ACE-Asia Aircraft: C-130 Aerosol Number Size distribution, 8-120 nm

ReadMe File for RCAD ACE-Asia data
[revised 5/22/02]

Contact:        Lynn Russell, Princeton University
(lrussell@princeton.edu)
Investigators:  Lynn Russell

These data are made available in the ACE-Asia archive as per the
ACE-Asia data sharing agreement, and use of these data is subject to
those guidelines.

NCAR Radially-Classified Aerosol Detector (RCAD) Measurements
The data included here are preliminary.  Users are advised to contact us
for updated corrections before using  or submitting these data.

This instrument counted size-classified aerosols in the approximate
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 61 channels of data over 60 seconds, for a voltage
range of 9 to 5000 volts. The files are in ASCII text format.  The sizes
given are diameters in micrometers.  The number concentrations are
normalized particle concentration, dN/dlogDp (in particles per cm3).  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 = 61 channels [number of channels for each ramp]
(Tau)_s = 1 s [characteristic mixing time for DMA-CPC configuration]
(Tau)_p = 6.5 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 size distributions have been corrected for instrument pressure and
temperature.  Size distributions were dried on entering the DMA.  The
format for the data is given below:

Flight,Date,Scan_Start,Scan_Stop,
AvgTemp,AvgPres,IntegralNumber,IntegralVolume,
Diam01,Diam02,Diam03,Diam04,Diam05,
Diam06,Diam07,Diam08,Diam09,Diam10,
Diam11,Diam12,Diam13,Diam14,Diam15,
Diam16,Diam17,Diam18,Diam19,Diam20,
Diam21,Diam22,Diam23,Diam24,Diam25,
Diam26,Diam27,Diam28,Diam29,Diam30,
Diam31,Diam32,Diam33,Diam34,Diam35,
Diam36,Diam37,Diam38,Diam39,Diam40,
Diam41,Diam42,Diam43,Diam44,Diam45,
Diam46,Diam47,Diam48,Diam49,Diam50,
Diam51,Diam52,Diam53,Diam54,Diam55,
Diam56,Diam57,Diam58,Diam59,Diam60,Diam61,
Num01,Num02,Num03,Num04,Num05,
Num06,Num07,Num08,Num09,Num10,
Num11,Num12,Num13,Num14,Num15,
Num16,Num17,Num18,Num19,Num20,
Num21,Num22,Num23,Num24,Num25,
Num26,Num27,Num28,Num29,Num30,
Num31,Num32,Num33,Num34,Num35,
Num36,Num37,Num38,Num39,Num40,
Num41,Num42,Num43,Num44,Num45,
Num46,Num47,Num48,Num49,Num50,
Num51,Num52,Num53,Num54,Num55,
Num56,Num57,Num58,Num59,Num60,Num61,

With the following sets of units:
Flight: number of research flight
Date: date of research flight
Scan_Start: start time of scan [HH:MM:SS]
Scan_Stop: end time of scan [HH:MM:SS]
AvgTemp: temperature INSIDE instrument [degress Celsius]
AvgPres: absolute pressure INSIDE instrument [bar]
IntegralNumber: total number of particles integrated over measured size
range [particles/cm^3]
IntegralVolume: total volume of particles integreated over measured size
range [(micrometer)^3/cm^3]
Diam01: diameter of particles in channel 1 [micrometers] – note that
these diameters change scan to scan, and alternate between increasing
and decreasing order
Num01: number of particles in channel 1, normalized to dN/dlogDp
[particles/cm^3]

The software used in this inversion was developed by Don Collins (Texas
A&M University) and are described in Collins et al. (2000).  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); newer inversion
techniques proposed by Collins et al. (2000) are generally more robust.

Contact: Lynn M. Russell
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