Scripts for Energy exchanges in Saturn's polar regions from Cassini observations: Eddy-zonal flow interactions

Scripts in IDL (Interactive Data Language) to read in gridded wind fields in Saturn's polar atmosphere, derived from the work of Antuñano et al. (2015) and available online from the Oxford Research archive (Antuñano et al. 2021), and to calculate and plot various diagnostics relating to the eddy-zonal flow interactions at latitudes > 60 degrees in both hemispheres. The methods and results are presented in a paper under consideration by J Geophys Res (Read et al. 2022; Figure references below refer to this paper). The purpose of each script is as follows.

gread_north.pro        Read in the gridded wind data onto a regular latitude-longitude grid, plot the u and v wind components in a polar
gread_south.pro        stereographic projection and calculate and plot the zonal mean zonal wind profile. [Figs S1, S2, 4]

Vordiv.pro                  Calculate the relative vorticity and horizontal divergence fields and plot in a polar stereographic projection. [Fig. 1]
Vordivs.pro        
            

uvcorr_n.pro              Calculate scatter plots of u' vs v' and momentum flux u'v' vs du/dy. Compute correlation coefficients between u'
uvcorr_s.pro              and v' and between u'v' and du/dy with plots. The latter reads in pre-computed correlation coefficients for both
uvcorr_plot.pro          hemispheres in files corr_north.dat and corr_southa.dat  [Fig. S5]
            
uvflux_anal_north2.pro    Calculate various diagnostics relating to the energetic interaction between non-axisymmetric eddies  and the
uvflux_anal_south.pro      zonal mean zonal wind. Plots latitude profiles of the following:
                                           rms u' and v'
                                           Eddy kinetic energy (EKE)
                                           u',v' correlation coefficient
                                           u'v' and du/dy
                                           KE/KZ conversion rate (u'v'.du/dy)
                                        Computes zonal KE spectrum and zonal Fourier decomposition of KE/KZ conversion rate [u.div(u'v')].  Plot      
                                        maps in (latitude, wavenumber) of KE/KZconversion rate and latitude profiles of both forms of KE/KZ
                                        conversion integrated over various latitude bands. [Figs 3, 5, 7, 8, 9, 14, S4]

plotscalesN.pro        Calculate latitude profiles of Rossby radius of deformation (L_D) and Rhines scale (L_R), either in km or degrees
plotscalesS.pro        of latitude. [Fig. 6]
            

Ampphase6.pro        Calculate latitude variations of the amplitudes and zonal phases of the m=6 component of u', v', u'v' for the latitude                                   band containing the north polar hexagon and display plots.                                                                                                Latitude profile of u'(m=6)
                                       Latitude profile of v'(m=6)
                                       Latitude profile of phase difference (u'(6)-v'(6))
                                       Latitude profile of u'v'(m=6)
                                       Latitude profile of u'v'(m=6) and u'v'(total)
                                       Longitude profile of v' @76.4 deg N
                                       Latitude profile of cos(phase diff(m=6))
                                       Map of u'(m=6)+ubar
                                       Map of v'(m=6)
                                       Map of u'(m=6)
                                       Map of u'(total)
                                       [Figs 10 and 11]

Users are recommended to run either gread_north or gread_south, depending on which hemisphere is of interest, and then the other scripts (in no particular order). 

References
Antuñano, A., del Rio-Gaztelurrutia, T., Sanchez-Lavega, A., & Hueso, R. (2015). Dynamics of Saturn's polar regions. J. Geophys. Res.: Planets, 120, 155-176. doi:10.1002/2014JE004709

Antuñano, A., del Rio-Gaztelurrutia, T., Hueso, R., Read, P. L., & Sanchez-Lavega, A. (2021). Cassini Saturn polar velocity fields. University of Oxford Research Archive, v.1 , [Dataset]. Retrieved from https://doi.org/10.5287/bodleian:X5dOD7ePD

Read, P. L., A. Antuñano, S. Cabanes, G. Colyer, T. del Rio Gaztelurrutia, and A. Sanchez-Lavega (2022). Energy exchanges in Saturn's polar regions from Cassini observations: Eddy-zonal flow interactions, J Geophys. Res., submitted.