mixed layer depth calculation based on TKE

#    if x == 0: # MLD based on TKE criterion (steiner&denman 2008)
#        depfull=squeeze(ncfile.variables['z'])
#        tke=squeeze(ncfile.variables['tke'])
#        tke1d=zeros(len(time))
#        for y in range(len(time)):
#            tke1d[y]=depfull[where(tke[y,:]<1e-5)[0][-1]]+0.5
#        plot(time_mean,mod_mean(tke1d,dt),'w',label='MLD')