Karhunen-Loève expansion of Spartan spatial random fieldsKarhunen-Loève expansion of Spartan spatial random fields Peer-Reviewed Journal Publication Δημοσίευση σε Περιοδικό με Κριτές 2018-11-012016enRandom fields (RFs) are important tools for modeling space-time processes and data. The Karhunen-Loève (K-L) expansion provides optimal bases which reduce the dimensionality of random field representations. However, explicit expressions for K-L expansions only exist for a few, one-dimensional, two-parameter covariance functions. In this paper we derive the K-L expansion of the so-called Spartan spatial random fields (SSRFs). SSRF covariance functions involve three parameters including a rigidity coefficient η1, a scale coefficient, and a characteristic length. SSRF covariances include both monotonically decaying and damped oscillatory functions; the latter are obtained for negative values of η1. We obtain the eigenvalues and eigenfunctions of the SSRF K-L expansion by solving the associated homogeneous Fredholm equation of the second kind which leads to a fourth order linear ordinary differential equation. We investigate the properties of the solutions, we use the derived K-L base to simulate SSRF realizations, and we calculate approximation errors due to truncation of the K-L series.http://creativecommons.org/licenses/by/4.0/Probabilistic Engineering Mechanics43132-147 Tsantili Ivi Τσαντιλη Ηβη Christopoulos Dionysios Χριστοπουλος Διονυσιος Elsevier Differentiable random field Dimension reduction Karhunen-Loève expansion Oscillating covariance Spartan covariance