GCHP global modelling output dataset for OH + NO2 (2021-2022)

These files contain model output for “Water dependence of OH+NO2 reaction reduces atmospheric oxidation” Winiberg et al., 2024. It was funded by the NERC BLEACH project (NE/W00724X/1).

The datasets are GEOS-Chem High Performance (GCHP) global model simulations of monthly mean or hourly mean of volume mixing ratios of atmospheric chemical species (e.g. Ozone (O3), PM2.5, hydroxide (OH), nitrogen dioxide (NO2) etc.) and of reaction rates of chemical reaction OH + NO2. For example, simulated O3 mixing ratio is represented by SpeciesConcVV_O3 in the netCDF files.

Files are COARDS compliant NetCDF generated by GEOS-Chem v14.2.2 to explore the global and regional impacts of changes to the OH+NO2 rate. There are 3 sets of data which each contain model output driven by two chemical mechanisms: standard mechanism in GCHP14.2.2 (directories starting 'STD_') and new mechanism with an updated rate constant (directories starting 'New_'). The calculation of reaction rate of OH+NO2 in new mechanism is updated based on the most recent measurements from JPL (NASA Jet Propulsion Laboratory). More details can be found in Winiberg et al., 2024.

The 3 sets of data included:
1) Global monthly means from July 2021 to June 2022 at C48 resolution (~200km grid resolution) on 72 vertical levels (directories STD_Global/, New_Global/)

2) The same but with anthropogenic emissions switched off to represent the preindustrial (directories STD_Global_anthOFF/, New_Global_anthOFF/)

3) Global hourly values at the surface for July 2022 at C200 with a Stretch Factor of 2 centred on Asia (20°N 98°E) (~25km grid resolution) (directories STD_nested_surface_level/, New_nested_surface_level/)

The file names generally follows GEOS-Chem naming convention GEOSChem.DefaultCollection.YYYYMMDD_HHMMz.nc4. YYYY, MM, DD, HH, MM represent year, month, day, hour and minute. Z means UTC here. Surface data file has an extension (Surface_level_) at the beginning of the filename, which is manually added by Hansen Cao et al. to differentiate from the files for all vertical layers.

The modelling was done by Hansen Cao, Killian Murphy and Mat Evans at the University of York.

COARDS stands for the Cooperative Ocean/Atmosphere Research Data Service and are a set of conventions for the standardization of NetCDF files.