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| Titel |
Detection of volcanic sulfate aerosol with Envisat MIPAS shown for the Kasatochi, Sarychev, and Nabro eruptions |
| VerfasserIn |
Sabine Griessbach, Lars Hoffmann, Reinhold Spang, Marc von Hobe, Rolf Müller, Martin Riese |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250074840
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| Zusammenfassung |
| Stratospheric sulfate aerosol is known to have a strong impact on climate. Transport pathways
of sulfur dioxide and sulfate aerosol to the stratosphere are still discussed. It is known that
volcanic eruptions can inject significant amounts of sulfur directly into the stratosphere. Most
sulfur, however, is injected into the troposphere and only a fraction of it can make its way into
the stratosphere. Global and altitude resolved time series of observations are a valuable
source of information for sulfur dioxide and sulfate aerosol detection. Here we present a new
aerosol detection method for the infrared limb sounder Michelson Interferometer for Passive
Atmospheric Sounding (MIPAS) and the results for the Kasatochi, Sarychev, and Nabro
eruptions.
The new detection method utilizes three infrared window regions that are located around
830, 960, and 1224 cm-1. The combination of these three windows allows for a better
detection of enhanced aerosol events in the troposphere as well as the discrimination from ice
clouds. With this new method the 10 year record of MIPAS measurements was analyzed. The
most remarkable sulfate aerosol events follow the Kasatochi, Sarychev, and Nabro eruptions.
After these eruptions enhanced aerosol is detected in the upper troposphere and lower
stratosphere (UTLS) region. Within one to two months it spreads over most of the northern
hemisphere. In the tropics the aerosol reaches altitudes up to around 20 km and in the Arctic
up to 15 km. The enhanced aerosol signal can be observed for about 5, 7, and up to 10
month for the Kasatochi, Sarychev, and Nabro eruptions, respectively. During this
period the enhanced aerosol detections decrease in number, strength, and observation
altitude.
After the Nabro eruption on 13 June 2011 volcanic aerosol is detected in the UTLS region
two days after the initial eruption. The following days the aerosol moves around the northern
edge of the Asian monsoon region, is then transported southwards and later westwards
around the Asian monsoon region. This observation contradicts a recent publication
(Bourassa, 2012) that states that no direct injection occurred and that the aerosol was
transported to the UTLS by convective uplift in the Asian monsoon only. Later in July
MIPAS aerosol observations in combination with ensemble trajectory studies indicate that
additional volcanic sulfate aerosol is transported into the UTLS via the Asian monsoon
region.
Bourassa, A. E., et al.: Large Volcanic Aerosol Load in the Stratosphere Linked to Asian
Monsoon Transport, Science, 337, 78-81, 2012. |
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