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| Titel |
Simulation of the Indian summer monsoon onset-phase rainfall using a regional model |
| VerfasserIn |
C. V. Srinivas, D. Hari Prasad, D. V. Bhaskar Rao, R. Baskaran, B. Venkatraman |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 33, no. 9 ; Nr. 33, no. 9 (2015-09-11), S.1097-1115 |
| Datensatznummer |
250121244
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| Publikation (Nr.) |
 copernicus.org/angeo-33-1097-2015.pdf |
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| Zusammenfassung |
| This study examines the ability of the Advanced Research WRF (ARW) regional
model to simulate Indian summer monsoon (ISM) rainfall climatology in
different climate zones during the monsoon onset phase in the decade
2000–2009. The initial and boundary conditions for ARW are provided from the
NCEP/NCAR Reanalysis Project (NNRP) global reanalysis. Seasonal onset-phase
rainfall is compared with corresponding values from 0.25° IMD (India Meteorological Department) rainfall
and NNRP precipitation data over seven climate zones (perhumid, humid,
dry/moist, subhumid, dry/moist, semiarid and arid) of India to see whether
dynamical downscaling using a regional model yields advantages over just using
large-scale model predictions. Results show that the model could simulate
the onset phase in terms of progression and distribution of rainfall in most
zones (except over the northeast) with good correlations and low error metrics.
The observed mean onset dates and their variability over different zones are
well reproduced by the regional model over most climate zones. It has been
found that the ARW performed similarly to the reanalysis in most zones and
improves the onset time by 1 to 3 days in zones 4 and 7, in which the NNRP
shows a delayed onset compared to the actual IMD onset times. The variations in the
onset-phase rainfall during the below-normal onset (June negative) and above-normal onset (June positive) phases are well simulated. The slight
underestimation of onset-phase rainfall in the northeast zone could be due
to failure in resolving the wide extent of topographic variations and the
associated multiscale interactions in that zone. Spatial comparisons showed
improvement of pentad rainfall in both space and quantity in ARW simulations
over NNRP data, as evident from a wider eastward distribution of pentad
rainfall over the Western Ghats, central and eastern India, as in IMD
observations. While NNRP under-represented the high pentad rainfall over
northeast, east and west coast areas, the ARW captured these regional
features showing improvement upon NNRP reanalysis, which may be due to the
high resolution (30 km) employed. The onset-phase rainfall characteristics
during the contrasting ISM of 2003 and 2009 are well simulated in terms of the
variations in the strength of low-level jet (LLJ) and outgoing long-wave radiation (OLR). |
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