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| Titel |
Downscaling Precipitation via Meiyu-like pattern |
| VerfasserIn |
Thorsten Simon, Andreas Hense, Tong Jiang, Clemens Simmer, Christian Ohlwein |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250089347
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| Publikation (Nr.) |
 EGU/EGU2014-5020.pdf |
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| Zusammenfassung |
| This study identifies daily Meiyu-like East Asian Summer Monsoon patterns that are
linked to precipitation observations in the Poyang lake catchment. This analysis
provides insight into the dynamics of strong, local precipitation events and has
the potential to improve projections of precipitation from coarse-grid numerical
simulations.
Precipitation observations between 1960 and 1999 are taken from 13 rain gauges
located in the Poyang lake catchment, which is a sub-catchment of the Yangtze River.
The analysis shows, that the observations are linked to daily patterns of relative
vorticity at 850 hPa (Vo850) and vertical velocity at 500 hPa (W500) taken from the
ERA-40 reanalysis data set. The patterns are derived by two approaches: (a) empirical
orthogonal function (EOF) analysis and (b) rotated EOF analysis. Vo850 and W500
refer to geostrophic and ageostrophic processes, respectively. A logistic regression
connects the large-scale dynamics to the local observations, whereby a forward
regression selects the patterns best suited as predictors for the probability of exceeding
thresholds of 24h accumulated rainfall at the gauges. The regression model is verified by
cross-validation.
The spatial structure of the detected patterns can be interpreted in terms of well-known
meso-α-scale disturbances called Southwest vortices. Overall, the proposed EOF and rotated
EOF patterns are both related to physical processes and have the potential to work as
predictors for exceedance rates of local precipitation in the Poyang catchment.
References
T. Simon, A. Hense, B. Su, T. Jiang, C. Simmer, and C. Ohlwein, 2013: Pattern-based
statistical downscaling of East Asian Summer Monsoon precipitation. Tellus A. 65.
http://dx.doi.org/10.3402/tellusa.v65i0.19749 |
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