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We have saved CAM-chem simulation output that is intended to be used as boundary conditions for regional modeling. We used CAM-chem at 0.9x1.25 horizontal resolution simulation with 56 vertical levels. Meteorology is driven by specified dynamics, by nudging with 50h relaxation (1%) to MERRA2 reanalysis. Data is saved as instantaneous fields every 6 hours. See a list of saved species. Files are collected as daily information (4 time-slices per file). Anthropogenic emissions are from CMIP6, CMIP6 2014 anthropogenic emissions are repeated for dates past 2014. Biogenic emissions are from online MEGAN2.1, fire emissions are from QFED. Note that fire emitted DMS 2001-2015 is from CMIP6 and in 2016 and 2017 is from GFAS.

  • Data Format: netCDF
  • File size: 4.8 GB per day (4 x 6-hour time slices per day)
  • Data coverage: January 2001 to June 2018

*** NOTE: This version of output has incorrect HCN and O3S, please do not use these species ***

Get the data

1. Subset from dates within the time period January 1, 2010 to June 30, 2018

A small subset of the boundary conditions are available via rapid access from the ACOM server:

Regional and temporal subsetting option can be found at:

2. All available dates January 1, 2001 to 2017

To access any of the complete dataset of shared files between January 2001 and June 2017 you will need a Globus account, which requires a Google account. Get Globus access here.

Once you can log into Globus, the boundary conditions are stored here:

Files can be transferred to another location using the Globus system. To set up a transfer point see the relevant page:


Note: direct download option from this site is in beta testing phase and should be available in the future.


To cite the data directly, please use:

Buchholz, R. R., Emmons, L. K., Tilmes, S., & The CESM2 Development Team. (2019). CESM2.1/CAM-chem Instantaneous Output for Boundary Conditions. UCAR/NCAR - Atmospheric Chemistry Observations and Modeling Laboratory. Subset used XXX, Accessed* dd mmm yyyy,

Please fill in the "subset used" with region and/or date of the subset you used (e.g. Lat: -10 to 10, Lon: 100 to 150, September 2015 - February 2016).

*Please fill in the "Accessed" date with the day, month, and year that you last accessed the data (e.g. - 5 Aug 2011).

We suggest to also cite the following paper that discusses the new configuration of CESM2/CAM-chem and assesses chemical species, including using output from this boundary condition simulation.

Emmons et al., in prep

Other simulations

Directions to access other experimental output can be found here: Benchmarks and Production

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