Monitoring Lakes Surface Water Velocity with SAR: A Feasibility Study on Lake Garda, Italy
The SAR Doppler frequencies are directly related to the motion of the scatterers in the illuminated area and have already been used in marine applications to monitor moving water surfaces. Here we investigate the possibility of retrieving surface water velocity from SAR Doppler analysis in medium-si...
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doaj-2f0310bb606244b0bfdf24a628fa5a4d2021-06-30T23:57:14ZengMDPI AGRemote Sensing2072-42922021-06-01132293229310.3390/rs13122293Monitoring Lakes Surface Water Velocity with SAR: A Feasibility Study on Lake Garda, ItalyMarina Amadori0Virginia Zamparelli1Giacomo De Carolis2Gianfranco Fornaro3Marco Toffolon4Mariano Bresciani5Claudia Giardino6Francesca De Santi7IREA-CNR, Institute for Electromagnetic Sensing of the Environment-National Research Council of Italy, 20133 Milan, ItalyIREA-CNR, Institute for Electromagnetic Sensing of the Environment-National Research Council of Italy, 80128 Naples, ItalyIREA-CNR, Institute for Electromagnetic Sensing of the Environment-National Research Council of Italy, 20133 Milan, ItalyIREA-CNR, Institute for Electromagnetic Sensing of the Environment-National Research Council of Italy, 80128 Naples, ItalyDepartment of Civil, Environmental and Mechanical Engineering, University of Trento, 38123 Trento, ItalyIREA-CNR, Institute for Electromagnetic Sensing of the Environment-National Research Council of Italy, 20133 Milan, ItalyIREA-CNR, Institute for Electromagnetic Sensing of the Environment-National Research Council of Italy, 20133 Milan, ItalyIREA-CNR, Institute for Electromagnetic Sensing of the Environment-National Research Council of Italy, 20133 Milan, ItalyThe SAR Doppler frequencies are directly related to the motion of the scatterers in the illuminated area and have already been used in marine applications to monitor moving water surfaces. Here we investigate the possibility of retrieving surface water velocity from SAR Doppler analysis in medium-size lakes. ENVISAT images of the test site (Lake Garda) are processed and the Doppler Centroid Anomaly technique is adopted. The resulting surface velocity maps are compared with the outputs of a hydrodynamic model specifically validated for the case study. Thermal images from MODIS Terra are used in support of the modeling results. The surface velocity retrieved from SAR is found to overestimate the numerical results and the existence of a bias is investigated. In marine applications, such bias is traditionally removed through Geophysical Model Functions (GMFs) by ascribing it to a fully developed wind waves spectrum. We found that such an assumption is not supported in our case study, due to the small-scale variations of topography and wind. The role of wind intensity and duration on the results from SAR is evaluated, and the inclusion of lake bathymetry and the SAR backscatter gradient is recommended for the future development of GMFs suitable for lake environments.https://www.mdpi.com/2072-4292/13/12/2293SARDoppler Centroid Anomalyinland watersphysical limnologyhydrodynamics |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Marina Amadori Virginia Zamparelli Giacomo De Carolis Gianfranco Fornaro Marco Toffolon Mariano Bresciani Claudia Giardino Francesca De Santi |
spellingShingle |
Marina Amadori Virginia Zamparelli Giacomo De Carolis Gianfranco Fornaro Marco Toffolon Mariano Bresciani Claudia Giardino Francesca De Santi Monitoring Lakes Surface Water Velocity with SAR: A Feasibility Study on Lake Garda, Italy Remote Sensing SAR Doppler Centroid Anomaly inland waters physical limnology hydrodynamics |
author_facet |
Marina Amadori Virginia Zamparelli Giacomo De Carolis Gianfranco Fornaro Marco Toffolon Mariano Bresciani Claudia Giardino Francesca De Santi |
author_sort |
Marina Amadori |
title |
Monitoring Lakes Surface Water Velocity with SAR: A Feasibility Study on Lake Garda, Italy |
title_short |
Monitoring Lakes Surface Water Velocity with SAR: A Feasibility Study on Lake Garda, Italy |
title_full |
Monitoring Lakes Surface Water Velocity with SAR: A Feasibility Study on Lake Garda, Italy |
title_fullStr |
Monitoring Lakes Surface Water Velocity with SAR: A Feasibility Study on Lake Garda, Italy |
title_full_unstemmed |
Monitoring Lakes Surface Water Velocity with SAR: A Feasibility Study on Lake Garda, Italy |
title_sort |
monitoring lakes surface water velocity with sar: a feasibility study on lake garda, italy |
publisher |
MDPI AG |
series |
Remote Sensing |
issn |
2072-4292 |
publishDate |
2021-06-01 |
description |
The SAR Doppler frequencies are directly related to the motion of the scatterers in the illuminated area and have already been used in marine applications to monitor moving water surfaces. Here we investigate the possibility of retrieving surface water velocity from SAR Doppler analysis in medium-size lakes. ENVISAT images of the test site (Lake Garda) are processed and the Doppler Centroid Anomaly technique is adopted. The resulting surface velocity maps are compared with the outputs of a hydrodynamic model specifically validated for the case study. Thermal images from MODIS Terra are used in support of the modeling results. The surface velocity retrieved from SAR is found to overestimate the numerical results and the existence of a bias is investigated. In marine applications, such bias is traditionally removed through Geophysical Model Functions (GMFs) by ascribing it to a fully developed wind waves spectrum. We found that such an assumption is not supported in our case study, due to the small-scale variations of topography and wind. The role of wind intensity and duration on the results from SAR is evaluated, and the inclusion of lake bathymetry and the SAR backscatter gradient is recommended for the future development of GMFs suitable for lake environments. |
topic |
SAR Doppler Centroid Anomaly inland waters physical limnology hydrodynamics |
url |
https://www.mdpi.com/2072-4292/13/12/2293 |
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