File updated 11/26/2003 2:41:27 PM IMPROVE Calculation Method List: Parameter Parameter Name Unique Code Calc. Algorithm Description Assumptions SO4 Sulfate: Fine 3*Sf Sulfate from sulfur element All elemental S is from sulfate. All sulfate is from ammonium sulfate. (NH4)2SO4 Ammonium sulfate ammSO4f 4.125*Sf Ammonium sulfate from sulfur element (NH4)2SO4 Ammonium sulfate ammSO4f 1.375*SO4f Ammonium sulfate from sulfate ion NH4NO3 Ammonium nitrate ammNO3f 1.29*NO3f Ammonium nitrate from nitrate ion Denuder efficiency is close to 100%. All nitrate is from ammonium nitrate. OC Carbon: total organic OCf O1+O2+O3+O4+OP Sum of organic carbon fractions from TORR OMC Organic mass by carbon OMCf 1.4*(O1+O2+O3+O4+OP) Organic carbon mass from OC Average organic molecule is 70% carbon. OC Carbon: total organic by hydrogen OCHf 11*(H-0.25*Sf) Organic carbon by hydrogen All sulfur is ammonium sulfate and there is no hydrogen from nitrate.  Organic mass is equal to 1.4*OCH OMH Organics by hydrogen OMHf 1.4*OCH Organic carbon by hydrogen All sulfur is ammonium sulfate and there is no hydrogen from nitrate.  Organic mass is equal to 1.4*OCH EC Carbon: total elemental ECf E1+E2+E3-OP Sum of elemental carbon fractions from TORR - OP SOIL Fine Soil SOILf 2.2*Al+2.49*Si+1.63*Ca+2.42*Fe+1.94*Ti Sum of common oxides of soil elements [Soil K]=0.6[Fe]. FeO and Fe2O3 are equally abundant. A factor of 1.16 is used for MgO, Na2O, H2O, CO2. RCFM Reconstructed fine mass RCFM ammSO4f + ammNO3f + ECf + OMCf + SOILf Fine mass reconstructed from major component species concentrations Represents dry ambient fine aerosol mass for continental sites. CM PM2.5-10: mass CM MT-MF Fine mass (PM2.5) subtracted from PM10 Consists only of insoluble soil particles. NaCl Sodium chloride NaClf 2.5*Naf Sodium Chloride from sodium element Typically CL is unreliable from PIXE, thus NaCl is based on Na concentration (NH4)2SO4_bext Ammonium sulfate extinction ammSO4f_bext 3*fRH*ammSO4f Use mass extinction efficiency of 3m2/g for ammonium sulfate and fRH NH4NO3_bext Ammonium nitrate extinction ammNO3f_bext 3*fRH*ammNO3f Use mass extinction efficiency of 3m2/g for ammonium nitrate and fRH OMC_bext Organic carbon extinction OMCf_bext 4*1.4*OCf Use mass extinction efficiency of 4 m2/g for organic carbon No relative humidity dependence for organics EC_bext Elemental carbon extinction ECf_bext 10*ECf Use mass extinction efficiency of 10m2/g for elemental carbon SOIL_bext Fine soil extinction SOILf_bext 1*SOILf Use mass extinction efficiency of 1m2/g for fine soil CM_bext Coarse mass extinction CM_bext 0.6*CM Use mass extinction efficiency of 0.6 m2/g for coarse mass aerosol_bext Aerosol extinction aerosol_bext ammSO4f_bext + ammNO3f_bext + OMCf_bext + ECf_bext + SOILf_bext + CM_bext Sum of major aerosol species mass extinction dv Deciview dv 10*ln(aerosol_bext+10)/10 Perception based visibility metric RH Relative humidity RHgrid gridded value Gridded value