This is the Oxford homepage of the Appraising the Direct Impacts of
Aerosol on Climate (ADIENT) project, the primary website for which
can be found here. The
objective of the project is quantifying the direct effect of
aerosols on the Earth's radiation budget, via scattering and/or
absorption of radiation. The project aims to deliver:
New FAAM measurements of the
physical, chemical and optical properties of aerosol over the UK and
Europe
A comprehensive description of the spatio-temporal evolution of
anthropogenic aerosol, in particular the single scatter albedo
An assessment of the radiative impact of anthropogenic aerosol
A comprehensive description of the physical properties of key
aerosol types
An assessment of the aerosol radiative forcing split into the
natural and anthropogenic contribution both regionally and
globally.
Oxford is the primary contractor for the project and Don Grainger
is the PI. Oxford's roles within the project are:
To provide satellite data, including retrieved aerosol fields, in
support of ADIENT aircraft campaigns
Investigate the errors in calculated aerosol optical properties
introduced by neglecting particle asphericity and inhomogeneity
(i.e. the effect of using Mie scattering for non-spherical or
inhomogeneous aerosol types such as mineral dust or soot)
Use the GlobAEROSOL and
AERONET data-sets to
investigate the evolution of aerosol loading in selected regions in
the period 1995-2005
Combining regional satellite, AERONET, aircraft and model aerosol
fields to produce a single description, with a partitioning between
natural and anthropogenic sources.
The primary people at Oxford involved in the ADIENT project
are:
Dr Don Grainger
ADIENT PI
Dr Gareth Thomas
Providing satellite products in support of aircraft campaigns
Analysis of GlobAEROSOL and AERONET data
Production of the synthesized aerosol product
Andy Smith
Investigation of the errors introduced by aerosol inhomogeneity and
non-sphericity
A primary task of Oxford in the ADIENT project is providing
satellite data in support of ADIENT aircraft measurement
campaigns. This encompasses both aiding flight planning by providing
information on where and when satellite overpasses will be occuring,
and providing easily digestible aerosol fields from satellite
sensors at near-real-time.
Links to downloadable satellite aerosol products corresponding to
each of the ADIENT flights are available below (more will be added
to this list as it becomes available).
A prototype IDL tool for extracting satellite data along the flight
path of the FAAM aircraft is now available for download. The tool is
available as both a IDL subroutine and as a standalone GUI
application (suitable for use with the
free IDL Virtual Machine):
A report on the errors introduced by using externally mixed,
homogeneous Mie-scattering as a model of inhomogensous or
nonspherical aerosols in satellite remote sensing has been produced
as part of the Oxford ADIENT deliverables. The report is available
to in PDF form (click the title to download).
In order to quantify the error in non-spherical aerosol optical
properties a method proposed by Dubovik (2006) will be followed. In
this method the computation time is reduced for the calculation of
light scattering by a mixture of spheroids by parameterizing the
numerical integration of spheroid optical properties over size and
shape using look-up tables of quadrature coefficients. These
coefficients will be determined using existing T-matrix code for sand,
ash, salt, ammonium sulphate and ammonium nitrate and black carbon
aerosol.
Depending on humidity, water condenses on the non-soluble
particles to form spherical particles. These cases will be modelled
using Mie code for layered spheres (Bohren & Huffman, 1983).
Optical properties (single scatter albedo, extinction coefficient
and phase function) produced by this method will then be compared to
equivalent properties produced using Mie scattering alone, thus
providing a quantitative measure of the improvement. These studies
complement the laboratory work to be completed within
APPRAISE CP2
and could link into the scattering and radiative transfer model
framework to be initiated within that activity.
Bohren, C.F. and D.R. Huffman. Absorption and scattering of
light by small particles, Wiley, 1983.
Dubovik, O. A. Sinyuk, T. Lapyonok, B.N. Holben, M. Mishchenko,
P. Yang, T.F. Eck, H. Volten, O. Munoz, B. Veihelmann, W.J. van der
Zande, J.-F. Leon, M. Sorokin, and I. Slutsker. Application of
spheroid models to account for aerosol particle nonsphericity in
remote sensing of desert dust. J. Geophys. Res., 111(D11),
doi:10.1029/2005JD006619, 2006.
