The ozone hole that opens every year over the Antarctic is on course to be the smallest in three decades, scientists have said.
科學家稱，南極上空每年出現的臭氧空洞將是30年來最小的。
Researchers say the hole is also a particularly unusual shape this year, being heavily skewed towards South America instead of centring on the South Pole.
研究人員說，今年臭氧空洞的形狀也特別不尋常，嚴重向南美洲傾斜，而不是以南極為中心。
The rare shape – never before observed – indicates a significant distortion to the usual polar vortex, which maintains low temperatures in the stratosphere.
這一罕見的異常形狀表明，常見的極地漩渦發生巨大的扭曲。極渦維持著平流層的低溫。
The hole is currently well under half the area that usually opens up by mid-September, and may have already reached its maximum size, a little smaller in area than the Antarctic continent.
目前，臭氧空洞的面積小於通常情況下9月中旬面積的一半，而且可能已經達到最大尺寸，比南極大陸的面積還要小一點。
Ozone is a gas formed in the upper atmosphere when electrical charges in the atmosphere combine with ultraviolet (UV) rays from the sun. The ozone layer absorbs the majority of the sun’s harmful UV radiation.
臭氧是大氣中的電荷與來自太陽的紫外線結合時在上層大氣中形成的一種氣體。臭氧層吸收了太陽大部分有害的紫外線輻射。
The hole disappears and reforms every year over the Antarctic due to the unique weather patterns that create incredibly cold circling winds above the pole.
由於獨特的天氣模式，南極上空形成了令人難以置信的寒冷迴旋風，臭氧空洞每年消失又復現。
According to the British Antarctic Survey, the hole had reached an area of 11 million square kilometres in early September, when the annual 「spring warming」 event kicked in much earlier than usual.
根據英國南極調查局的數據，9月初春季暖流比往年提早到來，臭氧空洞達到1100萬平方公裡。
In 2018, the hole reached a maximum area of 22.9 million square kilometres.
2018年，臭氧空洞的最大面積達到2290萬平方公裡。
In 2002, the polar vortex split in two, creating two separate ozone holes over the continent.
2002年，極地渦旋分裂成兩個，在南極大陸上空形成兩個獨立的臭氧空洞。
Anna Jones a scientist at the British Antarctic Survey told?The Independent?the shape of the hole this year was 「very unusual」.
英國南極調查局的科學家安娜·瓊斯告訴《獨立報》說，今年臭氧空洞的形狀很不尋常。
She said: 「Very occasionally in the Antarctic you will get disturbances. And I don’t think anybody knows what’s triggered it this year. This is a pretty new phenomenon. It could be a multiple collection of factors.」
她說：「在南極，很少會受到幹擾。我想沒有人知道是什麼引發了這種改變。這是一種全新的現象，可能是多種因素造成的。」
Satellite records for the polar vortex in Antarctica go back to the late 1970s, but the 2002 split vortex is the only other major change.
南極極地渦旋的衛星記錄可以追溯到20世紀70年代末，但2002年的分裂渦旋是此前唯一一次重大變化。
「Scientists haven’t quite figured it out yet … there are various things they can look at, but it’s certainly very unusual,」 Dr Jones said.
瓊斯博士說：「科學家們還沒有完全弄清楚，他們要考慮的有各種因素，但這確實很不尋常。」
Explaining how the polar vortex normally works, she said: "Over Antarctica you have a very strong westerly wind system which sets up over the winter. You get very cold temperatures over the Antarctic continent and the winds are very fast, which holds it in place."
在解釋極地渦旋通常是如何運轉時，她說：「在南極洲上空有一個非常強的西風系統，在冬季形成。南極大陸非常寒冷，風速也非常快，讓極地渦旋無法移動。」
"The winds are driven by the temperature difference between equatorial temperatures and polar temperatures. This is what you expect over the Antarctic."
「風是由赤道和極地之間的溫差驅動的。這是你在南極洲看到的景象。」
"In Antarctica you have a continent surrounded by a flat ocean. You don’t have a lot of stuff at ground level, so the air can flow around without anything getting in its way."
「南極洲大陸被平坦的海洋所包圍。在地平面上沒什麼東西，因此空氣可以在不受任何阻礙的情況下流動。」
"In the Arctic, it’s the opposite. You have an ocean surrounded by landmasses with mountains. So you don’t get the strength of the vortex you get in the Antarctic. "
「而在北極，情況恰恰相反。北冰洋被矗立著高山的陸地所包圍，因此不會有在南極的那種極地渦旋的強度。」
Dr Jones said the key to reducing the size of the ozone hole in the long term was continuing to clampdown on the illegal man-made chemicals causing the destruction. She also warned people living in South America could now be at risk from dangerous UV radiation as the ozone has thinned.
瓊斯博士說，長期來看，減小臭氧空洞的關鍵仍是打擊破壞臭氧層的非法人造化學品。她還警告說，隨著臭氧層變薄，居住在南美的人們現在可能面臨危險的紫外線輻射。
"The key thing is that the gases that destroy ozone are still around, still in the atmosphere," she said.
她說：「關鍵是，破壞臭氧層的氣體仍然存在於大氣中。」
But a warming planet due to climate change is also bad news for the ozone layer. Higher atmospheric temperatures could also degrade the conditions required to restore the ozone layer.
但是，氣候變化導致的全球變暖對臭氧層也不利。更高的大氣溫度也會降低恢復臭氧層所需的條件。
「If we warm the lower levels of the atmosphere, we actually cool the stratosphere,」 Dr Jones said. 「This could extend the lifetime of the ozone hole.」
瓊斯博士說：「如果我們使低層大氣變暖，實際上就會使平流層變冷。這可能會延長臭氧空洞的壽命。」
She added: 「This is an unusual feature resulting from unusual dynamics, but the chemistry which destroys ozone is still there.
她補充說：「這是由於不尋常的動力學而產生的一種不尋常的特徵，但是破壞臭氧的化學物質仍然存在。」
「I doubt we will see this again next year. We can’t be complacent, it absolutely doesn’t mean the ozone hole is never going to be seen again.」
「我懷疑明年我們還會看到這種情況。我們不能自滿，這絕不意味著臭氧空洞永遠消失。」