Entropy analysis of SPM patterns: case study of Liverpool Bay

Abstract

were analyzed by means of entropy analysis and factor analysis in order to identify the meteorological and oceanographic variables of importance for the characterisation of the shape of SPM size spectra. Entropy analysis of in situ particle size spectra revealed five basic types, each attributable to different sets of environmental conditions. The results of correlation analysis showed that changes in the position of the main modal are significantly related to several environmental variables. One important class of these relationships is represented by wave-related variables (e.g. wave energy, maximum orbital velocity). Another important class of correlations (e.g. with salinity, density, water depth) can be associated with the inshore-offshore gradient in depth and physicochemical conditions existing in the bay. The strongest correlations, however, were with the air and water temperatures. Factor analysis (with Varimax rotation) of the overall dataset extracted four factors, together explaining over 70% of variance. Factor 1 explains >21% of the total variance, and appears to be related to wave activity. Factor 2, explaining 18.5% of the total variance, appears to be related to tidal currents. Factor 3 explains 16.4% of the total variance observed, and appears to be related to temperaturemodulated seasonal differences in oceanographic conditions. Factor 4 explains 15.2% of the total variance observed, and represents the inshore-offshore gradient in depth and physicochemical conditions. These findings are a step towards a better characterisation of floc size and, therefore, more precise calculations of sedimentation and transport rates needed for an improved understanding of ecosystem functioning in Liverpool Bay and, for that matter, other similar settings.

Hydro-meteorological influences and multimodal suspended particle size distributions in the Belgian nearshore area (southern North Sea)

“…Applied to PSDs, entropy analysis allows grouping the size spectra without assumptions about the shape of the spectra and is therefore suited for analysis of unimodal, bimodal as well as multimodal distributions (Woolfe et al 1998). Entropy analysis has been successfully applied to grain size distributions from sedimentary deposits (Forrest and Clark 1989;Woolfe and Michibayashi 1995;Woolfe et al 1998;Orpin and Kostylev 2006) and to LISST particle size distributions of suspended matter Krivtsov et al 2011). Our analysis was carried out with the FORTRAN routine of Johnston and Semple (1983) extended with a module to calculate the optimal number of groups using the Calinski-Harabasz pseudo F-statistic (Orpin and Kostylev 2006;Stewart et al 2009).…”

Basin Testing of Wave Energy Converters in Trondheim: Investigation of Mooring Loads and Implications for Wider Research

“…It should be noted that investigations of mooring loads in renewable energy devices are important not only in relation to the issues of reliability and power take off [11], but also in terms of minimizing the adverse effects of mooring lines on bottom sediments [12], as well as indirect effects of the eroded particles on a wide range of aquatic processes [13][14][15][16]. The results presented here will become particularly relevant in the future, as more wave energy devices are deployed at sea in open water conditions [17].…”