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| Titel |
ENSO surface shortwave radiation forcing over the tropical Pacific |
| VerfasserIn |
K. G. Pavlakis, N. Hatzianastassiou, C. Matsoukas, A. Fotiadi, I. Vardavas |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 8, no. 18 ; Nr. 8, no. 18 (2008-09-18), S.5565-5577 |
| Datensatznummer |
250006384
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| Publikation (Nr.) |
 copernicus.org/acp-8-5565-2008.pdf |
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| Zusammenfassung |
| We have studied the spatial and temporal variation of the downward shortwave
radiation (DSR) at the surface of the Earth during ENSO events for a 21-year
period over the tropical and subtropical Pacific Ocean (40° S–40° N,
90° E–75° W). The fluxes were computed using a deterministic model for
atmospheric radiation transfer, along with satellite data from the ISCCP-D2
database, reanalysis data from NCEP/NCAR for the key atmospheric and surface
input parameters, and aerosol parameters from GADS (acronyms explained in
main text). A clear anti-correlation was found between the downward
shortwave radiation anomaly (DSR-A) time-series, in the region 7° S–5° N
160° E–160° W located west of the Niño-3.4 region, and the
Niño-3.4 index time-series. In this region where the highest in absolute
value DSR anomalies are observed, the mean DSR anomaly values range from −45 Wm−2
during El Niño episodes to +40 Wm−2 during La Niña
events. Within the Niño-3.4 region no significant DSR anomalies are
observed during the cold ENSO phase in contrast to the warm ENSO phase. A
high correlation was also found over the western Pacific (10° S–5° N,
120–140° E), where the mean DSR anomaly values range from +20 Wm−2
to −20 Wm−2 during El Niño and La Niña episodes, respectively.
There is also convincing evidence that the time series of the mean downward
shortwave radiation anomaly in the off-equatorial western Pacific region
7–15° N 150–170° E, precedes the Niño-3.4 index time-series by
about 7 months and the pattern of this anomaly is indicative of ENSO
operating through the mechanism of the western Pacific oscillator. Thus, the
downward shortwave radiation anomaly is a complementary index to the SST
anomaly for the study of ENSO events and can be used to assess whether or
not El Niño or La Niña conditions prevail. |
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