如何裁剪网格线，使它们不会出现在带有cartopy的大陆上？

import cartopy.crs as ccrs
import cartopy.feature as cfeature
import matplotlib.pyplot as plt

projection = ccrs.PlateCarree()

fig, ax = plt.subplots(figsize=(10, 6), subplot_kw=dict(projection=projection))

ax.add_feature(cfeature.LAND, edgecolor='black')
ax.add_feature(cfeature.OCEAN)
ax.add_feature(cfeature.COASTLINE)
ax.add_feature(cfeature.BORDERS, linestyle=':')

ax.gridlines(draw_labels=True, linewidth=0.5, color='gray', alpha=0.5)
ax.set_extent([-180, 180, -90, 90], crs=projection)
ax.outline_patch.set_visible(False)