Yngve Heggelund
University of Bergen
OceanographyGeologyClimatologyEcho soundingCategorization
What is this?
Publications 8
#2Yngve HeggelundH-Index: 6
Last. Inge K. EliassenH-Index: 5
view all 6 authors...
Abstract Sonars and echosounders are widely used for remote sensing of life in the marine environment. There is an ongoing need to make the acoustic identification of marine species more correct and objective and thereby reduce the uncertainty of acoustic abundance estimates. In our work, data from multi-frequency echosounders working simultaneously with nearly identical and overlapping acoustic beams are processed stepwise in a modular sequence to improve data, detect schools and categorize aco...
19 CitationsSource
Korneliussen, R. J., Heggelund, Y., Eliassen, I. K., and Johansen, G. O. 2009. Acoustic species identification of schooling fish. - ICES Journal of Marine Science, 66: 1111-1118.The development of methods for the acoustic identification of fish is a long-term objective aimed at reducing uncertainty in acoustic-survey estimates. The relative frequency response r(f) measured simultaneously at several frequencies is one of the main acoustic features that characterize the targets, but the relationsh...
63 CitationsSource
#2Yngve HeggelundH-Index: 6
Last. John DalenH-Index: 7
view all 6 authors...
Korneliussen, R. J., Heggelund, Y., Eliassen, I. K., Oye, O. K., Knutsen, T., and Dalen, J. 2009. Combining multibeam-sonar and multifrequency-echosounder data: examples of the analysis and imaging of large euphausiid schools. - ICES Journal of Marine Science, 66: 991-997.The first high-resolution, quantitative, multibeam sonar (Simrad MS70) ever developed was mounted in a keel of RV “G. O. Sars” with port-orientated beams. Each ping samples a volume of 60° horizontally × 45° vertically with 500...
34 CitationsSource
#1Yngve HeggelundH-Index: 6
#2Frode VikebøH-Index: 20
Last. Gunnar K. Furnes (Norsk Hydro)H-Index: 11
view all 4 authors...
In many numerical ocean models, the hydrostatic approximation is made. This approximation causes a considerable saving in computing time. However, for phenomena involving large vertical speeds, for many small scale phenomena, and in areas with weak stratification, the approximation becomes questionable. In this report, a σ-coordinate hydrostatic C-grid model is extended to include non-hydrostatic dynamics. The test cases involve gravitational adjustment of a downslope flow. The first test case h...
39 CitationsSource
Multifrequency split‐beam echo sounders with nearly identical and overlapping acoustic beams have been regularly used in acoustic surveys for fish stock abundance estimation. Calibrated raw data from up to six simultaneously working echo sounders at 18, 38, 70, 120, 200, and 364 kHz were applied for developing a new processing tool for real‐time acoustic target categorization and acoustic species identification. The system now handles raw data from the Simrad EK500 and EK60 split‐beam echo sound...
1 CitationsSource
#1Yngve Heggelund (University of Bergen)H-Index: 6
#2Jarle Berntsen (University of Bergen)H-Index: 20
A method for analysing different nesting techniques for the linearized shallow water equations is presented. The problem is formulated as an eigenvector–eigenvalue problem. A necessary condition for stability is that the spectral radius of the propagation matrix is less than or equal to one. Two test cases are presented. The first test case is analysed, and effects of enforcing volume conservation and nudging in time are studied. A nesting technique is found that causes no growth of any eigenvec...
10 CitationsSource
#1Inge K. Eliassen (University of Bergen)H-Index: 5
#2Yngve Heggelund (University of Bergen)H-Index: 6
Last. Magne HaakstadH-Index: 1
view all 3 authors...
A three dimensional σ-coordinate model has been implemented for simulating the circulation in Saltfjorden, Saltstraumen and Skjerstadfjorden. The model is run with atmospheric forcing, four components of the tide at open boundaries and river runoff. The general circulation in Saltfjorden and Skjerstadfjorden and the deepwater exchange through Saltstraumen are studied. A simplified two point model is used for investigating tidal phenomena seen in the three dimensional model. Variations in air tem...
17 CitationsSource
#1Yngve HeggelundH-Index: 6
#2Jarle BerntsenH-Index: 20
2 Citations