How do I make data transparent Matlab 2016b?

I am trying to plot surface pressure data over a map projection from m_map toolbox. How can I make the data transparent, so the landscape beneath it remains unobscured? Here is what I have so far.

figure
m_proj('stereographic','lat',90,'long',30,'radius',25);
m_ibcao('contour',[-3500:1000:-500],'b');
m_contourf (longitude,latitude,mean(sst(1:480,1:241,ice1time),3)')   
m_contour (longitude,latitude,mean(sst(1:480,1:241,ice1time),3)','k')
colorbar
colormap jet
caxis([-1,10])
m_grid('xtick',12,'tickdir','out','ytick',[70 80],'linest','-');

[Rik]

Hidden inside those functions, there's probably a patch or surf call, so you should be able to dig out the object and set the AlphaData property.

[Walter Roberson]

This appears to be using https://www.eoas.ubc.ca/~rich/map.html