On the Coherent and Incoherent Characteristics of Semidiurnal Internal Tides Near the Luzon Strait: Influences of Sampling Interval and Observation Duration

Abstract Internal tides (ITs) usually exhibit incoherent characteristics during their propagation. However, estimations of incoherent ITs from different platform (mooring and satellite) observations exhibit discrepancies, partly due to their different sampling intervals and observation durations. Based on 10‐year numerical simulation of ITs near the Luzon Strait, we examine influences of sampling interval and observation duration on the coherent and incoherent characteristics of semidiurnal ITs, that is, the M 2 IT steric height and incoherence of semidiurnal ITs in steric height. Results indicate that for 1‐hr interval (typical sampling interval of mooring observations), both the coherent and incoherent characteristics of semidiurnal ITs exhibit convergence with increasing duration. However, for 238‐hr interval (approximate repeating cycle of TOPEX/Poseidon/Jason‐1/Jason‐2 satellites), the coherent characteristic of semidiurnal ITs has a larger bias than that for 1‐hr interval, and this bias does not monotonously decrease with duration; the semidiurnal IT incoherence has a larger uncertainty than that for 1‐hr interval.