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| Titel |
Observations of water vapour and its isotopes in the tropical transition layer (TTL) and the “tropical pipe” by the balloon-borne Michelson Interferometer for Passive Atmospheric Sounding (MIPAS B2). |
| VerfasserIn |
Agnes Grossel, Hermann Oelhaf, Gerald Wetzel, Anne Kleinert, Felix Friedl-Vallon, Guido Maucher |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250036163
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| Zusammenfassung |
| Water vapour in the stratosphere is very important because of its role in the radiative budget
and the stratospheric chemistry. Understanding the mechanisms of entry of water into the
stratosphere and the possible trends is thus of great concern. As the main part of troposphere
to stratosphere transport occurs through the tropical tropopause, a strong focus has recently
been given to studies of the tropical transition layer (TTL). Different processes of water
transport trough the TTL into the lowermost stratosphere have been debated, especially the
role of convection. The isotopic composition of water vapor is valuable for studying the
transport pathways of water from the troposphere to the stratosphere. However isotopic
measurements are difficult and have led to contradictory observations. New observations are
needed to provide a consistent picture of the processes controlling water entry into the
stratosphere.
Two balloon campaigns were conducted at Teresina (Brazil, 5Ë S, 42Ë W) on June, 14th
2005 and June, 6th 2008, at different QBO phases. Several vertical profiles of H2O, H218O
and HDO were retrieved from infrared limb emission spectra measured by the Michelson
Interferometer for Passive Atmospheric Sounding balloon-borne instrument MIPAS-B2, from
14 to 37 km. These observations give direct information on the tropical stratosphere, where
the “tape recorder” effect caused by the annual cycle of water entry in the stratosphere is
observed. This effect is also visible in the mean δD profile. TTL observations can
also be used to study the water transport to the stratosphere during one season.
They show a good consistency with a temperature-controlled transport of water
(Rayleigh fractionation) and provide no sign of any significant convective transport. |
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