Title: Global modelling of secondary organic aerosol (SOA) with organic nucleation
Authors: Jialei Zhu, Joyce E. Penner
Contact: Jialei Zhu, jialeiz@umich.edu

Funded by NASA ACMAP Program, Grant # NNX15AE34G and NSF-GEO Grant # 1540954

Key Points:
- A new version of the CESM/IMPACT atmospheric model was developed to include three organic nucleation schemes.
- The aerosol concentration in the base case and three sensitivity cases were simulated. The result is presented.

Research Overview:
Organic nucleation has been identified as an important way to form secondary organic aerosol (SOA) and change the number concentration of aerosol and thus its climate effect. A global atmospheric chemistry model is developed to include a comprehensive organic nucleation scheme that includes heteromolecular nucleation of sulfuric acid and organics (HET), neutral (NON) and ion-induced (ION) pure organic nucleation. Our model simulation shows reasonable agreement with the seasonal as well as spatial pattern of organic carbon (OC) concentration in America, while it fails to predict the seasonal pattern of OC in Europe due to the lack of sharp increases in primary organic aerosol emissions in the winter. Including organic nucleation decreases the bias of the annual average particle number concentration at 54% of the available observation sites and increases the temporal correlation coefficients at 58% of the sites. ION contributes the most to the total organic nucleation rate, which peaks around 400hPa in the tropics. HET dominates the total organic nucleation rate in the summer and mostly occurs in the lower troposphere. The number concentration of particles formed from organic nucleation (newSOA) in the nucleation and Aitken modes is highest in the tropics, while accumulation mode newSOA is highest in the Northern Hemisphere due to growth as a result of the condensation of sulfate. Three sensitivity experiments suggest that more studies are needed to investigate the formation mechanism of newSOA, so that a more accurate simulation of the spatial and size distribution of newSOA can be developed. 

Methodology:
The data are model output for secondary organic aerosol simulations conducted using the Community Earth System Model (CESM) version 1.2.2.1 (http://www.cesm.ucar.edu/models/)coupled with the IMPACT aerosol module (‘Integrated Massively Parallel Atmospheric Chemical Transport’) developed by our group. The input files are default in the component set of “FC5” in CESM model for all cases. Please refer to the CESM model for instructions on using the code.

Files contained here:
We include four source code tar files and 48 major output netcdf files from simulations conducted in the paper. The ending of 1-12 stand for the 5-year average in each month from January to December. “BA_PD” stands for the base case. “T1_PD” stands for the first sensitivity case (EX1)r the present day. “T2_PD” stands for the second sensitivity case (EX2). “T3_PD” stands for the third sensitivity case (EX3).

The files are described below:

src.cam_BA_PD.zip
This tar file contains the source code of the IMPACT aerosol module that we implemented as additional aerosol module embedded in the CESM version1.2.2.1 which is publicly available from NCAR repository. This code is for the base case applied in the related publication.

src.cam_T1_PD.zip
This tar file contains the source code of the IMPACT aerosol module that we implemented as additional aerosol module embedded in the CESM version1.2.2.1 which is publicly available from NCAR repository. This code is for the first sensitivity case (EX1) applied in the related publication.

src.cam_T2_PD.zip
This tar file contains the source code of the IMPACT aerosol module that we implemented as additional aerosol module embedded in the CESM version1.2.2.1 which is publicly available from NCAR repository. This code is for the second sensitivity case (EX2) applied in the related publication.

src.cam_T3_PD.zip
This tar file contains the source code of the IMPACT aerosol module that we implemented as additional aerosol module embedded in the CESM version1.2.2.1 which is publicly available from NCAR repository. This code is for the third sensitivity case (EX3) applied in the related publication.

NC2_BA_PD-5a-**.nc
Netcdf output file of 5-year mean monthly meteorological and aerosol fields from the base case. 

NC2_BA_T1-5a-**.nc
Netcdf output file of 5-year mean monthly meteorological and aerosol fields from the first sensitivity case (EX1).

NC2_BA_T2-5a-**.nc
Netcdf output file of 5-year mean monthly meteorological and aerosol fields from the second sensitivity case (EX2).

NC2_BA_T3-5a-**.nc
Netcdf output file of 5-year mean monthly meteorological and aerosol fields from the third sensitivity case (EX3). 

Related publication(s):
Zhu, J and Penner, J. E.: Global modelling of secondary organic aerosol (SOA) with organic nucleation, (2019), submitted to Journal of Geophysical Research-Atmosphere.

Use and Access: 
This data set is made available under a Creative Commons Attribution-NonCommercial 4.0 International license(CC BY-NC 4.0).

To Cite Data: 
Zhu, J., and Penner, J.E. (2019). Global modelling of secondary organic aerosol (SOA) with organic nucleation [Data set]. University of Michigan - Deep Blue. https://doi.org/10.7302/1c53-zy98