July
2006 Issue 18
RECENT SPECIAL ISSUES
of JQSRT (Journal of Quantitative Spectroscopy and Radiative
Transfer):
“Light in Planetary Atmospheres and Other
Particulate Media” (special
issue honoring Professor Joop Hovenier,
Volume 101, Issue 3, 2006).
"Optics of Biological Particles" (Volume 102,
Issue 2, 2006).
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NEW BOOK:
S K Sharma and D J Somerford, “Light Scattering by Optically Soft Particles: Theory and Applications”.
Springer
Praxis 2006.
The present monograph deals with a particular class of approximation methods in the context of light
scattering by small particles. This class of approximations has been termed as eikonal or soft particle
approximations. The eikonal approximation was studied extensively in the potential scattering and then
adopted in optical scattering problems. In this context, the eikonal and other soft particle approximations
pertain to scatterers whose relative refractive index compared to surrounding medium is close to unity.
The study of these approximations is very important because soft particles occur abundantly in nature.
For example, the particles that occur in ocean optics, biomedical optics, atmospheric optics and in many
industrial applications can be classified as soft particles. This book was written in recognition of the
long-standing and current interest in the field of scattering approximations for soft particles. It should
prove to be a useful addition for researchers in the field of light scattering.
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MEETING: "Light Scattering and Radiative Transfer: Basic Research and Applications"
Session A10 at the Fall AGU meeting in
Light scattering and radiative transfer are two important branches of atmospheric physics essential to the
implementation of advanced remote sensing techniques and the investigation of the radiative forcings caused
by various atmospheric components (clouds and aerosols, in particular). This session provides a forum for
the presentation of recent advances in electromagnetic scattering (including the scattering properties of
nonspherical aerosol particles and ice crystals), 3-D radiative transfer, vector radiative transfer simulations,
fast radiative transfer models for applications to the interpretation of hyperspectral measurements, and the use
of basic light scattering and radiative transfer theories in active and passive remote sensing applications. The
link to the session at the AGU home page is
http://www.agu.org/meetings/fm06/?content=search&show=detail&sessid=88
where more details can be found.
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NEW CODE :
The Amsterdam DDA (ADDA) is a C software
package to calculate scattering and absorption of electromagnetic waves by
particles of arbitrary geometry using the Discrete Dipole Approximation (DDA).
It has been developed by Maxim A. Yurkin and Alfons G. Hoekstra at the
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NEW
PAPERS :
M.A. Yurkin, V.P. Maltsev, A.G. Hoekstra, "Convergence of the discrete dipole approximation.
Part I: theoretical analysis," J.Opt.Soc.Am.A 23(10), 2006.
We performed a rigorous theoretical convergence analysis of the discrete dipole approximation (DDA).
We prove that errors in any measured quantity are bounded by a sum of a linear term and a quadratic term in
the size of a dipole d when the latter is in the range of DDA applicability. Moreover, the linear term is
significantly smaller for cubically than for noncubically shaped scatterers. Therefore, for small d, errors for
cubically shaped particles are much smaller than for noncubically shaped ones. The relative importance of the
linear term decreases with increasing size; hence convergence of DDA for large enough scatterers is quadratic
in the common range of d. Extensive numerical simulations were carried out for a wide range of d. Finally, we
discuss a number of new developments in DDA and their consequences for convergence.
Preprint: http://josaa.osa.org/upcoming_pdf.cfm?id=67371
M.A. Yurkin, V.P. Maltsev, A.G. Hoekstra, "Convergence of the discrete dipole approximation.
Part II: an extrapolation technique to increase the accuracy," J.Opt.Soc.Am.A 23(10), 2006.
We propose an extrapolation technique that allows accuracy improvement of discrete dipole approximation
computations. The performance of this technique was studied empirically on the basis of extensive simulations
for five test cases using many different discretizations. The quality of the extrapolation improves with refining
discretization, reaching extraordinary performance especially for cubically shaped particles. A 2-order-of
magnitude decrease of error was demonstrated. We also propose estimates of the extrapolation error, which
were proven to be reliable. Finally, we propose a simple method to directly separate shape and discretization
errors and illustrated this for one test
case. Preprint: http://josaa.osa.org/upcoming_pdf.cfm?id=67373