs), two sets of retroreflective target sheets (RTSs), and two unmanned aerial vehicles (UAVs) with cameras. This systematic validation of the ICESat-2 data covered a variety of Antarctic ice surface conditions along the 520 km traverse from the coastal Zhongshan Station to the inland Taishan Station. This comprehensive investigation is complementary to the 750 km traverse validation of flat inland Antarctica containing a 300 km latitude traverse of 88∘ S by the mission team (Brunt et al., 2021). Overall, the validation results show that the elevation of the ATL06 ice surface points is accurate to 1.5 cm with a precision of 9.1 cm along the 520 km CHINARE route. The elevation of the ATL03 photons has an offset of 2.1 cm from a GNSS-surveyed CCR and is accurate to 2.5 cm with a precision of 2.7 cm as estimated by using RTSs. The validation results demonstrate that the estimated ICESat-2 elevations are accurate to 1.5–2.5 cm in this East Antarctic region, which shows the potential of the data products for eliminating mission biases by overcoming the uncertainties in the estimation of mass balance in East Antarctica. It should be emphasized that the results based on the CCR and RTS techniques can be improved by further aggregation of observation opportunities for a more robust assessment. The developed validation methodology and sensor system can be applied for continuous assessment of ICESat-2 data, especially for calibration against potential degradation of the elevation measurements during the later operation period.

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Assessment of ICESat-2 ice surface elevations over the CHINARE route, East Antarctica, based on coordinated multi-sensor observations

10.5194/tc-2020-330 ◽

2020 ◽

Author(s):

Rongxing Li ◽

Hongwei Li ◽

Tong Hao ◽

Gang Qiao ◽

Haotian Cui ◽

...

Keyword(s):

East Antarctica ◽

Continuous Assessment ◽

Antarctic Region ◽

Comprehensive Investigation ◽

Zhongshan Station ◽

Ice Surface ◽

Operation Period ◽

Antarctic Expedition ◽

Gnss Receivers ◽

Antarctic Research

Abstract. This paper presents the results of the assessment of ICESat-2 ice surface elevations along the CHINARE (CHINese Antarctic Research Expedition) route in East Antarctica. The validation campaign was designed and implemented in cooperation with the 36th CHINARE Antarctic expedition from December 2019 to February 2020. The assessment of the ICESat-2 ATL03 and ATL06 data was performed based on coordinated multi-sensor observations using two roof-mounted kinematic GNSS receivers, two line arrays of corner cube retroreflectors (CCRs), two sets of retroreflective target sheets (RTSs), and two unmanned aerial vehicles (UAVs) with cameras. This systematic validation of the ICESat-2 data covered a variety of Antarctic ice surface conditions along the 520 km traverse from the coastal Zhongshan Station to the inland Taishan Station. This comprehensive investigation is complementary to the 750 km traverse validation of flat inland Antarctica containing a 300 km latitude traverse of 88° S by the mission team in a previous study. Overall, the validation results show that the elevation of the ATL06 ice surface points is accurate to 1.1 cm with a precision of 9.7 cm along the 520 km CHINARE route. The elevation of the ATL03 photons has an offset of 2.4 cm from a GNSS-surveyed CCR, and is accurate to 2.5 cm with a precision of 2.7 cm as estimated by using RTSs. The validation results demonstrate that the estimated ICESat-2 elevations are accurate to 1.1–2.5 cm in this East Antarctic region, which is important for overcoming the uncertainties in the estimation of mass balance in East Antarctica. The developed validation methodology and sensor system can be improved for continuous assessment of ICESat-2 data, especially during the later operation period.

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Decadal GPS-derived ice surface velocity along the transect from Zhongshan Station to and around Dome Argus, East Antarctica, 2005–16

Annals of Glaciology ◽

10.1017/aog.2018.3 ◽

2018 ◽

Vol 59 (76pt1) ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

Yang Yuande ◽

Ke Hao ◽

Wang Zemin ◽

Li Fei ◽

Ding Minghu ◽

...

Keyword(s):

High Resolution ◽

Ground Truth ◽

East Antarctica ◽

Surface Velocity ◽

Interferometric Synthetic Aperture Radar ◽

Gps Measurements ◽

Zhongshan Station ◽

Ice Surface ◽

Ice Velocity ◽

Ice Sheet Dynamics

ABSTRACTUsing repeat GPS measurements during 2005–16, we calculated and updated two-dimensional high-resolution decadal ice surface velocity estimates along the traverse route from Zhongshan Station to and around Dome Argus, East Antarctica. Along the 71 sites of the transect, the magnitudes of ice velocity increased from near 0 in Dome Argus to 1, 10 and ~100 m a−1 at the sites DT416, DT333 and LT980, respectively. The comparison between GPS and interferometric synthetic aperture radar (InSAR) derived results agree well when the magnitude of the ice surface velocities is faster than 5 m a−1, and disagree for slower flow velocities. A scale value 1.15 and 0.12 can be applied to InSAR derived results over this region with ice surface velocity larger and <5 m a−1, respectively. We attributed the cause of the discrepancy to the insensitivity of InSAR to the magnitude of low ice surface velocities, thus confirming the importance of GPS fieldwork-based ground truth high-resolution ice velocity estimates to constrain ice-sheet dynamics.

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Satellite Altimeter Results Over East Antarctica

Annals of Glaciology ◽

10.3189/s0260305500002482 ◽

1982 ◽

Vol 3 ◽

pp. 32-35 ◽

Cited By ~ 2

Author(s):

R. L. Brooks

Keyword(s):

Tracking System ◽

Ice Sheet ◽

East Antarctica ◽

Satellite Altimeter ◽

Ice Shelves ◽

Ice Surface ◽

Operational Lifetime ◽

Waveform Retracking ◽

Better Than

During the operational lifetime of the Seasat altimeter from 3 July to 10 October 1978, more than 450 overflights were made over East Antarctica inland to latitude 72°S. An analysis of selected passes over a variety of ice features demonstrates that the oceanographic altimeter performed surprisingly well over the ice sheet and ice shelves, acquiring useful measurements during approximately 70% of each pass. The altimeter's onboard tracking system dampened out the ice-surface elevations, but post-flight retracking of the stored return waveforms reveals excellent ice-surface details. After waveform retracking, the altimeter repeatability is better than ±1 m.

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Properties of a marine ice layer under the Amery Ice Shelf, East Antarctica

Journal of Glaciology ◽

10.3189/002214309789470941 ◽

2009 ◽

Vol 55 (192) ◽

pp. 717-728 ◽

Cited By ~ 65

Author(s):

Mike Craven ◽

Ian Allison ◽

Helen Amanda Fricker ◽

Roland Warner

Keyword(s):

Sea Water ◽

Average Rate ◽

East Antarctica ◽

Ice Shelf ◽

Closure Rate ◽

Southern Limit ◽

Amery Ice Shelf ◽

Average Porosity ◽

Grounding Line ◽

Ocean Properties

AbstractThe Amery Ice Shelf, East Antarctica, undergoes high basal melt rates near the southern limit of its grounding line where 80% of the ice melts within 240 km of becoming afloat. A considerable portion of this later refreezes downstream as marine ice. This produces a marine ice layer up to 200 m thick in the northwest sector of the ice shelf concentrated in a pair of longitudinal bands that extend some 200 km all the way to the calving front. We drilled through the eastern marine ice band at two locations 70 km apart on the same flowline. We determine an average accretion rate of marine ice of 1.1 ± 0.2 m a−1, at a reference density of 920 kg m−3 between borehole sites, and infer a similar average rate of 1.3 ± 0.2 m a−1 upstream. The deeper marine ice was permeable enough that a hydraulic connection was made whilst the drill was still 70–100 m above the ice-shelf base. Below this marine close-off depth, borehole video imagery showed permeable ice with water-filled cavities and individual ice platelets fused together, while the upper marine ice was impermeable with small brine-cell inclusions. We infer that the uppermost portion of the permeable ice becomes impermeable with the passage of time and as more marine ice is accreted on the base of the shelf. We estimate an average closure rate of 0.3 m a−1 between the borehole sites; upstream the average closure rate is faster at 0.9 m a−1. We estimate an average porosity of the total marine ice layer of 14–20%, such that the deeper ice must have even higher values. High permeability implies that sea water can move relatively freely through the material, and we propose that where such marine ice exists this renders deep parts of the ice shelf particularly vulnerable to changes in ocean properties.

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Collocated OLCI optical imagery and SAR radar altimetry from Sentinel3 for enhanced sea ice surface classification

10.5194/egusphere-egu21-14968 ◽

2021 ◽

Author(s):

Dorsa Nasrollahi Shirazi ◽

Michel Tsamados ◽

Isobel Lawrence ◽

Sanggyun Lee ◽

Thomas Johnson ◽

...

Keyword(s):

Sea Ice ◽

Classification Algorithms ◽

Polar Regions ◽

Radar Altimetry ◽

Imaging Spectrometer ◽

Ice Surface ◽

Ice Roughness ◽

Elevation Data ◽

Optical Imagery ◽

Surface Classification

<p>The Copernicus operational Sentinel-3A since February 2016 and Sentinel-3B since April 2018 build on the CryoSat-2 legacy in terms of their synthetic aperture radar (SAR) mode altimetry providing high-resolution radar freeboard elevation data over the polar regions up to 81N. This technology combined with the Ocean and Land Colour Instrument (OLCI) imaging spectrometer offers the first space-time collocated optical imagery and radar altimetry dataset. We use these joint datasets for validation of several existing surface classification algorithms based on Sentinel-3 altimeter echo shapes. We also explore the potential for novel AI techniques such as convolutional neural networks (CNN) for winter and summer sea ice surface classification (i.e. melt pond fraction, lead fraction, sea ice roughness). For lead surface classification we analyse the winters of 2018/19 and 2019/20 and for summer sea ice feature classification we focus on the Sentinel-3A &3B tandem phase of the summer 2018. We compare our CNN models with other existing surface classification algorithms.</p>

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Modelling the response of the Lambert Glacier–Amery Ice Shelf system, East Antarctica, to uncertain climate forcing over the 21st and 22nd centuries

The Cryosphere ◽

10.5194/tc-8-1057-2014 ◽

2014 ◽

Vol 8 (3) ◽

pp. 1057-1068 ◽

Cited By ~ 20

Author(s):

Y. Gong ◽

S. L. Cornford ◽

A. J. Payne

Keyword(s):

Climate Model ◽

Global Environmental Change ◽

Ice Sheet ◽

Adaptive Mesh ◽

Ocean Model ◽

East Antarctica ◽

Ice Shelf ◽

Amery Ice Shelf ◽

Grounding Line ◽

Lambert Glacier

Abstract. The interaction between the climate system and the large polar ice sheet regions is a key process in global environmental change. We carried out dynamic ice simulations of one of the largest drainage systems in East Antarctica: the Lambert Glacier–Amery Ice Shelf system, with an adaptive mesh ice sheet model. The ice sheet model is driven by surface accumulation and basal melt rates computed by the FESOM (Finite-Element Sea-Ice Ocean Model) ocean model and the RACMO2 (Regional Atmospheric Climate Model) and LMDZ4 (Laboratoire de Météorologie Dynamique Zoom) atmosphere models. The change of ice thickness and velocity in the ice shelf is mainly influenced by the basal melt distribution, but, although the ice shelf thins in most of the simulations, there is little grounding line retreat. We find that the Lambert Glacier grounding line can retreat as much as 40 km if there is sufficient thinning of the ice shelf south of Clemence Massif, but the ocean model does not provide sufficiently high melt rates in that region. Overall, the increased accumulation computed by the atmosphere models outweighs ice stream acceleration so that the net contribution to sea level rise is negative.

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Changes of Wilkins Ice Shelf over the past 15 years and inferences on its stability

The Cryosphere ◽

10.5194/tc-3-41-2009 ◽

2009 ◽

Vol 3 (1) ◽

pp. 41-56 ◽

Cited By ~ 50

Author(s):

M. Braun ◽

A. Humbert ◽

A. Moll

Keyword(s):

Sar Interferometry ◽

Tidal Effects ◽

Ice Shelf ◽

Structural Mapping ◽

Ice Shelves ◽

Ice Surface ◽

Melt Ponds ◽

Elevation Data ◽

Break Up ◽

The Antarctic

Abstract. The Wilkins Ice Shelf is situated on the Antarctic Peninsula, a region where seven ice shelves disintegrated or retreated between 1995 and 2002. This study combines various remote sensing datasets from Wilkins Ice Shelf, with the aim of detecting its present and recent dynamics as well as recent changes. The survey includes structural mapping, ERS-1/2 SAR interferometry and analysis of ICESat GLAS ice surface elevation data. Ice front retreat rates from 1986 to 2008 showed several distinct break-up events, including one in February 2008, when 40% of a part of the ice shelf that connected two islands broke off. Surface elevations have been used to study tidal effects, crack formation and to estimate the ice thickness over the floating area. The derived interferometric velocities cover the south-eastern part of the ice shelf as well as major tributaries and reveal maximum inflow speeds of up to 330 m a−1. We show that drainage of melt ponds into crevasses were of no relevance for the break-up at Wilkins Ice Shelf. Buoyancy forces caused rift formation before the break-up in February 2008. Additionally, the evolution of failure zones of the order of tenths of kilometres in length in pre-conditioned locations at ice rises is shown. Investigation of the current (February 2009) situation shows that about 3100 km2 at the Northern Wilkins Ice Shelf are endangered, however, there is no visible signature that the remaining 8000 km2 are at risk.

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Protists in the marine ice of the Amery Ice Shelf, East Antarctica

Polar Biology ◽

10.1007/s00300-006-0169-7 ◽

2006 ◽

Vol 30 (2) ◽

pp. 143-153 ◽

Cited By ~ 24

Author(s):

D. Roberts ◽

M. Craven ◽

Minghong Cai ◽

I. Allison ◽

G. Nash

Keyword(s):

East Antarctica ◽

Ice Shelf ◽

Amery Ice Shelf

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Ice-Sheet flow in the Vicinity of Southern Victoria Land, Antarctica: Implications for Glacial Chronology

Journal of Glaciology ◽

10.1017/s0022143000014982 ◽

1979 ◽

Vol 24 (90) ◽

pp. 483

Author(s):

David J. Drewry

Keyword(s):

Ice Sheet ◽

East Antarctica ◽

Small Surface ◽

The North ◽

Ice Surface ◽

Glacial Chronology ◽

Victoria Land ◽

Dry Valley ◽

Radio Echo Sounding ◽

Taylor Glacier

Abstract Systematic radio echo-sounding during three seasons since 1971–72 has produced data on the configuration of the ice sheet in East Antarctica. In the sector extending inland from southern Victoria Land, the ice sheet exhibits a large ridge which drives ice towards David Glacier in the north and Mulock and Byrd Glaciers to the south. Within 100 km of the McMurdo dry-valley region soundings along ten sub-parallel lines (c. 10 km apart) provides detail on ice surface and flow patterns at the ridge tip. A small surface dome lies just inland of Taylor Glacier. The surface drops by 100 m or more before rising to join the major ridge in East Antarctica.

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