lon = np.linspace(-180, 180, 120)
lat = np.linspace(-90, 90, 60)
lon, lat = np.meshgrid(lon, lat)
d2r = np.pi/180
v = 2 - np.cos(np.pi * (np.arccos( np.cos(lon*d2r)*np.cos(lat*d2r) ) / (1.2*np.pi) ))