"ACE 1, Leg 2: PMEL 2-stage impactor samples collected onboard the Discoverer for gravimetric analysis." This is the text descriptor file for data contained in the file L2GRV_fin.csv. Please contact Trish Quinn when using these data (quinn@pmel.noaa.gov). The gravimetrically-determined mass concentrations are given in ug/m3. Submicron values represent the mass concentration in all particles with aerodynamic diameters < 1.0 um. Supermicron values are for particles with aerodynamic diameters > 1um and < 10 um. Diameters are given for the relative humidity of the sampled air stream. Uncertainties associated with the mass concentrations range from +/- 5 to 25%. Columns in the spreadsheet are: "1, Sample number" "2, Start time, GMT" "3, Stop time, GMT" "4, Start Latitude" "5, Stop Latitude" "6, Start Longitude" "7, Stop Longitude" "8, average % RH of the sampled air stream." "9, standard deviation of the RH of the sampled air stream." "10, % RH of the substrate during the pre-sampling weighing." "11, % RH of the substrate during the post-sampling weighing." "12, volume of sample (m3 of air)" "13, sub_mass, submicron mass concentration in ug/m3" "14, sup_mass, supermicron mass concentration in ug/m3" Codes used in the file: "NA, not available"