The Southern Hemisphere Antarctic stratosphere experienced two noteworthy events in 2015: a significant injection of sulfur from the Calbuco volcanic eruption in Chile in April and a record‐large Antarctic ozone hole in October and November. Here we quantify Calbuco's influence on stratospheric ozone depletion in austral spring 2015 using observations and an Earth system model. We analyze ozonesondes, as well as data from the Microwave Limb Sounder. We employ the Community Earth System Model, version 1, with the Whole Atmosphere Community Climate Model (WACCM) in a specified dynamics setup, which includes calculations of volcanic effects. The Cloud‐Aerosol Lidar with Orthogonal Polarization data indicate enhanced volcanic liquid sulfate 532 nm backscatter values as far poleward as 68°S during October and November (in broad agreement with WACCM). Comparison of the location of the enhanced aerosols to ozone data supports the view that aerosols played a major role in increasing the ozone hole size, especially at pressure levels between 150 and 100 hPa. Ozonesonde vertical ozone profiles from the sites of Syowa, South Pole, and Neumayer display the lowest individual October or November measurements at 150 hPa since the 1991 Mount Pinatubo eruption period, with Davis showing similarly low values, but no available 1990 data. The analysis suggests that under the cold conditions ideal for ozone depletion, stratospheric volcanic aerosol particles from the moderate‐magnitude eruption of Calbuco in 2015 greatly enhanced austral ozone depletion, particularly at 55–68°S, where liquid binary sulfate aerosols have a large influence on ozone concentrations.

The winter response of the Asian jet stream to global warming is investigated using the Coupled Model Intercomparison Project Phase 5 (CMIP5) multi-model dataset under the RCP4.5 scenario. We first evaluate model performances in reproducing the current climatology in the upper troposphere and select the best 27 models. A multi-model ensemble projection by the selected models indicates that the jet stream over the Indochina peninsula and the South China Sea is intensified on its equatorial side in the late 21st century, while the jet stream shifts poleward over the Eurasian continent and the North Pacific. The strengthening of the jet stream on the south side is associated with cyclonic (anticyclonic) circulation anomalies in the upper (lower) troposphere over the southern part of China and decreased upper tropospheric divergence over the Maritime Continent. The strength of the upper tropospheric divergence and the amplitude of the anticylonic eddy streamfunction are strongly correlated. These findings suggest that future changes in the jet stream are related to the weakening of a Matsuno-Gill response to tropical heating.(Citation: Harada, M., S. Hirahara, S. Hagiya, H. Murai, Y. Oikawa, and S. Maeda, 2013: Intensification of the south side of the Asian jet stream during the northern winter in CMIP5 models. SOLA, 9, 94−97,