  In this work we deepen and complement the analysis on the dynamics of Low
Earth Orbits (LEO), carried out by the authors within the H2020 ReDSHIFT
project, by characterising the evolution of the eccentricity of a large set of
orbits in terms of the main frequency components. Decomposing the
quasi-periodic time series of eccentricity of a given orbit by means of a
numerical computation of Fourier transform, we link each frequency signature to
the dynamical perturbation which originated it in order to build a frequency
chart of the LEO region. We analyse and compare the effects on the eccentricity
due to solar radiation pressure, lunisolar perturbations and high degree zonal
harmonics of the geopotential both in the time and frequency domains. In
particular, we identify the frequency signatures due to the dynamical
resonances found in LEO and we discuss the opportunity to exploit the
corresponding growth of eccentricity in order to outline decommissioning
strategies.
