black carbon mass loading, size distribution for CACTI - ground site

The Single-Particle Soot Photometer (SP2, Droplet Mea- surement Technologies) is an instrument that measures, in situ, the time-dependent scattering and incandescence signals produced by individual BC-containing particles as they travel through a continuous-wave laser beam. Any particle traversing the laser beam will scatter light, and the BC component of a BC-containing particle will absorb some of the laser energy until its temperature is raised to the point at which it incandesces (hereafter we adopt the standard terminology of the SP2 community and denote any substance determined by the SP2 to be BC as refractory black carbon (rBC)). The scattering signal provides information on particle size, and the incandescence signal is used for counting rBC-containing particles and yields the mass of the rBC component within each particle (obtained via calibration). Hence, the SP2 can determine size-resolved number and mass concentrations of rBC-containing particles and thus provides information on the rBC particle population-based mixing states within ambient aerosols rBC concentration is reported at STP conditions Time resolution: 1-min Uncertainty: ~ 30% SP2 Unit: 25 Location: Ascension Island, British Territory Location: 7° 56' S, 14° 25' W" SP2_dateTime: UTC rBC concentration is in units of ng/m^3 - dry air. Mass Equivalent Diameters [MED] used for size distribution (SP2_min; SP2_geo; and SP2_max) are in units of micrometers dN/dlogDp counts for a given size bin (SP2_geo) listed as 'SP2_cnts_0…SP2_cnts_199'. Column naming convention: 'SP2_cnts_X' are the number of particles in bin number _X. , where _X is the row number within the 'SP2_geo' size bin column that contains the mass equivalent diameter (e.g., SP2_cnts_0 = 0.01 microns; SP2_cnts_10 = 0.060 microns, etc…). The dN/dlogDp data is time-resolved where a given row is associated with the timestamp for that row. Note that the rBC column length is one field shorter than the SP2_datetime column. Last time field is not relevant to the rBC time series (see comment below on length of SP2_datetime column) Lengths for SP2_max; SP2_min; SP2_geo are one field longer then the number of SP2_cnts_XX columns . This is to provide bounds for image plots (if desired). Length for SP2_datetime is one field longer than that length of the SP2_cnts_XX columns This is to provide bounds for image plots (if desired) SP2 Calibration: Fullerene soot with corrrection applied for particle density as a function of particle size. No correction for OC content in Fullerene (recent study on SP2 sensitivity to differing black carbon types reports that non-refractory material content for fullerene soot is about 20%). Comments and/or requests are to be directed to Art Sedlacek ([e-mail])