1990 to 2050 Atmospheric SO2 Ancillary Files for HadCM3

SO2 emissions are a major source of uncertainty for climate model studies.  From the Coupled Model Intercomparison Project Phase 5 (CMIP5) historical data and representative concentration pathway (RCP) data is readily available for use in climate models. However the contribution from observational data ceases after 2005 and therefore simulations of the recent past are dependent on up to 10 year old projection data. Here the authors have made use of more recent observations and projection scenarios from the ECLIPSE_v5a global emissions dataset. The 5 yearly SO2 land observations have been combined with shipping data, split into surface and high level emissions, interpolated in time to give monthly values and converted to N96 in the data format used by the MetOffice HadCM3 family of climate models.  Data is available for the baseline current legislation (CLE), climate 2 degrees CLE and Maximally Technically Feasible reduction scenarios with data covering the period 1990 - 2050.  To broaden the reuse of this data for other climate models both MetOffice ancillary files and NetCDF output files are included as well as two different methods by which the allocation of different emitters to the low and high level layers.