scholarly journals Improving the Estimation of Water Level over Freshwater Ice Cover using Altimetry Satellite Active and Passive Observations

2020 ◽  
Vol 12 (6) ◽  
pp. 967 ◽  
Author(s):  
Jawad Ziyad ◽  
Kalifa Goïta ◽  
Ramata Magagi ◽  
Fabien Blarel ◽  
Frédéric Frappart
Keyword(s):  
Brightness Temperature ◽  
Water Level ◽  
Open Water ◽  
Ice Cover ◽  
Water Bodies ◽  
Radar Altimeter ◽  
Subarctic Lakes ◽  
Large Lakes ◽  
Water Ice

Owing to its temporal resolution of 10-day and its polar orbit allowing several crossings over large lakes, the US National Aeronautics and Space Administration (NASA) and the French Centre National d’Etudes Spatiales (CNES) missions including Topex/Poseidon, Jason-1/2/3 demonstrated strong capabilities for the continuous and long-term monitoring (starting in 1992) of large and medium-sized water bodies. However, the presence of heterogeneous targets in the altimeter footprint, such as ice cover in boreal areas, remains a major issue to obtain estimates of water level over subarctic lakes of similar accuracy as over other inland water bodies using satellite altimetry (i.e., R ≥ 0.9 and RMSE ≤ 10 to 20 cm when compared to in-situ water stages). In this study, we aim to automatically identify the Jason-2 altimetry measurements corresponding to open water, ice and transition (water-ice) to improve the estimations of water level during freeze and thaw periods using only the point measurements of open water. Four Canadian lakes were selected to analyze active (waveform parameters) and passive (brightness temperature) microwave data acquired by the Jason-2 radar altimetry mission: Great Slave Lake, Lake Athabasca, Lake Winnipeg, and Lake of the Woods. To determine lake surface states, backscattering coefficient and peakiness at Ku-band derived from the radar altimeter waveform and brightness temperature at 18.7 and 37 GHz measured by the microwave radiometer contained in the geophysical data records (GDR) of Jason-2 were used in two different unsupervised classification techniques to define the thresholds of discrimination between open water and ice measurements. K-means technique provided better results than hierarchical clustering based upon silhouette criteria and the Calinski-Harabz index. Thresholds of discrimination between ice and water were validated with the Normalized Difference Snow Index (NDSI) snow cover products of the MODIS satellite. The use of open water threshold resulted in improved water level estimation compared to in situ water stages, especially in the presence of ice. For the four lakes, the Pearson coefficient (r) increased on average from about 0.8 without the use of the thresholds to more than 0.90. The unbiased RMSE were generally lower than 20 cm when the threshold of open water was used and more than 22 cm over smaller lakes, without using the thresholds.

scholarly journals Theoretical study of ice cover phenology at large freshwater lakes based on SMOS MIRAS data

2018 ◽  
Vol 12 (8) ◽  
pp. 2727-2740 ◽  
Author(s):  
Vasiliy Tikhonov ◽  
Ilya Khvostov ◽  
Andrey Romanov ◽  
Evgeniy Sharkov
Keyword(s):  
Brightness Temperature ◽  
Open Water ◽  
Ice Cover ◽  
Freshwater Lakes ◽  
Ice Melt ◽  
Bear Lake ◽  
Ocean Salinity ◽  
Satellite Microwave ◽  
Transportation Routes ◽  
Temperature Time

Abstract. The paper presents a theoretical analysis of seasonal brightness temperature variations at a number of large freshwater lakes: Baikal, Ladoga, Great Bear Lake (GBL), Great Slave Lake (GSL), and Huron, retrieved from Microwave Imaging Radiometer with Aperture Synthesis (MIRAS) data (1.4 GHz) of the Soil Moisture and Ocean Salinity (SMOS) satellite. The analysis was performed using the model of microwave radiation of plane layered heterogeneous nonisothermal medium. The input parameters for the model were real regional climatological characteristics and glaciological parameters of ice cover of the study lakes. Three distinct seasonal brightness temperature time regions corresponding to different phenological phases of the lake surfaces: complete ice cover, ice melt and deterioration, and open water were revealed. The paper demonstrates the possibility to determine the beginning of ice cover deterioration from satellite microwave radiometry data. The obtained results can be useful for setting the operating terms of winter crossings and roads on ice, as with the beginning of ice deterioration, these transportation routes across water bodies (rivers, lakes, water reservoirs) become insecure and cannot be used any more.

scholarly journals Regional melt-pond fraction and albedo of thin Arctic first-year drift ice in late summer

2015 ◽  
Vol 9 (1) ◽  
pp. 255-268 ◽  
Author(s):  
D. V. Divine ◽  
M. A. Granskog ◽  
S. R. Hudson ◽  
C. A. Pedersen ◽  
T. I. Karlsen ◽  
...  
Keyword(s):  
Sea Ice ◽  
Open Water ◽  
Ice Cover ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
First Year ◽  
Surface Type ◽  
Melt Pond ◽  
Melt Ponds

Abstract. The paper presents a case study of the regional (≈150 km) morphological and optical properties of a relatively thin, 70–90 cm modal thickness, first-year Arctic sea ice pack in an advanced stage of melt. The study combines in situ broadband albedo measurements representative of the four main surface types (bare ice, dark melt ponds, bright melt ponds and open water) and images acquired by a helicopter-borne camera system during ice-survey flights. The data were collected during the 8-day ICE12 drift experiment carried out by the Norwegian Polar Institute in the Arctic, north of Svalbard at 82.3° N, from 26 July to 3 August 2012. A set of > 10 000 classified images covering about 28 km2 revealed a homogeneous melt across the study area with melt-pond coverage of ≈ 0.29 and open-water fraction of ≈ 0.11. A decrease in pond fractions observed in the 30 km marginal ice zone (MIZ) occurred in parallel with an increase in open-water coverage. The moving block bootstrap technique applied to sequences of classified sea-ice images and albedo of the four surface types yielded a regional albedo estimate of 0.37 (0.35; 0.40) and regional sea-ice albedo of 0.44 (0.42; 0.46). Random sampling from the set of classified images allowed assessment of the aggregate scale of at least 0.7 km2 for the study area. For the current setup configuration it implies a minimum set of 300 images to process in order to gain adequate statistics on the state of the ice cover. Variance analysis also emphasized the importance of longer series of in situ albedo measurements conducted for each surface type when performing regional upscaling. The uncertainty in the mean estimates of surface type albedo from in situ measurements contributed up to 95% of the variance of the estimated regional albedo, with the remaining variance resulting from the spatial inhomogeneity of sea-ice cover.

scholarly journals Inland Water Bodies Monitoring using Satellite Altimetry over Indian Region

2014 ◽  
Vol XL-8 ◽  
pp. 1035-1041 ◽  
Author(s):  
S. Chander ◽  
D. Ganguly ◽  
A. K. Dubey ◽  
P. K. Gupta ◽  
R. P. Singh ◽  
...  
Keyword(s):  
Water Level ◽  
Satellite Altimetry ◽  
Tide Gauge ◽  
Water Bodies ◽  
High Rate ◽  
Inland Water ◽  
Gps Survey ◽  
Level Information ◽  
Inland Water Bodies

Satellite altimetry for inland water applications has evolved from investigation of water height retrieval to monitoring since last two decades. Altimetry derived reservoir/ river levels can subsequently be used to deal with key inland water resources problems such as flood, rating curve generation for remote locations, reservoir operations, and calibration of river/lake models. In this work 29 inland water bodies were selected over Indian region to monitor from satellite altimetry. First cut selection of potential water bodies was based on availability of altimeter tracks and geographic locations. Then feasibility study was carried out to check the potential of availability of in-situ measurement and scope of GPS survey for final selection. An algorithm is proposed and tested for the waterlevel retrieval over the Ukai Reservoir which fulfil all the necessary requirements. The methodology is based on averaged high rate waveforms, modified retracker and range corrections. The results were then validated with the GPS survey and in-situ tide gauge dataset. SARAL derived water-level information for six different retrackers were compared with the in-situ tide-gauge dataset installed close to the Ukai Dam. Averaged high rate waveforms were analysed for better performance, i.e. single 40 Hz, and multiple 40-Hz. A field trip was conducted on 17th January 2014, same day on the SARAL pass, using two Dual frequency GPS instruments. New improved retracker work best with overall RMSE within the range of 8 cm. The results supports that AltiKa dataset can be utilized for more accurate water level information over inland water bodies.

Water level changes in Swedish lake systems using pixel-specific Sentinel-1 phase change

2021 ◽  
Author(s):  
Saeid Aminjafari ◽  
Fernando Jaramillo
Keyword(s):  
Phase Change ◽  
Water Level ◽  
Open Water ◽  
Water Levels ◽  
Large Lakes ◽  
Radar Altimetry ◽  
Water Level Changes ◽  
Level Data ◽  
Wide Range ◽  
Image Pairs

<p>Sweden has approximately 100,000 lakes covering roughly nine percent of the country’s surface area. These lakes are one of the important sources of fresh water for urban, industrial, and agricultural use, further providing a wide range of ecosystem services. In order to conserve and protect the lakes from the impacts of climate change, hydrologic monitoring should ideally be conducted in all of these lakes. However, it is almost impossible to gauge all of these lakes on a regular basis, due to economical and logistic constraints. Radar altimetry has been successfully used to obtain water levels from specific lakes; however, the technology can only be used in large lakes that are located precisely under the orbit of the satellite, thus excluding most Swedish lakes. We here develop a new procedure based on the application of differential interferometric synthetic aperture radar (DInSAR) on sequential image pairs with short temporal baseline to measure the water level of 36 lakes. We processed Sentinel-1 twin satellite data with 6-day revisiting intervals, pair by pair, from March 2019 to November 2019. In total, we constructed 41 interferograms considering only the pixels with coherence values greater than 0.2 in all interferograms to ensure consistent scattering and good coherence in all images. We found that the pixels located near tree trunks in flat areas or near steep cliffs in mountainous areas showed a steady phase change in all interferograms that could be converted to water level change. In some of these lakes, the water level changes derived from this methodology correlated well with the in-situ water level of the gauge stations provided by the Swedish Meteorological and Hydrological Institute. We believe that this methodology has good potential for monitoring water level data in small lakes that cannot be monitored by radar altimetry, and serves as evidence of the unknown potential of DInSAR to track hydrological changes in open water surfaces.</p>

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 Synergy between Satellite Altimetry and Optical Water Quality Data towards Improved Estimation of Lakes Ecological Status

2021 ◽  
Vol 13 (4) ◽  
pp. 770
Author(s):  
Ave Ansper-Toomsalu ◽  
Krista Alikas ◽  
Karina Nielsen ◽  
Lea Tuvikene ◽  
Kersti Kangro
Keyword(s):  
Water Quality ◽  
European Union ◽  
Water Level ◽  
Satellite Data ◽  
Ecological Status ◽  
Quality Data ◽  
Altimetry Data ◽  
Radar Altimeter ◽  
Water Quality Data

European countries are obligated to monitor and estimate ecological status of lakes under European Union Water Framework Directive (2000/60/EC) for sustainable lakes’ ecosystems in the future. In large and shallow lakes, physical, chemical, and biological water quality parameters are influenced by the high natural variability of water level, exceeding anthropogenic variability, and causing large uncertainty to the assessment of ecological status. Correction of metric values used for the assessment of ecological status for the effect of natural water level fluctuation reduces the signal-to-noise ratio in data and decreases the uncertainty of the status estimate. Here we have explored the potential to create synergy between optical and altimetry data for more accurate estimation of ecological status class of lakes. We have combined data from Sentinel-3 Synthetic Aperture Radar Altimeter and Cryosat-2 SAR Interferometric Radar Altimeter to derive water level estimations in order to apply corrections for chlorophyll a, phytoplankton biomass, and Secchi disc depth estimations from Sentinel-3 Ocean and Land Color Instrument data. Long-term in situ data was used to develop the methodology for the correction of water quality data for the effects of water level applicable on the satellite data. The study shows suitability and potential to combine optical and altimetry data to support in situ measurements and thereby support lake monitoring and management. Combination of two different types of satellite data from the continuous Copernicus program will advance the monitoring of lakes and improves the estimation of ecological status under European Union Water Framework Directive.

scholarly journals Theoretical study of ice cover phenology at large freshwater lakes based on SMOS MIRAS data

2018 ◽  
Author(s):  
Vasiliy Tikhonov ◽  
Ilya Khvostov ◽  
Andrey Romanov ◽  
Evgeniy Sharkov
Keyword(s):  
Brightness Temperature ◽  
Open Water ◽  
Ice Cover ◽  
Freshwater Lakes ◽  
Ice Melt ◽  
Bear Lake ◽  
Ocean Salinity ◽  
Satellite Microwave ◽  
Transportation Routes ◽  
Temperature Time

Abstract. The paper presents a theoretical analysis of seasonal brightness temperature variations at a number of large freshwater lakes – Baikal, Ladoga, Great Bear Lake (GBL), Great Slave Lake (GSL), and Huron – retrieved from Microwave Imaging Radiometer with Aperture Synthesis (MIRAS) data (1.4 GHz) of the Soil Moisture and Ocean Salinity (SMOS) satellite. The analysis was performed using the model of microwave radiation of plane layered heterogeneous nonisothermal medium. The input parameters for the model were real regional climatological characteristics and glaciological parameters of ice cover of the study lakes. Three distinct seasonal brightness temperature time regions corresponding to different phenological phases of the lake surfaces: complete ice cover, ice melt and deterioration, and open water, were revealed. The paper demonstrates the possibility to determine the beginning of ice cover deterioration from satellite microwave radiometry data. The obtained results can be useful for setting the operating terms of winter crossings and roads on ice, since with the beginning of ice deterioration, these transportation routes across water bodies (rivers, lakes, water reservoirs) become insecure and cannot be used any more.

scholarly journals Relationship between specular returns in CryoSat-2 data, surface albedo, and Arctic summer minimum ice extent

Elem Sci Anth ◽  
2018 ◽  
Vol 6 ◽  
Author(s):  
R. Kwok ◽  
G. F. Cunningham ◽  
T. W. K. Armitage
Keyword(s):  
Sea Ice ◽  
Large Scale ◽  
Relative Rate ◽  
Open Water ◽  
Ice Cover ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Radar Altimeter ◽  
Ice Surface ◽  
Summer Minimum

Specular (mirror-like) reflections in radar altimeter returns are sensitive indicators of flat open water in leads and melt ponds within the Arctic sea ice cover. Here we find increased specular and near-specular returns in CryoSat-2 waveforms as the sea ice cover transitions from a high albedo snow-covered surface to a lower albedo surface dominated by ponds from snow melt. During early melt, mid-May to late June, increases in fractional coverage of specular returns (FSR) show spatial correspondence with concurrent decreases in albedo. To examine the utility of FSR, we compared its efficacy with that of satellite-derived albedo in forecasting summer minimum ice extent (SMIE). Regression analysis of the area-averaged FSR (F—SR\documentclass[10pt]{article}\usepackage{wasysym}\usepackage[substack]{amsmath}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage[mathscr]{eucal}\usepackage{mathrsfs}\usepackage{pmc}\usepackage[Euler]{upgreek}\pagestyle{empty}\oddsidemargin -1.0in\begin{document}\[{\bar F}_{SR}\]\end{document}) (2011–2017) shows that ~72% of SMIE variance can be explained by the dates when F—SR\documentclass[10pt]{article}\usepackage{wasysym}\usepackage[substack]{amsmath}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage[mathscr]{eucal}\usepackage{mathrsfs}\usepackage{pmc}\usepackage[Euler]{upgreek}\pagestyle{empty}\oddsidemargin -1.0in\begin{document}\[{\bar F}_{SR}\]\end{document} climbs to 0.5 within two latitudinal bands covering 70–80°N and 80–90°N. The lag between the two crossing dates provides a measure of the relative rate of the poleward progression of melt. Approximately 93% of SMIE variance can be explained by the date when albedo drops to 0.6 in these same latitudinal bands. Standard errors for these regressions are 0.37 and 0.19 × 106 km2, respectively. Calculating the regression coefficients using only 2011–2016, the 2017 SMIE was forecast with residuals of 0.06 (2% of the total extent) and –0.17 × 106 km2 (4%). Using only 2011–2015 yielded residuals that are less than 0.5 × 106 km2 (~10%) in forecasts of both 2016 and 2017 SMIE, demonstrating the robustness of the regression models. Even though large-scale changes in albedo during summer melt is a characteristic feature of the ice surface, available albedo fields have not been directly used in SMIE forecasts. While this CryoSat-2 record is short, these results suggest that both FSR and albedo could be potentially useful for enhancing forecasts of SMIE.

Phytoplankton of cold-water lake ecosystems under the influence of natural and anthropogenic factors

2021 ◽  
pp. 42-49
Author(s):  
Andrey N. Sharov
Keyword(s):  
Heavy Metals ◽  
Cold Water ◽  
Arctic Lakes ◽  
Water Bodies ◽  
The Arctic ◽  
Anthropogenic Factors ◽  
Large Lakes ◽  
Arctic Water ◽  
The North ◽  
Natural And Anthropogenic Factors

Based on the study of the spatio-temporal aspects of the development of phytoplankton in the lakes of the North and North-West of the European territory of Russia (large lakes – Imandra, Onega and Chudsko-Pskovskoye and small lakes of the Arctic and Subarctic), the features of its structure and dynamics under the influence of natural and anthropogenic factors (eutrophication, heavy metal pollution, acidification, thermification). The species composition and quantitative characteristics of phytoplankton of large lakes of the North of Russia, small arctic lakes and lakes of subarctic regions are studied. It has been shown that diatoms predominate in arctic water bodies according to species diversity, and green and diatoms predominate in boreal ones. By biomass, diatoms dominate mainly in all cold-water lakes, with the exception of small arctic lakes, where golden algae lead. The features of the reorganization of phytoplankton in response to the action of anthropogenic factors are revealed. It is proved that in the northern water bodies the complex action of heavy metals and nutrients does not lead to inhibition of phytoplankton, and the effect of acidification in combination with heavy metals enhances the toxic effect of the latter. A feature of the response to acidification is an increase in the variability of the dynamics of the biomass of phytoplankton. It has been shown that in different types of lakes of East Antarctica under severe climate conditions under light and biogenic limitation, redistribution of autotrophic components in the formation of the biota of water bodies occurs: against the background of a decrease in the abundance and diversity of phytoplankton, the role of microphytobenthos and periphyton increases.

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