scholarly journals Ground truth data on chlorophyll-a, chromophoric dissolved organic matter and suspended sediment concentrations in the upper water layer as obtained by LIF lidar at high spatial resolution

2017 ◽  
Vol 38 (7) ◽  
pp. 1967-1982 ◽  
Author(s):  
Vadim Pelevin ◽  
Andras Zlinszky ◽  
Elizaveta Khimchenko ◽  
Viktor Toth
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Chlorophyll A ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Water Layer ◽  
Ground Truth ◽  
Chromophoric Dissolved Organic Matter ◽  
Ground Truth Data ◽  
Suspended Sediment Concentrations

scholarly journals Parameterization of the light absorption properties of chromophoric dissolved organic matter in the Baltic Sea and Pomeranian lakes

Ocean Science ◽  
2016 ◽  
Vol 12 (4) ◽  
pp. 1013-1032 ◽  
Author(s):  
Justyna Meler ◽  
Piotr Kowalczuk ◽  
Mirosława Ostrowska ◽  
Dariusz Ficek ◽  
Monika Zabłocka ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Absorption Coefficient ◽  
Baltic Sea ◽  
Chlorophyll A ◽  
Chromophoric Dissolved Organic Matter ◽  
The Baltic Sea ◽  
Absorption Properties ◽  
Chlorophyll A Concentration ◽  
The Baltic

Abstract. This study presents three alternative models for estimating the absorption properties of chromophoric dissolved organic matter aCDOM(λ). For this analysis we used a database containing 556 absorption spectra measured in 2006–2009 in different regions of the Baltic Sea (open and coastal waters, the Gulf of Gdańsk and the Pomeranian Bay), at river mouths, in the Szczecin Lagoon and also in three lakes in Pomerania (Poland) – Obłęskie, Łebsko and Chotkowskie. The variability range of the chromophoric dissolved organic matter (CDOM) absorption coefficient at 400 nm, aCDOM(400), lay within 0.15–8.85 m−1. The variability in aCDOM(λ) was parameterized with respect to the variability over 3 orders of magnitude in the chlorophyll a concentration Chl a (0.7–119 mg m−3). The chlorophyll a concentration and aCDOM(400) were correlated, and a statistically significant, nonlinear empirical relationship between these parameters was derived (R2 =  0.83). On the basis of the covariance between these parameters, we derived two empirical mathematical models that enabled us to design the CDOM absorption coefficient dynamics in natural waters and reconstruct the complete CDOM absorption spectrum in the UV and visible spectral domains. The input variable in the first model was the chlorophyll a concentration, and in the second one it was aCDOM(400). Both models were fitted to a power function, and a second-order polynomial function was used as the exponent. Regression coefficients for these formulas were determined for wavelengths from 240 to 700 nm at 5 nm intervals. Both approximations reflected the real shape of the absorption spectra with a low level of uncertainty. Comparison of these approximations with other models of light absorption by CDOM demonstrated that our parameterizations were superior (bias from −1.45 to 62 %, RSME from 22 to 220 %) for estimating CDOM absorption in the optically complex waters of the Baltic Sea and Pomeranian lakes.

scholarly journals Production of Chromophoric Dissolved Organic Matter (CDOM) in Laboratory Cultures of Arctic Sea Ice Algae

Water ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 926
Author(s):  
Guiju Li ◽  
Huixiang Xie ◽  
Guisheng Song ◽  
Michel Gosselin
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Sea Ice ◽  
Chlorophyll A ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Chromophoric Dissolved Organic Matter ◽  
Ice Algae ◽  
Production Rates ◽  
Arctic Sea

Chromophoric dissolved organic matter (CDOM) is highly enriched in bottom sea ice in the Arctic during ice algal blooms, giving rise to multifaceted ecological implications in both the sea ice and the underlying seawater. We conducted laboratory culture incubations to assess the potential role of ice algae in the accumulation of CDOM in Arctic sea ice. Non-axenic monocultures of Attheya septentrionalis and Nitzschia frigida and a natural ice algal assemblage (NIAA) were grown at 4 °C in an f/2 medium under cool white fluorescent light. Culture samples were collected several days apart throughout the exponential, stationary, and senescent phases, and analyzed for CDOM absorbance, chlorophyll a, and bacterial cell abundance. The cultures displayed apparent specific growth rates of algal and bacterial cells comparable to those in the field. Accumulations of CDOM were observed in all cultures during the time-course incubations, with the senescent phase showing the largest accumulations and the highest production rates. The senescent-phase production rate for NIAA was ~40% higher than that for A. septentrionalis. The chlorophyll a-normalized CDOM production rates in the cultures are comparable to those reported for Arctic first-year sea ice. The absorption spectra of CDOM in the cultures exhibited characteristic short-ultraviolet shoulders similar to those previously identified in sea ice. This study demonstrates that ice algal-derived CDOM can account for the springtime accumulation of CDOM in Arctic sea ice.

Automatic individual tree based analysis of high spatial resolution aerial images on naturally regenerated boreal forests

1999 ◽  
Vol 29 (10) ◽  
pp. 1464-1478 ◽  
Author(s):  
Tomas Brandtberg
Keyword(s):  
Spatial Resolution ◽  
Boreal Forests ◽  
High Spatial Resolution ◽  
Ground Truth ◽  
Aerial Images ◽  
Individual Tree ◽  
Ground Truth Data ◽  
European Aspen ◽  
Rms Error ◽  
Complementary Image

Individual tree based forest surveys are feasible using modern computer technology. The presented approach for analysing high spatial resolution (pixel size 10 cm) aerial images of naturally regenerated boreal forests is based on visible significant trees. Sunlight patches on the ground are suppressed, followed by optimal image smoothing. The problem with inclined illumination is handled by adapted thresholding. Each connected threshold segment (a collection of one or more trees) is further smoothed. A selection of the resulting convex edge segments is used for identifying significant tree crown circles. Six complementary image variables are estimated and used for regression analysis. An evaluation of the ground-truth data in central Sweden gives good results on the stem position estimate (a root mean square (RMS) error of 108 cm) and the stem number estimate (a relative RMS error of 11%). The complementary variables contribute significantly to the stem diameter prediction, resulting in the following experimental values: Scots pine (Pinus sylvestris L.) (R2 = 59.5%, s = 4.9 cm, N = 157), Norway spruce (Picea abies (L.) Karst.) (R2 = 21.9%, s = 6.4 cm, N = 398), birch (Betula pubescens Ehrh.) (R2 = 35.4%, s = 5.3 cm, N = 133), and European aspen (Populus tremula L.) (R2 = 61.4%, s = 4.6 cm, N = 13). The results indicate strong species dependence.

scholarly journals Posidonia oceanica as a Source of Chromophoric Dissolved Organic Matter for the Oligotrophic NW Mediterranean Coast

2020 ◽  
Vol 8 (11) ◽  
pp. 911
Author(s):  
Francesca Iuculano ◽  
Carlos M. Duarte ◽  
Jaime Otero ◽  
Xosé Antón Álvarez-Salgado ◽  
Susana Agustí
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Rocky Shore ◽  
Posidonia Oceanica ◽  
Mediterranean Coast ◽  
Balearic Islands ◽  
Chromophoric Dissolved Organic Matter ◽  
Absorption Increase ◽  
Seagrass Meadows ◽  
Nw Mediterranean

Posidonia oceanica is a well-recognized source of dissolved organic matter (DOM) derived from exudation and leaching of seagrass leaves, but little is known about its impact on the chromophoric fraction of DOM (CDOM). In this study, we monitored for two years the optical properties of CDOM in two contrasting sites in the Mallorca Coast (Balearic Islands). One site was a rocky shore free of seagrass meadows, and the second site was characterized by the accumulation of non-living seagrass material in the form of banquettes. On average, the integrated color over the 250–600 nm range was almost 6-fold higher in the beach compared with the rocky shore. Furthermore, the shapes of the CDOM spectra in the two sites were also different. A short incubation experiment suggested that the spectral differences were due to leaching from P. oceanica leaf decomposition. Furthermore, occasionally the spectra of P. oceanica was distorted by a marked absorption increase at wavelength < 265 nm, presumably related to the release of hydrogen sulfide (HS−) associated with the anaerobic decomposition of seagrass leaves within the banquettes. Our results provide the first evidence that P. oceanica is a source of CDOM to the surrounding waters.

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