  Spatial environmental processes often exhibit dependence in their large
values. In order to model such processes their dependence properties must be
characterized and quantified. In this paper we introduce a measure that
evaluates the dependence among extreme observations located in two separated
regions of locations of R^2. We compute the range of this new dependence
measure, which extends the existing {\lambda}-madogram concept, and compare it
with extremal coefficients, finding generalizations of the known relations in
pairwise approach. Estimators for this measure are introduced and asymptotic
normality and strong consistency are shown. An application to the annual maxima
precipitation in Portuguese regions is presented.
