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Namespace Prefixes

Prefix	IRI
dcterms	http://purl.org/dc/terms/
dc	http://purl.org/dc/elements/1.1/
n9	http://vocab.nerc.ac.uk/collection/P06/current/UAAA/
skos	http://www.w3.org/2004/02/skos/core#
void	http://rdfs.org/ns/void#
rdf	http://www.w3.org/1999/02/22-rdf-syntax-ns#
n6	http://vocab.nerc.ac.uk/collection/P07/current/TISEXP3S/1/
n12	http://vocab.nerc.ac.uk/.well-known/
owl	http://www.w3.org/2002/07/owl#
xsdh	http://www.w3.org/2001/XMLSchema#
n3	http://purl.org/pav/
n7	http://mmisw.org/ont/cf/parameter/
n2	http://vocab.nerc.ac.uk/standard_name/sea_surface_wave_mean_from_direction/

Statements

Subject Item

n2:

rdf:type

skos:Concept

owl:versionInfo

1

owl:sameAs

n2: n7:sea_surface_wave_mean_from_direction

skos:prefLabel

sea_surface_wave_mean_from_direction

dcterms:identifier

SDN:P07::TISEXP3S

dc:identifier

SDN:P07::TISEXP3S

dcterms:date

2024-05-20 20:39:48.0

skos:definition

The wave direction in each frequency band, calculated from the first-order components of the wave directional spectrum. The full directional wave spectrum is described as a Fourier series: S = a0/2 + a1cos(theta) + b1sin(theta) + a2cos(2theta) + b2sin(2theta). The Fourier coefficients a1, b1, a2, & b2 can be converted to polar coordinates as follows: R1 = (SQRT(a1a1+b1b1))/a0, R2 = (SQRT(a2a2+b2b2))/a0, ALPHA1 = 270.0-ARCTAN(b1,a1), ALPHA2 = 270.0-(0.5*ARCTAN(b2,a2)+{0 or 180, whichever minimizes the difference between ALPHA1 and ALPHA2}). ALPHA1 is the mean wave direction, which is determined from the first-order Fourier coefficients. This spectral parameter is a separate quantity from the bulk parameter (MWDIR), which has the standard name sea_surface_wave_from_direction_at_variance_spectral_density_maximum. The phrase "from_direction" is used in the construction X_from_direction and indicates the direction from which the velocity vector of X is coming. The direction is a bearing in the usual geographical sense, measured positive clockwise from due north.

skos:notation

SDN:P07::TISEXP3S

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false

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n3:authoredOn

2024-05-20 20:39:48.0

n3:hasCurrentVersion

n6:

n3:version

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