SOS99NASH_WP3D_AERSL.txt  read me file
 
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Principal Investigators:
Brock, Charles 
NOAA Aeronomy Laboratory
325 Broadway R/AL7 
Boulder, CO 80305
cbrock@al.noaa.gov
303-497-3795

Wilson, J. Charles 
Department of Engineering
University of Denver
Denver, CO 80208
jwilson@du.edu
303-871-3002

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Description:  Files contain particle number, surface, and volume integrated over specific size increments as measured by the University of Denver's and NOAA's aerosol instruments.  The data mean values centered on 10-second intervals.  Particles with diameters from 5 nm to 60 nm are measured with a five-channel condensation particle counter.  Particles with diameters from 80 to 1200 nm are measured with a focused laser cavity aerosol size spectrometer.  Reported values are particle number, surface area, and volume in size bins from 5-20, 20-100, 100-500, and 500-1200 nm.  The units are number per standard cubic centimeter (1 atmosphere, 273 Kelvin), square micrometers per standard cubic centimeter, and cubic micrometers per standard cubic centimeter for number, surface and volume, respectively. These values have been corrected for anisokinetic effects in the double-diffusing inlet (in which the flow is measured).  Ram heating and active sample heating result in sample relative humidities which are always <40% and usually <20%.  The assumed refractive index for the optical particle counter is 1.44 - 0i.  Particle size distributions are calculated by combining cumulative concentrations over fixed size intervals from the two instruments and applying a numerical inversion, or fitting, technique to determine a size distribution consistent with the observations within experimental uncertainties.

Uncertainties:  Measurement precision varies with particle concentration and propagates nonlinearly through the data reduction technique, but has been calculated for typical planetary boundary layer conditions in SOS using a Monte Carlo method.  Estimated precisions (2-sigma) are +/-15%, +/-32%, and +/-34% for number, surface area, and volume concentrations, respectively.  Possible biases are estimated to be <8%, <32%, and <39%, respectively.  

There are no data for the flight on 07/06/99 due to instrument failure.  

References:  Jonsson, H. H., et al., J. Atmos. Oceanic Tech., 12, 115-129.1995; Brock et al., J. Geophys. Res., 105, 26,555-26,567, 2000; Brock et al., J. Geophys. Res., in press, 2001.

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