Long-term high frequency phytoplankton dynamics, recorded from a coastal water autonomous measurement system in the eastern English Channel

In this paper, high frequency fluorescence fluctuations, recorded from 2004 to 2011 using an autonomous underwater monitoring system in the eastern English Channel, at 20-min time resolutions, are analyzed. Annual blooms are superposed to multiscale fluctuations. The probability density function (pdf) of the fluorescence time series obeys a power law with slope −2. The pdf for annual portions also obeys power laws, with slopes related to the annual average. Empirical mode decomposition (EMD) is used to study the dynamics and display the power spectrum, which is different from the temperature power spectrum. EMD is also used to extract a trend and isolate the blooms from the high frequency dynamics.