West Antarctica, and in particular the Antarctic Peninsula, are regions that have experienced dramatic warming and sea ice loss in the past 50 years. A suspected mechanism, when only the atmosphere is considered, is the variability of the Amundsen – Bellingshausen Seas Low (ABSL), a semi-permanent area of low pressure off the coast of West Antarctica in the vicinity of the Amundsen and Bellingshausen Seas. Here, analysis is conducted to better interpret results from earlier work and more precisely determine the role that stratospheric ozone depletion and increases in carbon dioxide have on the intensity and position of the ABSL. The analysis is based on multiple chemistry-climate model (CCM) simulations and three global atmospheric reanalysis datasets where differences in geopotential heights at three different pressure levels: 850 hPa, 500 hPa, and 100 hPa are examined.
Results from these comparisons indicate that ozone depletion causes significantly lower heights in the ABSL region in the troposphere and particularly in the stratosphere during austral summer (December-February). Ozone depletion also causes lower 500 hPa heights within the vicinity of the ABSL during austral autumn (March-May) but this is only significant for two of the models. It was also found that while the presence of CO2-induced climate change may result in slightly higher heights in the ABSL region in the troposphere, these differences are not statistically significant. It is therefore concluded that ozone depletion causes a stronger ABSL during summer and at 100 hPa during autumn, but its autumn influence is questionable in the troposphere; CO2-induced climate change has very little discernible influence in this region. It is anticipated that as ozone levels recover during the next half-century, the ABSL will most likely weaken during summer.