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| Titel |
Effect of surface BRDF of various land cover types on geostationary observations of tropospheric NO2 |
| VerfasserIn |
K. Noguchi, A. Richter, V. Rozanov, A. Rozanov, J. P. Burrows, H. Irie, K. Kita |
| 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 ; 7, no. 10 ; Nr. 7, no. 10 (2014-10-10), S.3497-3508 |
| Datensatznummer |
250115932
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| Publikation (Nr.) |
 copernicus.org/amt-7-3497-2014.pdf |
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| Zusammenfassung |
| We investigated the effect of surface reflectance anisotropy, bidirectional reflectance distribution function (BRDF), on satellite retrievals of
tropospheric NO2. We assume the geometry of geostationary
measurements over Tokyo, which is one of the worst air-polluted regions in
East Asia. We calculated air mass factors (AMF) and box AMFs (BAMF) for
tropospheric NO2 to evaluate the effect of BRDF by using the
radiative transfer model SCIATRAN. To model the BRDF effect, we utilized the
Moderate Resolution Imaging Spectroradiometer (MODIS) products (MOD43B1 and
MOD43B2), which provide three coefficients to express the
RossThick–LiSparse reciprocal model, a semi-empirical and kernel-based model
of BRDF. Because BRDF depends on the land cover type, we also utilized the
High Resolution Land-Use and Land-Cover Map of the Advanced Land Observing
Satellite (ALOS)/Advanced Visible and Near Infrared Radiometer type 2
(AVNIR-2), which classifies the ground pixels over Tokyo into six main types:
water, urban, paddy, crop, deciduous forest, and evergreen forest. We first
develop an empirical model of the three BRDF coefficients for each land cover
type over Tokyo and then apply the model to the calculation of land-cover-type-dependent AMFs and BAMFs. Results show that the variability of AMF among
the land types is up to several tens of percent, and if we neglect the
reflectance anisotropy, the difference with AMFs based on BRDF reaches 10%
or more. The evaluation of the BAMFs calculated shows that not considering
BRDF will cause large errors if the concentration of NO2 is high
close to the surface, although the importance of BRDF for AMFs decreases for
large aerosol optical depth (AOD). |
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