CORSO Deliverable 3.1 - Database of existing Δ14CO2 measurements

Estimating continental-scale fossil CO2 emissions from 14CO2 observations e.g. over Europe or North America require reliable boundary conditions for the targeted area. These can be defined by global inversions that need to be based on hemispheric (or global) background observations at marine or coastal sites or observations from the free troposphere > 3500 m a.s.l. over the continents. A corresponding database of such 14CO2 observations from globally distributed monitoring stations has been compiled within task 3.1, which will be used by the global and regional inversions (tasks 3.3 and 3.4) for the period 2004-2024. The database includes published datasets from the global monitoring programs of NOAA/INSTAAR, SIO/LLNL, SIO/UCI, and GNS/NIWA, as well as published and unpublished data from the UHEI global 14CO2 network and from Baring Head, New Zealand. To estimate compatibility of this merged dataset, we revisited inter-laboratory comparison results of the contributing institutions and laboratories, that showed 14CO2 compatibility < 2 ‰. Further comparison of measurements from different monitoring programs conducted in the same latitudinal bands (within ca. 10° lat.) did not reveal any trends of potential offsets between institutions over the last two decades. Comparison of data collected from the 1980s onwards at Baring Head, New Zealand and Cape Grim, Tasmania, Australia shows no offset. All datasets have been complemented with meta data describing the individual station characteristics, sampling and analysis methods, time period coverage, data sources, and references. For each record, two datasets are delivered. The first contains all measurements from the station. The second contains only those data which have been identified as representing large-scale background conditions. The data are currently openly available, at a server of UHEI. FAIR data principles will be applied to the final data compilations with the data being shared via the ICOS ERIC Carbon Portal.