  Spatial networks have recently attracted great interest in various fields of
research. While the traditional network-theoretic viewpoint is commonly
restricted to their topological characteristics (often disregarding existing
spatial constraints), this work takes a geometric perspective, which considers
vertices and edges as objects in a metric space and quantifies the
corresponding spatial distribution and alignment. For this purpose, we
introduce the concept of edge anisotropy and define a class of measures
characterizing the spatial directedness of connections. Specifically, we
demonstrate that the local anisotropy of edges incident to a given vertex
provides useful information about the local geometry of geophysical flows based
on networks constructed from spatio-temporal data, which is complementary to
topological characteristics of the same flow networks. Taken both structural
and geometric viewpoints together can thus assist the identification of
underlying flow structures from observations of scalar variables.
