The Antarctica’s ozone hole has now reached its maximum size, according to an analysis of data collected by ESA’s Copernicus Sentinel-5P satellite.
Each year for the past few decades during the southern hemisphere spring, chemical reactions involving chlorine and bromine cause ozone in the southern polar region to be destroyed rapidly and severely. This depleted region is known as the ozone hole.
The size of the ozone hole fluctuates on a regular basis. From August to October, it increases in size, reaching a maximum between mid-September and mid-October.
When temperatures high up in the stratosphere start to rise, the ozone depletion slows, the polar vortex weakens and finally breaks down, and by the end of December ozone levels return to normal.
New measurements from Copernicus Sentinel-5P show that this year’s ozone hole reached its maximum size of around 25 million km2 on October 2, comparable to the sizes of 2018 and 2015.
Last year, the ozone hole not only closed earlier than usual, but was also the smallest hole recorded in the last 30 years.
The variability of the size of the ozone hole is largely determined by the strength of a strong wind band that flows around the Antarctic area.
This strong wind band is a direct consequence of Earth’s rotation and the strong temperature differences between polar and moderate latitudes.
If the band of wind is strong, it acts like a barrier: air masses between polar and temperate latitudes can no longer be exchanged.
The air masses then remain isolated over the polar latitudes and cool down during the winter.
“Our observations show that the 2020 ozone hole has grown rapidly since mid-August, and covers most of the Antarctic continent — with its size well above average,” said Dr. Diego Loyola, a researcher at the German Aerospace Center.
“What is also interesting to see is that the 2020 ozone hole is also one of the deepest and shows record-low ozone values.”
“The total ozone column measurements from the Tropomi instrument on Sentinel-5P reached close to 100 Dobson Units on October 2.”
“The Sentinel-5P total ozone columns provide an accurate means to monitor ozone hole occurrences from space,” added Copernicus Sentinel-5P mission manager Dr. Claus Zehner, of ESA.
“Ozone hole phenomena cannot be used in straightforward manner for monitoring global ozone changes as they are determined by the strength of regional strong wind fields that flow around polar areas.”
This article is based on text provided by the European Space Agency.