Title:   Ace-Asia: Gosan in-situ measurements of aerosol hygroscopic 
         growth for 1um and 10 um aerosol size cuts.

Contact:

     John A. Ogren   (john.ogren@noaa.gov, phone: (303)497-6210)
     Anne Jefferson  (anne.jefferson@noaa.gov, phone: (303)497-6493)
     NOAA Climate Monitoring and Diagnostics Laboratory (CMDL)
     325 Broadway R/CMDL 1                                    
     Boulder, CO 80305, USA                   
     Fax: (303)497-5590
     Web:  http://www.cmdl.noaa.gov/aero/

Data Set Description:

     The data files cmdl_frh_total and cmdl_frh_sub contain data 
     describing the change in the aerosol scattering coefficient with 
     increasing relative humidity for sub 10 micron and sub micron size 
     aerosol respectively. The measurements were made with two TSI model 
     3563 nephelometers in series. The reference nephelometer measured 
     the aerosol scattering coefficient at a relative humidity close to 
     40% (bsp(ref)). The second ?wet? nephelometer had a humidifier 
     downstream of the inlet which ramped the relative humidity from 40% 
     to 90%. The humidification cycle occurred hourly. During the 
     humidification cycle the aerosol impactors toggled between sub 10 
     micron and submicron aerosol aerodynamic size cuts every 6 minutes. 
     The data from these scans were fit to the following empirical 
     equation.
     
          Bsp(wet)/Bsp(ref) =a[100 ? RH]^-b

     From the fit parameter b the aerosol hygroscopic growth factor, fRH, 
     and ambient scattering coefficient can be calculated.
     
          fRH = Bsp(85% RH)/Bsp(40% RH) =([100-40]/[100-85])^b = 4^b

          Bsp(ambient) = Bsp(ref) ([100-ref_RH]/[100-ambient_RH])^b 

     The data files contain hygroscopic growth factors and b fit 
     parameters for three wavelengths 450, 550 and 700 nm radiation and 
     two aerosol sizes, sub 10 micron and submicron. The data are in comma 
     separated files with 15 columns. The file format is as follows:

       Col 1: Station name
       Col 2: year
       Col 3: day of year
       Col 4 : size flag (0 for sub 10 micron, 1 for sub micron)
       Col 5: fRH at 450 nm
       Col 6: chi-squared value of fit for Bsp(wet) at 450 nm
       Col 7: fit parameter b for Bsp(wet) at 450 nm
       Col 8: day of year
       Col 9: fRH at 550 nm
       Col 10: chi-squared value of fit for Bsp(wet) at 550 nm
       Col 11: fit parameter b for Bsp(wet) at 550 nm
       Col 12: day of year
       Col 13: fRH at 700 nm
       Col 14: chi-squared value of fit for Bsp(wet) at 700 nm
       Col 15: fit parameter b for Bsp(wet) at 700 nm