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| Titel |
Statistical assessments of extreme precipitation and dry periods in the Mediterranean area until the end of the 21st century |
| VerfasserIn |
E. Hertig, J. Jacobeit, A. Paxian, G. Vogt, S. Seubert, H. Paeth |
| 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 |
250061976
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| Zusammenfassung |
| In the context of future climate change, questions about changes related to precipitation are of
particular interest. Thus, the present contribution is related to changes of heavy rainfall
events, dry periods and the relation of these extremes to total precipitation changes in the
Mediterranean area until the end of the 21st century.
Based on high-resolution (0.25Ë ) gridded precipitation data, seasonal precipitation totals
as well as different percentile-based indices of extreme precipitation are defined with a
seasonal resolution: the number of events exceeding the 95th percentile of daily precipitation
from the reference period 1961-1990, percentage, total amount and mean daily intensity of
precipitation from these events. Furthermore, the number of consecutive dry days is taken
into account to represent dry periods.
Mediterranean precipitation is generally induced by large-scale advection and/or it is a
matter of smaller-scale convective activity. Therefore various predictors are chosen to
describe the large-scale circulation as well as convective processes.
Generalized linear models (GLMs) are used to derive relationships of the various
predictands with the large-scale predictors. A specific statistical ensemble technique which
comprises up to five statistical ensemble members per grid box with varying calibration
periods is used for the assessments. This leads to a range of possible future realizations of
precipitation changes depending on the specific predictors-predictand-relationships identified
in the individual calibration periods. Furthermore two different scenarios (A1B and B1),
multiple runs for each scenario, and output of two different AOGCMs (ECHAM5 and
HadCM3) are included.
As a result, a different evolution of precipitation-related events over the western and
central-northern Mediterranean regions becomes apparent compared to the eastern
Mediterranean area. This feature has already been described for observational periods and
may be seen in the context of the so-called “Mediterranean Oscillation”. Thus, in general,
total and extreme precipitation over the western and central-northern Mediterranean area are
mostly reduced in summer and autumn, but increased in winter. In contrast to that,
precipitation over the eastern Mediterranean area shows widespread increases in summer and
autumn, but it declines in winter. Only in spring, this opposite behaviour is not
apparent, total and extreme precipitation decreases rather dominate over the whole
Mediterranean area and are often accompanied by a prolongation of the maximum number
of consecutive dry days. Commonly precipitation increases are accompanied by
dry-period decreases with the exception of large parts around the central-northern
Mediterranean area in winter indicating increases of both precipitation and dry period
length.
The research is done within the framework of the KLIWEX-MED project (climate change
and extreme events in the Mediterranean area). This joint research project of the Universities
of Augsburg and Wuerzburg is funded by the German Research Foundation DFG. |
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