Hypothesized Climate Forcing Time Series for the Last 500 Years: Readme file
---------------------------------------------------------------------
              World Data Center for Paleoclimatology, Boulder
                                and 
                   NOAA Paleoclimatology Program
---------------------------------------------------------------------
NOTE: PLEASE CITE ORIGINAL REFERENCE WHEN USING THIS DATA!!!!!

NAME OF DATA SET: Hypothesized Climate Forcing Time Series for the Last 500 Years 

LAST UPDATE: 10/2002 Correction to data file VAI.txt:  
Corrected value for 1784, Lat=-76, from -0.0027 to 0.0027 
  
CONTRIBUTOR: Alex Robertson

IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2001-057

SUGGESTED DATA CITATION: Robertson, A. et al., 2001, 
Hypothesized Climate Forcing Time Series for the Last 500 Years, 
IGBP PAGES/World Data Center for Paleoclimatology 
Data Contribution Series #2001-057.  
NOAA/NGDC Paleoclimatology Program, Boulder CO, USA. 

ORIGINAL REFERENCE: 
Robertson, A., Overpeck, J., Rind, D., Mosley-Thompson, E., Zielinski, G., 
Lean, J., Koch, D., Penner, J., Tegen, I., and Healy, R. 2001. 
Hypothesized climate forcing time series for the last 500 years 
J. Geophys. Res. Atmos. Vol. 106 , No. D14 , p. 14,783, 27 July 2001 (2000JD900469) 


GEOGRAPHIC REGION: Global 
PERIOD OF RECORD: 1500-1997 AD

LIST OF FILES: Readme.Robertson2000.txt (this file), 
modern_tropo_aerosols.xls (Microsoft Excel format), 
1990.anthro.sulfate.txt, 1990.natural.sulfate.txt
1990.total.dust.txt, 1990.total.carbon.txt,
regional_definitions.txt, regional_emissions.txt, 
trace_gas.txt, vai.txt (Tab-delimited ASCII format).

DESCRIPTION:
Modern_tropo_aerosols.xls
A MSExcel file with arrays of optical depth as a function of modern 
tropospheric aerosols from four sources:  
natural mineral dust (Tegen et al., 1997), natural sulfate (Koch et al. 1999), 
anthropogenic sulfate (Koch et al. 1999) and anthropogenic carbon (Liousse et al. 1996).
Also presented as tab-delimited text files: 1990.anthro.sulfate.txt, 
1990.natural.sulfate.txt, 1990.total.dust.txt, and 1990.total.carbon.txt.


Dimensions:  90oN to 90oS, at 7.83o latitude resolution; 170oW to 180oE at 10o longitude 
resolution; optical depth plotted within the grid


regional_definitions.txt
A tab-delimited text file defining nine different regions of the world 
(modified from Marland et al. 1994) for the regional scaling of tropospheric aerosols

Dimensions:  90oN to 90oS, at 7.83o latitude resolution; 170oW to 180oE at 10o longitude 
resolution; regional name plotted within the grid

regional_emissions.txt
A tab-delimited text file containing the time series of CO2-emissions-based 
scaling ratios for each of the 9 regions defined in regional_definitions.txt, 
standardized to 1990 values of 1.0 (the year for which the maps of tropospheric 
optical depths are based on in modern_tropo_aerosols.xls).

Dimensions:  AD1850 to AD1996 at one year resolution; 9 regions (region 1 through 9); 
scaling ratio relative to AD1990 values plotted within the grid.


trace_gas.txt
A tab-delimited text file containing time series of annually and globally -averaged 
atmospheric volumetric concentrations of CO2, CH4, and N2O.

Dimensions:  AD1500 to AD1997 at one year resolution; three trace gases (CO2, CH4, N2O); 
annual and globally averaged volumetric concentration 
(in ppmv, ppbv, and ppbv, respectively) of trace gases plotted within the grid.


vai.txt
A tab-delimited text file containing the gridded array of zonal stratospheric optical 
depths, from AD1500 to AD1983, spanning 88oS to 88oN, at a latitudinal resolution of 4o.

Dimensions:  AD1500 to AD1983 at one year resolution;   88oS to 88oN, at 4o latitude 
resolution; annually averaged volcanic (stratospheric) optical depth plotted within 
the grid.