Size Distribution Data for: NEAQS 2004

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VESSEL: R/V RONALD H. BROWN  DEPARTED: Portsmouth, New Hampshire on 05 July, 2004 ARRIVED: Portsmouth, New Hampshire on 23 July 2004 DEPARTED: Portsmouth, New Hampshire on 26 July 2004 ARRIVED: Portsmouth, New Hampshire on 12 August 2004 Link to more NEAQS 2004 pages

13-February-2006
PLEASE NOTE: These data are subject to revision and, thus, are passsword protected. If you wish to have the data please contact Jim Johnson or Timothy Bates for a password.

• The first 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 data have been separated into legs 1 and 2. The distributions have been cleaned of all data from times of instrument malfunction or calibration. Additionally, only those distributions where the total CN concentrations were stable over the course of each measurement have been included. Finally, the Accumulation DMPS diameters were adjusted to larger sizes based on post-cruise calibrations.
  files: NEAQS2002_nsd_dmps_leg1_filter.csv NEAQS2002_nsd_dmps_leg2_filter.csv

• The second 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. All measurements were made at a relative humidity of 60%. The APS data have been cleaned exactly like the DMPS files described above.
  file: NEAQS2004_nsd_aps_leg1_filter.csv NEAQS2004_nsd_aps_leg2_filter.csv

• The third data sets include particle number-size distributions in the diameter range of 0.020 to 7.6 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 distrubutions. All measurements were made at a relative humidity of 60%.
  file: NEAQS2004_nsd_dmps_aps_leg1_filter.csv NEAQS2004_nsd_dmps_aps_leg2_filter.csv

More information about these data can be found by clicking on the blue "Instrument Information" tab above.

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