Open AccessDecomposing observations of high‐frequency radar‐derived surface currents by their forcing mechanisms: Decomposition techniques and spatial structures of decomposed surface currents
Author(s) -
Kim Sung Yong,
Cornuelle Bruce D.,
Terrill Eric J.
Publication year - 2010
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2010jc006222
Subject(s) - decorrelation , geology , forcing (mathematics) , ocean current , current meter , current (fluid) , radar , climatology , oceanography , telecommunications , algorithm , computer science
Surface current observations from a high‐frequency radar network deployed in southern San Diego are decomposed according to their driving forces: pure tides and their neighboring off‐band energy, local winds, and low frequency. Several superposed ocean responses are present as a result of the complicated bottom topography and relatively weak winds off southern San Diego, as opposed to coastal regions where circulation can be explained by a dominant forcing mechanism. This necessitates an application of a statistical decomposition approach. Surface currents coherent with pure tides are calculated using harmonic analysis. Locally wind‐driven surface currents are estimated by regression of observed winds on observed surface currents. The dewinded and detided surface currents are filtered by weighted least‐squares fitting assuming white noise and three colored signal bands: low‐frequency band (less than 0.4 cycles per day) and near‐tidal peaks at the diurnal ( K 1 ) and semidiurnal ( M 2 ) frequencies. The spatial and temporal variability of each part of the decomposed surface currents is investigated in terms of ocean response to the driving forces. In addition, the spatial correlations of individual components exhibit Gaussian and exponential shapes with varying decorrelation length scales.