572
Time Series Analysis of Diurnal Cycles
in Small-Scale Turbulence
N.H. Chan,
J.B. Kadane,
and T. Jiang
Abstract:
Two unconventional time series techniques are employed to study the
diurnal effect in deep stratified layers in the upper equatorial
ocean. A modified spectral approach and a modified time domain
approach based on the variogram are used to handle unequally spaced
data. A new criterion based on the exceedances of mixing activities is
introduced to identify local nights and days adaptively. Using these
techniques, diurnal cycles that cannot be explained by simple heat
convection are found in deep mixed layers. Tentative ARMA models of
the detrended data are entertained. Instead of fitting highly
complicated models, the modified approach together with simple ARMA
models provide useful tools in analyzing data sets of this nature.
This paper offers a rigorous statistical method that can be used to
detect diurnal effects in oceanography.
KEY WORDS AND PHRASES: ARMA, Diurnal cycles, Exdeedance,
Periodogram, Time series, Unequally spaced data, Variogram, Viscous
dissipation rate.