python - transforming to/from earth relative and grid relative for flow vectors in metpy

Question

I've tried looking through the source code, but there doesn't seem to be support for this in MetPy. For example, I have a set of wind vectors relative to the Earth coordinate system (speed, direction) which I want to transform to (u,v) relative to a grid on a Lambert Conformal projection.

Answer 1

MetPy 不处理坐标系变换，它让 CartoPy 处理。它确实支持将速度和方向转换为组件。所以你想做：

import cartopy.crs as ccrs
import metpy.calc as mpcalc

proj = ccrs.LambertConformal()

u_earth, v_earth = mpcalc.wind_components(speed, direction)
u_grid, v_grid = proj.transform_vectors(ccrs.PlateCarree(), lon, lat, u_earth, v_earth)

使用PlateCarree组件的源投影告诉 CartoPy 坐标和组件是 lon/lat 和地球相关的。