CGRG Bibliography of Canadian Geomorphology
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Author : Du, S.; and Pagiatakis, S.
Date : 2008.
Title : Determination of sea surface topography using tide gauge and atmospheric data.
Publication : Joint Annual Meeting of the Canadian Geophysical Union and the Canadian Geomorphology Research Group. May 11-14, Banff, Alberta.
Issue :
Page(s) :
Abstract
While the Mean Sea Level (MSL) serves mostly in the definition of the vertical datum, it is actually not a level surface due to many effects such as, meteorological, ocean tides and currents, variable ocean water properties and other. These effects introduce a Sea Surface Topography (SST), which expresses the departure of the MSL from the geoid. In order to determine the geoid rigorously, we need accurate values of the SST together with the observed MSL at tide gauges. We aim to estimate the SST using tide gauge and atmospheric data, which have been observed at various stations along the Canadian coasts for decades. The data comprise raw hourly values from thirteen tide gauges obtained from Marine Environmental Data Services (MEDS) and raw atmospheric data (pressure, temperature and wind speed and direction) at the same stations obtained from Environment Canada. From wind speed and direction we produce two time series for each station, comprising the wind speeds parallel to the coast and normal to it respectively. We decimate all series to a three-hour interval using a low-pass filter with cut-off frequency of 0.03cph (8.33µHz) to eliminate most of the tidal signals and other high frequency content. Subsequently we produce least-squares spectra of the filtered series by simultaneously removing long-term tidal constituents. The spectral analyses provide four spectra at each station namely for pressure, temperature, and for the two wind speeds. The concept of our analysis is to identify unique common peaks between the tide gauge data and each of the atmospheric series to use them in a response analysis. This is achieved by appropriate combinations of product spectra and relevant statistics. Determination of the sea level response to the atmospheric driving forces at zero frequency provides the SST. We will present first results on the SST and comparisons with satellite altimetry estimations in Hudson Bay.
Bibliography of Canadian Geomorphology