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Titel |
Impact of the sea surface temperature forcing on hindcasts of Madden-Julian Oscillation events using the ECMWF model |
VerfasserIn |
E. Boisséson, M. A. Balmaseda, F. Vitart, K. Mogensen |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1812-0784
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Digitales Dokument |
URL |
Erschienen |
In: Ocean Science ; 8, no. 6 ; Nr. 8, no. 6 (2012-12-11), S.1071-1084 |
Datensatznummer |
250006018
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Publikation (Nr.) |
copernicus.org/os-8-1071-2012.pdf |
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Zusammenfassung |
This paper explores the sensitivity of hindcasts of the Madden Julian
Oscillation (MJO) to the use of different sea surface temperture (SST)
products as lower boundary conditions in the European Centre for Medium-range
Weather Forecasts (ECMWF) atmospheric model. Three sets of monthly hindcast
experiments are conducted, starting from initial conditions from the ERA
interim reanalysis. First, as a reference, the atmosphere is forced by the
SST used to produce ERA interim. In the second and third experiments, the SST
is switched to the OSTIA (Operational Sea Surface Temperature and Sea-Ice
Analysis) and the AVHRR-only (Advanced Very High Resolution Radiometer)
reanalyses, respectively. Tests on the temporal resolution of the SST show
that monthly fields are not optimal, while weekly and daily resolutions
provide similar MJO scores. When using either OSTIA or AVHRR, the propagation
of the MJO is degraded and the resulting scores are lower than in the
reference experiment. Further experiments show that this loss of skill cannot
be attributed to either the difference in mean state or temporal variability
between the SST products. Additional diagnostics show that the phase
relationship between either OSTIA or AVHRR SST and the MJO convection is
distorted with respect to satellite observations and the ERA interim
reanalysis. This distortion is expected to impact the MJO hindcasts, leading
to a relative loss of forecast skill. A realistic representation of
ocean–atmosphere interactions is thus needed for MJO hindcasts, but not all
SST products – though accurate for other purposes – fulfill this requirement. |
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