CK calculation

The code calculates the local barotropic energy conversion (CK) following the Maloney (2001) formulation, which measures how kinetic energy is transferred between the mean flow and perturbations. How to use: 1、Provide perturbation fields (up, vp) and mean flow fields (um, vm) 2、Input latitude and longitude arrays for coordinate calculations 3、The function returns the local barotropic energy conversion with the same dimensions as the input perturbation fields Reference: Maloney, E. D., & Hartmann, D. L. (2001). The Madden–Julian oscillation, barotropic dynamics, and North Pacific tropical cyclone formation. Part I: Observations. Journal of the Atmospheric Sciences, 58(17), 2545–2558. https://doi.org/10.1175/1520-0469(2001)0582545:TMJOBD2.0.CO;2