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| Titel |
Investigation of aerosol effects on rain drop size distribution |
| VerfasserIn |
S. K. Das, J. P. Chen |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250062981
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| Zusammenfassung |
| Recently it is being increasingly realized that aerosols play an important role in the present
climate change processes by perturbing the Earth’s radiation budget directly through
interacting with the incoming solar and outgoing terrestrial radiations and indirectly by
altering cloud lifetime and precipitation. However, ‘complete’ understanding of all possible
interactions between various mechanisms of these tiny particles with different atmospheric
processes is lacking. The present study demonstrates the aerosol effects on rain drop size
distribution and the consequent effects on climate change. Simultaneous observations of
ground-based impact type disdrometer and Lower Atmosphere Wind Profiler (LAWP) radar
were carried out to observe rain drop size distribution change during the premonsoon
season at Gadanki (13.5Ë N, 79.2Ë E), a tropical station in India. After two months
drought condition the first precipitation occurred on 21st May 2011. Disdrometer
observations show that this initial rain was relatively weak with peak rain rate of about 5
mm/hr for ten minutes duration and the mean raindrop diameter was about 1 mm.
However, initial few minutes rain could not reach the ground, as noticed from LAWP
observations. This could be due to either advection (meaning that it might reach ground at
downwind locations) or strong evaporation. The relatively small raindrops and low
precipitation flux indicate that the initial rain might experience strong evaporation
while falling to the ground, and this strong evaporation could be due to either a dry
below-cloud air or small rain drops to begin with. The space borne observations from
MODIS-Aqua and OMI-Aura suggest that there is high loading of dust aerosols and
CALIPSO observations identify a dust layer present in between 2 to 6 km as well
as boundary layer absorbing aerosols. The high aerosol loading may cause not
only significant changes in cloud microphysical properties and thus resulting in
smaller raindrops but also warming of the atmosphere, both of which can intensify
the evaporation of the falling rain drop. This study applied observation and model
simulation to determine which process is the most likely reason for light rain with
smaller droplet sizes during premonsoon season in the Indian subtropical region. |
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