The Effects of Ozone Change on Southern Ocean MOC, Heat Uptake and Storage

Ozone depletion above Antarctica plays a vital role in Southern Ocean (SO) climate change. It alters atmospheric winds and thereby SO meridional overturning circulation (MOC). Along with the change in SO MOC, ozone depletion is expected to redistribute the heat in the SO and reorganize the patterns of SO heat uptake and storage. Here, we use Community Earth System Model (CESM) historical simulations and accompanying fixed ozone experiments to quantify the ozone effects on SO heat uptake and storage. We find that ozone depletion strengthens both ocean heat uptake (peaking at 56°S) and northward heat transport (peaking at 50°S), which leads to the increase of ocean heat storage in almost all the SO (peaking at 43°S). The increase of ocean heat storage corresponds to an increase of water temperature from surface to a depth of 1000m. The effects of ozone depletion also show seasonal features. During austral summer, ocean heat storage is positive from 40°S to 70°S with peak appearing at around 47°S. However, during austral winter ocean heat storage is negative from 40°S to 70°S. This seasonal difference results from opposite changes in ocean heat uptake and northward heat transport during summer and winter.