Δημοσιεύσεις
Δημοσιεύσεις
2020 |
Banks, A. C.; Drakopoulos, P. G.; Chaikalis, S.; Spyridakis, N.; Karageorgis, A. P.; Psarra, S.; V.Taillandier,; D'Ortenzio, F.; Sofianos, S.; de Madron, Xavier Durrieu vol. 11524, Eighth International Conference on Remote Sensing and Geoinformation of the Environment (RSCy2020) Proceedings of SPIE, 2020. Links | BibTeX | Ετικέτες: backscatter, calibration, ocean optics, radiometry, satellite, sensors, water @conference{Banks2020, |
2019 |
Karageorgis, A. P.; Drakopoulos, P. G.; Chaikalis, S.; Lagaria, A.; Spyridakis, N.; S. Psarra, Proc. SPIE The LEVECO project Bio-Optics experiment in the northwestern Levantine Sea: Preliminary results Conference vol. 11174, Seventh International Conference on Remote Sensing and Geoinformation of the Environment (RSCy2019) Proceedings of SPIE, 2019. Links | BibTeX | Ετικέτες: backscatter, ocean optics, particles, reflectivity, remote sensing, sensors, signal attenuation @conference{Karageorgis2019, |
2017 |
Karageorgis, A. P.; Drakopoulos, P. G.; Chaikalis, S.; Spyridakis, N.; Psarra, S. In: Proceedings of SPIE, vol. 10444, no. 1B, 2017. Links | BibTeX | Ετικέτες: backscatter, ocean optics, particles, refractive index, scattering, signal attenuation, water @article{Karageorgis2017, |
Papadopoulou, A.; Drakopoulos, P. G.; Psarra, S.; Karageorgis, A. P.; Lagaria, A.; Spyridakis, N.; Zervakis, Vassilis 3rd International Ocean Colour Science meeting Lisbon Portugal, 2017, (15-19 Μay ). Abstract | Links | BibTeX | Ετικέτες: NE Aegean Sea, ocean colour, ocean optics, remote sensing @conference{Papadopoulou2017, In the Aegean Sea and Eastern Mediterranean there are large discrepancies between in situ and satellite ocean colour derived chlorophyll concentrations. The quantity that is monitored by ocean colour satellites and that can be used in the estimation of chlorophyll concentration is the remote sensing reflectance, defined as the ratio of the water leaving spectral radiance to the downwelling spectral irradiance. It can be determined in the field, with either above or in-water radiance and irradiance measurements. The complex optical properties of the North-East Aegean Sea, including radiance and irradiance, were studied during the AegeanMarTech project. Chlorophyll concentration estimates were derived from simultaneous above and in-water radiometric measurements. These were validated against chlorophyll concentration field data and compared against concurrent MODIS data from which chlorophyll was derived using two simple empirical algorithms. It was found that the MedOC3 algorithm outperforms the operational OC3M-547 algorithm and produces the least bias when compared against HPLC derived in situ chlorophyll. It is concluded that the greatest uncertainty in the inversion arises due to CDOM absorption below the 488 nm band. The reflectance ratios indicated that there is always an excess of yellow matter present in the study area and the water type could not be characterized optically as "typical open ocean" Case 1. |
2015 |
Drakopoulos, P. G.; Banks, A. C.; Kakagiannis, G.; Karageorgis, A. P.; Lagaria, A.; Papadopoulou, A.; Psarra, S.; Spyridakis, N.; Zervakis, V. Estimating chlorophyll concentrations in the optically complex waters of the North Aegean Sea from field and satellite ocean colour measurements Journal Article In: Proceedings of SPIE, vol. 9535, 2015. Abstract | Links | BibTeX | Ετικέτες: algorithm development, MODIS, ocean optics, reflectivity, remote sensing, satellites, water @article{Drakopoulos2015c, In the Aegean Sea and Eastern Mediterranean there are large discrepancies between in situ and satellite ocean colour derived chlorophyll concentrations. The quantity that is monitored by ocean colour satellites and that can be used in the estimation of chlorophyll concentration is the remote sensing reflectance, defined as the ratio of the water leaving spectral radiance to the downwelling spectral irradiance. It can be determined in the field, with either above or in-water radiance and irradiance measurements. The complex optical properties of the North-East Aegean Sea, including radiance and irradiance, were studied during the AegeanMarTech project. Chlorophyll concentration estimates were derived from simultaneous above and in-water radiometric measurements. These were validated against chlorophyll concentration field data and compared against concurrent MODIS data from which chlorophyll was derived using two simple empirical algorithms. It was found that the MedOC3 algorithm outperforms the operational OC3M-547 algorithm and produces the least bias when compared against HPLC derived in situ chlorophyll. It is concluded that the greatest uncertainty in the inversion arises due to CDOM absorption below the 488 nm band. The reflectance ratios indicated that there is always an excess of yellow matter present in the study area and the water type could not be characterized optically as ‘’typical open ocean” Case 1. |
Drakopoulos, P. G.; Banks, A. C.; Kakagiannis, G.; Karageorgis, A. P.; Lagaria, A.; Papadopoulou, A.; Psarra, S.; Spyridakis, N.; Zervakis, V. Proc. 11th Panhel. Symp. Oceanogr. & Fish. 2015, ISBN: 978-960-9798-08-2. Abstract | Links | BibTeX | Ετικέτες: NE Aegean Sea, ocean color, ocean optics, remote sensing @conference{Drakopoulos2015, The optically complex properties of NE Aegean Sea were studied during the AegeanMarTech project. Simultaneous above and in-water ocean colour measurements were validated with chlorophyll concentration field data and compared against concurrent MODIS images. It was found that the Med-OC3 algorithm outperforms the operational OC3M-547 algorithm and produces the least bias when compared against HPLC derived in situ [Chl]. Satellite derived concentrations tend to underestimate [Chl] by >10% at best, the greatest uncertainty arising due to CDOM absorption below the 488 nm band. Relevant reflectance ratios indicated that there is always an excess of yellow mater present in the study area and the water type could not be characterized optically as " typical open ocean " Case 1. Further investigation is under way. |
Papadopoulou, A.; Drakopoulos, P. G.; Karageorgis, A. P.; Spyridakis, N.; Psarra, S.; Banks, A. C.; Zervakis, V. Proc. 11th Panhel. Symp. Oceanogr. & Fish. 2015, ISBN: 978-960-9798-08-2. Abstract | Links | BibTeX | Ετικέτες: absorption, AC-S scattering corrections methods, attenuation, ocean optics @conference{Papadopoulou2015b, Absorption and attenuation data were collected in the North Aegean Sea during the Perseus and AegeanMarTech cruises using the spectral absorption and attenuation meter AC-S (WETLabs, Inc). Instrument drift, temperature, salinity and scattering corrections were applied to obtain accurate results. Negative absorption and attenuation coefficient values were observed at longer wavelengths. A range of methods were used to estimate absorption: the proportional scattering method appears to overestimate, while the flat method to underestimate absorption. The Kirk scattering method was found to provide the most reasonable results. However, further pure water calibrations are necessary to obtain more precise data. |