Remote Sensing of Ecosystem Structure—Part 2: Initial Findings of Ecosystem Functioning through Intra- and Inter-Annual Comparisons with Earth Observation Data

This study examines the response of a cold-regions deltaic wetland ecosystem in northwestern Canada to two separate and differing seasonal wetting cycles. The goal of this paper was to examine the nature of reflected electromagnetic energy measured by earth observation (EO) satellites, and to assess whether seasonal wetland hydroperiod and episodic flooding events impact the information retrieved by the Sentinel-2 sensors. The year 2018 represents a year characterized by a large spring freshet and ice-jam flooding, while 2019 represents a year characterized more by summer open-water flooding. We applied the Modified Normalized Difference Wetness Index (MNDWI) to address the effects of the wetting cycles. The response of the vegetative cover was tracked using the fraction of the absorbed photosynthetically active radiation (fAPAR) and the Leaf Area Index (LAI). All three indices were viewed through the lens of cover classes as derived through a previously published study by the authors. The study provides a framework for designing longer-term studies where multiple intra- and inter-annual hydrological cycles can be accessed via EO data. Future studies will enable the examination of lag times inherent in the response to the various water sources applied to spectral response and incorporate this EO approach into a monitoring framework

Meris imageries to investigate surface chlorophyll in the upper gulf of Thailand

Medium Resolution Imaging Spectrometer Instrument (MERIS) Level 2 data were used to investigate the seasonal patterns of surface chlorophyll-a (chl-a) distribution related to eutrophic conditions in the upper Gulf of Thailand (UGoT). Initial overestimation of chl-a using MERIS Rrs was reduced when Rrs ratios were used. A local in-water algorithm, named Chula algorithm, was embedded into MERIS data due to higher accuracy in chl-a prediction, compared to standard MERIS chl-a products. Subsequent MERIS-derived chl-a maps revealed that during the northeast monsoon, high chl-a water moves westward, while during the southwest monsoon, it accumulates in the northeast corner of UGoT. These seasonal patterns of movement agree well with previous investigations on seasonal circulation and red tides in UGoT. Compared to other satellite data having larger spatial resolutions, MERIS chl-a images provide more details on chl-a distribution which may be useful for oceanographic studies in such a small coastal area as UGoT

Meris imageries to investigate surface chlorophyll in the upper gulf of Thailand

Medium Resolution Imaging Spectrometer Instrument (MERIS) Level 2 data were used to investigate the seasonal patterns of surface chlorophyll-a (chl-a) distribution related to eutrophic conditions in the upper Gulf of Thailand (UGoT). Initial overestimation of chl-a using MERIS Rrs was reduced when Rrs ratios were used. A local in-water algorithm, named Chula algorithm, was embedded into MERIS data due to higher accuracy in chl-a prediction, compared to standard MERIS chl-a products. Subsequent MERIS-derived chl-a maps revealed that during the northeast monsoon, high chl-a water moves westward, while during the southwest monsoon, it accumulates in the northeast corner of UGoT. These seasonal patterns of movement agree well with previous investigations on seasonal circulation and red tides in UGoT. Compared to other satellite data having larger spatial resolutions, MERIS chl-a images provide more details on chl-a distribution which may be useful for oceanographic studies in such a small coastal area as UGoT

Foliar and woody materials discriminated using terrestrial LiDAR in a mixed natural forest

Separation of foliar and woody materials using remotely sensed data is crucial for the accurate estimation of leaf area index (LAI) and woody biomass across forest stands. In this paper, we present a new method to accurately separate foliar and woody materials using terrestrial LiDAR point clouds obtained from ten test sites in a mixed forest in Bavarian Forest National Park, Germany. Firstly, we applied and compared an adaptive radius near-neighbor search algorithm with a fixed radius near-neighbor search method in order to obtain both radiometric and geometric features derived from terrestrial LiDAR point clouds. Secondly, we used a random forest machine learning algorithm to classify foliar and woody materials and examined the impact of understory and slope on the classification accuracy. An average overall accuracy of 84.4% (Kappa = 0.75) was achieved across all experimental plots. The adaptive radius near-neighbor search method outperformed the fixed radius near-neighbor search method. The classification accuracy was significantly higher when the combination of both radiometric and geometric features was utilized. The analysis showed that increasing slope and understory coverage had a significant negative effect on the overall classification accuracy. Our results suggest that the utilization of the adaptive radius near-neighbor search method coupling both radiometric and geometric features has the potential to accurately discriminate foliar and woody materials from terrestrial LiDAR data in a mixed natural forest

a low-activity cold seep in the Larsen B area, western Weddell Sea, Antarctica

First videographic indication of an Antarctic cold seep ecosystem was recently obtained from the collapsed Larsen B ice shelf, western Weddell Sea (Domack et al., 2005). Within the framework of the R/V Polarstern expedition ANTXXIII-8, we revisited this area for geochemical, microbiological and further videographical examinations. During two dives with ROV Cherokee (MARUM, Bremen), several bivalve shell agglomerations of the seep-associated, chemosynthetic clam <I>Calyptogena</I> sp. were found in the trough of the Crane and Evans glacier. The absence of living clam specimens indicates that the flux of sulphide and hence the seepage activity is diminished at present. This impression was further substantiated by our geochemical observations. Concentrations of thermogenic methane were moderately elevated with 2 μM in surface sediments of a clam patch, increasing up to 9 μM at a sediment depth of about 1 m in the bottom sections of the sediment cores. This correlated with a moderate decrease in sulphate from about 28 mM at the surface down to 23.4 mM, an increase in sulphide to up to 1.43 mM and elevated rates of the anaerobic oxidation of methane (AOM) of up to 600 pmol cm<sup>−3</sup> d<sup>−1</sup> at about 1 m below the seafloor. Molecular analyses indicate that methanotrophic archaea related to ANME-3 are the most likely candidates mediating AOM in sediments of the Larsen B seep

Biogeochemistry of a low-activity cold seep in the Larsen B area, western Weddell Sea, Antarctica

First videographic indication of an Antarctic cold seep ecosystem was recently obtained from the collapsed Larsen B ice shelf, western Weddell Sea (Domack et al., 2005). Within the framework of the R/V Polarstern expedition ANTXXIII-8, we revisited this area for geochemical, microbiological and further videographical examinations. During two dives with ROV Cherokee (MARUM, Bremen), several bivalve shell agglomerations of the seep-associated, chemosynthetic clam <I>Calyptogena</I> sp. were found in the trough of the Crane and Evans glacier. The absence of living clam specimens indicates that the flux of sulphide and hence the seepage activity is diminished at present. This impression was further substantiated by our geochemical observations. Concentrations of thermogenic methane were moderately elevated with 2 μM in surface sediments of a clam patch, increasing up to 9 μM at a sediment depth of about 1 m in the bottom sections of the sediment cores. This correlated with a moderate decrease in sulphate from about 28 mM at the surface down to 23.4 mM, an increase in sulphide to up to 1.43 mM and elevated rates of the anaerobic oxidation of methane (AOM) of up to 600 pmol cm<sup>−3</sup> d<sup>−1</sup> at about 1 m below the seafloor. Molecular analyses indicate that methanotrophic archaea related to ANME-3 are the most likely candidates mediating AOM in sediments of the Larsen B seep