The Study Of Ocean Warming Trend In Southern Hemisphere During Hiatus

Global warming hiatus is an import scientific topic in climate change in recent years.Studies have shown that heat sinking into deep ocean is the main reason for this warming hiatus.Ocean has high specific heat and huge capacity,which is an important heat reservoir and plays an important role in climate change.In this paper,in order to estimate the warming trend of ocean,the GRACE gravity satellite and altimeter are combined to calculate the thermal expansion component of sea level change(called Net SLA here).Net SLA can reflect the trend of the whole layer's ocean heat content well.It has high positive correlation with the 1500 m ocean heat content,with the most areas at 0.6-0.95.The result shows that the ocean warming trend of the Southern Hemisphere is 2.7 times of the Northern Hemisphere during the hiatus period.The main warming oceans are South Pacific(4.52mm/yr),Indian Ocean(5.04mm/yr)and west Antarctic seas(3.06mm/yr).Further studies indicate that these accelerated warming in the Southern Hemisphere Ocean may relate to the enhancement of the Southern Annular Mode(SAM).The SAM can control the zonal wind above the Southern Hemisphere Ocean.The analysis shows that low latitudes and middle latitudes have east wind anomalies,and high latitudes have west wind anomalies.The anomalies of the zonal winds can strengthen the curl of wind stress which can modulate the subtropical ocean circulation,the Ekman transport and the absorbed heat flux.In addition,the rapid warming areas have high correlation coefficients with SAM index(about 0.7)which indicates the effect of the SAM in ocean warming and further stresses the importance of the SAM in climate change.