Covariance functions on spheres cross time: Beyond spatial isotropy and temporal stationarity

Anne Estrade, Alessandra Fariñas, Emilio Porcu

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Spectral representations uniquely define the covariance functions associated to random fields defined over spheres or spheres cross time. Covariance functions on spheres cross time are usually modeled under the assumptions of either spatial isotropy or axial symmetry, and the assumption of temporal stationarity. This paper goes beyond these assumptions. In particular, we consider the problem of spatially anisotropic covariance functions on spheres. The crux of our criterion is to escape from the addition theorem for spherical harmonics. We also challenge the problem of temporal nonstationarity in nonseparable space–time covariance functions, where space is the n-dimensional sphere.

Original languageBritish English
Pages (from-to)1-7
Number of pages7
JournalStatistics and Probability Letters
Volume151
DOIs
StatePublished - Aug 2019

Keywords

  • Gegenbauer polynomial
  • Positive definite
  • Space–time random field
  • Spectral representation
  • Spherical harmonic

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