Observational evidence for asymmetric changes in tropospheric heights over Antarctica on decadal time scales

We use monthly values of geopotential height (GPH) from seven Antarctic stations to examine decadal variations and trends in the overlying troposphere. Whereas the stratospheric signal in our analyses associated with springtime ozone depletion is very detectable, documenting changes in the troposphere is complicated by strong decadal variability and geographical asymmetry. On the Indian-Ocean coast of Antarctica, negative trends in 500-hPa GPH prevail from December through May but lower GPH following extreme depletion episodes is only found from December through February. In contrast, the South Pole, McMurdo, and Halley Stations show positive trends for most months and heights with no depletion signal evident in GPH at the South Pole and Halley Stations except at and above 100 hPa. These observed seasonal and geographical asymmetries suggest that the internal dynamical response in the troposphere over Antarctica to climate change and ozone depletion is more complex than is captured in current models.