An Interpolation Method, Based on Double Fourier Expansion for the Calculation of Atmospheric Kinetic Energy Spectra, Compared with Bilinear Interpolation

Abstract

A crucial step in the calculation of spectra from objective analyses is the transformation of the analysis to the latitude-longitude grid by some interpolation method. By analysing a synthetic two-dimensional function of known spectral content, it is shown that an interpolation method based on double Fourier expansion yields better results than the conventional linear interpolation. In particular, the minus-third- power profile of the high-wavenumber part of the spectrum is very well reproduced.