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

2020 ◽  
Author(s):  
Rongxing Li ◽  
Hongwei Li ◽  
Tong Hao ◽  
Gang Qiao ◽  
Haotian Cui ◽  
...  

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.

2021 ◽  
Vol 15 (7) ◽  
pp. 3083-3099
Author(s):  
Rongxing Li ◽  
Hongwei Li ◽  
Tong Hao ◽  
Gang Qiao ◽  
Haotian Cui ◽  
...  

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.


Author(s):  
H. Cui ◽  
R. Li ◽  
H. Li ◽  
T. Hao ◽  
G. Qiao ◽  
...  

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.


2018 ◽  
Vol 59 (76pt1) ◽  
pp. 1-9 ◽  
Author(s):  
Yang Yuande ◽  
Ke Hao ◽  
Wang Zemin ◽  
Li Fei ◽  
Ding Minghu ◽  
...  

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.


2020 ◽  
Author(s):  
Tong Hao ◽  
Rongxing Li ◽  
Gang Qiao ◽  
Hongwei Li ◽  
Gang Hai ◽  
...  

&lt;p&gt;NASA launched the Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) satellite on September 15, 2018. The photon counting altimeter of ICESat-2 is designed to provide centimeter-level accuracy surface elevation observations and is expected to reduce the uncertainty of the estimated sea level rise contribution from Antarctica. The ICESat-2 mission team has conducted a validation campaign and stated that the data released in the first year met the design requirements. In this study we designed and implemented an independent validation scheme along the 36&lt;sup&gt;th&lt;/sup&gt; CHINARE (Chinese Antarctic Research Expedition) route in East Antarctica as a different validation site. 1) GNSS data collected during a week in December 2019 along the 500-km traverse from the Zhongshan Station to the Taishan Station are compared with the crossover ICESat-2 points. The GNSS receiver (CHC i70) was fixed on the roof of the Pisten Bully Polar 300 and cooperated with 5 GNSS base stations spaced every ~100 km. 2) To investigate photons reflectivity we used a rectangular area target for each site at three Chinese stations, with considerations of the reflectivity and satellite tracks. 22 upward-looking optical prisms were installed to capture photons with known ground elevations. 3) Finally, we utilized DJI Phantom 4 unmanned aerial vehicles (UAVs) to obtain centimeter-level DEMs of ice sheet surface and compare with the ICESat-2 points. The results are analyzed for several applications and compared against the published validation results of the mission team.&lt;/p&gt;


2019 ◽  
Vol 59 (1) ◽  
pp. 39-48 ◽  
Author(s):  
A. S. Boronina ◽  
S. V. Popov ◽  
G. V. Pryakhina

Broknes Peninsula (the area of the Progress station, Larsemann Hills, Princess Elisabeth Land, East Antarctica) is characterized by the presence of well developed hydrographic network consisting of reservoirs located not only in the bedrock, but also inside the glacier thickness and on its surface. As a rule, most of them are dammed by natural snowice weirs, which are often destroyed during the Antarctic summer. As a result of this process, glacial water outburst may occur. In the course of the summer season of the 63‑th Russian  Antarctic Expedition (RAE) intensive hydrological field observations were carried out for identification and comprehensive investigation of potentially outburstprone reservoirs located in close proximity to Russian and foreign stations and field bases (area of the  Progress station and the field base Law-Racovita). The works included: the organization of temporary pile and depth-stick water gauge stations, mapping positions of the shoreline of lakes (reservoirs), bathymetric surveys of them, as well as field hydro-chemical express analyses. Based on the results of the level measurement, it was found that most of the lakes of the oasis are characterized by a sharp drop in the height of the water surface level associated with the breakthroughs. In particular, the authors witnessed the breakthrough of the Discussion Lake, which occurred on January 22, 2018. This resulted in decrease of the water level by 0.95 m. Based on the data of the bathymetric surveys, the morphometric (hydrometric) characteristics of the lakes were calculated and detailed grids (regular net of rectangular matrices, in the nodes of which some effective values of the mapped values are located) were formed for the following numerical modeling of hypothetical and real breakthroughs of water bodies and construction of estimated hydrographs.


1982 ◽  
Vol 3 ◽  
pp. 32-35 ◽  
Author(s):  
R. L. Brooks

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.


1988 ◽  
Vol 11 ◽  
pp. 219
Author(s):  
Shinji Mae

The Japanese Antarctic Research Expedition (JARE) has conducted glaciological studies on Mizuho Plateau since 1981. We have already reported that the ice sheet flowing from Mizuho Plateau into Shirase Glacier is thinning at a rate of about 70 cm/year and that the profile of the distribution of basal shear stress is similar to that of surging glaciers. A 5 year glaciological programme on Mizuho Plateau and in east Queen Maud Land is now being carried out and we have obtained the following new results: (1) The ice sheet in the down-stream region (where ice elevation is lower than about 2400 m) is thinning, based on measurements of horizontal and vertical flow velocity, strain-rate, the slope of the ice surface, the accumulation rate and densification of snow. (2) δ18O analysis of deep ice cores obtained at Mizuho Station (2240 m a.s.l.) and point G2 (1730 m a.s.l.) shows that δ18O increased about 200 years ago at Mizuho Station and about 400 years ago at point G2. If we can assume that the increase in δ18O is caused by the thinning of the ice sheet, then this result means that this thinning propagates to up-stream areas. (3) Radio-echo-sounding measurements on Mizuho Plateau show that the ice base in the down-stream region is wet. This supports the result described in (1), since the basal sliding due to a wet base causes ice-sheet thinning, as proposed in our previous studies. In summary, a possible explanation of ice-sheet variation on Mizuho Plateau is as follows: the thinning of the ice sheet, caused by the basal sliding due to basal ice melting, started at Shirase Glacier and has been propagating up-stream to reach its present position. A simple calculation, using flow velocities, shows that the thinning started at Shirase Glacier about 1500–2000 years ago.


1979 ◽  
Vol 24 (90) ◽  
pp. 483
Author(s):  
David J. Drewry

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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