Unwrap Phase Angle in a contour plot

Hello,

I am trying to plot amplitude and phase angle for stress components in soil for a constant frequency. Everything looks good (Amplitude, Real, and Imaginary part) But when it comes to calculate phase angle, I get unreasonable results due to jumps in phase angle. I know the function "unwrap" would fix this problem when angle is plotted with respect to frequency, but here the frequency is constant and the location (vertical, horizontal) is changing.

I really appreciate any suggestion/guidance. The following code is for plotting phase angle, while I put real, imag, and amplitude figures for reference.

phase angle is calculated as arctan(Imag/Real) and adjusted to have the value of -pi to pi.

clc; clear all; x = load('horizontal.txt'); z = load('vertical.txt');

Phase_shear = load('shearphase.txt');

% use meshgrid to create X and Y mesh

nlin = 100;

xlin = linspace(min(x),max(x),nlin);

zlin = linspace(min(z),max(z),nlin);

[X,Z] = meshgrid(xlin,zlin);

s_s = griddata(x,z,Phase_shear,X,Z);

figure (1) contourf(X,Z,s_s,1000,'linestyle','none'); colorbar; xlabel('x/a') ylabel('z/a') % caxis([0, 2*pi()]) % ylim([0 5]) xlim([0 2.5]) set(gca,'YDir','Reverse') title('\tau_r_z/p Phase Angle (Radians)')

Thank you, Bahar