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| Titel |
Ozone mixing ratios inside tropical deep convective clouds from OMI satellite measurements |
| VerfasserIn |
J. R. Ziemke, J. Joiner, S. Chandra, P. K. Bhartia, A. Vasilkov, D. P. Haffner, K. Yang, M. R. Schoeberl, L. Froidevaux, P. F. Levelt |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 9, no. 2 ; Nr. 9, no. 2 (2009-01-27), S.573-583 |
| Datensatznummer |
250006743
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| Publikation (Nr.) |
 copernicus.org/acp-9-573-2009.pdf |
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| Zusammenfassung |
| We have developed a new technique for estimating ozone
mixing ratio inside deep convective clouds. The technique uses the concept
of an optical centroid cloud pressure that is indicative of the photon path
inside clouds. Radiative transfer calculations based on realistic cloud
vertical structure as provided by CloudSat radar data show that because deep
convective clouds are optically thin near the top, photons can penetrate
significantly inside the cloud. This photon penetration coupled with
in-cloud scattering produces optical centroid pressures that are hundreds of
hPa inside the cloud. We combine measured column ozone and the optical
centroid cloud pressure derived using the effects of rotational-Raman
scattering to estimate O3 mixing ratio in the upper regions of deep
convective clouds. The data are obtained from the Ozone Monitoring
Instrument (OMI) onboard NASA's Aura satellite. Our results show that low
O3 concentrations in these clouds are a common occurrence throughout
much of the tropical Pacific. Ozonesonde measurements in the tropics
following convective activity also show very low concentrations of O3
in the upper troposphere. These low amounts are attributed to vertical
injection of ozone poor oceanic boundary layer air during convection into
the upper troposphere followed by convective outflow. Over South America and
Africa, O3 mixing ratios inside deep convective clouds often exceed 50 ppbv
which are comparable to mean background (cloud-free) amounts and are
consistent with higher concentrations of injected boundary layer/lower
tropospheric O3 relative to the remote Pacific. The Atlantic region in
general also consists of higher amounts of O3 precursors due to both
biomass burning and lightning. Assuming that O3 is well mixed (i.e.,
constant mixing ratio with height) up to the tropopause, we can estimate the
stratospheric column O3 over clouds. Stratospheric column ozone derived
in this manner agrees well with that retrieved independently with the Aura
Microwave Limb Sounder (MLS) instrument and thus provides a consistency
check of our method. |
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