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| Titel |
Seasonal variation of bromine monoxide over the Rann of Kutch salt marsh seen from space |
| VerfasserIn |
Christoph Hörmann, Steffen Beirle, Marloes Penning de Vries, Holger Sihler, Ulrich Platt, Thomas Wagner |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250110628
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| Publikation (Nr.) |
 EGU/EGU2015-10652.pdf |
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| Zusammenfassung |
| Bromine monoxide (BrO) is an important catalyst in the depletion of tropospheric and
stratospheric ozone (O3). In the troposphere, reactive bromine can be released from sea ice,
volcanoes, sea-salt aerosol or salt lakes. For all of these natural sources enhanced BrO
vertical column densities (VCDs) have been successfully observed from ground using
Differential Optical Absorption Spectroscopy (DOAS). Until now, satellite observations were
only reported for polar regions during springtime and volcanic emissions (mostly for major
eruptions).
We present the first satellite observations of enhanced monthly mean BrO VCDs over a
salt marsh, the Rann of Kutch (India/Pakistan), during 2004-2014 as seen by the Ozone
Monitoring Instrument (OMI). The Rann of Kutch is a so-called ‘seasonal’ salt marsh.
During India’s summer monsoon (June/July – September/October), the flat desert of salty
clay and mudflats, which average 15 meters above sea level, fills with standing rain and
sea water. With more than 7500 km2 it is the largest salt desert in the world and
additionally one of the hottest areas of India with summer temperatures around 50 Ë
C and winter temperatures decreasing below 0 Ë C. Probably due to these rather
extreme conditions, the Rann of Kutch has not been yet investigated for atmospheric
composition measurements by ground-based instruments. Satellite observations, however,
provide the unique possibility to investigate the entire area remotely over a long-time
period.
The OMI data reveals recurring maximum BrO VCDs during April/May, but no
enhanced column densities during the monsoon season while the area is flooded.
In the following months the signal only recovers slowly while the salty surface
dries up. We discuss the possible effects of temperature, precipitation and relative
humidity on the release of enhanced reactive bromine concentrations. In order to
investigate a possible diurnal cycle of the BrO concentration, the OMI results (at a local
overflight time around ~13:30) are compared to corresponding results from the
Global Ozone Monitoring Instrument (GOME-2, local overflight time at ~9:30). |
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