Interannual Adjustment And Mechanism Of Sea Mesoscale Eddy In The Subtropical Southeast Indian Ocean

This article use SODA and AVISO to study the energy source and the interannual change of eddy activity on basis of former study. The results as follow:EKE in subtropical ocean usually get energetic in the interior ocean and in the ocean western boundary, but there is an exception in SEIO. There is a high EKE distribution near the northwest coast of Australia. The EKE get stronger in the middle and east part of South Indian Ocean. This is very different from the rule that EKE get stronger in the western boundary. So what makes the EKE distribution in SEIO like this will be investigated.With more and more investigation, there is an abnormal current–Leeuwin Current (LC). LC is so different from the eastern boundary current in south semi‐sphere. LC flow from low latitude to high latitude and LC is one of the reason that why SEIO has high EKE in the western boundary. LC is driven by large scale meridianal gradient pressure. Warm water in western Pacific through Indonesian archipelago into SEIO and one of the branch is LC. Because LC flow from low latitude to high latitude, the physical and chemical character is different from the sea water around it. So LC make a great affect in SEIO. As we know the western pacific have obviously interannual change, so LC may have interannual change. When thermocline in western Pacific changed, it will transfer to SEIO through Indonesian archipelago. When LC gets into SEIO, it will change the heat flux and momentum flux on the west coast of Australia. LC area is one of the eddy kinetic source of SEIO, so it will profoundly affect SEIO.Eddy kinetic energy has two source in the interior SEIO. One is the instability of South Indian Counter Current (SICC) and South Equator Current (SEC) of SEIO. This instability have two form: baroclinic conversion rate (BCR) and barotropic conversion rate(BTR). Calculated with SODA in the upper200m, both of BCR and BTR can provide eddy kinetic energy for eddy activity in SEIO. But BCR is important than BTR. The other eddy kinetic energy source is zonal eddy energy flux from LC region. High zonal eddy energy flux between20°S‐30°S is the area where has high EKE distribution. The zonal eddy energy flux from LC region help maintain the high EKE distribution in interior SEIO. So the zonal eddy energy flux from LC region is one of the important source of eddy activity in SEIO.