Jeff,
 
Thanks for the quick reply, below is my plotting code. Here are the answers to your question about my arrray:

>>> type(Zdat); type(zdat)
<type 'numpy.ndarray'>
<type 'numpy.ndarray'>
>>> shape(Zdat); shape(zdat)
(180, 360)
(596, 596)
>>> shape(lons); shape(x)
(360,)
(596, 596)
>>> shape(lats); shape(y)
(180,)
(596, 596)
 
I would like to use contourf, but ultimately I want to plot the log(zdat), and since my data have so many null or zero values, I can't get that to work with contourf, whereas imshow seems to handle it.
 
Thanks!!

 

PLOTTING FUNCTION HERE:

def fp_plot(datain):
    from matplotlib.toolkits.basemap import Basemap, shiftgrid
   
    Zdat=datain;
    n,m=N.shape(Zdat)
    lons=N.array([i-179.5 for i in range(m)])
    lats=N.array([i-89.5 for i in range(n)])
    print "The array is bounded: %s : %s lat, %s : %s lon " % (N.min(lats),N.max(lats),N.min(lons),N.max(lons))
    # Set up basmap.
    m = Basemap(llcrnrlon=-180.,llcrnrlat=-90.,urcrnrlon=180.,urcrnrlat= 90.0,\
                rsphere=(6378137.00,6356752.3142),\
                resolution='l',area_thresh=1000.,projection='npstere',\
                lat_1=80.,lon_0=0., boundinglat=40.)
    # transform to nx x ny regularly spaced native projection grid
    nx = int((m.xmax-m.xmin)/20000.)+1; ny = int((m.ymax-m.ymin)/20000.)+1
    zdat,x,y = m.transform_scalar(Zdat,lons,lats,nx,ny,returnxy=True)
    # create the figure.
    fig=figure(figsize=(12,8))
    # add an axes, leaving room for colorbar on the right.
    ax = fig.add_axes([0.1,0.1,0.7,0.7])

    # plot image over map with imshow. Want to use this, but no success yet.
    anorm=normalize(.015*N.max(zdat),0.95*N.max(zdat));
    # Draw flexpart output
    m.imshow(x,y,zdat)
    
    # Draw map components
    m.drawcoastlines()
    m.drawcountries()
    m.drawstates()
    meridians=arange(-170.,180.,20.)
    m.drawmeridians(meridians,labels=[1,1,0,0])
    paralles=arange(-85.,85.,5.)
    m.drawparallels(paralles, labels=[0,0,0,1]); show();

Now, to answer your question, Zdat, or datain is a numpy array with the following characteristics: