Does the low frequency variability of mesoscale dynamics explain a part of the phytoplankton and zooplankton spectral variability?

Abstract

Observational studies of the last 20 years have revealed a spatial distribution of phytoplankton characterized by a wavenumber spectrum whose slope ranges between k−1 and k−3 (with k being the wavenumber), over horizontal scales ranging from 10 to 100 km. This strong spectral variability can be due either to the physics and/or to the biology. We show in this note that the low frequency variability (LFV) linked to the mesoscale dynamics may explain a significant part of the observed variability. Our numerical results also suggest that the difference between the phytoplankton and zooplankton spectral slopes can depend on the dynamical LFV.