Oceanic mesoscale motions including eddies, meanders, fronts, and
filaments comprise a dominant fraction of oceanic kinetic energy and
contribute to the redistribution of tracers in the ocean such as heat,
salt, and nutrients. This reservoir of mesoscale energy is regulated by
the conversion of potential energy and transfers of kinetic energy
across spatial scales. Whether and under what circumstances mesoscale
turbulence precipitates forward or inverse cascades, and the rates of
these cascades, remain difficult to directly observe and quantify
despite their impacts on physical and biological processes. Here we use
global observations to investigate the seasonality of surface kinetic
energy and upper ocean potential energy. We apply spatial filters to
along-track satellite measurements of sea surface height to diagnose
surface eddy kinetic energy across 60-300 km scales. A geographic and
scale dependent seasonal cycle appears throughout much of the
mid-latitudes, with eddy kinetic energy at scales less than 60 km
peaking 1-4 months before that at 60-300 km scales. Spatial patterns in
this lag align with geographic regions where the conversion of potential
to kinetic energy are seasonally varying. In mid-latitudes, the
conversion rate peaks 0-2 months prior to kinetic energy at scales less
than 60 km. The consistent geographic patterns between the seasonality
of potential energy conversion and kinetic energy across spatial scale
provide observational evidence for the inverse cascade, and demonstrate
that some component of it is seasonally modulated. Implications for
mesoscale parameterizations and numerical modeling are discussed.