The UFLUX ensemble of multiple-scale carbon, water, and energy fluxes.

In light of the challenges posed by climate change, global governments, including the United Kingdom (UK), have committed to addressing and mitigating the impacts of climate change, emphasizing the pursuit of Net Zero objectives. The terrestrial ecosystems on a global scale, functioning as pivotal carbon reservoirs, assume a critical role in climate change mitigation, especially within the context of an imminent scenario marked by accelerated warming and drying conditions. Recognizing that the carbon sequestration capacity of ecosystems is intricately linked to their energy and water cycling dynamics, this study presents the Uniform FLUXes (UFLUX)-ensemble dataset (https://sites.google.com/view/uflux) that accurately quantifies carbon, water, and energy fluxes across ecosystems in a consistent and mutually comparable manner. The UFLUX ensemble, relying on the upscaling of in-situ eddy covariance (EC) tower measurements using satellite vegetation proxies and meteorology reanalysis, constitutes the methodological foundation of this research.

The UFLUX originated from our prior investigations into filling gaps in EC fluxes. This is due to the analogous nature of the procedures involved in flux gap-filling and upscaling, wherein both entail the interpolation/extrapolation of fluxes, albeit in the temporal and spatial domains, respectively. The fluxes in UFLUX are upscaled through the application of a uniform set of algorithms and environmental determinants, aiming to mitigate the sources of uncertainty. The UFLUX methodology has demonstrated effectiveness in capturing the global CO₂ fertilization effect. Furthermore, it has exhibited resilience to agricultural management interventions and has adeptly captured flux variability at a high spatial resolution of 20 meters in southwest England. These accomplishments lay the groundwork for generating the UFLUX-ensemble dataset.

The resulting UFLUX-ensemble dataset incorporates 60 members considering specific advantages of multiple satellite and meteorology reanalysis products. Aligned with the Net Zero vision articulated by nations, and recognizing the imperative of addressing data storage requirements, the dataset is made available on three scales: 1) daily 100-m resolution for the UK, 2) half-yearly 100-m resolution for Europe, and 3) monthly 0.25°×0.25°resolution for the entire globe. This diverse data provision is designed to assist climate actions, particularly in countries grappling with specific socio-economic challenges. A rigorous technical validation underscores the merits of the UFLUX ensemble, demonstrating its ability to capture 0.8 % of the flux variability with errors amounting to 0.76 g C m^-2 d^-1 and 11.67 W m^-2. The UFLUX-ensemble dataset serves as a valuable resource, offering insights to inform land management practices, including nature-based solutions, with the overarching objective of augmenting carbon sequestration in terrestrial ecosystems and contributing to the realization of a carbon-neutral future.