scholarly journals Evaluation of historic and operational satellite radar altimetry missions for constructing consistent long-term lake water level records

2021 ◽  
Vol 25 (3) ◽  
pp. 1643-1670
Author(s):  
Song Shu ◽  
Hongxing Liu ◽  
Richard A. Beck ◽  
Frédéric Frappart ◽  
Johanna Korhonen ◽  
...  
Keyword(s):  
Water Level ◽  
Lake Water ◽  
Small Lakes ◽  
Radar Altimetry ◽  
Lake Water Level ◽  
Systematic Biases ◽  
Data Missing ◽  
Satellite Radar ◽  
Satellite Radar Altimetry

Abstract. A total of 13 satellite missions have been launched since 1985, with different types of radar altimeters on board. This study intends to make a comprehensive evaluation of historic and currently operational satellite radar altimetry missions for lake water level retrieval over the same set of lakes and to develop a strategy for constructing consistent long-term water level records for inland lakes at global scale. The lake water level estimates produced by different retracking algorithms (retrackers) of the satellite missions were compared with the gauge measurements over 12 lakes in four countries. The performance of each retracker was assessed in terms of the data missing rate, the correlation coefficient r, the bias, and the root mean square error (RMSE) between the altimetry-derived lake water level estimates and the concurrent gauge measurements. The results show that the model-free retrackers (e.g., OCOG/Ice-1/Ice) outperform the model-based retrackers for most of the missions, particularly over small lakes. Among the satellite altimetry missions, Sentinel-3 gave the best results, followed by SARAL. ENVISAT has slightly better lake water level estimates than Jason-1 and Jason-2, but its data missing rate is higher. For small lakes, ERS-1 and ERS-2 missions provided more accurate lake water level estimates than the TOPEX/Poseidon mission. In contrast, for large lakes, TOPEX/Poseidon is a better option due to its lower data missing rate and shorter repeat cycle. GeoSat and GeoSat Follow-On (GFO) both have an extremely high data missing rate of lake water level estimates. Although several contemporary radar altimetry missions provide more accurate lake level estimates than GFO, GeoSat was the sole radar altimetry mission, between 1985 and 1990, that provided the lake water level estimates. With a full consideration of the performance and the operational duration, the best strategy for constructing long-term lake water level records should be a two-step bias correction and normalization procedure. In the first step, use Jason-2 as the initial reference to estimate the systematic biases with TOPEX/Poseidon, Jason-1, and Jason-3 and then normalize them to form a consistent TOPEX/Poseidon–Jason series. Then, use the TOPEX/Poseidon–Jason series as the reference to estimate and remove systematic biases with other radar altimetry missions to construct consistent long-term lake water level series for ungauged lakes.

scholarly journals Evaluation of Historic and Operational Satellite Radar Altimetry Missions for Constructing Consistent Long-term Lake Water Level Records

2020 ◽  
Author(s):  
Song Shu ◽  
Hongxing Liu ◽  
Richard A. Beck ◽  
Frédéric Frappart ◽  
Johanna Korhonen ◽  
...  
Keyword(s):  
Water Level ◽  
Lake Water ◽  
Small Lakes ◽  
Radar Altimetry ◽  
Lake Water Level ◽  
Systematic Biases ◽  
Data Missing ◽  
Satellite Radar ◽  
Satellite Radar Altimetry

Abstract. Thirteen satellite missions have been launched since 1985, with different types of radar altimeters onboard. This study intends to make a comprehensive evaluation of historic and currently operational satellite radar altimetry missions for lake water level retrieval over the same set of lakes and to develop a strategy for constructing consistent long-term water level records for inland lakes at global scale. The lake water level estimates produced by different retracking algorithms (retrackers) of the satellite missions were compared with the gauge measurements over twelve lakes in four countries. The performance of each retracker was assessed in terms of the data missing rate, the correlation coefficient r, the bias, and the Root Mean Square Error (RMSE) between the altimetry-derived lake water level estimates and the concurrent gauge measurements. The results show that the model-free retrackers (e.g. OCOG/Ice-1/Ice) outperform the model-based retrackers for all missions, particularly over small lakes. Among the satellite altimetry missions, Sentinel-3 gave the best results, followed by SARAL. ENVISat has slightly better lake water level estimates than Jason-1 and -2, but its data missing rate is higher. For small lakes, ERS-1 and ERS-2 missions provided more accurate lake water level estimates than Topex/Poseidon mission. In contrast, for large lakes Topex/Poseidon is a better option due to its lower data missing rate and shorter repeat cycle. GeoSat and GeoSat Follow-On (GFO) both have extremely high data missing rate. Although several contemporary radar altimetry missions provide more accurate lake level estimates than GFO, GeoSat was the sole radar altimetry mission between 1985 and 1990 that provided the lake water level estimates. With a full consideration of the performance and the operational duration, the best strategy for constructing long-term lake water level records should be a two-step bias correction and normalization procedure. In the first step, use Jason-2 as the initial reference to estimate the systematic biases with Topex/Poseidon, Jason-1 and Jason-3 and then normalize them to form a consistent Topex/Poseidon-Jason series. Then, use Topex/Poseidon-Jason series as the reference to estimate and remove systematic biases with other radar altimetry missions to construct consistent long-term lake water level series for ungauged lakes.

Indus river water level monitoring using satellite radar altimetry

2020 ◽  
Author(s):  
Arjumand Z. Zaidi ◽  
Stefano Vignudelli ◽  
Zarif Khero ◽  
Badar M.K. Ghauri ◽  
Ramsha Muzaffer ◽  
...  
Keyword(s):  
Water Level ◽  
River Water ◽  
Indus River ◽  
Radar Altimetry ◽  
Satellite Radar ◽  
Satellite Radar Altimetry ◽  
Level Monitoring ◽  
Water Level Monitoring

scholarly journals Publisher’s Note: Intercomparison and validation of continental water level products derived from satellite radar altimetry

2013 ◽  
Vol 6 (1) ◽  
pp. 060103 ◽  
Author(s):  
Martina Ričko ◽  
Charon M. Birkett ◽  
James A. Carton ◽  
Jean-François Crétaux
Keyword(s):  
Water Level ◽  
Radar Altimetry ◽  
Satellite Radar ◽  
Satellite Radar Altimetry

scholarly journals Satellite radar altimetry for monitoring small river and lakes in Indonesia

2014 ◽  
Vol 11 (3) ◽  
pp. 2825-2874 ◽  
Author(s):  
Y. B. Sulistioadi ◽  
K.-H. Tseng ◽  
C. K. Shum ◽  
H. Hidayat ◽  
M. Sumaryono ◽  
...  
Keyword(s):  
Southeast Asia ◽  
Water Level ◽  
Satellite Altimetry ◽  
Water Bodies ◽  
Radar Altimeter ◽  
Radar Altimetry ◽  
Inland Water ◽  
Rivers And Lakes ◽  
Satellite Radar ◽  
Satellite Radar Altimetry

Abstract. Remote sensing and satellite geodetic observations are capable for hydrologic monitoring of freshwater resources. For the case of satellite radar altimetry, limited temporal resolutions (e.g., satellite revisit period) prohibit the use of this method for a short (< weekly) interval monitoring of water level or discharge. On the other hand, the current satellite radar altimeter footprints limit the water level measurement for rivers wider than 1 km. Some studies indeed reported successful retrieval of water level for small-size rivers as narrow as 80 m; however, the processing of current satellite altimetry signals for small water bodies to retrieve accurate water levels, remains challenging. To address this scientific challenge, this study tries to monitor small (40–200 m width) and medium-sized (200–800 m width) rivers and lakes using satellite altimetry through identification and choice of the over-water radar waveforms corresponding to the appropriately waveform-retracked water level. This study addresses the humid tropics of Southeast Asia, specifically in Indonesia, where similar studies do not yet exist and makes use Level 2 radar altimeter measurements generated by European Space Agency's (ESA's) Envisat (Environmental Satellite) mission. This experiment proves that satellite altimetry provides a good alternative, or the only means in some regions, to measure the water level of medium-sized river (200–800 m width) and small lake (extent < 1000 km2) in Southeast Asia humid tropic with reasonable accuracy. In addition, the procedure to choose retracked Envisat altimetry water level heights via identification or selection of standard waveform shapes for inland water is recommended and should be a standard measure especially over small rivers and lakes. This study also found that Ice-1 is not necessarily the best retracker as reported by previous studies, among the four standard waveform retracking algorithms for Envisat radar altimetry observing inland water bodies.

scholarly journals Satellite radar altimetry for monitoring small rivers and lakes in Indonesia

2015 ◽  
Vol 19 (1) ◽  
pp. 341-359 ◽  
Author(s):  
Y. B. Sulistioadi ◽  
K.-H. Tseng ◽  
C. K. Shum ◽  
H. Hidayat ◽  
M. Sumaryono ◽  
...  
Keyword(s):  
Satellite Altimetry ◽  
Water Levels ◽  
Water Bodies ◽  
Small Rivers ◽  
Small Lakes ◽  
Radar Altimetry ◽  
Small Water ◽  
Waveform Retracking ◽  
Satellite Radar ◽  
Satellite Radar Altimetry

Abstract. Remote sensing and satellite geodetic observations are capable of hydrologic monitoring of freshwater resources. Although satellite radar altimetry has been used in monitoring water level or discharge, its use is often limited to monitoring large rivers (>1 km) with longer interval periods (>1 week) because of its low temporal and spatial resolutions (i.e., satellite revisit period). Several studies have reported successful retrieval of water levels for small rivers as narrow as 40 m. However, processing current satellite altimetry signals for such small water bodies to retrieve water levels accurately remains challenging. Physically, the radar signal returned by water bodies smaller than the satellite footprint is most likely contaminated by non-water surfaces, which may degrade the measurement quality. In order to address this scientific challenge, we carefully selected the waveform shapes corresponding to the range measurement resulting from standard retrackers for the European Space Agency's (ESA's) Envisat (Environmental Satellite) radar altimetry. We applied this approach to small (40–200 m in width) and medium-sized (200–800 m in width) rivers and small lakes (extent <1000 km2) in the humid tropics of Southeast Asia, specifically in Indonesia. This is the first study that explored the ability of satellite altimetry to monitor small water bodies in Indonesia. The major challenges in this study include the size of the water bodies that are much smaller than the nominal extent of the Envisat satellite footprint (e.g., ~250 m compared to ~1.7 km, respectively) and slightly smaller than the along-track distance (i.e., ~370 m). We addressed this challenge by optimally using geospatial information and optical remote sensing data to define the water bodies accurately, thus minimizing the probability of non-water contamination in the altimetry measurement. Considering that satellite altimetry processing may vary with different geographical regions, meteorological conditions, or hydrologic dynamic, we further evaluated the performance of all four Envisat standard retracking procedures. We found that satellite altimetry provided a good alternative or the only means in some regions of measuring the water level of medium-sized rivers and small lakes with high accuracy (root mean square error (RMSE) of 0.21–0.69 m and a correlation coefficient of 0.94–0.97). In contrast to previous studies, we found that the commonly used Ice-1 retracking algorithm was not necessarily the best retracker among the four standard waveform retracking algorithms for Envisat radar altimetry observing inland water bodies. As a recommendation, we propose to include the identification and selection of standard waveform shapes to complete the use of standard waveform retracking algorithms for Envisat radar altimetry data over small and medium-sized rivers and small lakes.

Sign in / Sign up

Export Citation Format

Share Document