How to find a specific area in the mesh plot.

How can I integrated the following 3D plot at specific points using trapz?

mesh(data0)

[Bjorn Gustavsson]

Do you mean the the horizontal rectangle? Or some other area? In the figure you have marked 2 vertical lines from zero to "0.8" and two horizontal lines from the orange points...

[Vahram Voskerchyan]

Yes I am interested in the horizontal rectangle, it's the area from that points ownward till the end.