Size Distribution Data for: WACS 2012

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VESSEL: R/V Ronald H. Brown  DEPARTED: Boston, Massachusetts on 19 August, 2012 ARRIVED: St. George's, Bermuda on 27 August 2012

WACS Sizing Download Info

24-May-2013

PLEASE NOTE: These data are subject to revision.

1. The first two data sets include particle number-size distributions in the diameter range of 0.020 to 0.8 micrometers Stokes diameter made with an "Aitken" DMPS (20 to 200 nm) and an "Accumulation" DMPS (200 to 800nm). All measurements were made at a relative humidity of 60%. The distributions have been cleaned of all data from times of instrument malfunction or calibration. Additionally, the data set with “SeaSweep” in the name contains only those distributions collected while the seasweep was deployed and connected to the inlet. The files files without the keyword contain distributions taken during normal, ambient sampling.
   files: WACS_nsd_dmps_vX.csv WACS_nsd_dmps_SeaSweep_vX.csv

2. The second two data sets include particle number-size distributions in the diameter range of 0.96 to 10 micrometers aerodynamic diameter. The APS diameters are aerodynamic and have not been corrected to Stokes diameter via calculation or estimates of particle density. The APS data larger than 10 micrometers are not useful due to significant particle losses in the inlets including the ship's sampling mast, distribution tubing and APS inlet. During seasweep sampling the upper diameter limit was reducde to 6.5 micrometers due to the extra tubing. All measurements were made at a relative humidity of 60%. The APS data have been cleaned exactly like the DMPS files described above.
   file: WACS_nsd_aps_vX.csv WACS_nsd_aps_SeaSweep_vX.csv

3. The third two data sets include particle number-size distributions in the diameter range of 0.020 to 10 micrometers Stokes diameter. The distributions are a combination of DMPS and APS data where the APS data have been converted to Stokes diameters. This conversion was done using densities calculated from measured chemistry. The diameter channels in the overlap region were chosen in the following manner: the last DMPS channel was discarded and, after converting to Stokes diameters, the first APS diameter channel that was larger than the last valid DMPS channel was chosen as the first APS channel. Each combined distribution was regridded onto a common set of diameters. Finally, the regridded distributions were cleaned to eliminate values at the larger sizes from the APS where “phantom” counts resulted in a spurious coarse mode in the surface and volume distributions. All measurements were made at a relative humidity of 60%.
   file: WACS_nsd_dmps_aps_vX.csv WACS_nsd_dmps_aps_SeaSweep_vX.csv

4. The fourth two data sets include particle mass-size distributions in the diameter range of 0.020 to 10 micrometers Stokes diameter, calculated from the number-size distributions described in the section 3 above. The conversion of number to mass was done using densities calculated from measured chemistry. (download only – not available for plotting)
   file: WACS_msd_dmps_aps_vX.csv WACS_msd_dmps_aps_SeaSweep_vX.csv

The following files are available for downloading. Please note: one data file may cover more than one time period, thus,some files may be listed more than once. All files are in csv (comma separated value) format. After several lines of general information each file starts with a first row that contains the particle diameter in microns for that column. The first column contains the date/time in Day-of-Year, DOY. DOY 32.5 is 1200 noon UTC on 1-February. All data are in units of dN/dlog10(Dp), N/cm^3. Missing data are designated by a -99 or a -999.

U.S.Dept of Commerce / NOAA / OAR / PMEL / Atmospheric Chemistry