XII INCONTRO DEI DOTTORANDI IN ECOLOGIA E · PDF fileThe first part of my PhD thesis work is...
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ATMOSPHERIC CORRECTION BIO-OPTICAL MODEL Rrs The use of remote sensing for the detection of water quality parameters requires an accurate estimation of remote sensing reflectance (Rrs),a key physical quantity for parameters retrieval. The Rrs signal generally only accounts for around 10% of the total signal recorded at sensor, while atmospheric contribution, due to gases and aerosol presence, is predominant. The first part of my PhD thesis work is focused on the analysis of different techniques for atmospheric correction of satellite images of inland and coastal waters. In the second part, the best technique will be thus selected and applied in time series imagery for assessing water quality by using bio-optical models. The target areas include lakes and coastal waters with different trophic conditions. The images acquired by the latest generation of satellite sensors are used to monitor both large and small water bodies. • Landsat-8 and Sentinel-2 for their high spatial resolution (10-30 m) and • Sentinel-3, for its high temporal resolution (daily frequency) XII INCONTRO DEI DOTTORANDI IN ECOLOGIA E SCIENZE DEI SISTEMI ACQUATICI, Trieste, 15 – 17 Giugno 2016 Cazzaniga I. 1,2 , Colombo R. 2 , Bassani C. 3 , Giardino C. 1 , Bresciani M. 1 (1) CNR- Institute for Electromagnetic Sensing of the Environment, Milano, Italy (2) Remote Sensing of Environmental Dynamics Lab (DISAT), University of Milano-Bicocca, Milano, Italy (3) CNR- Institute of Atmospheric Pollution Research, Roma, Italy E-mail address: [email protected] Atmospheric techniques considered in this work are all based on radiative transfer theory which include the physic of aerosols, whose characterisation can be based on both pre-defined models or on in situ measurements. The following RT codes are used for comparative analysis to retrieve the Rrs: ACOLITE 1 , SEADAS 2 , 6SV 3 , Atcor 4 . Bio-optical models are then used to estimate water quality parameters from Rrs. In this work the bio-optical model implemented in BOMBER 5 will be used. It estimates chlorophyll-a and total suspended matter concentrations and coloured dissolved organic matter. WATER QUALITY MAPS Acknowledgments Field campaigns were founded by GLaSS (7 th Framework Programme, proj. N. 313256). Landsat-8 data available from the U.S. Geological Survey. • Sun-photometers measurements, available in the study areas are exploited to accurately describe aerosol characteristics. • Rrs spectra and water quality parameters are also gathered from dedicated field campaigns. First results show accurate description of aerosol allows a more accurate estimation of Rrs, key quantity for water parameters retrieval. AOD daily mean time series (below) and AERONET sun-photometers located in Sirmione on Lake Garda (left). Lake Garda Bibliography 1. Vanhellemont Q., Ruddick K., Remote Sens. Environ. 2014, 145, 105–115. 2. Franz B.A. et al., J. Appl. Remote Sens. 2015, 9(1), 096070. 3. Kotchenova S.Y. et al., Appl. Opt. 2006, 45, 6762–6774. 4. Richter R., Atmospheric/Topographic Correction for Satellite Imagery. 5. Giardino C. et al., Comput. Geosci. 2012, 45, 313–318. Suspended matter (top) and chl-a (bottom) maps obtained from the a Landsat-8 image (10/6/2014): different values of AOD or different aerosol models could bring different results. SPM mg/m 3 0 5 2003 2011 6sv – default continental model 6sv – photometer parametrization ACOLITE 6sv – default continental model 6sv – photometer parametrization ACOLITE chl-a mg/m 3 0 2 In situ st2 st3 Chl-a (mg/m 3 ) 0.72 0.96
Transcript of XII INCONTRO DEI DOTTORANDI IN ECOLOGIA E · PDF fileThe first part of my PhD thesis work is...
ATMOSPHERIC CORRECTION
BIO-OPTICAL MODEL
Rrs
The use of remote sensing for the detection of water quality parameters requires an accurate estimation of remote sensing reflectance (Rrs),a keyphysical quantity for parameters retrieval. The Rrs signal generally only accounts for around 10% of the total signal recorded at sensor, whileatmospheric contribution, due to gases and aerosol presence, is predominant.The first part of my PhD thesis work is focused on the analysis of different techniques for atmospheric correction of satellite images of inland andcoastal waters. In the second part, the best technique will be thus selected and applied in time series imagery for assessing water quality by usingbio-optical models. The target areas include lakes and coastal waters with different trophic conditions.
The images acquired by the latestgeneration of satellite sensors areused to monitor both large and smallwater bodies.• Landsat-8 and Sentinel-2 for their
high spatial resolution (10-30 m)and
• Sentinel-3, for its high temporalresolution (daily frequency)
XII INCONTRO DEI DOTTORANDI IN ECOLOGIA E SCIENZE DEI SISTEMI ACQUATICI, Trieste, 15 – 17 Giugno 2016
Cazzaniga I.1,2, Colombo R.2, Bassani C.3, Giardino C.1, Bresciani M.1
(1) CNR- Institute for Electromagnetic Sensing of the Environment, Milano, Italy(2) Remote Sensing of Environmental Dynamics Lab (DISAT), University of Milano-Bicocca, Milano, Italy
(3) CNR- Institute of Atmospheric Pollution Research, Roma, ItalyE-mail address: [email protected]
Atmospheric techniques considered in this work are all based on radiativetransfer theory which include the physic of aerosols, whosecharacterisation can be based on both pre-defined models or on in situmeasurements.The following RT codes are used for comparative analysis to retrieve theRrs: ACOLITE1, SEADAS2, 6SV3, Atcor4.
Bio-optical models are then used to estimate water quality parametersfrom Rrs. In this work the bio-optical model implemented in BOMBER5
will be used. It estimates chlorophyll-a and total suspended matterconcentrations and coloured dissolved organic matter.
WATER QUALITY MAPS
AcknowledgmentsField campaigns were founded by GLaSS (7th Framework Programme, proj. N. 313256). Landsat-8 data available from the U.S. Geological Survey.
• Sun-photometers measurements,available in the study areas are exploitedto accurately describe aerosolcharacteristics.
• Rrs spectra and water quality parametersare also gathered from dedicated fieldcampaigns.
First results show accurate description of aerosol allows a more accurateestimation of Rrs, key quantity for water parameters retrieval.
AOD daily mean time series (below) and AERONET sun-photometers located in Sirmione
on Lake Garda (left).
Lake Garda
Bibliography1. Vanhellemont Q., Ruddick K., Remote Sens. Environ. 2014, 145, 105–115.2. Franz B.A. et al., J. Appl. Remote Sens. 2015, 9(1), 096070.3. Kotchenova S.Y. et al., Appl. Opt. 2006, 45, 6762–6774.4. Richter R., Atmospheric/Topographic Correction for Satellite Imagery.5. Giardino C. et al., Comput. Geosci. 2012, 45, 313–318.
Suspended matter (top) and chl-a (bottom) mapsobtained from the a Landsat-8 image (10/6/2014): differentvalues of AOD or differentaerosol models could bringdifferent results.
SPM mg/m30 52003 2011
6sv –
defau
lt co
ntin
entalm
od
el
6sv –
ph
oto
meter
param
etrization
AC
OLITE
6sv –
defau
lt co
ntin
entalm
od
el
6sv –
ph
oto
meter
param
etrization
AC
OLITE
chl-a mg/m30 2
In situ st2 st3
Chl-a (mg/m3)
0.72 0.96
