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| Titel |
Development the EarthCARE aerosol classification scheme |
| VerfasserIn |
Ulla Wandinger, Holger Baars, Anja Hünerbein, Dave Donovan, Gerd-Jan van Zadelhoff, Jürgen Fischer, Jonas von Bismarck, Michael Eisinger, Dulce Lajas, Tobias Wehr |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250106561
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| Publikation (Nr.) |
 EGU/EGU2015-6238.pdf |
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| Zusammenfassung |
| The Earth Clouds, Aerosols and Radiation Explorer (EarthCARE) mission is a joint
ESA/JAXA mission planned to be launched in 2018. The multi-sensor platform carries a
cloud-profiling radar (CPR), a high-spectral-resolution cloud/aerosol lidar (ATLID), a
cloud/aerosol multi-spectral imager (MSI), and a three-view broad-band radiometer (BBR).
Three out of the four instruments (ATLID, MSI, and BBR) will be able to sense the global
aerosol distribution and contribute to the overarching EarthCARE goals of sensor synergy
and radiation closure with respect to aerosols. The high-spectral-resolution lidar ATLID
obtains profiles of particle extinction and backscatter coefficients, lidar ratio, and linear
depolarization ratio as well as the aerosol optical thickness (AOT) at 355 nm. MSI
provides AOT at 670 nm (over land and ocean) and 865 nm (over ocean). Next to
these primary observables the aerosol type is one of the required products to be
derived from both lidar stand-alone and ATLID-MSI synergistic retrievals. ATLID
measurements of the aerosol intensive properties (lidar ratio, depolarization ratio) and
ATLID-MSI observations of the spectral AOT will provide the basic input for aerosol-type
determination.
Aerosol typing is needed for the quantification of anthropogenic versus natural
aerosol loadings of the atmosphere, the investigation of aerosol-cloud interaction,
assimilation purposes, and the validation of atmospheric transport models which
carry components like dust, sea salt, smoke and pollution. Furthermore, aerosol
classification is a prerequisite for the estimation of direct aerosol radiative forcing and
radiative closure studies. With an appropriate underlying microphysical particle
description, the categorization of aerosol observations into predefined aerosol types
allows us to infer information needed for the calculation of shortwave radiative
effects, such as mean particle size, single-scattering albedo, and spectral conversion
factors.
In order to ensure the consistency of EarthCARE retrievals, to support aerosol description
in the EarthCARE simulator ECSIM, and to facilitate a uniform specification of broad-band
aerosol optical properties, a hybrid end-to-end aerosol classification model (HETEAC) is
developed which serves as a baseline for EarthCARE algorithm development and evaluation
procedures. The model’s theoretical description of aerosol microphysics (bi-modal size
distribution, spectral refractive index, and particle shape distribution) is adjusted to
experimental data of aerosol optical properties, i.e. lidar ratio, depolarization ratio, Ångström
exponents (hybrid approach). The experimental basis is provided by ground-based
observations with sophisticated multi-wavelength, polarization lidars applied in
the European Aerosol Research Lidar Network (EARLINET) and in dedicated
field campaigns in the Sahara (SAMUM-1), Cape Verde (SAMUM-2), Barbados
(SALTRACE), Atlantic Ocean (Polarstern and Meteor cruises), and Amazonia. The model is
designed such that it covers the entire loop from aerosol microphysics via aerosol
classification to optical and radiative properties of the respective types and allows
consistency checks of modeled and measured parameters (end-to-end approach). Optical
modeling considers scattering properties of spherical and non-spherical particles. A
suitable set of aerosol types is defined which includes dust, clean marine, clean
continental, pollution, smoke, and stratospheric aerosol. Mixtures of these types are
included as well. The definition is consistent with CALIPSO approaches and will thus
enable the establishment of a long-term global four-dimensional aerosol dataset. |
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