[英]How to convert display coordinates to geographoc coordinates (lat, lon) using cartopy?
[英]How to plot in Albera Equal area projection using lat lon pairs in cartopy?
我正在尝试使用 cartopy 对纬度对数据中的 plot PM 数据进行处理。 我使用两种不同的投影进行了尝试。 (PM25['lat'] 有 lat 值,PM25['lon'] 有 lon 值,val 是 PM25 浓度的网格):
a) 为什么Albera等面积圆锥投影中的colors看起来更平滑?
b) 如何在圆锥区域投影中添加 state 边界?
阿尔贝拉投影代码
extent = [-125,-65,25,50]
fig = plt.figure(figsize=(8,4))
ax.set_extent(extent)
ax.coastlines(resolution="110m",linewidth=1)
ax.gridlines(linestyle='--',color='black')
ax.add_feature(cfeature.BORDERS.with_scale('50m'), alpha=1)
ax.add_feature(cfeature.STATES)
projection = ccrs.AlbersEqualArea(central_longitude=-100)
ax.add_feature(COUNTIES, facecolor='none', edgecolor='gray', alpha =0.5)
projection = ccrs.AlbersEqualArea(central_longitude=-100)
fig.add_axes([-.05, -.05, 1.2, 1.2], projection=projection)
ax.add_feature(cfeature.STATES)[enter image description here][1]
clevs = np.arange(0,40)
plt.contourf(PM25['lon'], PM25['lat'], val,clevs, transform=ccrs.PlateCarree(),cmap='viridis',vmin=0,
vmax =16)
板卡雷投影代码
from matplotlib import colorbar, colors
extent = [-125,-65,25,50]
fig = plt.figure(figsize=(8,4))
ax = plt.axes(projection=ccrs.PlateCarree())
ax.set_extent(extent)
ax.coastlines(resolution="110m",linewidth=1)
ax.gridlines(linestyle='--',color='black')
ax.add_feature(cfeature.BORDERS.with_scale('50m'), alpha=1)
ax.add_feature(cfeature.STATES)
#ax.add_feature(COUNTIES, facecolor='none', edgecolor='gray', alpha =0.5)
clevs = np.arange(0,40)
plt.contourf(PM25['lon'], PM25['lat'], val,clevs, transform=ccrs.PlateCarree(),cmap='viridis',vmin=0,
vmax =16)
a) 我觉得 Albers 看起来更平滑可能只是因为投影不同,投影 Plate Carre 的图形被压成带状。
b) 您应该首先设置轴投影,就像在Plate Carre plot 中一样,然后 shapefile 多边形将显示在图中。
fig = plt.figure(figsize=(8,4))
projection = ccrs.AlbersEqualArea(central_longitude=-100)
ax = plt.axes(projection=projection)
ax.add_feature(...)
ax.add_feature(...)
....
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