A Modified Empirical Retracker for Lake Level Estimation Using Cryosat-2 SARin Data

Han, Xue; Liao, Jingjuan; Zhao, Lifei

doi:10.3390/w10111584

Cited by 8 publications

(17 citation statements)

References 26 publications

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“…The gradual shrinkage before 1999 and rapid expansion since 2000 at Memar Co were similar to most endorheic lakes on the TP (e.g., Lei et al, 2014). Many studies have shown that precipitation has increased significantly on the interior TP since the late 1990s (Yang et al, 2014;Treichler et al, 2019), which has led to the significant lake expansion (Lei et al, 2014). Between 1972 and 2018, the lake level and water storage of Memar Co increased by 10.4 ± 0.6 m and 1.62 ± 0.11 Gt (from 1.86 to 3.49 Gt), respectively.…”

Section: Impact Of the Meltwater On The Inter-annual Lake Level Changes In Memar Comentioning

confidence: 56%

“…ICESat altimetry data were processed after Li et al (2014) and were used to examine water level variations between 2003 and 2009. CryoSat-2 data were processed after Xue et al (2018) and were used to investigate water level variations between 2010 and 2018. Both lakes were observed by the ICESat satellite two or three times a year (Phan et al, 2012) and by the CryoSat-2 satellite every 2 or 3 months (Kleinherenbrink et al, 2015;Jiang et al, 2017).…”

Section: Satellite Observationmentioning

confidence: 99%

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Response of downstream lakes to Aru glacier collapses on the western Tibetan Plateau

et al. 2021

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Abstract. The lower parts of two glaciers in the Aru range on the western Tibetan Plateau (TP) collapsed on 17 July and 21 September 2016, respectively, causing fatal damage to local people and their livestock. The giant ice avalanches, with a total volume of 150 × 106 m3, had almost melted by September 2019 (about 30 % of the second ice avalanche remained). The impact of these extreme disasters on downstream lakes has not been investigated yet. Based on in situ observation, bathymetry survey and satellite data, we explore the impact of the ice avalanches on the two downstream lakes (i.e., Aru Co and Memar Co) in terms of lake morphology, water level and water temperature in the subsequent 4 years (2016–2019). After the first glacier collapse, the ice avalanche slid into Aru Co along with a large amount of debris, which generated great impact waves in Aru Co and significantly modified the lake's shoreline and underwater topography. An ice volume of at least 7.1 × 106 m3 was discharged into Aru Co, spread over the lake surface and considerably lowered its surface temperature by 2–4 ∘C in the first 2 weeks after the first glacier collapse. Due to the large amount of meltwater input, Memar Co exhibited more rapid expansion after the glacier collapses (2016–2019) than before (2003–2014), in particular during the warm season. The melting of ice avalanches was found to contribute to about 23 % of the increase in lake storage between 2016 and 2019. Our results indicate that the Aru glacier collapses had both short-term and long-term impacts on the downstream lakes and provide a baseline in understanding the future lake response to glacier melting on the TP under a warming climate.

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Section: Impact Of the Meltwater On The Inter-annual Lake Level Changes In Memar Comentioning

confidence: 56%

Section: Satellite Observationmentioning

confidence: 99%

Response of downstream lakes to Aru glacier collapses on the western Tibetan Plateau

et al. 2021

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“…Lake boundaries were extracted in false color image by manual delineation using ArcGIS 9.2 software. ICESat and Cryosat-2 satellite altimetry data were used to detect lake level changes between 2003 and 2017 (Li et al, 2014;Xue et al, 2018). Memar Co was monitored by ICESat satellite twice a year (pre-monsoon and post monsoon seasons) between 2003 and 2009 (Phan et al, 2012;Zhang et al, 2011).…”

Section: Satellite Observationmentioning

confidence: 99%

Tracking the impacts of the Aru glacier collapses on downstream lakes

Lei

Tian

Sheng

et al. 2020

Preprint

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Abstract. Two giant glaciers at the Aru range, western Tibetan Plateau, collapsed suddenly on 17 July and 21 September 2016, respectively, causing fatal damage to local people and their livestock. The ice avalanches, with a total volume of 150 × 106 m3, had almost melted by September 2019. Based on in-situ observation, bathymetry survey and satellite data, here we show the impacts of the two glacier collapses on the downstream lakes, the outflow Aru Co and the terminal Memar Co, in terms of lake morphology, water level and water temperature in the subsequent four years (2016–2019). After the first glacier collapse, the ice avalanche slid into Aru Co along with a large amount of debris, which significantly modified the lake’s shoreline and bathymetry. Lake surface temperature (LST) at Aru Co and Memar Co exhibited a significant decrease of 2–4 oC in the first 1–2 weeks after the first glacier collapse due to the intruding ice into Aru Co and its melting. Memar Co significantly deepened by 12.5 m between 2000 and 2018, with accelerated lake level increase after the glacier collapses. Memar Co expanded rapidly at a rate of 0.80 m/yr between 2016 and 2019, which is about 30 % higher than the average rising rate between 2003 and 2014. The meltwater from ice avalanches was found to contribute to about 26.4 % of the increase in lake storage between 2016 and 2019. This study implies that the Aru glacier collapses had long-term and dramatic impacts on the downstream lakes.

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“…Using synthetic aperture radar (SAR) technology, Cryosat-2, and Sentinel-3 can monitor inland water at a finer along-track resolution, and with interferometric SAR technologies, Cryosat-2 can determine the cross-track angle of arrival of the radar echoes [19], [20]. Although the data produced using these techniques improve the quality of observation points to some extent, there is still a problem of complex waveform pollution [4], [8], [21].…”

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confidence: 99%

“…Villadsen et al [8] developed a multiple waveform persistent peak (MWaPP) algorithm by assuming that one peak reflected by the inland water occurs in all waveforms, but other peaks reflected by other bright targets or off-nadir water bodies are less likely to be persistent, which could deal effectively with complex multipeak waveforms affected by land. Xue et al [4] focused on Cryosat-2 synthetic aperture radar interferometer (SARin) waveforms and developed an improved ImpMWaPP retracker using a robust statistical method to obtain a reference water level and identifying the water-surface signal of the waveform based on this reference water level, thereby improving the processing performance for multipeak waveforms. Huang et al [22] used an improved waveform retracking, called the TIC (50% Threshold and Ice-1 Combined algorithm) to derive water This work is licensed under a Creative Commons Attribution 4.0 License.…”

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confidence: 99%

Improved Lake Level Estimation From Radar Altimeter Using an Automatic Multiscale-Based Peak Detection Retracker

Chen

Liao

Chao

2021

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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Satellite radar altimetry is an important technique for monitoring the water levels of oceans and inland water bodies, especially in areas where in-situ data are sparse or nonexistent. This study presented an automatic multiscale-based peak detection retracker (AMPDR). The retracker can extract a robust threshold level for each track, then the stable lake level can be obtained from the multipeak waveforms using a shortest-path algorithm. Additionally, the retracker can be used for mountain lakes and for flat lakes, and is also suitable for many kinds of altimetry data, such as those of Cryosat-2, Sentinel-3, and Jason-2/3. To validate the lake levels derived by the AMPDR retracker, the in-situ gauge data of seven lakes in the Tibetan Plateau and two lakes in a flat area are used. Moreover, seven existing retrackers are compared to evaluate the performance of the proposed AMPDR retracker. The results suggest that AMPDR can efficiently process many complex multipeak waveforms, and the AMPDR has the lowest mean of all track standard deviations over all lakes. The root-mean-squared error (RMSE) of the lake level time series obtained using AMPDR is the lowest over several lakes: The mean RMSEs of all the lakes overpassed by Cryosat-2, Sentinel-3, and Jason-2/3 are 0.149, 0.139, and 0.181 m, respectively. The AMPDR retracker is easy to implement, computationally efficient, and can give a height estimate for even the most contaminated waveforms.

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A Modified Empirical Retracker for Lake Level Estimation Using Cryosat-2 SARin Data

Cited by 8 publications

References 26 publications

Response of downstream lakes to Aru glacier collapses on the western Tibetan Plateau

Response of downstream lakes to Aru glacier collapses on the western Tibetan Plateau

Tracking the impacts of the Aru glacier collapses on downstream lakes

Improved Lake Level Estimation From Radar Altimeter Using an Automatic Multiscale-Based Peak Detection Retracker

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