使用print(data_nc.variables['U'])获取该变量的信息：

<class 'netCDF4._netCDF4.Variable'>
float32 U(Time, bottom_top, south_north, west_east_stag)
    FieldType: 104
    MemoryOrder: XYZ
    description: x-wind component
    units: m s-1
    stagger: X
    coordinates: XLONG_U XLAT_U XTIME
unlimited dimensions: Time
current shape = (73, 36, 69, 70)
filling on, default _FillValue of 9.969209968386869e+36 used

<class 'netCDF4._netCDF4.Variable'>
float32 V(Time, bottom_top, south_north_stag, west_east)
    FieldType: 104
    MemoryOrder: XYZ
    description: y-wind component
    units: m s-1
    stagger: Y
    coordinates: XLONG_V XLAT_V XTIME
unlimited dimensions: Time
current shape = (73, 36, 70, 69)
filling on, default _FillValue of 9.969209968386869e+36 used

*************************************************************
# u是有36层
u = wrf.getvar(data_nc, 'U', timeidx=1)
print(u.shape)
结果：(36, 69, 70)
# 海平面气压slp，只有一层海平面高度
u = wrf.getvar(data_nc, 'slp', timeidx=1)
print(u.shape)
结果：(69, 69)
# U10即10米高度的风，只有一层即10米高度
u = wrf.getvar(data_nc, 'U10', timeidx=1)
print(u.shape)
结果：(69, 69)