Abstract. The spatiotemporal distribution and characterization of
aerosol particles are usually determined by remote-sensing and optical in
situ measurements. These measurements are indirect with respect to
microphysical properties, and thus inversion techniques are required to
determine the aerosol microphysics. Scattering theory provides the link
between microphysical and optical properties; it is not only needed for such
inversions but also for radiative budget calculations and climate modeling.
However, optical modeling can be very time-consuming, in particular if
nonspherical particles or complex ensembles are involved. In this paper we present the MOPSMAP package (Modeled optical
properties of ensembles of aerosol particles), which is computationally fast for optical
modeling even in the case of complex aerosols. The package consists of a data set
of pre-calculated optical properties of single aerosol particles, a Fortran
program to calculate the properties of user-defined aerosol ensembles, and a
user-friendly web interface for online calculations. Spheres, spheroids, and
a small set of irregular particle shapes are considered over a wide range of
sizes and refractive indices. MOPSMAP provides the fundamental optical
properties assuming random particle orientation, including the scattering
matrix for the selected wavelengths. Moreover, the output includes tables of
frequently used properties such as the single-scattering albedo, the
asymmetry parameter, or the lidar ratio. To demonstrate the wide range of
possible MOPSMAP applications, a selection of examples is presented, e.g.,
dealing with hygroscopic growth, mixtures of absorbing and non-absorbing
particles, the relevance of the size equivalence in the case of nonspherical
particles, and the variability in volcanic ash microphysics. The web interface is designed to be intuitive for expert and nonexpert users.
To support users a large set of default settings is available, e.g., several
wavelength-dependent refractive indices, climatologically representative size
distributions, and a parameterization of hygroscopic growth. Calculations are
possible for single wavelengths or user-defined sets (e.g., of specific
remote-sensing application). For expert users more options for the
microphysics are available. Plots for immediate visualization of the results
are shown. The complete output can be downloaded for further applications.
All input parameters and results are stored in the user's personal folder so
that calculations can easily be reproduced. The web interface is provided at
https://mopsmap.net (last access: 9 July 2018) and
the Fortran program including the data set is freely available for offline
calculations, e.g., when large numbers of different runs for sensitivity
studies are to be made.