ORCID Profile
0000-0001-6328-0001
Current Organisation
Leibniz-Institut für Gewässerökologie und Binnenfischerei
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Publisher: MDPI AG
Date: 27-07-2020
DOI: 10.3390/RS12152410
Abstract: Recently, the United States Geological Service (USGS) released a new provisional product which estimates aquatic reflectance from Landsat 8 Operational Land Imager (OLI), called Landsat 8 Provisional Aquatic Reflectance (L8PAR). However, as indicated in the product guide, the use of this product for inland waters needs further verification and improvements. The goal of this study was to determine how the novel L8PAR product performs for different small turbid and eutrophic lakes in Northern Germany compared to in situ measurements of above water remote sensing reflectance (Rrs). For several recent scenes during our monitoring, the L8PAR product failed to produce full data for the lakes of our interest. For the best scene with in situ spectra, L8PAR was not able to retrieve any information for band 1 and not all information for bands 2, 3 and 4. The pixels with valid values for reflectance showed a weak relationship for band 2 (R2 of 0.24) and a medium relationship for bands 3 and 4 (R2 of 0.68 and 0.72, respectively). Compared to other atmospheric correction routines (ACOLITE, C2RCC, C2X, iCOR and L8SR), L8PAR was the only product which was not able to retrieve Rrs for all match up s les. This work provides an evaluation of the L8PAR product for inland waterbodies. Although more analysis and validation need to be conducted, our study suggests that the L8PAR product cannot be used for small inland lakes in its current state and has to be used with care for inland waters in general.
Publisher: Copernicus GmbH
Date: 19-04-2022
DOI: 10.5194/ESSD-14-1857-2022
Abstract: Abstract. Water stable isotopes (δ18O and δ2H) were analyzed in s les collected in lakes, associated with riverine systems in northeastern Germany, throughout 2020. The dataset (Aichner et al., 2021 0.1594/PANGAEA.935633) is derived from water s les collected at (a) lake shores (s led in March and July 2020), (b) buoys which were temporarily installed in deep parts of the lake (s led monthly from March to October 2020), (c) multiple spatially distributed spots in four selected lakes (in September 2020), and (d) the outflow of Müggelsee (s led biweekly from March 2020 to January 2021). At shores, water was s led with a pipette from 40–60 cm below the water surface and directly transferred into a measurement vial, while at buoys a Limnos water s ler was used to obtain s les from 1 m below the surface. Isotope analysis was conducted at IGB Berlin, using a Picarro L2130-i cavity ring-down spectrometer, with a measurement uncertainty of .15 ‰ (δ18O) and .0 ‰ (δ2H). The data give information about the vegetation period and the full seasonal isotope litude in the s led lakes and about spatial isotope variability in different branches of the associated riverine systems.
Publisher: Copernicus GmbH
Date: 07-10-2021
Abstract: Abstract. Water isotopes (δ2H and δ18O) were analyzed in s les collected in lakes associated to riverine systems in northeastern Germany throughout 2020. The dataset (Aichner et al., 2021) is derived from water s les collected at a) lake shores (s led in March and July 2020) b) buoys which were temporarily installed in deep parts of the lake (s led monthly from March to October 2020) c) multiple spatially distributed spots in four selected lakes (s led in September 2020) d) the outflow of Müggelsee (s led biweekly from March 2020 to January 2021). At shores, water was s led with a pipette from 40–60 cm below water surface and directly transferred into a measurement vial, while at deeper parts of the lake a Limnos water s ler was used to obtain s les from 1 m below surface. Isotope analysis was conducted at IGB Berlin, using a Picarro L2130-i cavity ring-down spectrometer. The data give information about the seasonal isotope litude in the s led lakes and about spatial isotope patterns in different branches of the associated riverine systems.
Publisher: MDPI AG
Date: 16-04-2021
DOI: 10.3390/RS13081542
Abstract: Eutrophication of inland waters is an environmental issue that is becoming more common with climatic variability. Monitoring of this aquatic problem is commonly based on the chlorophyll-a concentration monitored by routine s ling with limited temporal and spatial coverage. Remote sensing data can be used to improve monitoring, especially after the launch of the MultiSpectral Instrument (MSI) on Sentinel-2. In this study, we compared the estimation of chlorophyll-a (chl-a) from different bio-optical algorithms using hyperspectral proximal remote sensing measurements, from simulated MSI responses and from an MSI image. For the satellite image, we also compare different atmospheric corrections routines before the comparison of different bio-optical algorithms. We used in situ data collected in 2019 from 97 s ling points across 19 different lakes. The atmospheric correction assessment showed that the performances of the routines varied for each spectral band. Therefore, we selected C2X, which performed best for bands 4 (root mean square error—RMSE = 0.003), 5 (RMSE = 0.004) and 6 (RMSE = 0.002), which are usually used for the estimation of chl-a. Considering all s les from the 19 lakes, the best performing chl-a algorithm and calibration achieved a RMSE of 16.97 mg/m3. When we consider only one lake chain composed of meso-to-eutrophic lakes, the performance improved (RMSE: 10.97 mg/m3). This shows that for the studied meso-to-eutrophic waters, we can reliably estimate chl-a concentration, whereas for oligotrophic waters, further research is needed. The assessment of chl-a from space allows us to assess spatial dynamics of the environment, which can be important for the management of water resources. However, to have an accurate product, similar optical water types are important for the overall performance of the bio-optical algorithm.
Location: Germany
Location: Brazil
Location: United States of America
No related grants have been discovered for Igor Ogashawara.