Future Arctic ozone recovery: the importance of chemistry and dynamics
Future Arctic ozone recovery: the importance of chemistry and dynamics
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DOI：
10.5194/acp-16-12159-2016
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发表时间：
2016-09-28
影响因子：
6.3
通讯作者：
Pyle, John A.
中科院分区：
文献类型：
--
作者：
Bednarz, Ewa M.;Maycock, Amanda C.;Pyle, John A.
利用英国气象局统一模式（UM-UKCA）模拟1960-2100年期间的7个成员组合，评估了北极春季总臭氧柱的未来趋势及其化学和动力驱动因素。整个21世纪，北极平均3月总臭氧层以类似于11.5 DU 10年（-1）的速度增加，预计到2030年代末将恢复到1980年的水平。然而，这些综合数据表明，即使在2060年以后，北极春季臭氧也会偶发地减少50-100 DU，低于该时期相应的长期综合平均值，达到接近当今平均水平的特征值。与本世纪全球无机氯（Cl-y）减少的趋势一致，2001-2020年和2061-2080年期间，北极春季低层大气中估计的平均卤素引起的化学臭氧损失减少了约2倍。然而，在寒冷而强烈的极地涡旋存在的情况下，在本世纪下半叶的模拟中，卤素引起的臭氧损失将继续高于相应的长期平均值。整体显示北极冬季平流层中高层有明显的降温趋势，但对平流层低层（100-50 hPa）的预估温度趋势可信度较低。这在一定程度上是由于冬季北极极地帽上的下流增加，这增加了臭氧进入极地地区的运输，并推动了绝热变暖，部分抵消了辐射驱动的平流层冷却。然而，个别赢家的特征是明显抑制下流，减少输运和异常低温在未来继续发生。我们的结论是，尽管预计北极臭氧将长期恢复，但预计未来将继续存在较大的年际动态变率，从而促进春季臭氧柱的间歇性减少。虽然我们的研究结果表明，未来确定北极春季臭氧的动力过程的相对作用将增加，但卤素化学在未来几十年仍将是一个较小但不可忽略的贡献。
Future trends in Arctic springtime total column ozone, and its chemical and dynamical drivers, are assessed using a seven-member ensemble from the Met Office Unified Model with United Kingdom Chemistry and Aerosols (UM-UKCA) simulating the period 1960-2100. The Arctic mean March total column ozone increases throughout the 21st century at a rate of similar to 11.5 DU decade(-1), and is projected to return to the 1980 level in the late 2030s. However, the integrations show that even past 2060 springtime Arctic ozone can episodically drop by similar to 50-100 DU below the corresponding long-term ensemble mean for that period, reaching values characteristic of the near-present-day average level. Consistent with the global decline in inorganic chlorine (Cl-y) over the century, the estimated mean halogen-induced chemical ozone loss in the Arctic lower atmosphere in spring decreases by around a factor of 2 between the periods 2001-2020 and 2061-2080. However, in the presence of a cold and strong polar vortex, elevated halogen-induced ozone losses well above the corresponding long-term mean continue to occur in the simulations into the second part of the century. The ensemble shows a significant cooling trend in the Arctic winter mid-and upper stratosphere, but there is less confidence in the projected temperature trends in the lower stratosphere (100-50 hPa). This is partly due to an increase in downwelling over the Arctic polar cap in winter, which increases transport of ozone into the polar region as well as drives adiabatic warming that partly offsets the radiatively driven stratospheric cooling. However, individual win-ters characterised by significantly suppressed downwelling, reduced transport and anomalously low temperatures continue to occur in the future. We conclude that, despite the projected long-term recovery of Arctic ozone, the large interannual dynamical variability is expected to continue in the future, thereby facilitating episodic reductions in springtime ozone columns. Whilst our results suggest that the relative role of dynamical processes for determining Arctic springtime ozone will increase in the future, halogen chemistry will remain a smaller but non-negligible contributor for many decades to come.