README

Scripts for creating ice core reconstruction-based 
volcanic forcing for CAM a la Bethke et al. 2017. 


create_CAM_volcanic_forcing.py: 

  Creates CAM volcanic forcing file from volcanic eruption history input file.

  The input file is in text format with columns 
    1=eruption year 
    2=location flag (1 tropical, 2/3 NH/SH extratropical) 
    3=stratospheric volcanic aerosol mass load in TG

  The temporal coverage in model time is set with "year1" and "yearn" in the 
  script. 
  
  The value of "offset" is added to the year information from the 
  reconstruction. 

  Writing of eruption histories in text format is toggled with "output_text".

  To use a forcing file CCSM4_volcanic_forcing_0001-2500.nc, 
  copy the file to inputdata/atm/cam/volc and add following lines to CAM's namelist 
  &prescribed_volcaero_nl
   prescribed_volcaero_datapath           = '$DIN_LOC_ROOT/atm/cam/volc'
   prescribed_volcaero_file               = 'CCSM4_volcanic_forcing_0001-2500.nc'
  /


create_CAM_volcanic_forcing_resample.py: 
 
  Creates stochastic CAM volcanic forcing files from volcanic eruption history 
  input file using random resampling.

  The input file is in text format with columns 
    1=eruption year 
    2=location flag (1 tropical, 2/3 NH/SH extratropical) 
    3=stratospheric volcanic aerosol mass load in TG

  The temporal coverage in model time is set with "year1" and "yearn" in the 
  script. The number of forcing realisations is set with "nmem".  
 
  Writing of netcdf forcing files is toggled with "output_netcdf". 
  
  Writing of eruption histories in text format is toggled with "output_text".
  The files can be modified and then used as input for create_CAM_volcanic_forcing.py
  
  To use a forcing file CCSM4_volcanic_forcing_0001-9999_mem01.nc, 
  copy the file to inputdata/atm/cam/volc and add following lines to CAM's namelist 
  &prescribed_volcaero_nl
   prescribed_volcaero_datapath           = '$DIN_LOC_ROOT/atm/cam/volc'
   prescribed_volcaero_file               = 'CCSM4_volcanic_forcing_0001-9999_mem01.nc'
  /


nature14565-s6_stratAerosolMass.txt: 

  Input file based on data in nature14565-s6.xlsx from Sigl et al. 2015. 


CCSM4_volcanic_1850-2008_prototype1.nc: 

  CESM default historical volcanic forcing (Ammann et al. 2003). Used to extract 
  vertical shape function for stratospheric volcanic aerosol load.


volc_samples.nc: 

  Generic shape functions for space-time evolution of stratospheric volcanic 
  aerosol load. These are extracted CCSM4_volcanic_1850-2008_prototype1.nc 


Literature (in http://ns9039k.web.sigma2.no/ingo/people/guido/literature): 

  nclimate3394.pdf, nclimate3394-s1.pdf: Bethke et al. 2017 with SI 

  nature14565.pdf, nature14565-s6.xlsx: Sigl et al. 2015 with SI, contains 
                                        Gao et al. 2007 for estimation of 
                                        stratospheric load 
  
  2006JD007461.pdf: Gao et al. 2007 

  2020EF001803.pdf, 2020ef001803-sup-0001-supporting information si-s01.docx: 
      Wenmin et al. 2021., spin-off study of Bethke et al. 2017 with 
      additional info on forcing creation/validation in SI  

  ammann03.pdf: Ammann et al. 2003, description of CCSM default volcanic forcing