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RESOURCES
SUBJECTS
Science Information By:
Overview
ISDM databases contain over 6 million observed wave spectra from 500 locations in the Canadian area of interest (35 to 90 degrees north and 40 to 180 degrees west), all of which is available for direct download from this web site.
The ISDM Wave Climate Study Office (WCS) was formed in 1971 and for the next 25 years operated an active field program of wave acquisition. Although the field program has been discontinued, MEDS continues to process delayed-mode wave data as submitted from researchers, universities, regional institutes and the oil and gas industry in support marine science activities.
Today, on a daily basis, ISDM acquires wave buoy data from buoys operated by the Meteorological Service of Canada MSC as transmitted through the GOES satellite network. As well, ISDM acquires wave buoy data from buoys operating within the Canadian area of interest by the US National Data Buoy Center NDBC as transmitted over the GTS network.
ISDM performs a subjective quality inspection (QC) of each observed wave spectra prior to update into the database. Flags are assigned to the observed and derived parameters reflecting data quality. Quality control is performed by examining the energy distribution of the power spectrum and comparing relative values of significant wave height and peak period between neighboring buoys.
For the ISDM WCS historical buoy data, wave spectral density (meters squared per Hertz) was obtained by Fast Fourier Transform of the original 20-minute surface elevation time series record. There are approximately 60 estimates of spectral density supplied at equal intervals of frequency between 0.05 and 0.5 Hz. Spectral data from other data sources may not contain this level of detail. Axys Environmental Consulting Ltd provides some detail about the buoys used by the MSC. The Axys technical document describes the NOMAD and DISCUS buoys in particular.
Significant wave height is defined as four times the square root of the area under the variance spectrum of the water surface elevation. The peak period is defined as the inverse of the frequency for which the variance spectrum is a maximum.
