Impact of Increasing Stratospheric Water Vapor on Ozone Depletion and Temperature Change

Using a detailed, fully coupled chemistry climate model （CCM）, the effect of increasing stratospheric H20 on ozone and temperature is investigated. Different CCM time-slice runs have been performed to investigate the chemical and radiative impacts of an assumed 2 ppmv increase in H20. The chemical effects of this H20 increase lead to an overall decrease of the total column ozone （TCO） by ～1% in the tropics and by a maximum of 12% at southern high latitudes. At northern high latitudes, the TCO is increased by only up to 5% due to stronger transport in the Arctic. A 2-ppmv H2O increase in the model＇s radiation scheme causes a cooling of the tropical stratosphere of no more than 2 K, but a cooling of more than 4 K at high latitudes. Consequently, the TCO is increased by about 2%-6%. Increasing stratospheric H2O, therefore, cools the stratosphere both directly and indirectly, except in the polar regions where the temperature responds differently due to feedbacks between ozone and H2O changes. The combined chemical and radiative effects of increasing H2O may give rise to more cooling in the tropics and middle latitudes but less cooling in the polar stratosphere. The combined effects of H2O increases on ozone tend to offset each other, except in the Arctic stratosphere where both the radiative and chemical impacts give rise to increased ozone. The chemical and radiative effects of increasing H2O cause dynamical responses in the stratosphere with an evident hemispheric asymmetry. In terms of ozone recovery, increasing the stratospheric H2O is likely to accelerate the recovery in the northern high latitudes and delay it in the southern high latitudes. The modeled ozone recovery is more significant between 2000 ～2050 than between 2050～2100, driven mainly by the larger relative change in chlorine in the earlier period.

北极海冰对平流层臭氧损耗的响应

在过去40年里,北极地区经历了几次平流层臭氧极端损耗事件,但北极平流层臭氧极端损耗对气候系统的影响仍然不十分清楚.本文发现北极平流层臭氧的极端损耗与春、夏季喀拉海、拉普捷夫海和东西伯利亚海的海冰密集度及海冰厚度的减少存在联系.这是由于平流层臭氧减少造成极地涡旋强度增强且持续时间延长,使得更多的海冰从巴伦支海-喀拉海和东西伯利亚海漂移到弗拉姆海峡,最终移出北极.此外,云层长波辐射和地表反照率辐射反馈增强了北极海冰的融化,特别是沿欧亚大陆海岸的海冰融化.本研究表明,准确预测北极海冰变化需要考虑平流层-对流层的相互作用对海冰的影响.