Merging gauge data and models with satellite data from multiple sources to aid the understanding of long-term trends in chlorophyll-a concentrations

2017 ◽  
Vol 8 (5) ◽  
pp. 419-428 ◽  
Author(s):  
N. Sravanthi ◽  
P. Yunus Ali ◽  
A. C. Narayana
Keyword(s):  
Chlorophyll A ◽  
Satellite Data ◽  
Multiple Sources ◽  
Gauge Data ◽  
Long Term Trends

scholarly journals Assessing the Effect of Tandem Phase Sentinel-3 OLCI Sensor Uncertainty on the Estimation of Potential Ocean Chlorophyll-a Trends

2020 ◽  
Vol 12 (16) ◽  
pp. 2522 ◽  
Author(s):  
Matthew L. Hammond ◽  
Stephanie A. Henson ◽  
Nicolas Lamquin ◽  
Sébastien Clerc ◽  
Craig Donlon
Keyword(s):  
Chlorophyll A ◽  
Probability Distributions ◽  
Temporal Separation ◽  
Future Studies ◽  
Northern Latitudes ◽  
Long Term Trends ◽  
Cross Calibration ◽  
First Time ◽  
Reducing Potential

The Sentinel-3 tandem project represents the first time that two ocean colour satellites have been flown in the same orbit with minimal temporal separation (~30 s), thus allowing them to have virtually identical views of the ocean. This offers an opportunity for understanding how differences in individual sensor uncertainty can affect conclusions drawn from the data. Here, we specifically focus on trend estimation. Observational chlorophyll-a uncertainty is assessed from the Sentinel-3A Ocean and Land Colour Imager (OLCI-A) and Sentinel-3B OLCI (OLCI-B) sensors using a bootstrapping approach. Realistic trends are then imposed on a synthetic chlorophyll-a time series to understand how sensor uncertainty could affect potential long-term trends in Sentinel-3 OLCI data. We find that OLCI-A and OLCI-B both show very similar trends, with the OLCI-B trend estimates tending to have a slightly wider distribution, although not statistically different from the OLCI-A distribution. The spatial pattern of trend estimates is also assessed, showing that the probability distributions of trend estimates in OLCI-A and OLCI-B are most similar in open ocean regions, and least similar in coastal regions and at high northern latitudes. This analysis shows that the two sensors should provide consistent trends between the two satellites, provided future ageing is well quantified and mitigated. The Sentinel-3 programme offers a strong baseline for estimating long-term chlorophyll-a trends by offering a series of satellites (starting with Sentinel-3A and Sentinel-3B) that use the same sensor design, reducing potential issues with cross-calibration between sensors. This analysis contributes an important understanding of the reliability of the two current Sentinel-3 OLCI sensors for future studies of climate change driven chlorophyll-a trends.

scholarly journals The content of plant pigments in bottom sediments of Batorino Lake and their spectral pigment indices

2021 ◽  
pp. 84-96
Author(s):  
Hanna A. Zhukava ◽  
Volha S. Smolskaya ◽  
Ekaterina A. Vishnevetskaya ◽  
Jūratė Karosienė
Keyword(s):  
Chlorophyll A ◽  
Bottom Sediments ◽  
Pigment Composition ◽  
Long Term Trends ◽  
Wet Weight ◽  
Different Depths ◽  
Water Ecosystems ◽  
Structural Indicators ◽  
Qualitative Characteristics

Studies on the Batorino Lake were aimed at assessing the quantitative and qualitative characteristics of the autotrophic component of bottom sediments, as well as searching for their relationships with the data of spectral analysis of the pigment composition. The content of total chlorophyll a (without correction for the presence of phaeopigments) was relatively low – 12.7 ± 10.2 µg/g wet weight of bottom sediments. The content of carotenoids averaged 10.24 ± 4.89 µg/g wet weight of bottom sediments. It has been shown that pigment indices: Е450 /Е480, Е480/Е664, Е430/Е664, Е430/Е412, characterise the structural indicators of bottom sediments and reflect the long-term trends in the development of primary producers in water ecosystems, primarily phytoplankton. During the preliminary analysis, auxiliary pigment indices for controlling the purity of the extract and the clarity of the prescribed spectrum were calculated: Е664/Е720, Е430/Е720, Е530/Е720, Е412/Е720, Е430/Е530, Е664/Е530, Е412/Е664. A close inverse relationship was revealed between Е430/Е664 index and the amount of chlorophyll a at different depths of bottom sediments (r = – 0.7), as well as an average correlation between the Е430/ Е412 index and the proportion of phaeopigments (r = – 0.56).

Climate and Chlorophyll a: Long-Term Trends in the Central North Pacific Ocean

Science ◽  
1987 ◽  
Vol 238 (4823) ◽  
pp. 70-72 ◽  
Author(s):  
E. L. VENRICK ◽  
J. A. MCGOWAN ◽  
D. R. CAYAN ◽  
T. L. HAYWARD
Keyword(s):  
Pacific Ocean ◽  
Chlorophyll A ◽  
North Pacific ◽  
North Pacific Ocean ◽  
Long Term Trends ◽  
Central North Pacific
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