README -- Describes contents of HEMCO/MERCURY/v2014-09/JVALUES directory
12 Mar 2015
GEOS-Chem Support Team
geos-chem-support@g.harvard.edu


Overview:
===============================================================================

This directory contains archived J-Value data (in COARDS-compliant netCDF 
format) that are required for the GEOS-Chem mercury simulation.  These data 
used to be read in GeosCore/global_br_mod.F and in GeosCore/mercury_mod.F.


Files:
===============================================================================

jBrO.daytime.geos5.2x25.nc

 -- Photolysis frequency for BrO, averaged over daylight hours. Calculated 
    in a preliminary GEOS-Chem Br-y simulation for 2002 (courtesy J. Parella).
    This simulation did not include wet scavenging of Br-y species as this 
    was not yet included in the Br-y model. BrO J-values are used to calculate
    [Br]/[BrO] ratio in the marine boundary layer.

    Resolution  : GEOS-Chem 2 x 2.5 grid (144 x 72 boxes)
    Units       : pptv
    Timestamps  : Monthly, 2002/01thru 2002/12
    Compression : Level 1 (e.g. nccopy -d1)


jvalues.noon.geos5.2x25
 
 -- Photolysis frequency for NO2, instantaneous at local noon. Calculated in 
    GEOS-Chem full chemistry simulation for 2008 (courtesy J. Mao). NO2
    J-values (with imposed diurnal cycle) are used to calculate the reduction 
    rate of Hg(II) in clouds. 

    Resolution  : GEOS-Chem 2 x 2.5 grid (144 x 72 boxes)
    Units       : pptv
    Timestamps  : Monthly, 2002/01thru 2002/12
    Compression : Level 1 (e.g. nccopy -d1)


References:
===============================================================================

Mao, J., D.J. Jacob, M.J. Evans, J.R. Olson, X. Ren, W.H. Brune, J.M.S. Clair,
 J.D. Crounse, K.M. Spencer, M.R. Beaver, P.O. Wennberg, M.J. Cubison, J.L.
 Jimenez, A. Fried, P. Weibring, J.G. Walega, S.R. Hall, A.J. Weinheimer, R.C.
 Cohen, G. Chen, J.H. Crawford, L. Jaegle, J.A. Fisher, R.M. Yantosca, P.
 Le Sager, and C. Carouge, Chemistry of hydrogen oxide radicals (HOx) in the
 Arctic troposphere in spring, Atmos. Chem. Phys., 10, 5823-5838,
 doi:10.5194/acp-10-5823-2010, 2010.

Parrella, J.P., D.J. Jacob, Q. Liang, Y. Zhang, L.J. Mickley, B. Miller, 
 M.J. Evans, X. Yang, J.A. Pyle, N. Theys, and M. Van Roozendael, 
 Tropospheric bromine chemistry: implications for present and pre-industrial 
 ozone and mercury, Atmos. Chem. Phys., 12, 6,723-6,740, 2012.


How the netCDF files were created:
===============================================================================

Bob Yantosca converted the bpch files in the prior GEOS_2x25/mercury_201007/
data directory to netCDF using the GAMAP routine BPCH2COARDS, following 
the procedure outlined here:

   http://wiki.geos-chem.org/Preparing_data_files_for_use_with_HEMCO#Converting_files_from_binary_punch_format_to_netCDF

The following NCO operations were then done to edit attributes for better
COARDS compliance:

  ncatted -a long_name,lev,o,c,"GEOS-Chem levels" jvalues.noon.geos5.2x25.nc

  ncrename -v JV_MAP_S__JNO2,JNO2                 jvalues.noon.geos5.2x25.nc
  ncatted  -a gamap_category,JNO2,o,c,"JV-MAP-$"  jvalues.noon.geos5.2x25.nc

  ncrename -v JV_MAP_S__JO3,JO3                   jvalues.noon.geos5.2x25.nc
  ncatted  -a gamap_category,JO3,o,c,"JV-MAP-$"   jvalues.noon.geos5.2x25.nc

  ncatted  -a References,global,o,c,"www.geos-chem.org; wiki.geos-chem.org" jvalues.noon.geos5.2x25.nc

  ncatted  -a Contact,global,o,c,"GEOS-Chem Support Team (geos-chem-support@g.harvard.edu)" jvalues.noon.geos5.2x25.nc