ReadMe File for RCAD ACE1 data [revised January 1997] Contact: Lynn Russell, Princeton University (lrussell@princeton.edu) Investigators: Lynn Russell, Richard Flagan and John Seinfeld These data are made available in the ACE1 archive as per the ACE1 data sharing agreement, and use of these data is subject to those guidelines. Radially-Classified Aerosol Detector (RCAD) Measurements The data included here are preliminary. No data released at this time should be considered final, and consequently users are advised to contact us for updated corrections before using or submitting these data. This instrument counted size-classified aerosols in the range 0.005 to 0.15 microns during the ACE1 experiment. The instrument was operated with a flow split of 8.3 cc/s (aerosol) and 83 cc/s (sheath), recording 36 channels of data in 45 seconds, for a voltage range of 9 to 5000 volts. The files are in ASCII text format. The first column lists the diameter (in micrometers). The second column lists the normalized particle concentration, dn/dlogDp (in particles per cm3). Each of the files included here contains the 45 channels of data describing a single size distribution. The name of the file gives the date and time of the size distribution (JDT, first 3 digits give the Julian date, between 300 and 350). To obtain size distributions, the following parameters describe the operating parameters for the transfer function used in the data inversion: (Tau)_c = 1 s [counting time for one channel of data] n = 45 channels [number of channels for each ramp] (Tau)_s = 1.1 s [characteristic mixing time for DMA-CPC configuration] (Tau)_p = 8 s [characteristic plumbing time for DMA-CPC configuration] Q_c = Q_m = 83 cc/s [sheath flow rate for DMA] Q_a = Q_s = 8.3 cc/s [sample flow rate for DMA] Q_cpc = 16.6 cc/s [CPC flow rate] Q_d = 8.3 cc/s [flow rate of dilution air] The appropriate kernel function for inverting these data is described in L.M. Russell, M.R. Stolzenburg, S.H. Zhang, R. Caldow, R.C. Flagan, and J.H. Seinfeld, J. Atmos. Ocean. Tech., 1996 (June). The algorithm recommended in that work for performing the inversion is MICRON (J.K. Wolfenbarger and J.H. Seinfeld, J. Aerosol Sci., 1990). Lynn M. Russell Assistant Professor email: lrussell@princeton.edu Tel:(609)258-1144 Fax:(609)258-0211 Secretary:(609)258-1830 Address: Department of Chemical Engineering Princeton University A319 Engineering Quadrangle Princeton, NJ 08544