Measurements of aerosol scattering and hemispheric backscattering coefficients were made with an integrating nephelometer (Model 3563, TSI Inc.) at wavelengths of 450, 550, and 700 nm at approximately 55% RH. Data are reported at the measurement RH, 0 degC, and 1013 mb. Values measured directly by the nephelometer were corrected for an offset determined by measuring filtered air over a period of several hours [Anderson and Ogren, 1998]. Data have been corrected for angular non-idealities, including truncation errors and nonlambertian response, of the nephelometer using the method of Anderson and Ogren .
Measurement RH: The measurement RH was controlled to near 55% RH. The RH was measured inside the nephelometer sensing volume. The measurement RH, T, and P values are given in the data file. Also given are the ambient T and RH measured at 18 masl near the main aerosol inlet on the ship.
Inlet: Two single-stage Berner impactors, one with a D50,aero(55% RH) of 1.1um and one with a D50,aero(55% RH) of 10 um were placed upstream of the nephelometer. An automated valve switched between the two impactors every 15 minutes so that sampling alternated between sub-1 um and sub-10 um aerosol.
Averaging interval: 30 min
Time stamp: Decimal day of year where DOY 75.5 is noon on March 16th. Time given is the mid-point of the 30 min averaging interval.
Time period covered by data: DOY 75.1667 to 109.292 (March 16th - April 19th).
Calibration: The neph was calibrated with air and CO2 during the campaign at the beginning, middle, and end.
Anderson and Ogren, Aer. Sci. Tech., 29, 57 - 69, 1998.
Data can be downloaded in ACF format by following the ASCII link, or in binary netCDF file format by following the netCDF link