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| Titel |
On the correlation between aerosol optical depth and precipitation over hyperarid regions: A case study from the Arabian Peninsula |
| VerfasserIn |
Mijael Rodrigo Vargas Godoy, Prashanth Reddy Marpu, Matteo Chiesa, Annalisa Molini |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250147983
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| Publikation (Nr.) |
 EGU/EGU2017-12207.pdf |
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| Zusammenfassung |
| Atmospheric turbidity plays a crucial – and controversial – role in the hydroclimatology of
arid regions, with atmospheric aerosols both acting as rainfall inhibitors and enhancers.
Aircraft observations and model simulations show that cloud development is strongly
modulated by dust-cloud interactions at the microscales, during the drop formation process.
However, the influence of aerosols and dust on precipitation remains poorly understood,
mainly due to our limited knowledge of the dynamical processes that – acting over
a wider range of spatial and temporal scales – drive cloud formation and trigger
precipitation. The effects of dust and aerosols on precipitation mostly depend on the
concentration of dust particles acting as cloud condensation nuclei (CCNs) and ice nuclei
(IN), their chemical composition, size and morphology. In the recent years, the
application of satellite data to characterize aerosol distribution has advanced dramatically
through the systematic acquisition of aerosol optical depth (AOD) data over land from
space borne sensors like MODIS onboard the EOS-Terra satellite. Although AOD
is not a direct measure of the aerosol concentration in atmosphere, but rather an
estimate of the atmospheric optical thickness due to scattering and absorption by
aerosols, it is frequently used as a proxy of dust concentration in the atmospheric
column.
Many studies have analyzed the coupling between dust/aerosol abundance and
precipitation through the use of remotely sensed data of AOD and precipitation. However,
their focus has been mainly on the long-term influence (at monthly or annual scales) of
dust/aerosols on precipitation onset, and on the influence of transport processes (through
Lagrangian tracking). In this contribution, we move our attention to hyperarid regions – and
in particular to a large region centered on the Arabian Peninsula, Persia and Eastern Africa
– where precipitation events are highly sporadic and scattered in space. We use
aerosol optical depth (AOD) data from MODIS Terra and precipitation fields from the
Tropical Rainfall Measuring Mission (TRMM), to investigate the diverse correlation
patterns between aerosols and rain-occurrence across the region. The main focus is
on daily scales, due to the extremely intermittent nature of precipitation events in
the region. The role of data uncertainty and validation is also put in context and
discussed. |
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