Numerical evaluation of internal tide characteristics extracted from mobile float observations: A case study near the Luzon Strait

Abstract

With the development of ocean observation technology, data from specially-designed mobile profiling floats have been used to study the internal tides (ITs). However, the accuracy of IT characteristics extracted from such observations has not been fully evaluated. Based on numerical simulations of ITs and background circulation with hundreds of free-moving floats near the Luzon Strait, this study examines the IT characteristics extracted from the float observations based on statistics. For the case in which only the M2 constituent is considered, the lowest error level of extracted M2 temperature fluctuation amplitudes (TFAs) is 40−50%, which appears at 200−1500 m depth. Increasing the sampling frequency of the float from daily to hourly does not decrease the lowest error level. The quasi-daily sampling and other tidal constituents also have an impact on the extracted M2 TFAs and increase their errors. The different patterns of background currents mainly influence the errors of extracted M2 TFAs in the upper 200 m. The relation between TFA and vertical displacement of ITs and the two error sources of the TFA extracted from float observations are discussed in this study.