排序方式： 共有6条查询结果，搜索用时 15 毫秒
1
1.
Nicolas Barrier Anne-Marie Treguier Christophe Cassou Julie Deshayes 《Climate Dynamics》2013,41(5-6):1159-1171
Interannual variability of subtropical sea-surface-height (SSH) anomalies, estimated by satellite and tide-gauge data, is investigated in relation to wintertime daily North-Atlantic weather regimes. Sea-level anomalies can be viewed as proxies for the subtropical gyre intensity because of the intrinsic baroclinic structure of the circulation. Our results show that the strongest correlation between SSH and weather regimes is found with the so-called Atlantic-Ridge (AR) while no significant values are obtained for the other regimes, including those related to the North Atlantic Oscillation (NAO), known as the primary actor of the Atlantic dynamics. Wintertime AR events are characterized by anticyclonic wind anomalies off Europe leading to a northward shift of the climatological wind-stress curl. The latter affects subtropical SSH annual variability by altered Sverdrup balance and ocean Rossby wave dynamics propagating westward from the African coast towards the Caribbean. The use of a simple linear planetary geostrophic model allows to quantify those effects and confirms the primary importance of the winter season to explain the largest part of SSH interannual variability in the Atlantic subtropical gyre. Our results open new perspectives in the comprehension of North-Atlantic Ocean variability emphasizing the role of AR as a driver of interannual variability at least of comparable importance to NAO. 相似文献
2.
Holton L. Deshayes J. Backeberg B. C. Loveday B. R. Hermes J. C. Reason C. J. C. 《Climate Dynamics》2017,48(7-8):2107-2121
Climate Dynamics - Investigating the variability of Agulhas leakage, the volume transport of water from the Indian Ocean to the South Atlantic Ocean, is highly relevant due to its potential... 相似文献
3.
A land stratification of the French territory had been previously performed based on time series of vegetation and texture indices. This stratification led to 300 radiometrically homogenous regions that were considered as land units (LUs). In this paper, we present a quantitative analysis of the LUs, with the aim of testing if these LUs are linked to landscape. In this sense, an evaluation of their thematic meaning in terms of environmental variables and land cover was performed. In order to achieve this, we first conducted a statistical analysis at national scale using a set of environmental variables and land cover by means of Moran’s autocorrelation index and Spearman rank correlation index. Second, to analyze the quality of the boundaries between neighboring LUs, we developed a method based on the Spearman rank correlation index calculated on test areas across the boundaries. The first analyses showed that the most explanatory variables of the LUs were land cover, topography and parent material. The boundaries analysis was applied at a regional scale (Pyrenean region), and showed that 89% of the boundaries were well explained by the land cover compositions. The results obtained support the hypothesis that time series of broad resolution remote-sensing images can capture landscape identities and produce LUs maps that have an environmental and land occupation sense. 相似文献
4.
5.
A. Voldoire E. Sanchez-Gomez D. Salas y Mélia B. Decharme C. Cassou S. Sénési S. Valcke I. Beau A. Alias M. Chevallier M. Déqué J. Deshayes H. Douville E. Fernandez G. Madec E. Maisonnave M.-P. Moine S. Planton D. Saint-Martin S. Szopa S. Tyteca R. Alkama S. Belamari A. Braun L. Coquart F. Chauvin 《Climate Dynamics》2013,40(9-10):2091-2121
A new version of the general circulation model CNRM-CM has been developed jointly by CNRM-GAME (Centre National de Recherches Météorologiques—Groupe d’études de l’Atmosphère Météorologique) and Cerfacs (Centre Européen de Recherche et de Formation Avancée) in order to contribute to phase 5 of the Coupled Model Intercomparison Project (CMIP5). The purpose of the study is to describe its main features and to provide a preliminary assessment of its mean climatology. CNRM-CM5.1 includes the atmospheric model ARPEGE-Climat (v5.2), the ocean model NEMO (v3.2), the land surface scheme ISBA and the sea ice model GELATO (v5) coupled through the OASIS (v3) system. The main improvements since CMIP3 are the following. Horizontal resolution has been increased both in the atmosphere (from 2.8° to 1.4°) and in the ocean (from 2° to 1°). The dynamical core of the atmospheric component has been revised. A new radiation scheme has been introduced and the treatments of tropospheric and stratospheric aerosols have been improved. Particular care has been devoted to ensure mass/water conservation in the atmospheric component. The land surface scheme ISBA has been externalised from the atmospheric model through the SURFEX platform and includes new developments such as a parameterization of sub-grid hydrology, a new freezing scheme and a new bulk parameterisation for ocean surface fluxes. The ocean model is based on the state-of-the-art version of NEMO, which has greatly progressed since the OPA8.0 version used in the CMIP3 version of CNRM-CM. Finally, the coupling between the different components through OASIS has also received a particular attention to avoid energy loss and spurious drifts. These developments generally lead to a more realistic representation of the mean recent climate and to a reduction of drifts in a preindustrial integration. The large-scale dynamics is generally improved both in the atmosphere and in the ocean, and the bias in mean surface temperature is clearly reduced. However, some flaws remain such as significant precipitation and radiative biases in many regions, or a pronounced drift in three dimensional salinity. 相似文献
6.
The role of salinity in the decadal variability of the North Atlantic meridional overturning circulation 总被引：1，自引：1，他引：0
An OGCM hindcast is used to investigate the linkages between North Atlantic Ocean salinity and circulation changes during
1963–2003. The focus is on the eastern subpolar region consisting of the Irminger Sea and the eastern North Atlantic where
a careful assessment shows that the simulated interannual to decadal salinity changes in the upper 1,500 m reproduce well
those derived from the available record of hydrographic measurements. In the model, the variability of the Atlantic meridional
overturning circulation (MOC) is primarily driven by changes in deep water formation taking place in the Irminger Sea and,
to a lesser extent, the Labrador Sea. Both are strongly influenced by the North Atlantic Oscillation (NAO). The modeled interannual
to decadal salinity changes in the subpolar basins are mostly controlled by circulation-driven anomalies of freshwater flux
convergence, although surface salinity restoring to climatology and other boundary fluxes each account for approximately 25%
of the variance. The NAO plays an important role: a positive NAO phase is associated with increased precipitation, reduced
northward salt transport by the wind-driven intergyre gyre, and increased southward flows of freshwater across the Greenland–Scotland
ridge. Since the NAO largely controlled deep convection in the subpolar gyre, fresher waters are found near the sinking region
during convective events. This markedly differs from the active influence on the MOC that salinity exerts at decadal and longer
timescales in most coupled models. The intensification of the MOC that follows a positive NAO phase by about 2 years does
not lead to an increase in the northward salt transport into the subpolar domain at low frequencies because it is cancelled
by the concomitant intensification of the subpolar gyre which shifts the subpolar front eastward and reduces the northward
salt transport by the North Atlantic Current waters. This differs again from most coupled models, where the gyre intensification
precedes that of the MOC by several years. 相似文献
1