Supporting data for the manuscript: "Aitken-mode aerosols buffer decoupled mid-latitude boundary layer clouds against precipitation depletion"

This repository contains data supporting the manuscript "Aitken-mode aerosols buffer decoupled mid-latitude boundary layer clouds against precipitation depletion", which has been submitted for publication in the Journal of Geophysical Research.

The repository has five subdirectories:

• SourceCode/
• Forcings/
• OUT_STAT/
• OUT_2D/
• OUT_3D/

The source code, a modified version of the System for Atmospheric Modeling (SAM, Khairoutinov and Randall, 2003), is in the SourceCode/ directory.  This includes the Aitken-aerosol enabled microphysics of Wyant et al (2022) in the SRC/MICRO_M2005_MA/ subdirectory, which itself built upon the earlier work of Berner et al (2013).  The choices for microphysics, radiation and subgrid parameterizations can be found in the Build file within SAM's main directory.  This version differs in several ways from the public release of SAM, which is available at http://rossby.msrc.sunysb.edu/~marat/SAM.html.

The forcings and namelist settings for the different simulations in the paper are included in the Forcings/ directory.  The namelist settings are in files with names like prm.v7f_Hopv0_ra1.  The last three characters can be used to distinguish the simulations and associate them with those presented in the manuscript:

• ra1: spinup simulation for Ctrl and other simulations in 25.6 km square domain.
• ra2: Ctrl simulation (restarted from ra1 at 9 UTC)
• ra3: HfAc simulation (restarted from ra1 but with accumulation mode aerosol scaled by 0.5)
• ra4: HfAcNoAit simulation (restarted from ra1 but with accumulation mode aerosol scaled by 0.5 and Aitken aerosol scaled by 1e-4)
• ra5: NoAit simulation (restarted from ra1 but with Aitken aerosol scaled by 1e-4)
• ra6: HopV1 simulation (restarted from ra1 but using modified Hoppel Transfer scheme, V1 in appendix)
• ra7: HopV2 simulation (restarted from ra1 but using modified Hoppel Transfer scheme, V2 in appendix)
• rc1: spinup simulation for large-domain (LD) simulation
• rc2: LD simulation (restarted from rc1 at 9 UTC)

In runs with modified aerosols (e.g., HfAc), the initial and boundary conditions are scaled by the designated factors at the start of the simulation.

Model output is included in three directories:

• OUT_STAT/: timeseries and time-height profiles of domain-average and conditionally-averaged quantities
• OUT_2D/: timeseries of two-dimensional fields (e.g., surface fluxes, integrated quantities like cloud water path, and radiative fluxes).
• OUT_3D/: Snapshots of selected 3D fields at full resolution.  Only the fields needed for figures 2 and 11 are included.

Only a limited number of time snapshots and fields have been included in the 2D and 3D output to limit the size of the archive.

References:

• Berner, A. H., Bretherton, C. S., Wood, R., & Muhlbauer, A. (2013). Marine boundary layer cloud regimes and POC formation in a CRM coupled to a bulk aerosol scheme. Atmospheric Chemistry and Physics, 13(24), 12549–12572. https://doi.org/10.5194/acp-13-12549-2013
• Khairoutdinov, M. F., and D. A. Randall (2003). Cloud Resolving Modeling of the ARM Summer 1997 IOP: Model Formulation, Results, Uncertainties, and Sensitivities. J. Atmos. Sci., 60, 607–625, https://doi.org/10.1175/1520-0469(2003)060<0607:CRMOTA>2.0.CO;2.
• Wyant, M. C., Bretherton, C. S., Wood, R., Blossey, P. N., & McCoy, I. L. (2022). High free-tropospheric Aitken-mode aerosol concentrations buffer cloud droplet concentrations in large-eddy simulations of precipitating stratocumulus. Journal of Advances in Modeling Earth Systems, 14, e2021MS002930. https://doi.org/10.1029/2021MS002930