使用matplotlib和底图的极坐标投影的奇怪等高线图

Question

I am making Polar Stereographic Projection maps of some climate model outputs. For some of these data, the plot looks weird. For example, in this figure:

only two color contours showed up while the actual data should span much wider range. Furthermore, a large portion of the region should be blank since the data are masked out by netcdf module already (they are undefined).

from netCDF4 import Dataset
import matplotlib
matplotlib.use('agg')
import matplotlib.pyplot as plt
import numpy as np    
from mpl_toolkits.basemap import Basemap    
from pylab import *
fig_index=1
fig = plt.figure(num=fig_index, figsize=(12,7), facecolor='w')
fbot_levels = arange(0.05,1.0,0.05)
fname='alb.nc4'
ncfile = Dataset(fname, 'r', format='NETCDF4')
TS2=ncfile.variables['SIALB'][0]
LON=ncfile.variables['lon'][:]
LAT=ncfile.variables['lat'][:]
ncfile.close()
lon,lat=np.meshgrid(LON,LAT)
ax2 = plt.axes([0.2, 0.225, 0.6, 0.6])
meridians=[0,1,1,1]
m = Basemap(projection='spstere',lon_0=0,boundinglat=-45)
m.drawcoastlines()
x, y =m(lon,lat)
plt.contourf(x,y,TS2, fbot_levels, origin='lower')
m.drawparallels(np.arange(-90.,120.,15.),labels=[1,0,0,0]) # draw parallels
m.drawmeridians(np.arange(0.,420.,30.),labels=meridians) # draw meridians
coloraxis = [0.1, 0.1, 0.8, 0.035]
cx = fig.add_axes(coloraxis, label='m', title='K')
cbar=plt.colorbar(cax=cx,orientation='horizontal',ticks=list(fbot_levels))
plt.show()

You can find the dataset in netcdf format which is used to generate the figure here

https://dl.dropboxusercontent.com/u/45427012/alb.nc4

I am using basemap-1.0.6 with matplotlib-1.2.1 on py2.7.

Answer 1

Your Basemap object (m) also serves as the mpl axes. When plotting, you should use that instead of using plt. . So:

m.contourf(x,y,TS2, fbot_levels, origin='lower')

Stretching the levels between 0.5 and 0.9 highlights the different contours further.