Awesome additions Irobot.
On top of this I add some more interesting data that shows the devices they built to monitor chemtrail saturation at ground level. This document also includes 4 years of data collected using these devices in the late 90's :www.arm.gov/publications/proceedings/conf11/extended_abs/sheridan_pj.pdf
Eleventh ARM Science Team Meeting Proceedings, Atlanta, Georgia, March 19-23, 2001
Four Years of Continuous Surface Aerosol Measurements Introduction
from the DOE/ARM Southern Great Plains CART Site
P. J. Sheridan, D. J. Delene, and J. A. Ogren
Climate Monitoring and Diagnostics Laboratory
National Oceanic and Atmospheric Administration
D. J. Delene
Cooperative Institute for Research in Environmental Sciences
University of Colorado
Boulder, Colorado [/b]
Continuous measurements of the optical and microphysical properties of aerosol particles have been
made at the U.S. Department of Energy’s (DOE’s) Atmospheric Radiation Measurement (ARM)
Program Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) site covering the 4-year
period from July 1996 through June 2000. The Aerosol Observing System (AOS) is housed in a single
trailer at the SGP CART site Central Facility and samples atmospheric aerosols at a height of 10 m
above the ground through a large-diameter intake stack. Aerosols are passed from the stack through a manifold and into several sampling lines that deliver sample air to the various instruments. Figure 1 is a schematic of the AOS showing stack, sampling lines, manifold, and instruments. Major upgrades were performed in early 1997 to permit switching between different aerosol size ranges and again in late 1998 with the addition of a second integrating nephelometer to determine the change in light scattering associated with changes in relative humidity.
Measurements of the microphysical, chemical, and optical properties of atmospheric aerosol particles
are made by the AOS. The sample air stream is gently heated when necessary to maintain a sample
relative humidity of < 40 percent. A switched inertial impactor system periodically removes particles
larger than 1 µm aerodynamic diameter, resulting in Dp < 1 µm (submicrometer) and Dp < 10 µm
aerosol size fractions. Table 1 provides the details of AOS instruments and measurements and shows
definitions for all measurement symbols and acronyms. From the primary light scattering and
absorption measurements, a number of derived quantities, many of which are important for aerosol
radiative forcing estimates, are calculated. These quantities include the aerosol single-scattering albedo, ω0, the hemispheric backscatter fraction, b, the Ĺngström exponent, ĺ, the fraction of light scattering attributable to submicrometer particles, Rsp, and the aerosol hygroscopic growth factor, f(RH). In addition to our
2 Figure 1. Schematic of the aerosol observing system.
aerosol measurements listed in Table 1, daily filter samples of Dp < 1 µm particles are collected and
analyzed by researchers at National Oceanic and Atmospheric Administration’s Pacific Marine
Environmental Laboratories. This practice permits relating the chemical properties of the aerosols to
their optical and microphysical characteristics.
Hourly, daily, and monthly statistics have been calculated that illustrate aerosol variability over a range of time scales. In general, aerosol distributions plotted by day of the week showed little variability from one day to the next, suggesting that day-of-the-week has only a minor influence on the observed aerosol variability. Some parameters, including condensation nucleus (CN) and σap, showed appreciably lower values in their distributions on Sunday and Monday than on the rest of the week, possibly from reduced vehicular traffic or less agricultural burning in the area on the weekends. Other parameters showed distribution values for Sunday and Monday that were either slightly lower or nearly identical with those from the other weekdays. Daily and annual aerosol cycles are discussed in following section. Figure 2. Statistical distributions of hourly-average, Dp < 10 µm aerosol data collected
over the 4-year period and grouped by hour of the day
A strong daily cycle was observed for total particle number, with the large peak in CN occurring during
local afternoon. A different (albeit subtle) cycle was found for OPC counts (particles between 0.1 and 10 µm diameter) and σsp, with peaks between 1000 and 1300 UTC. Finally, σap and ω0 showed inverse cycles, which is expected if variability in σap levels is driving the observed variability in ω0.
Annual Aerosol Cycles (July 1996 to June 2000)
Statistical distributions of hourly-average, Dp < 10 µm aerosol data collected over the 4-year period and grouped by month of the year are presented in Figure 3. The σsp at a wavelength of 550 nm for the 4-year period showed a median value of 33 Mm-1 and was highest in February and August. The Figure 3. Statistical distributions of hourly-average, Dp < 10 µm aerosol data collected
over the 4-year period and grouped by month of the year.
median fraction of aerosol light scattering at 550 nm due to particles < 1 µm aerodynamic diameter was 0.85 over the entire record. The median aerosol light absorption coefficient, σap, for the 4-year period was ~1.5 Mm-1 and was observed to be highest in late summer and autumn. The σap showed an increasing trend of nearly 0.5 Mm-1/yr, possibly due to increased agricultural field burning in the area.
The occurrence of an autumn decrease in single-scattering albedo, ω0, was observed and may be caused by regional-scale agricultural, transportation activities, or seasonal changes in atmospheric flow patterns. The median value for ω0 over the 4-year period was 0.95, but this value has decreased ~ 1 - 2 percent per year presumably due to increased agricultural burning. Numerous field fires during the second half of 1999 influenced the surface aerosol at the CART site causing substantial variability of aerosol optical properties. Aerosol Hygroscopic Growth Factor (1999 to 2000)
Statistical distributions of hourly-average, Dp < 10 µm aerosol f(RH) data grouped by hour of the day
(upper plot) and month of the year (lower plot) for the 2-year period from January 1999 to December
2000 are presented in Figure 4. A weak daily cycle is evident that shows higher f(RH) values during
local afternoon and lower f(RH) values at night. No obvious annual cycle was observed during this
period. The February minimum and December maximum are likely statistical artifacts related to
instrument problems resulting in insufficient humidified nephelometer measurements at these times.
For the year 1999, a study was performed that related the aerosol hygroscopic growth factor,
corresponding to a relative humidity increase of 40 - 85 percent, to several probable aerosol types.
Figure 5 shows f(RH) frequency distributions for various criteria. The median f(RH) values for all Dp
< 10 µm and Dp < 1 µm aerosol particles were 1.83 and 1.86, respectively. Aerosols that were probably impacted by locally-generated soil dust (Rsp < 0.6) and smoke from agricultural burning (ω0 < 0.
showed much lower f(RH) values, at 1.59 and 1.55, respectively.
The first 4 years of continuous aerosol optical property measurements at the ARM SGP CART site have
produced a wealth of surface aerosol measurements useful in evaluating aerosol radiative forcing. When
analyzed statistically over various time scales, numerous aerosol cycles become apparent. Hour-of-the-
day and month-of-the-year variability in aerosol properties is typically more statistically significant
when related to the entire data set variability than is day-of-the-week variability. Several of the stronger
aerosol cycles, including the afternoon rise in CN and the autumn decrease in ω0, are also apparent at the
rural continental aerosol-monitoring site at Bondville, Illinois (Delene and Ogren 2001). The aerosol
hygroscopic growth factor showed a median value of 1.83 for Dp < 10 µm particles, but was much lower
for probable dust- and smoke-influenced aerosols. For a more complete discussion of the aerosol
variability over the first 4 years of AOS operation, please see Sheridan et al. (2001).
P. J. Sheridan, firstname.lastname@example.org
, (303) 497-6672 References
Bond, T. C., T. L. Anderson, and D. Campbell, 1999: Calibration and intercomparison of filter-based
measurements of visible light absorption by aerosols. Aerosol Sci. Technol., 30, 582-600.
Delene, D. J., and J. A. Ogren, 2001: Variability of aerosol optical properties at four North American
surface monitoring sites. J. Atmos. Sci., submitted.
Sheridan, P. J., D. J. Delene, and J. A. Ogren, 2001: Four years of continuous surface measurements
from the DOE/ARM Southern Great Plains CART site. JGR-Atmospheres, accepted.