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| Titel |
Spatial Coherence of Tropical Rainfall |
| VerfasserIn |
Ram Ratan, V. Venugopal, Jai Sukhatme, Raghu Murtugudde |
| 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 |
250098711
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| Publikation (Nr.) |
 EGU/EGU2014-14414.pdf |
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| Zusammenfassung |
| We characterise the spatial coherence of tropical rain and its wet spells from observations
(TRMM) and assess if models (CMIP5) are able to reproduce the observed features. Based on
15 years (1998-2012) of TRMM 3B42 (V7) 1-degree, daily rainfall, we estimate the spatial
decorrelation scale (e-folding distance) of rain at each location in the tropics. A ratio of zonal
to meridional spatial scales clearly illustrates that while rain patterns tend to be anisotropic
(ratio of 4) over tropical ocean regions (particularly over Pacific ITCZ); over land
regions, rain tends to be mostly isotropic. This contrast between ocean and land
appears to be reasonably well captured by CMIP5 models, although the anisotropy
(ratio) over ocean is much higher than in observations. A very curious behaviour in
observations is the presence of a coherent band of spatial decorrelation lengths
straddling the equator, in the East Pacific, reminiscent of a double ITCZ that some
models tend to simulate. A similar analysis of wet spells of different durations
suggests that the decorrelation scale is largely independent of the duration of wet
spell. |
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