DATE: May 18, 2016 SUMMARY CEDS VOC emissions are split into species groups using the splits developed by TNO as used in the RETRO project (and also HTAPv2). **** NOTE netCDF internal variable names have changed from previous versions **** At the request of PCMDI, netCDF internal variable names are now consistent with the variable_id in the metadata and variable_id in the filename. (As in previous versions, dashes ("-") are replaced by underscores ("_") for the variable name to avoid errors with some software packages.) As a result, variable names changed for the speciated VOC supplemental emission files. NMVOC emissions are split into the following 23 species groups: VOC_id VOC_name molecular weight VOC1 alcohols 46.2 VOC2 ethane 30 VOC3 propane 44 VOC4 butanes 57.8 VOC5 pentanes 72 VOC6 hexanes_plus_higher_alkanes 106.8 VOC7 ethene 28 VOC8 propene 42 VOC9 ethyne 26 VOC12 other_alkenes_and_alkynes 67 VOC13 benzene 78 VOC14 toluene 92 VOC15 xylene 106 VOC16 trimethylbenzenes 120 VOC17 other_aromatics 126.8 VOC18 esters 104.7 VOC19 ethers 81.5 VOC20 chlorinated_hydrocarbons 138.8 VOC21 methanal 30 VOC22 other_alkanals 68.8 VOC23 ketones 75.3 VOC24 acids 59.1 VOC25 other_voc 68.9 It is assumed that isoprene (number 10) and terpenes (number 11) are not emitted in significant quantities by anthropogenic sources, and are not included in the anthropogenic split. The split between these 23 categories was done by extracting from the 0.5 degree gridded RETRO speciation files ( downloaded from the HTAPv2 wiki web site. Sector-specific speciation profiles were extracted for each country and, where necessary, renormalized to sum to 1. These profiles were applied to each country and sector in the CEDS emissions data. The profiles are held constant over time. Note that these are the same species groups that were used in the CMIP5 emissions dataset (Lamarque et al. 2010), although the filenames are different here. Note in VOC gridded emissions files(2017-05-01), the variable name within the NetCDF file only uses underscore "_" as delimiter ( e.g., VOC06_hexanes_pl_em_speciated_VOC_anthro), which is also identical to variable_id entry in the metadata of the file. Speciated VOC files for speciated aircraft emissions are not provided due to the relatively low rate of emissions and the large size of the files that would result. A suggested speciation for aircraft emissions is provided below as used in EDGAR (thanks to Greet Maenhout). Two profiles are provided, Takeoff_landing, and Aircraft_Exhaust. We suggest, for simplicity, applying the Takeoff_landing profile to the lowest two layers (0.305 km and 0.915 km) in the aircraft emissions file. Contact: Profiles for aircraft emissions data source: USEPA SPECIATE 4.4 database This profile can be used for aircraft exhausts VOC_species weight (%) Pentanes 0.19801 Trimethylbenzenes 0.510026 Methylbenzene 0.642032 Ethane 0.521026 Dimethylbenzenes 0.448022 Benzene 1.681084 Alkanones 0.369018 Alkanols 1.80509 Other alk(adi)enes/alkynes 13.35667 Other alkanals 21.9461 Ethene 15.46177 Propane 0.078004 Propene 4.534227 Ethyne 3.939197 Hexanes and higher 18.11991 Other aromatics 4.079204 Methanal 12.31062 This profile can be used for Aircraft Landing/Takeoff VOC_species weight (%) Methanal 15.87872 Methylbenzene 0.550253 Propene 5.154408 Propane 0.224593 Pentanes 0.213363 Other aromatics 2.930938 Other alkanals 12.5772 Ethyne 4.143739 Other 13.21729 Ethane 1.033127 Hexanes and higher 10.66816 Ethene 17.40595 Dimethylbenzenes 0.494104 Alkanones 3.290286 Alkanols 2.032566 Other alk(adi)enes/alkynes 8.175182 Benzene 2.010107 ********************************************************* DOCUMENT HISTORY 5-18-2017 Updated to describe filename format for 2017-05-01 and later releases of gridded data. Filenames were updated at the request of PCMDI for consistency with CMIP6 data naming conventions. Note that in this release file formats and variable names are consistent across all years. In the previous data release there was an inconsistency within the gridded VOC emissions files between the preindustrial and 1851-2014 data. In the previous preindustrial data netCDF files (v2016-06-18) the species number in the filename is separated from the rest of the name by an underscore (e.g., "VOC06_hexanes_pl_em_speciated_VOC"), while for the previous 1851-2014 files (v2016-07-26), this was changed to a dash (e.g., "VOC06-hexanes_pl_em_speciated_VOC"). 11-11-2016 Updated to note speciated VOC variable naming inconsistency in gridded files. 05-16-2017 Updated to note variable naming convention in CEDS grids version 2017-05-01.