Application Of Altimetry Observation In Ocean Energy Cascade And Its Aliasing Elimination

The ocean is a turbulent system,and the cascade of ocean energies(through the interaction of non-linear turbulences that enable the conversion of energy on different ocean scales)not only plays a very important role in ocean energy balance,but also is meaning for the transport and redistribution of substances and energy such as heat,salinity and nutrients in the ocean(Qiu,Scott et al.,2008,Zhang et al.,2013).Classical turbulent turbulence theory gives the path of kinetic energy cascades of barotropic mode and baroclinic mode,but lacks verification of ocean observation data and does not systematically summarize the global changes.In the first part of this paper,the global variations of kinetic energy fluxes of the geostrophic turbulence in barotropic mode of and the baroclinic(first baroclinic)mode were investigated using the global ECCO2 reanalysis data.It was found that the first baroclinic kinetic energy cascade are very consistent with the altimeter surface energy cascade.In addition,we find that the reverse cascade of kinetic energy in barotropic mode mainly occurs in the Antarctic Circumpolar Current region(ACC),followed by the Kuroshio Extension and the Gulf Stream region.While in the interior of the ocean,the reverse cascade of barotropic kinetic energy is very weak.The intensity and range of the baroclinic inverse cascade exceed that of barotropic inverse cascade.The most intense baroclinic inverse cascade occur at the eastward current with strong eddy energy,Such as ACC,the Gulf Stream,and the Kuroshio Extension.On the other hand,the inject scale and the arrested scale of the barotropic and baroclinic inverse cascade increase with the decrease of the latitude.In the mid-high latitudes,the inject scale of barotropic energy cascade is larger than the Rossby deformation scale that predicted by the geostrophic turbulence theory.The injection scale of baroclinic inverse cascade and the most unstable feature scale predicted by the linear instability theory share many similarities in the distribution,indicating that energy source of the baroclinic inverse cascade is mainly provided by the baroclinic instability of mean current.The distribution of arrested scale of the barotropic inverse cascade and baroclinic reverse cascade are close to the corresponding scale of barotropic and baroclinic kinetic energy spectrum,indicating that the kinetic energy shifts to and accumulates the large scale.From the change of baroclinic kinetic energy flux at the different depth,the reverse cascade of baroclinic kinetic energy occurs above the main thermocline,which is consistent with the distribution of baroclinic eddy kinetic energy.In addition to,the satellite altimetry data and World Ocean Atlas(WOA)climatological data were used to investigate the seasonal variations of eddy kinetic energy spectra in the North Pacific Subtropical Countercurrent zone(STCC).It was found that the baroclinic instability and the seasonal variation of kinetic energy inverse cascade in STCC resulted in the seasonal variation of kinetic energy spectrum.Finally,the paper investigates the sea surface height aliasing in the satellite altimetry observation caused by the barotropic pressure and high frequency signal in the Sea of Japan,and the method of using the bottom pressure data to de-aliasing from sea surface height gridded products with multiple altimeter merge is proposed.The dealiased products were compared with the tide gauge and drifting data,and it is found that the de-aliased gridded products of sea surface height can better reflect the mesoscale signals in the ocean.