Elongation Ratios & Fractal Dimension Data For Marine Snow Particles In The NE Gulf Of Mexico
Description
Marine snow images were collected using the towed SIPPER v.3 camera system, which was developed by the College of Marine Science, University of South Florida, to assess the abundance and distribution of particles, phytoplankton, zooplankton, and larval fish (Remsen et al., 2004). Particles were sampled through a square 9.6 cm sampling tube, having a 92.2 cm2 mouth area, which extended in front of the towed platform. As particles passed down the tube they were imaged by a Dalsa Piranha-2 line-scan camera, which imaged 36,000 lines per second and used a pseudo-collimated LED generated light sheet to image the shadows and outlines of resolvable particles. The Plankton Imaging Classification Extraction Software (PICES) was used to extract and classify SIPPER images using a Support Vector Machines (SVM) approach, and to manage the images and environmental data collected (Kramer, 2010). A total of 117,058,275 marine snow images were validated for this project. All particles > 0.053 mm2 (area of 100 pixels) were extracted. This dataset provides measures of marine snow particle shape (elongation) and surface roughness (fractal dimension) during and after the Deepwater Horizon oil spill between May 2010 and August 2014. Elongation ratios (ER) were determined as ER = 1 - aspect ratio, where the aspect ratio is the minor axis length of the particle over the major axis length. Fractal dimension were used to assess the surface roughness or boundary irregularity of particles and were computed using a variation of the box counting method in which the grid comprised rectangular boxes maintaining the same aspect ratio as the particle (Kilps et al. 1994, Brown 1995). File names are: NormalizedDataReport_Cruise name_Station name. Both elongation ratios and fractal dimensions are ratios and therefore do not have units. Depth is in meters; Volume sampled is in m^3; ESDbinstart is the Equivalent Spherical Diameter (ESD) of the particle at the beginning of a size range; ESDbinend is the end of the size range; Particle size is in millimeters; TotalNumberOfParticlesAtDepthESD is the total number of particles in the size range at the listed depth (no units); Elongation is the elongation ratio (no units) of particles in the size range an the listed depth; FractalDim is the fractal dimension of the particles (no units); Abundance is the number of particles in the ESD size range at the listed depth having the listed elongation ratio and fractal dimension.