Atmospheric Chemistry and Physics
www.atmos-chem-phys.net
1680-7316
1680-7324
7
12
2007
10.5194/acp-7-3341-2007
http://www.atmos-chem-phys.net/7/3341/2007/
http://www.atmos-chem-phys.net/7/3341/2007/acp-7-3341-2007.html
http://www.atmos-chem-phys.net/7/3341/2007/acp-7-3341-2007.pdf
3341
3351
2007-06-27
Aerosol single-scattering albedo and asymmetry parameter from MFRSR observations during the ARM Aerosol IOP 2003
E. I. Kassianov
evgueni.kassianov@pnl.gov
C. J. Flynn
T. P. Ackerman
J. C. Barnard
Pacific Northwest National Laboratory, Richland, 99352, USA
University of Washington, Seattle, 98195, USA
Multi-filter Rotating Shadowband Radiometers (MFRSRs) provide routine
measurements of the aerosol optical depth (τ) at six wavelengths
(0.415, 0.5, 0.615, 0.673, 0.870 and 0.94 μm). The single-scattering
albedo (π<sub>0</sub>) is typically estimated from the MFRSR measurements by
assuming the asymmetry parameter (<I>g</I>). In most instances, however, it is
not easy to set an appropriate value of <I>g</I> due to its strong temporal and
spatial variability. Here, we introduce and validate an updated version of
our retrieval technique that allows one to estimate simultaneously π<sub>0</sub> and
<I>g</I> for different types of aerosol. We use the aerosol and
radiative properties obtained during the Atmospheric Radiation Measurement
(ARM) Program's Aerosol Intensive Operational Period (IOP) to validate our
retrieval in two ways. First, the MFRSR-retrieved optical properties are
compared with those obtained from independent surface, Aerosol Robotic
Network (AERONET), and aircraft measurements. The MFRSR-retrieved optical
properties are in reasonable agreement with these independent measurements.
Second, we perform radiative closure experiments using the MFRSR-retrieved
optical properties. The calculated broadband values of the direct and
diffuse fluxes are comparable (~5 W/m<sup>2</sup>) to those obtained from
measurements.
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