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| Titel |
Estimation of the direct aerosol radiative effect over China based on satellite remote sensing measurements |
| VerfasserIn |
A.-M. Sundström, J. Huttunen, A. Arola, P. Kolmonen, L. Sogacheva, G. de Leeuw |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250068012
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| Zusammenfassung |
| Aerosols influence the radiative budget of the Earth-atmosphere system directly by scattering
and absorbing solar and thermal infrared radiation, and indirectly by modifying the
microphysical, and hence the radiative properties and lifetimes of clouds. However, the
quantification of aerosol radiative effects is complex and large uncertainties still exist, mainly
due to the high spatial and temporal variation of the aerosol concentration and mass, as well
as their relatively short lifetime in the atmosphere. The clear-sky direct aerosol radiative
effect at the top of the atmosphere (TOA) is defined as the difference between the
net solar flux ΔFTOA (difference between downward and upward fluxes) defined
with (F) and without (F0) aerosols. The negative values of ΔFTOA correspond to
planetary cooling, whereas positive values correspond to increased atmospheric
warming.
Satellites offer an opportunity to observe the spatial distribution of aerosol properties with
adequate resolution and coverage from regional to global scales. In this work multisensor
satellite observations are used to estimate the direct aerosol radiative effect at the top of
the atmosphere over China within the shortwave (SW, 0.3-5 microns) region. The
Moderate Imaging Spectroradiometer onboard (MODIS) NASA’s Terra and Aqua
platforms offer global observations of aerosol and cloud optical properties nearly on a
daily basis, whereas the Clouds and the Earth’s Radian Energy System (CERES)
instruments measure simultaneously TOA broadband fluxes e.g. in the shortwave
region. Hence, the instantaneous aerosol direct radiative effect for a month at TOA
can be estimated using the MODIS aerosol optical depth (AOD) and coincident
broadband flux from the CERES instrument. The values for F and F0 are obtained by
performing a linear regression between MODIS AOD at 0.55 microns wavelength
and CERES SW flux. The instantaneous values are converted to monthly means
by using a radiative transfer code. Preliminary results of the aerosol direct effect
over China between 2004 and 2009 will be introduced. In addition, the results are
compared with radiative transfer calculations and AERONET sunphotometer inversions. |
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