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| Titel |
A 4-D climatology (1979-2009) of the monthly tropospheric aerosol optical depth distribution over the Mediterranean region from a comparative evaluation and blending of remote sensing and model products |
| VerfasserIn |
P. Nabat, S. Somot, M. Mallet, I. Chiapello, J. J. Morcrette, F. Solmon, S. Szopa, F. Dulac, W. Collins, S. Ghan, L. W. Horowitz, J. F. Lamarque, Y. H. Lee, V. Naik, T. Nagashima, D. Shindell  , R. Skeie |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 6, no. 5 ; Nr. 6, no. 5 (2013-05-17), S.1287-1314 |
| Datensatznummer |
250017894
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| Publikation (Nr.) |
 copernicus.org/amt-6-1287-2013.pdf |
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| Zusammenfassung |
| Since the 1980s several spaceborne sensors have been used to retrieve the
aerosol optical depth (AOD) over the Mediterranean region. In parallel, AOD
climatologies coming from different numerical model simulations are now also
available, permitting to distinguish the contribution of several aerosol
types to the total AOD. In this work, we perform a comparative analysis of
this unique multi-year database in terms of total AOD and of its
apportionment by the five main aerosol types (soil dust, sea-salt, sulfate,
black and organic carbon). We use 9 different satellite-derived monthly AOD
products: NOAA/AVHRR, SeaWiFS (2 products), TERRA/MISR, TERRA/MODIS,
AQUA/MODIS, ENVISAT/MERIS, PARASOL/POLDER and MSG/SEVIRI, as well as 3 more
historical datasets: NIMBUS7/CZCS, TOMS (onboard NIMBUS7 and Earth-Probe)
and METEOSAT/MVIRI. Monthly model datasets include the aerosol climatology
from Tegen et al. (1997), the climate-chemistry models LMDz-OR-INCA and RegCM-4,
the multi-model mean coming from the ACCMIP exercise, and the reanalyses GEMS
and MACC. Ground-based Level-2 AERONET AOD observations from 47 stations
around the basin are used here to evaluate the model and satellite data. The
sensor MODIS (on AQUA and TERRA) has the best average AOD scores over this
region, showing a relevant spatio-temporal variability and highlighting high
dust loads over Northern Africa and the sea (spring and summer), and sulfate
aerosols over continental Europe (summer). The comparison also shows
limitations of certain datasets (especially MERIS and SeaWiFS standard
products). Models reproduce the main patterns of the AOD variability over the
basin. The MACC reanalysis is the closest to AERONET data, but appears to
underestimate dust over Northern Africa, where RegCM-4 is found closer to
MODIS thanks to its interactive scheme for dust emissions. The vertical
dimension is also investigated using the CALIOP instrument. This study
confirms differences of vertical distribution between dust aerosols showing a
large vertical spread, and other continental and marine aerosols which are
confined in the boundary layer. From this compilation, we propose a 4-D
blended product from model and satellite data, consisting in monthly time
series of 3-D aerosol distribution at a 50 km horizontal resolution over the
Euro-Mediterranean marine and continental region for the 2003–2009 period.
The product is based on the total AOD from AQUA/MODIS, apportioned into
sulfates, black and organic carbon from the MACC reanalysis, and into dust
and sea-salt aerosols from RegCM-4 simulations, which are distributed
vertically based on CALIOP climatology. We extend the 2003–2009
reconstruction to the past up to 1979 using the 2003–2009 average and
applying the decreasing trend in sulfate aerosols from LMDz-OR-INCA, whose
AOD trends over Europe and the Mediterranean are median among the ACCMIP
models. Finally optical properties of the different aerosol types in this
region are proposed from Mie calculations so that this reconstruction can be
included in regional climate models for aerosol radiative forcing and
aerosol-climate studies. |
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