Observing the continental-scale carbon balance: assessment of sampling complementarity and redundancy in a terrestrial assimilation system by means of quantitative network design

Abstract

Abstract. This paper investigates the relationship between the heterogeneity of the terrestrial carbon cycle and the optimal design of observing networks to constrain it. We combine the methods of quantitative network design and carboncycle data assimilation to a hierarchy of increasingly heterogeneous descriptions of the European terrestrial biosphere as indicated by increasing diversity of plant functional types. We employ three types of observations, flask measurements of CO 2 concentrations, continuous measurements of CO 2 and pointwise measurements of CO 2 flux. We show that flux measurements are extremely efficient for relatively homogeneous situations but not robust against increasing or unknown complexity. Here a hybrid approach is necessary, and we recommend its use in the development of integrated carbon observing systems.

Reviews and syntheses: guiding the evolution of the observing system for the carbon cycle through quantitative network design

“…The presentation of the methodology follows Kaminski and Rayner (2008) and Kaminski et al (2012b) using the notation introduced to this special issue by Rayner et al (2016). The underlying algebra is provided by Tarantola (2005) and Rayner et al (2016).…”

“…The choice of the control vector is a subjective element in the QND procedure. A good choice covers all input factors with high uncertainty and high impact on simulated observations y mod or target quantities f (Kaminski et al, 2012b;Rayner et al, 2016). The target quantity may be any quantity that can be extracted from a simulation with the underlying model, i.e.…”

“…The study of Szolgayová et al (2016) builds on the flux and flask network definitions of Kaminski et al (2012b). It employed the CCDAS QND system to assess the uncertainty reduction in CO 2 fluxes through the combined network.…”

“…A more systematic assessment of the complementarity of atmospheric and ecosystem measurements was performed by Kaminski et al (2012b). The study employed the prognostic Biosphere Energy-Transfer Hydrology (BETHY; Knorr, 2000) model, which composes the global vegetation out of 13 PFTs.…”

“…For example, the QND systems by Kaminski et al (2012b) used a terrestrial biosphere model coupled to two atmospheric transport models to evaluate the combination of one terrestrial and two atmospheric networks with surface flux integrals as target quantities. To reduce the computational demands one may think of a strategy that treats the QND problem separately per model and network component and then integrates the results (in the following termed "separate QND").…”