The manuscript presents an approach for enabling direct flux measurements of greenhouse gases to already existing tall tower networks by simply adding a 3D sonic anemometer to each station. This way, the spatial information density about the land surface exchange and quantifying temporal sources and sinks of greenhouse gases would be significantly improved with little extra instrumental effort. Slower-response analyzers may be used for flux measurements as the relevant frequency ranges at tall towers differ from those closer to the land surface. Tall tower measurements have larger footprints than classical eddy-covariance ecosystem sites, which further amplify spatial coverage of observations. Still, detailed knowledge of surrounding footprints is needed. The presented concept is of high relevance within the scientific greenhouse gas community and may act as a blueprint for bridging scales between atmospheric and ecosystem networks.

I agree with the handling aditor that this is a very useful and comprehensive study and deserves wide attention.