lon = np.linspace(-np.pi, np.pi, 100)
lat = np.linspace(-np.pi/2, np.pi/2, 50)
lon, lat = np.meshgrid(lon, lat)
v = 2 - np.cos(np.pi * (np.arccos( np.cos(lon)*np.cos(lat) ) / (1.2*np.pi) ))