21 documents found, page 1 of 3
Piece‐wise constant cluster modelling of dynamics of upwelling patterns
Nascimento, Susana; Martins, Alexandre; Relvas, Paulo; Luis, Joaquim; Mirkin, BorisA comprehensive approach is presented to analyse season's coastal upwelling represented by weekly sea surface temperature (SST) image grids. Our three-stage data recovery clustering method assumes that the season's upwelling can be divided into shorter periods of stability, ranges, each to be represented by a constant core and variable shell parts. Corresponding clustering algorithms parameters are automaticall...
Novel cluster modeling for the spatiotemporal analysis of coastal upwelling
Nascimento, Susana; Martins, Alexandre; Relvas, Paulo; Luis, Joaquim; Mirkin, BorisThis work proposes a spatiotemporal clustering approach for the analysis of coastal upwelling from Sea Surface Temperature (SST) grid maps derived from satellite images. The algorithm, Core-Shell clustering, models the upwelling as an evolving cluster whose core points are constant during a certain time window while the shell points move through an in-and-out binary sequence. The least squares minimization of c...
The generic mapping tools version 6
Wessel, P.; Luis, Joaquim; Uieda, L.; Scharroo, R.; Wobbe, F.; Smith, W. H. F.; Tian, D.The Generic Mapping Tools (GMT) software is ubiquitous in the Earth and ocean sciences. As a cross-platform tool producing high-quality maps and figures, it is used by tens of thousands of scientists around the world. The basic syntax of GMT scripts has evolved very slowly since the 1990s, despite the fact that GMT is generally perceived to have a steep learning curve with many pitfalls for beginners and experi...
The seagoing scientist's toolbox: integrated methods for quality control of mar...
Hamilton, Michael; Wessel, Paul; Luis, Joaquim; Taylor, Brian; Ko, YoungtakWe announce a new and integrated system for planning and executing marine geophysical surveys and for scrutinizing and visualizing incoming shipboard data. The system incorporates free software designed for use by scientists and shipboard operators and pertains to underway geophysics and multibeam sonar surveys. Regarding underway data, a crucial first step in the approach is to reduce and merge incoming center...
Producing marine geophysical archive files from raw underway data
Hamilton, Michael; Wessel, Paul; Taylor, Brian; Luis, JoaquimPreserving costly marine geophysical trackline data is of paramount importance but variability in priorities, funding, personnel, and technology impact our data archival capacity. We have addressed one crucial facet of this dilemma by devising an open source approach to merge and reduce underway geophysical data and to generate marine geophysical archive files using common command line programs along with the G...
Importance of the mesoscale in the decadal changes observed in the northern Can...
Relvas, Paulo; Luis, Joaquim; Santos, A. Miguel P.Analysis of sea surface temperature (SST) time series since 1960 from existing data bases shows a generalized warming trend in the northern Canary upwelling system. The field of the satellite-derived SST trends off Western Iberia was built at the pixel scale (4 x 4 km) for the period 1985-2008, revealing significant spatial differences in the warming rates. Weaker warming trends fit to the known upwelling patte...
The GMT/MATLAB Toolbox
Wessel, Paul; Luis, JoaquimThe GMT/MATLAB toolbox is a basic interface between MATLAB (R) (or Octave) and GMT, the Generic Mapping Tools, which allows MATLAB users full access to all GMT modules. Data may be passed between the two programs using intermediate MATLAB structures that organize the metadata needed; these are produced when GMT modules are run. In addition, standard MATLAB matrix data can be used directly as input to GMT module...
Temperature is not a limiting factor for the expansion of Halophila stipulacea ...
Georgiou, Dimos; Alexandre, Ana; Luis, Joaquim; Santos, RuiThe seagrass Halophila stipulacea is a Lessepsian migrant that has spread from the Red Sea into the Mediterranean Sea where some authors consider it invasive. It has been suggested that the range of expansion of the species in the Mediterranean will be limited by the 15 degrees C sea surface isotherm. Here we tested the effects of temperature on survival, photosynthesis, leaf growth and clonal growth of H. stip...
New study on the 1941 Gloria Fault earthquake and tsunami
Baptista, Maria Ana; Miranda, Jorge Miguel; Batllo, Josep; Lisboa, Filipe; Luis, Joaquim; Macia, RamonThe M similar to 8.3-8.4 25 November 1941 was one of the largest submarine strike-slip earthquakes ever recorded in the Northeast (NE) Atlantic basin. This event occurred along the Eurasia-Nubia plate boundary between the Azores and the Strait of Gibraltar. After the earthquake, the tide stations in the NE Atlantic recorded a small tsunami with maximum amplitudes of 40 cm peak to through in the Azores and Madei...
An open source geophysical software for studying speleothem growth bands and co...
Veiga-Pires, C.; Coelho, Catarina; Moura, Delminda; Luis, JoaquimSpeleothem growth bands are commonly referred as one of the parameters that are used for paleoclimate reconstructions. Accordingly, this work presents a new tool for detecting these bands based on the gray-scale image of the speleothem using the Mirone open source geophysical software. This program has initially been developed for working on georeferenciated images for geophysical studies, as for instance for r...