Universal Spectrum for Atmospheric Suspended Particulates: Comparison with Observations: Data Set I - Rain Formation in Warm Clouds: General Systems Theory - page 62

interval d r a ; and (iii) d(ln r an ) is equal to dr
r

a

for the aerosol radius class interval r a

to r a + d r a . a

3.6.1 Analysis Results, Data I: TARFOX_WALLOPS_SMPS,

Aerosol Size Spectra

A total of 23 data sets between 16 July and 26 July 1996 are available for the study.
The data consists of particle number concentration per cc in 59 class intervals rang-
ing from 10.7 to 749 nm (fine mode) for the particle diameter. The midpoint diam-
eter of the class interval was used to compute the corresponding value of d(ln r an ).
The average aerosol size spectra for each of the 23 data sets are plotted on the
left-hand side and the total average spectrum for the 23 data sets is plotted on the
right-hand side in Fig. 3.1a along with the model predicted scale independent aero-
sol size spectrum. The corresponding standard deviations for the average spectra are
shown as error bars in Figs. 3.1a . The average values of mean volume radius (nm),
total number concentration (cm −3 ), the number of spectra, the number of particle
size class intervals for each of the 23 data sets and the upper and lower bounds of
particle size (diameter in nm) intervals are given in Fig. 3.1b .
The aerosol size spectra cover the fine size range and display large deviations
from the mean, particularly for the individual flights (left-hand side of Fig. 3.1a ).
The source of the uncertainties displayed by the error bars (Fig. 3.1a ) may be due to
measurement noise, independent in every size interval, also may be due to different
aerosol sources with different particle substance densities. However, a major por-
tion of the total average aerosol size spectrum (right-hand side of Fig. 3.1a ) shows
a reasonably good fit (within plus or minus two standard deviations) to the model
predicted universal spectrum for homogeneous aerosols, i.e., same aerosol source.

3.6.2 Analysis Results, Data II: CIRPAS Twin Otter

Flight Data Sets, Aerosol Size Spectra

ARM Aerosol IOP at the SGP site over a 3-4 week period centered on May 2003.
CIRPAS Twin Otter flight data sets using the PCASP. A total of 16 data sets are
available for the study.
The aerosol particle size concentrations ranging in diameter from 0.1 to
3.169701 µm consisting of accumulation mode (up to 1 µm) and coarse mode (di-
ameter > 1 µm) were measured in 20 channels (size ranges). The geometric mean
radius of the class interval was used for computing d(ln r an ). The data sets were ob-
tained from ARM IOP Data Archive http://www.archive.arm.gov/armlogin/login.
jsp. The average aerosol size spectra for each of the 16 data sets are plotted on the
left-hand side and the total average spectrum for the 16 data sets is plotted on the
right and side in Fig. 3.2a along with the model predicted scale independent aerosol