Python结合Basemap/Cartopy绘制NOAA风场流线图的问题求助

Basemap 方案：解决'y must be strictly increasing'错误 #

问题原因 #

NOAA提供的纬度数据默认从北到南递减（例如从60°N到-20°S），但streamplot要求输入的y坐标必须严格递增，这是报错的核心原因。另外代码中存在几处变量名笔误（如U1应为U4，lat_ticks应为parallels等）。

修正代码 #

from netCDF4 import Dataset as NetCDFFile 
import matplotlib.pyplot as plt
import numpy as np
from mpl_toolkits.basemap import Basemap

fig = plt.figure(figsize=(12,9))
ax = fig.add_subplot(111)
nc2 = NetCDFFile('E:/cycle-of-Mjo/NOAA/nc/u850b1.nc')
nc4 = NetCDFFile('E:/cycle-of-Mjo/NOAA/nc/v850b1.nc')

# 读取并反转纬度数组，使其从南到北递增
lat = nc2.variables['lat'][:][::-1]
lon = nc2.variables['lon'][:]
# 同步反转U、V数据的纬度维度，匹配新的纬度顺序
U4 = nc2.variables['uwnd'][:][:, ::-1, :]
V4 = nc4.variables['vwnd'][:][:, ::-1, :]

map = Basemap(projection='cyl', lon_0=0, lat_0=-20, 
              llcrnrlon=0., llcrnrlat=-20., urcrnrlon=360., urcrnrlat=61., 
              resolution='i', suppress_ticks=False)
plt.tick_params(labelleft=False, labelbottom=False, axis='both', which='major')
map.drawcoastlines()

parallels = np.arange(-20., 61., 20.)
meridians = np.arange(0, 360., 50.)
map.drawparallels(parallels, labels=[0,0,0,0], fontsize=10, dashes=(0,1), fontweight='bold')
map.drawmeridians(meridians, labels=[0,0,0,0], fontsize=10, dashes=(0,1), fontweight='bold')

lons, lats = np.meshgrid(lon, lat)
x, y = map(lons, lats)
# 使用修正后的U4、V4数据绘制流线
map.streamplot(x, y, U4[0, :, :], V4[0, :, :], density=2)

plt.show()

Cartopy 方案：解决160°E-160°W区域流线缺失问题 #

问题原因 #

设置central_longitude=180后，Cartopy投影以180°为中心，但streamplot无法自动处理0-360经度的跨180°连续数据，导致该区域流线断裂。同时代码中存在U1应为U4的笔误。

修正方案1：将经度转换为-180~180范围 #

把原始0-360的经度转换为-180到180，配合central_longitude=180的投影，可完整绘制所有区域流线：

from netCDF4 import Dataset as NetCDFFile 
import numpy as np  
import cartopy.crs as ccrs 
import matplotlib.pyplot as plt
from cartopy.mpl.ticker import LatitudeFormatter, LongitudeFormatter

nc2 = NetCDFFile('E:/cycle-of-Mjo/NOAA/nc/u850b1.nc')
nc4 = NetCDFFile('E:/cycle-of-Mjo/NOAA/nc/v850b1.nc')

lat = nc2.variables['lat'][:]
# 将0-360经度转换为-180~180范围
lon = nc2.variables['lon'][:]
lon[lon > 180] -= 360
U4 = nc2.variables['uwnd'][:]
V4 = nc4.variables['vwnd'][:]

# 保持中心经度180的投影
ax = plt.axes(projection=ccrs.PlateCarree(central_longitude=180.0))
ax.coastlines()
# 设置显示范围为转换后的经度区间
ax.set_extent([-180, 180, -20, 60], crs=ccrs.PlateCarree())  

# 设置刻度并格式化，显示为0-360样式
ax.set_xticks(np.arange(-180, 181, 50), crs=ccrs.PlateCarree())
ax.xaxis.set_major_formatter(LongitudeFormatter(zero_direction_label=True))
ax.set_yticks(np.arange(-20, 61, 20), crs=ccrs.PlateCarree())
ax.yaxis.set_major_formatter(LatitudeFormatter())

# 使用转换后的经度和正确的U4、V4数据绘制流线
strm = plt.streamplot(lon[::5], lat[::5], U4[0,::5,::5], V4[0,::5,::5], 
                      color='blue', density=1, arrowstyle='->', arrowsize=1, 
                      transform=ccrs.PlateCarree())  

plt.show()

修正方案2：不修改经度，使用默认0°中心投影 #

如果不想调整经度数据，可直接使用默认PlateCarree投影（中心经度0），同样能完整绘制：

from netCDF4 import Dataset as NetCDFFile 
import numpy as np  
import cartopy.crs as ccrs 
import matplotlib.pyplot as plt
from cartopy.mpl.ticker import LatitudeFormatter, LongitudeFormatter

nc2 = NetCDFFile('E:/cycle-of-Mjo/NOAA/nc/u850b1.nc')
nc4 = NetCDFFile('E:/cycle-of-Mjo/NOAA/nc/v850b1.nc')

lat = nc2.variables['lat'][:]
lon = nc2.variables['lon'][:]
U4 = nc2.variables['uwnd'][:]
V4 = nc4.variables['vwnd'][:]

# 使用默认PlateCarree投影（中心经度0）
ax = plt.axes(projection=ccrs.PlateCarree())
ax.coastlines()
ax.set_extent([0, 360, -20, 60], crs=ccrs.PlateCarree())  

# 设置0-360的经度刻度
ax.set_xticks(np.arange(0, 360, 50), crs=ccrs.PlateCarree())
ax.xaxis.set_major_formatter(LongitudeFormatter(zero_direction_label=True))
ax.set_yticks(np.arange(-20, 61, 20), crs=ccrs.PlateCarree())
ax.yaxis.set_major_formatter(LatitudeFormatter())

strm = plt.streamplot(lon[::5], lat[::5], U4[0,::5,::5], V4[0,::5,::5], 
                      color='blue', density=1, arrowstyle='->', arrowsize=1, 
                      transform=ccrs.PlateCarree())  

plt.show()

内容的提问来源于stack exchange，提问作者Sedighe