Carbonate sand deposit model in Nordland
Description
ÔÇó Model run in UTM zone 33N
ÔÇó The model was run in 2014 by NIVA
ÔÇó Data collected 2011-2013 by NGU, NIVA included absences from kelp surveys
ÔÇó The data were collected in Nordland county, but the models covers also a small part of Troms in the North and Tr├©ndelag in the south.
ÔÇó 1078 datapoints, but only data down to 100 m depth and with more than 50 % carbonate content were included, resulting in 473 presences.
ÔÇó Modelled using Maxent on presence data, validated with 139 presences and 740 absences (the validation points are spatially biased towards areas shallower than 40 m depth)
ÔÇó Modelled the probability of finding carbonate sand with more that 50 % carbonate content (carbonate contact below 50 % is absence together with rocky seabed and other non-carbonate sand areas)
ÔÇó Input variables: depth, slope, curvature (with both 250, 500 and 1000 m calculation window), wave exposure, maximum current speed and mean current speed
ÔÇó Depth, slope, curvature and wave exposure had spatial resolution of 25 m, models developed by NIVA. The current speed had 200 m spatial resolution (developed from NorKyst800).
ÔÇó Cut-off value for identifying polygon presences: 0.31
 spatial (horizontal) distribution is.
ÔÇó AUC=0.88 using independent validation presences and absences
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