I do not have your data so I created my own.
You may have to experiment with this with your data:
The Code —
x = linspace(-5, 5, 50);
[X,Y] = meshgrid(x);
Z = abs(cos(X) + sin(2*pi*Y/5));
mesh(X, Y, Z)
fill3([x x(1)], -5*ones(1,size(x,2)+1), [Z(1,:) Z(1,1)], 'k')
It should work with your data with minor modifications.
The Plot —