Abstract

We use ground-based spectroscopic remote sensing measurements of the stratospheric trace gases O₃, HCl, ClO, BrO, HNO₃, NO₂, OClO, ClONO₂, N₂O and HF, along with radiosonde profiles of temperature to track the springtime development of the 2019 ozone hole over Arrival Heights (77.8°S, 166.7°E, AHTS), Antarctica, during, and after, the 2019 stratospheric sudden warming (SSW) event. Both measurements and model simulations show that the 2019 SSW caused an extraordinarily warm stratosphere within the polar vortex, resulting in record low ozone depletion over AHTS. We also contrast the evolution of the 2019 ozone hole to that in 2002, which also had a major springtime SSW event.

The SSW event started around 28^th August. By ∼17^th September, stratospheric temperatures inside the polar vortex over AHTS were ∼45 K higher than the climatological average. The SSW did not cause an en masse displacement of mid-latitude air over AHTS as in the 2002 SSW event. However, the increased temperatures did cause an unusually early reduction in polar stratospheric clouds, halting the denitrification early and leading to increased gas-phase HNO₃ and record high levels of NO₂ (‘renoxification’). This caused the earliest observed deactivation of chlorine, returning all active chlorine into the chlorine reservoir species, HCl and ClONO₂. The deactivation rate into HCl remained relatively unaffected by the SSW, whilst there was a dramatic increase in ClONO₂ formation. This chlorine deactivation pathway via ClONO₂ is typical of the Arctic and atypical for the Antarctic.

At AHTS, record high levels of springtime ozone were observed. The measured ozone total column did not drop below 220 DU. Record high stratospheric temperatures persisted until 7^th October over AHTS. By 22^nd October, AHTS was not beneath the polar vortex. The polar vortex break-up date on 9^th November was one of the earliest observed.

摘要

我们使用平流层痕量气体 O ₃、HCl、ClO、BrO、HNO ₃、NO ₂、OClO、ClONO ₂、N ₂ O 和 HF 的地面光谱遥感测量，以及无线电探空仪的温度分布来跟踪春季2019 年南极洲到达高度（77.8°S，166.7°E，AHTS）臭氧空洞的发展，在 2019 年平流层突然变暖 (SSW) 事件期间和之后。测量和模型模拟都表明，2019 年 SSW 在极地涡旋内造成了异常温暖的平流层，导致 AHTS 上空的臭氧消耗量创下历史新低。我们还将 2019 年臭氧空洞的演变与 2002 年的演变进行了对比，后者也发生了重大的春季 SSW 事件。

SSW 活动于8 月28^日左右开始。到9 月17^日，AHTS 上空极地涡旋内的平流层温度比气候平均值高 45 K。SSW 并没有像 2002 年的 SSW 事件那样导致AHTS 上空的中纬度空气大量转移。然而，升高的温度确实导致极地平流层云异常提前减少，提前停止反硝化作用并导致气相 HNO ₃增加和 NO ₂的高水平（“再氧化”）。这导致了最早观察到的氯失活，将所有活性氯返回到氯储库物种 HCl 和 ClONO ₂. 进入 HCl 的失活率相对不受 SSW 的影响，而 ClONO _{2 的}形成显着增加。这种通过 ClONO _{2 的}氯钝化途径在北极地区是典型的，而在南极地区则是非典型的。

在 AHTS，观察到了创纪录的春季臭氧水平。测得的臭氧总柱没有低于 220 DU。在 AHTS 上空，创纪录的高平流层温度一直持续到10 月7^日。通过22^次月，AHTS不是极涡的下方。11 月9^日的极涡破裂日期是最早观测到的日期之一。