摘要
The low-frequency atmosphere ocean coupled vestigated using observation data over 1958-2010 variability of the southern Indian Ocean （SIO） was in- These data were obtained from ECMWF for sea level pressure （SLP） and wind, from NCEP/NCAR for heat fluxes, and from the Hadley Center for SST. To obtain the coupled air-sea variability, we performed SVD analyses on SST and SLP. The primary coupled mode represents 43% of the total square covariance and is featured by weak westerly winds along 45~ 30~S. This weakened subtropical anticyclone forces fluctuations in a well-known subtropical dipole structure in the SST via wind-induced processes. The SST changes in response to atmosphere forcing and is predictable with a lead-time of 1 2 months. Atmosphere ocean coupling of this mode is strongest during the austral summer. Its principle component is characterized by mixed interannual and interdeeadal fluctuations. Titere is a strong relationship between the first mode and Antarctic Oscillation （AAO）. The AAO can influence tile coupled processes in the SIO by modulating the subtropical high. The second mode, accounting for 30% of the total square covariance, represents a 25-year period interdecadal oscillation in tile strength of the subtropical anticyclone that is accompanied by fluctuations of a monopole structure in the SST along the 35~ 25~S band. It is caused by subsidence of the atmosphere. The present study also shows that physical processes of both local thermodynamic and ocean circulation in the SIO have a crucial role in the fornmtion of the atmosphere-ocean eovariability.
The low-frequency atmosphere ocean coupled vestigated using observation data over 1958-2010 variability of the southern Indian Ocean （SIO） was in- These data were obtained from ECMWF for sea level pressure （SLP） and wind, from NCEP/NCAR for heat fluxes, and from the Hadley Center for SST. To obtain the coupled air-sea variability, we performed SVD analyses on SST and SLP. The primary coupled mode represents 43% of the total square covariance and is featured by weak westerly winds along 45~ 30~S. This weakened subtropical anticyclone forces fluctuations in a well-known subtropical dipole structure in the SST via wind-induced processes. The SST changes in response to atmosphere forcing and is predictable with a lead-time of 1 2 months. Atmosphere ocean coupling of this mode is strongest during the austral summer. Its principle component is characterized by mixed interannual and interdeeadal fluctuations. Titere is a strong relationship between the first mode and Antarctic Oscillation （AAO）. The AAO can influence tile coupled processes in the SIO by modulating the subtropical high. The second mode, accounting for 30% of the total square covariance, represents a 25-year period interdecadal oscillation in tile strength of the subtropical anticyclone that is accompanied by fluctuations of a monopole structure in the SST along the 35~ 25~S band. It is caused by subsidence of the atmosphere. The present study also shows that physical processes of both local thermodynamic and ocean circulation in the SIO have a crucial role in the fornmtion of the atmosphere-ocean eovariability.
基金
supported by the Major Project of the National Natural Science Foundation of China (Grant No.40890151)
the National Natural Science Foundation of China (Grant No.41106016)
