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| Titel |
Small-scale variability of the raindrop size distribution |
| VerfasserIn |
Alexis Berne, Joel Jaffrain, Marc Schleiss |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250050253
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| Zusammenfassung |
| The raindrop size distribution (DSD) is an important piece of information to understand
rainfall variability. The DSD is controlled by the interactions between cloud microphysics
and atmospheric dynamics. It is also crucial to quantitatively interpret measurements
collected using remote sensing, and in particular by weather radar systems. The spatial
variability of the DSD at small scales (i.e., a few km) is not well documented and understood,
mainly because of a lack of appropriate data. This variability and its structure in
space and time are key factors for comparing observations/simulations at different
scales taking into account the subgrid variability (e.g., measurements vs model
simulations) and for improving the conversion of radar observations into reliable rain rate
estimates.
A network of 16 disdrometers covering a typical operational radar pixel (1 Ã 1 km2) has
been designed and set up over EPFL campus in Lausanne, Switzerland, for about 16Â months.
The collected data set (with a temporal resolution of 30Â s) is used to investigate the
small-scale variability of the DSD. It is shown (i) that there exists a spatial variability within a
typical radar pixel (which can not be solely explained by the sampling uncertainty associated
with each disdrometer), (ii) that it is structured in space, and (iii) that it is different at point
and pixel scales. This spatial structure must be taken into account when considering DSDs at
different scales, in order to limit the uncertainties for example when comparing DSD
measurements at point and larger scales or when using empirical power laws derived
from point measurements to convert radar observations into rain rate estimates. |
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