DOI: 10.5061/dryad.4j0zpc8qh
title: Magnitude uncertainty dominates intermodel spread in zonal-mean precipitation response to anthropogenic aerosol increase

description: Anthropogenic aerosols are an important driver of historical climate
 change, but the climate response is not fully understood, and the climate
 model simulations suffer from large uncertainties. Based on a multi-model
 ensemble of historical aerosol forcing simulations for a period of global
 aerosol increase during 1965–1989, here, we show that the precipitation
 response shares a common southward displacement of the tropical rain band,
 but the magnitude differs markedly among models, accounting for 76% of the
 intermodel uncertainty in zonal-mean precipitation change. Our analysis of
 atmospheric energetics further reveals key mechanisms for magnitude
 uncertainty: aerosol radiative forcing drives, cloud radiative feedback
 amplifies, and ocean circulation damps the intermodel uncertainty in
 cross-equatorial atmospheric energy transport change and the meridional
 shift of tropical rain bands. This has important implications for
 understanding and reducing intermodel uncertainty in anthropogenic climate
 change.
description: # Magnitude uncertainty dominates intermodel spread in zonal-mean
 precipitation response to anthropogenic aerosol increase Dataset DOI:
 [10.5061/dryad.4j0zpc8qh](10.5061/dryad.4j0zpc8qh) ## Description of the
 data and file structure The zip file contains the variables of 13
 CMIP6-DAMIP models in hist-aer and hist-GHG single-forcing simulations and
 the variables of 7 models in piClim-histaer simulation that I used in this
 study. ### Files and variables #### File: Geng_2025.zip **Description:** 
 The dataset archive (Geng_2025.zip) contains three subfolders
 corresponding to three CMIP6 simulation experiments: hist-aer: Historical
 simulations with anthropogenic aerosol-only forcing hist-GHG: Historical
 simulations with greenhouse gas–only forcing piClim-histaer: An
 Atmospheric General Circulation Model experiment where SST is kept
 constant at the pre-industrial monthly climatology, and only the
 anthropogenic aerosols radiative forcing varies historically over time.
 **Folder Structure** Within the hist-aer folder, there are 13 subfolders,
 each representing one variable (hfls, hfss, od550aer, pr, rlds, rlus,
 rlut, rsds, rsdt, rsus, rsut, rsutcs, ts). The hist-GHG folder contains 11
 variable folders (hfls, hfss, pr, rlds, rlus, rlut, rsds, rsdt, rsus,
 rsut, ts). The piClim-histaer folder contains one subfolder named Amon,
 which includes 3 variable folders (rlut, rsdt, rsut). Each variable folder
 includes NetCDF files (.nc) from multiple CMIP6 models (13 models for
 hist-aer and hist-GHG, and 7 models for piClim-histaer). All files were
 downloaded from the ESGF CMIP6 archive and then regridded to a uniform
 resolution of 2.5° × 2.5° using bilinear interpolation for consistency
 across models. **NetCDF** **File naming convention** The NetCDF file names
 follow a standardized naming pattern. For example:
 *hfls_ACCESS-CM2_hist-aer_ungrid_r1_185001-202012.nc* This filename can be
 interpreted as follows: hfls: Variable name ACCESS-CM2: Name of the
 climate model hist-aer: The simulation experiment (historical
 anthropogenic aerosol-only forcing) ungrid: Indicates that the data have
 been regridded to a common resolution (2.5° × 2.5°) r1: Member ID – this
 is the first ensemble member for this experiment of this model
 185001-202012: Time span of the data, representing monthly means from
 January 1850 to December 2020 This naming convention is applied
 consistently across all variables, models, and experiments in the dataset.
 **Variable List and Descriptions** The following CMIP6 standard variables
 are included in this dataset. All definitions, units, and data types are
 also embedded in the metadata of the NetCDF files. | Variable |
 Description | Unit | | -------- |
 -------------------------------------------- | ------------ | | hlfs |
 Surface Upward Latent Heat Flux | W m⁻² | | hfss | Surface Upward Sensible
 Heat Flux | W m⁻² | | od550aer | Ambient Aerosol Optical Depth at 550 nm |
 number (0–1) | | pr | Precipitation Flux | kg m⁻² s⁻¹ | | rlds | Surface
 Downwelling Longwave Radiation | W m⁻² | | rlus | Surface Upwelling
 Longwave Radiation | W m⁻² | | rlut | TOA Outgoing Longwave Radiation | W
 m⁻² | | rsds | Surface Downwelling Shortwave Radiation | W m⁻² | | rsdt |
 TOA Incident Shortwave Radiation | W m⁻² | | rsus | Surface Upwelling
 Shortwave Radiation | W m⁻² | | rsut | TOA Outgoing Shortwave Radiation |
 W m⁻² | | rsutcs | TOA Outgoing Shortwave Radiation (Clear Sky) | W m⁻² |
 | ts | Surface Temperature | K | ## Access information Other publicly
 accessible locations of the data: * NA Data was derived from the following
 sources: *
 [https://esgf-node.llnl.gov/search/cmip6/](https://esgf-node.llnl.gov/search/cmip6/)