Investigation Using Empirical Orthogonal Functions and Objective Analysis toAnalyse the Vertical Temperature Structure of a Gulf Stream Meander

摘要

Expendable bathymetric temperature (XBT) data taken from an anticyclonic meandercrest within the Gulf Stream (Hummon 1991) is analysed by looking at the empirical vertical structure. The ensemble averaged data is formed into a projection matrix that compares the value of the temperature at one depth with the temperature at a second depth. The data was smoothed with the correlation analysis being performed at ten metre intervals from five metres to a depth of 800 metres. The first four empirical orthogonal functions (EOF's) of the projection matrix were computed and the modal amplitudes for each XBT determined. sing objective analysis the modal amplitudes were interpolated onto a specified grid. Synthetic XBT's were then reconstructed at the grid positions using the interpolated grid modal amplitude values. A measure of the error at each grid point was determined. The objective analysis was subsequently repeated using successively fewer XBT's from the data set, until the resulting error in the interpolated XBT's at the grid points became unacceptable.