Successful Implementation of Real-Time Look-Ahead Resistivity Measurements in the North Sea

2018 ◽  
Author(s):  
Haitham Khalil ◽  
Jean Seydoux ◽  
Jeanmi Denichou ◽  
Dzevat Omeragic ◽  
Diogo Salim ◽  
...  
Keyword(s):  
Real Time ◽  
North Sea ◽  
Successful Implementation ◽  
Resistivity Measurements ◽  
The North ◽  
Look Ahead ◽  
The North Sea

scholarly journals Depth-averaged instantaneous currents in a tidally dominated shelf sea from glider observations

2016 ◽  
Author(s):  
Lucas Merckelbach
Keyword(s):  
Real Time ◽  
North Sea ◽  
Current Data ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Real Time Mode ◽  
The North ◽  
Shelf Sea ◽  
The North Sea ◽  
Better Than

Abstract. Ocean gliders have become ubiquitous observation platforms in the ocean in recent years. They are also increasingly used in coastal environments. The coastal observatory system COSYNA has pioneered the use of gliders in the North Sea, a shallow tidally energetic shelf sea. For operational reasons, the gliders operated in the North Sea are programmed to resurface every 3–5 hours. The glider's deadreckoning algorithm yields depth averaged currents, averaged in time over each subsurface interval. Under operational conditions these averaged currents are a poor approximation of the instantaneous tidal current. In this work an algorithm is developed that estimates the instantaneous current (tidal and residual) from glider observations only. The algorithm uses a second-order Butterworth low-pass filter to estimate the residual current component, and a Kalman filter based on the linear shallow water equations for the tidal component. A comparison of data from a glider experiment with current data from an ADCP deployed nearby shows that the standard deviations for the east and north current components are better than 7 cm s−1 in near-real time mode, and improve to better than 5 cm s−1 in delayed mode, where the filters can be run forward and backward. In the near-real time mode the algorithm provides estimates of the currents that the glider is expected to encounter during its next few dives. Combined with a behavioural and dynamic model of the glider, this yields predicted trajectories, the information of which is incorporated in warning messages issued to ships by the (German) authorities. In delayed mode the algorithm produces useful estimates of the depth averaged currents, which can be used in (process-based) analyses in case no other source of measured current information is available.

scholarly journals Depth-averaged instantaneous currents in a tidally dominated shelf sea from glider observations

2016 ◽  
Vol 13 (24) ◽  
pp. 6637-6649 ◽  
Author(s):  
Lucas Merckelbach
Keyword(s):  
Real Time ◽  
North Sea ◽  
Current Data ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Real Time Mode ◽  
The North ◽  
Shelf Sea ◽  
The North Sea ◽  
Better Than

Abstract. Ocean gliders have become ubiquitous observation platforms in the ocean in recent years. They are also increasingly used in coastal environments. The coastal observatory system COSYNA has pioneered the use of gliders in the North Sea, a shallow tidally energetic shelf sea. For operational reasons, the gliders operated in the North Sea are programmed to resurface every 3–5 h. The glider's dead-reckoning algorithm yields depth-averaged currents, averaged in time over each subsurface interval. Under operational conditions these averaged currents are a poor approximation of the instantaneous tidal current. In this work an algorithm is developed that estimates the instantaneous current (tidal and residual) from glider observations only. The algorithm uses a first-order Butterworth low pass filter to estimate the residual current component, and a Kalman filter based on the linear shallow water equations for the tidal component. A comparison of data from a glider experiment with current data from an acoustic Doppler current profilers deployed nearby shows that the standard deviations for the east and north current components are better than 7 cm s−1 in near-real-time mode and improve to better than 6 cm s−1 in delayed mode, where the filters can be run forward and backward. In the near-real-time mode the algorithm provides estimates of the currents that the glider is expected to encounter during its next few dives. Combined with a behavioural and dynamic model of the glider, this yields predicted trajectories, the information of which is incorporated in warning messages issued to ships by the (German) authorities. In delayed mode the algorithm produces useful estimates of the depth-averaged currents, which can be used in (process-based) analyses in case no other source of measured current information is available.

Real-time microseismic monitoring in the North Sea with advanced noise removal methods

2016 ◽  
Author(s):  
Ben Dando ◽  
Kamran Iranpour ◽  
Volker Oye ◽  
Sascha Bussat ◽  
Louise Bjerrum
Keyword(s):  
Real Time ◽  
North Sea ◽  
Noise Removal ◽  
Microseismic Monitoring ◽  
The North ◽  
The North Sea

Real-Time Geological Positioning of a Well in the North Sea

2001 ◽  
Author(s):  
Tom Schroeder ◽  
Paul Boonen ◽  
Herb Illfelder ◽  
Graham McElhinney ◽  
Gerhard Templeton
Keyword(s):  
Real Time ◽  
North Sea ◽  
The North ◽  
The North Sea

scholarly journals WATeRS: an open Web Map Service with near‐real time MODIS Level‐2 standard chlorophyll products of the North Sea

2007 ◽  
Vol 28 (16) ◽  
pp. 3693-3699
Author(s):  
M. A. Eleveld ◽  
A. J. Wagtendonk ◽  
R. Pasterkamp ◽  
N. O. de Reus
Keyword(s):  
Real Time ◽  
North Sea ◽  
Web Map ◽  
The North ◽  
The North Sea ◽  
Map Service ◽  
Level 2

scholarly journals To blend or not to blend? The role of morphological traits for the detection of marine macrobenthos in bulk DNA and eDNA from the ethanol preservative

2021 ◽  
Vol 4 ◽  
Author(s):  
Sofie Derycke ◽  
Sara Maes ◽  
Laure Van den Bulcke ◽  
Joran Vanhollebeke ◽  
Jan Wittoeck ◽  
...  
Keyword(s):  
North Sea ◽  
Beta Diversity ◽  
Coi Gene ◽  
Reference Database ◽  
Successful Implementation ◽  
Diversity Patterns ◽  
The North ◽  
Dna Metabarcoding ◽  
The North Sea ◽  
The Impact

The impact of methodological choices on the reliability and reproducibility of DNA metabarcoding need to be well understood to allow successful implementation in routine monitoring frameworks. For macrobenthos communities, the metabarcoding protocol focuses on a fragment of the mitochondrial COI gene and depending on the primer set used for amplification of COI, different taxa can be detected. To identify the primer set that allows the best diversity estimates for macrobenthos in the North Sea region, we sampled four distinct and well characterised communities and identified macrobenthos using traditional morpho-taxonomy before molecular processing. Of the five primer sets tested, the Leray primer set yielded the highest number of non-chimeric reads, detected the highest number of macrobenthos species and best recovered beta diversity patterns. Despite the availability of a nearly complete reference database, 19 out of the 59 morphological species were not picked up with DNA metabarcoding. Next to primer choice, the DNA source used in metabarcoding studies can affect whether or not a species is detected. DNA can be extracted from bulk specimens or from the ethanol preservative in which the macrobenthos sample was preserved. The latter DNA source would greatly speed up processing time of samples in the laboratory. We therefore compared species detection in bulk DNA and eDNA from the ethanol preservative from the four macrobenthos communities in the North Sea. Our results show that community composition differed significantly between bulk DNA and eDNA samples, but both sample types are able to differentiate the four macrobenthos communities from the North Sea. Of the 49 species that are detected in both sample types, 27 are also found in the morphological dataset. The 14 species that are exclusively detected in the ethanol preservative are mainly pelagic species. In view of the low read numbers allocated to these species (at most 153 reads) they most likely represent “contaminant” DNA molecules that are attached to the specimens or the organic debris. To better understand the different results between bulk DNA and eDNA from the ethanol preservative, we investigated the importance of four categorical traits in explaining the probability of detecting a species in the two sample types: body, larval stage (benthic or pelagic), longevity and body skeleton (chitin, CaCO3 or soft tissue). A generalized linear mixed effects model approach shows that the probability of detecting a species in the eDNA from the ethanol preservative is significantly lower than for bulk DNA for macrobenthos species having small to medium body size and for species having chitine or CaCO3 in their skeleton. In contrast, detection in the bulk DNA samples is not affected by the investigated traits. Although the ethanol preservative can be used to characterize beta diversity patterns, our results show that monitoring of macrobenthos species will be most robust when using bulk DNA as template for metabarcoding.

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