Vector sensor processing relies on the covariance matrix for both a single vector sensor and a larger matrix from a vector sensor array. The elements of these covariance matrices have physical interpretation in terms of complex intensity. The presence of reactive intensity on the array shows up in the off diagonal elements of the covariance matrix and has significant implications on direction of arrival (DOA) algorithms. Sources of reactive intensity in an underwater waveguide are dependent on the geometry of the system and fluctuations in these quantities affect the ability to increase the array aperture to better resolve arrival angles.