太平洋内区经向热输送的季节变化分析

为刻画整个太平洋内区经向热输送的基本特征及其季节变化,并初步探讨变化的原因,基于Argo温盐资料,利用P矢量法反演了太平洋的绝对地转流(AGC),并结合Ekman流,分析了年平均和季节平均的经向热输送。结果显示,在13°S~13°N,经向热输送主要由Ekman经向热输送控制,季节变化显著,且南北半球变化相反,北半球1-3月有北向输送最大值,8-10月当经向热输送转为南向时,Ekman经向热输送达到最小;南北太平洋经向热输送的季节变化存在显著的不对称特征,北太平洋的明显强于南太平洋,低纬度海域的明显大于高纬度海域。分析表明,经向热输送的季节变化与纬向风应力的变化直接相关,由于未能有效包含西边界流及赤道区域,对比前人的研究结果后推测,西边界流和赤道流在维持南北太平洋经向热输送的平衡中扮演了重要角色。

Seasonal variability of meridional heat transport in interior Pacific Ocean

To depict the essential feature and seasonal variability of the meridional heat transport in the whole interior Pacific Ocean and to give the preliminary analysis of the reasons, the absolute geostrophic currents(AGC) were calculated based on the monthly gridded Argo data, using the P-vector method. On the basis of the calculated AGC and the Ekman currents using wind products, the annual mean and seasonal mean of the meridional heat transport were studied. The results show that the meridional heat transports is mainly governed by the Ekman component in the area of 13°S-13°N, where the seasonal variability of the meridional heat transport is remarkable and that the variability in the northern hemisphere is counter to that in the southern hemisphere. In the North Pacific, the northward transport reaches a maximum during January and March, and the Ekman components reach minimums during August and October while the meridional heat transport turns to southward. There exists a remarkable asymmetric characteristic of the seasonal variability of the meridional heat transport in the whole Pacific Ocean, and the heat transport is obviously stronger in the North Pacific than in the South Pacific and in the lower latitudes than in the higher latitudes. The analysis indicates that the seasonal variability of the meridional heat transport is directly related to the variability of zonal windstress. After comparing with previous results, it is deduced that the meridional heat transport in the areas of the western boundary currents and the equator, which is not involved in this paper, plays an important role in maintaining heat balance in the North and South Pacific.