Measure-Valued CARMA Processes
Fred Espen Benth, Sven Karbach, Asma Khedher
TL;DR
This work extends continuous-time autoregressive moving-average (CARMA) theory to measure-valued processes on Banach spaces by defining measure-valued CARMA processes as cone-invariant, analytically weak solutions of linear state-space models driven by Lévy subordinators. It develops the existence, positivity, and moment structure (first and second moments) of these processes, and establishes explicit stationarity conditions via two-sided Lévy input and completely monotone transfer functions. The paper then specializes to the Banach space of finite measures, highlights absolutely continuous cases, and provides concrete parameter-sets and examples including CARMA fields and ambit-field connections, thereby enabling spatio-temporal modeling of renewable-energy dynamics and related financial applications. Finally, it presents methods for evaluating expectation functionals and performing measure changes (Esscher transforms) to support risk-adjusted pricing of forward and derivative contracts within this flexible framework. Overall, the results offer a rigorous, scalable approach to infinite-dimensional CARMA modeling with direct relevance to climate, energy markets, and stochastic spatial systems.
Abstract
In this paper, we examine continuous-time autoregressive moving-average (CARMA) processes on Banach spaces driven by Lévy subordinators. We show their existence and cone-invariance, investigate their first and second order moment structure, and derive explicit conditions for their stationarity. Specifically, we define a measure-valued CARMA process as the analytically weak solution of a linear state-space model in the Banach space of finite signed measures. By selecting suitable input, transition, and output operators in the linear state-space model, we show that the resulting solution possesses CARMA dynamics and remains in the cone of positive measures defined on some spatial domain. We also illustrate how positive measure-valued CARMA processes can be used to model the dynamics of functionals of spatio-temporal random fields and connect our framework to existing CARMA-type models from the literature, highlighting its flexibility and broader applicability.
