scholarly journals Evaluation of MERIS Chlorophyll-a Retrieval Processors in a Complex Turbid Lake Kasumigaura over a 10-Year Mission

2017 ◽  
Vol 9 (10) ◽  
pp. 1022 ◽  
Author(s):  
Salem Salem ◽  
Marie Strand ◽  
Hiroto Higa ◽  
Hyungjun Kim ◽  
Komatsu Kazuhiro ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Lake Kasumigaura ◽  
Turbid Lake

scholarly journals Inter-Comparison of Methods for Chlorophyll-a Retrieval: Sentinel-2 Time-Series Analysis in Italian Lakes

2021 ◽  
Vol 13 (12) ◽  
pp. 2381
Author(s):  
Milad Niroumand-Jadidi ◽  
Francesca Bovolo ◽  
Lorenzo Bruzzone ◽  
Peter Gege
Keyword(s):  
Chlorophyll A ◽  
Central Italy ◽  
Large Lakes ◽  
Chl A ◽  
Subalpine Lakes ◽  
Pros And Cons ◽  
High Consistency ◽  
Semi Empirical ◽  
Turbid Lake ◽  
Sentinel 2

Different methods are available for retrieving chlorophyll-a (Chl-a) in inland waters from optical imagery, but there is still a need for an inter-comparison among the products. Such analysis can provide insights into the method selection, integration of products, and algorithm development. This work aims at inter-comparison and consistency analyses among the Chl-a products derived from publicly available methods consisting of Case-2 Regional/Coast Colour (C2RCC), Water Color Simulator (WASI), and OC3 (3-band Ocean Color algorithm). C2RCC and WASI are physics-based processors enabling the retrieval of not only Chl-a but also total suspended matter (TSM) and colored dissolved organic matter (CDOM), whereas OC3 is a broadly used semi-empirical approach for Chl-a estimation. To pursue the inter-comparison analysis, we demonstrate the application of Sentinel-2 imagery in the context of multitemporal retrieval of constituents in some Italian lakes. The analysis is performed for different bio-optical conditions including subalpine lakes in Northern Italy (Garda, Idro, and Ledro) and a turbid lake in Central Italy (Lake Trasimeno). The Chl-a retrievals are assessed versus in situ matchups that indicate the better performance of WASI. Moreover, relative consistency analyses are performed among the products (Chl-a, TSM, and CDOM) derived from different methods. In the subalpine lakes, the results indicate a high consistency between C2RCC and WASI when aCDOM(440) < 0.5 m−1, whereas the retrieval of constituents, particularly Chl-a, is problematic based on C2RCC for high-CDOM cases. In the turbid Lake Trasimeno, the extreme neural network of C2RCC provided more consistent products with WASI than the normal network. OC3 overestimates the Chl-a concentration. The flexibility of WASI in the parametrization of inversion allows for the adaptation of the method for different optical conditions. The implementation of WASI requires more experience, and processing is time demanding for large lakes. This study elaborates on the pros and cons of each method, providing guidelines and criteria on their use.

Parameterization of chlorophyll a-specific absorption coefficients and effects of their variations in a highly eutrophic lake: a case study at Lake Kasumigaura, Japan

Hydrobiologia ◽  
2012 ◽  
Vol 691 (1) ◽  
pp. 157-169 ◽  
Author(s):  
Kazuya Yoshimura ◽  
Nobuhiro Zaitsu ◽  
Yuta Sekimura ◽  
Bunkei Matsushita ◽  
Takehiko Fukushima ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Eutrophic Lake ◽  
Lake Kasumigaura ◽  
Absorption Coefficients ◽  
Specific Absorption

High-Resolution electron crystallography of the light-harvesting chlorophyll-a/b protein complex from chloroplast membranes

1990 ◽  
Vol 48 (1) ◽  
pp. 610-610
Author(s):  
Werner Kühlbrandt ◽  
Da Neng Wang ◽  
K.H. Downing
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Chlorophyll A ◽  
Protein Complex ◽  
Structural Integrity ◽  
Light Harvesting ◽  
Lhc Ii ◽  
Diffraction Patterns ◽  
Difference Fourier ◽  
2D Crystals

The light-harvesting chlorophyll-a/b protein complex (LHC-II) is the most abundant membrane protein in the chloroplasts of green plants where it functions as a molecular antenna of solar energy for photosynthesis. We have grown two-dimensional (2d) crystals of the purified, detergent-solubilized LHC-II . The crystals which measured 5 to 10 μm in diameter were stabilized for electron microscopy by washing with a 0.5% solution of tannin. Electron diffraction patterns of untilted 2d crystals cooled to 130 K showed sharp spots to 3.1 Å resolution. Spot-scan images of 2d crystals were recorded at 160 K with the Berkeley microscope . Images of untilted crystals were processed, using the unbending procedure by Henderson et al . A projection map of the complex at 3.7Å resolution was generated from electron diffraction amplitudes and high-resolution phases obtained by image processing .A difference Fourier analysis with the same image phases and electron diffraction amplitudes recorded of frozen, hydrated specimens showed no significant differences in the 3.7Å projection map. Our tannin treatment therefore does not affect the structural integrity of the complex.

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