印度洋波浪诱导的水体输运效应及其对赤道SST异常的影响

The Wave-induced Transport in the Indian Ocean and Its Influence on Tropical SST Anomaly

波浪诱导的水体输运会对海洋产生大尺度影响。结合波浪大尺度效应的研究现状和印度洋涌浪分布的事实,利用ECMWF-CERA20的波浪、海表面温度(SST)及风场数据,采用多种统计分析方法,研究了波浪输运与赤道印度洋SST的潜在关系。结果显示:中高纬度波浪输运异常的低频信号在空间、周期上与赤道SST异常均有高度相似性;Stokes漂流纬向、经向异常呈现出南—北、东—西的振荡,其第二模态时间序列与印度洋偶极子(Indian Ocean Dipole,IOD)指数存在强相关性并在La Ni a次年的负IOD事件中达到最高:相关系数在ACC区域纬向异常超前6个月时接近0.6,中纬度区域经向异常在超前3个月时达到0.7。在La Ni a次年的负IOD中,波浪经向输运异常的相位(超前三个月)与赤道SST异常相位呈全年反相位,经向浪致输运异常造成的东—西热量输运差异对赤道SST异常分布有不可忽略的贡献。

The wave-induced mass/heat transport could have large scale influence on the ocean.Combined with previous theories on the wave-induced large scale effect and the existence of swells in mid-high latitudes of the Indian Ocean,monthly averaged ocean data including wave parameters,sea surface temperature(SST)and sea surface wind(SSW)are used to investigate the relationship between the wave-induced transport and tropical SST in the Indian Ocean.The results indicate that the spatial and periodic characteristics of low-frequency wave-induced transport anomalies are highly similar to those of the equatorial SST anomalies(SSTA).Both the zonal and meridional anomalies of Stokes drift show strong N—S/E—W oscillation and their second-mode variabilities are significantly correlated with the Indian Ocean Dipole(IOD)index,particularly in negative IOD events occurred following the La Ni a.The correlation of zonal anomaly in the Antarctic Circumpolar Current(ACC)region reaches 0.6 when it leads by 6 months,and that of meridional anomaly at mid latitudes(30°~40°S)is close to 0.7 when leads by 3 months.In the negative IOD events following La Ni a,the phases of the meridional anomalous transport(3 months lead time)and the equatorial SST are opposite throughout the year.The E—W meridional thermal flux difference caused by the wave transport has a non-negligible contribution to the SSTA variation.