Column closure studies of lower tropospheric aerosol and water vapor during ACE-Asia using airborne Sun photometer and airborne in situ and ship-based lidar measurements
Author
Schmid, B.
Hegg, D.A.
Wang, J.
Bates, D.
Redemann, J.
Russell, P.B.
Livingston, J.M.
Jonsson, H.H.
Welton, E.J.
Seinfled, J.H.
Flagan, R.C.
Covert, D.S.
Dubovik, O.
Jefferson, A.
Date
2003Metadata
Show full item recordAbstract
We assess the consistency (closure) between solar beam attenuation by aerosols and
water vapor measured by airborne Sun photometry and derived from airborne in situ and
ship-based lidar measurements during the April 2001 Asian Pacific Regional Aerosol
Characterization Experiment (ACE-Asia). The airborne data presented here were obtained
aboard the Twin Otter aircraft. Comparing aerosol extinction sep(550 nm) from four
different techniques shows good agreement for the vertical distribution of aerosol layers.
However, the level of agreement in absolute magnitude of the derived aerosol extinction
varied among the aerosol layers sampled. The sep(550 nm) computed from airborne in
situ size distribution and composition measurements shows good agreement with airborne
Sun photometry in the marine boundary layer but is considerably lower in layers
dominated by dust if the particles are assumed to be spherical. The sep(550 nm) from
airborne in situ scattering and absorption measurements are about 13% lower than those
obtained from airborne Sun photometry during 14 vertical profiles. Combining lidar and
the airborne Sun photometer measurements reveals the prevalence of dust layers at
altitudes up to 10 km with layer aerosol optical depth (from 3.5 to 10 km altitude) of 0.1
to 0.2 (500 nm) and extinction-to-backscatter ratios of 59–71 sr (523 nm). The airborne
Sun photometer aboard the Twin Otter reveals a relatively dry atmosphere during ACEAsia
with all water vapor columns <1.5 cm and water vapor densities rw < 12 g/m3.
Comparing layer water vapor amounts and rw from the airborne Sun photometer to the
same quantities measured with aircraft in situ sensors leads to a high correlation (r2 = 0.96),
but the Sun photometer tends to underestimate rw by 7%.
Description
Journal of Geophysical Research, 108(D23), 8656
The article of record as published may be located at http://dx.doi.org/10.1029/2002JD003361.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.Collections
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