import numpy as np

a = np.load("/home/ruomu/Desktop/test.npz")

b = a['value']
lon = a['lon']
lat = a['lat']

a = np.load("/home/ruomu/Desktop/test2.npz")['value']


np.savez("/home/ruomu/Desktop/test2.npz", value=np.max(b,axis=0), lon=lon, lat=lat)