Lawrence Berkeley National Laboratory, California, United States
Data from eddy covariance sites and remote sensing systems have allowed advancing ecological understanding of ecosystems at multiple scales, ranging from a leaf to the globe, and for processes happening within single days all the way to decades. Measurements of carbon, water, and energy fluxes at eddy covariance sites are inherently heterogeneous, with differences in ecosystem characteristics, instrumentation deployed, and data processing choices, among many others. One of the goals for creating the FLUXNET data products was to make data from different flux sites more comparable. FLUXNET is a network of regional flux networks, including AmeriFlux, ICOS, European Fluxes Database, OzFlux, and many others, each of which bring together flux sites at a regional scale. FLUXNET2015 is the third global data product for FLUXNET and it brought standardization to many of the data processing steps and the data and metadata formats for flux data. This processing now relies on the ONEFlux ONEFlux (Open Network-Enabled Flux processing pipeline) software package, which is jointly developed by the AmeriFlux Management Project, the European Fluxes Database, and the ICOS Ecosystem Thematic Centre. Using ONEFlux, regional networks have been generating updated data products for sites within their network that are fully compatible with FLUXNET2015 and are called FLUXNET data products. In this presentation, we describe these data products and a few of the key considerations when using them alongside remote sensing data products, including: (a) combining data from different sites and representing multiple ecosystems; (b) dealing with different types of uncertainties in flux data; (c) choosing the right variables from the FLUXNET data product for different applications; (d) using quality flags and information about gaps to filter data; (e) using tower-based optical measurements and more directly connecting to remote sensing measurements; and, (f) understanding eddy covariance tower footprints, which are not yet part of the standard suite of FLUXNET data products, but still a critical consideration. Better understanding of strengths and limitations of flux and remote sensing data products, and how they can be combined, allow asking and answering new questions about a multitude of ecological phenomena across scales.
