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41.
Takeshi Izumo Matthieu Lengaigne Jérôme Vialard Jing-Jia Luo Toshio Yamagata Gurvan Madec 《Climate Dynamics》2014,42(1-2):291-310
The Indian Ocean Dipole (IOD) can affect the El Niño–Southern Oscillation (ENSO) state of the following year, in addition to the well-known preconditioning by equatorial Pacific Warm Water Volume (WWV), as suggested by a study based on observations over the recent satellite era (1981–2009). The present paper explores the interdecadal robustness of this result over the 1872–2008 period. To this end, we develop a robust IOD index, which well exploits sparse historical observations in the tropical Indian Ocean, and an efficient proxy of WWV interannual variations based on the temporal integral of Pacific zonal wind stress (of a historical atmospheric reanalysis). A linear regression hindcast model based on these two indices in boreal fall explains 50 % of ENSO peak variance 14 months later, with significant contributions from both the IOD and WWV over most of the historical period and a similar skill for El Niño and La Niña events. Our results further reveal that, when combined with WWV, the IOD index provides a larger ENSO hindcast skill improvement than the Indian Ocean basin-wide mode, the Indian Monsoon or ENSO itself. Based on these results, we propose a revised scheme of Indo-Pacific interactions. In this scheme, the IOD–ENSO interactions favour a biennial timescale and interact with the slower recharge-discharge cycle intrinsic to the Pacific Ocean. 相似文献
42.
D. J. Bernie E. Guilyardi G. Madec J. M. Slingo S. J. Woolnough 《Climate Dynamics》2007,29(6):575-590
The diurnal cycle is a fundamental time scale in the climate system, at which the upper ocean and atmosphere are routinely
observed to vary. Current climate models, however, are not configured to resolve the diurnal cycle in the upper ocean or the
interaction of the ocean and atmosphere on these time scales. This study examines the diurnal cycle of the tropical upper
ocean and its climate impacts. In the present paper, the first of two, a high vertical resolution ocean general circulation
model (OGCM), with modified physics, is developed which is able to resolve the diurnal cycle of sea surface temperature (SST)
and current variability in the upper ocean. It is then validated against a satellite derived parameterization of diurnal SST
variability and in-situ current observations. The model is then used to assess rectification of the intraseasonal SST response
to the Madden–Julian oscillation (MJO) by the diurnal cycle of SST. Across the equatorial Indo-Pacific it is found that the
diurnal cycle increases the intraseasonal SST response to the MJO by around 20%. In the Pacific, the diurnal cycle also modifies
the exchange of momentum between equatorially divergent Ekman currents and the meridionally convergent geostrophic currents
beneath, resulting in a 10% increase in the strength of the Ekman cells and equatorial upwelling. How the thermodynamic and
dynamical impacts of the diurnal cycle effect the mean state, and variability, of the climate system cannot be fully investigated
in the constrained design of ocean-only experiments presented here. The second part of this study, published separately, addresses
the climate impacts of the diurnal cycle in the coupled system by coupling the OGCM developed here to an atmosphere general
circulation model. 相似文献