THIS POST IS A CRITICAL REVIEW OF A NASA REPORT IN NOVEMBER 2020 THAT A “LARGE DEEP OZONE HOLE” HAD OPENED UP IN THE SOUTH POLE AND THE FURTHER DISCUSSION OF ITS ORIGINS AND IMPLICATIONS IN TERMS OF THE ROWLAND MOLINA THEORY OF OZONE DEPLETION.

PART-1: WHAT THE NASA REPORT SAYS

Large, Deep Antarctic Ozone Hole in 2020, September 20, 2020

Persistent cold temperatures and strong circumpolar winds supported the formation of a large and deep Antarctic ozone hole in 2020, and it is likely to persist into November: On September 20, 2020, the annual ozone hole reached its peak area at 24.8 million square kilometers with a near-complete elimination of ozone for several weeks in a column 6-kilometer high column of the stratosphere near the geographic South Pole. The map above shows the size and shape of the ozone hole over the South Pole on September 20, the day of its maximum as calculated by the NASA Ozone Watch team. NASA and NOAA monitor the ozone hole via complementary instrumental methods. NASA’s Aura satellite, the NASA-NOAA Suomi NPP satellite, and NOAA’s JPSS NOAA-20 satellite all measure ozone from space. Aura’s Microwave Limb Sounder also estimates levels of ozone-destroying chlorine. This year brought the 12th-largest ozone hole (by area) in 40 years of satellite records, with the 14th-lowest ozone readings in 33 years of balloon-borne instrumental measurements. However, scientists noted that ongoing declines in the atmospheric concentration of ozone-depleting chemicals prevented the hole from being as large as it might have been under the same weather conditions 20 years ago. We have a long way to go, but that improvement made a big difference this year. The hole would have been about a million square miles larger if there was still as much chlorine in the stratosphere as there was in 2000. This year represented a dramatic turnabout from 2019, when warm temperatures in the stratosphere and a weak polar vortex hampered the formation of polar stratospheric clouds (PSCs). The particles in PSCs activate forms of chlorine and bromine compounds that destroy ozone. Last year’s ozone hole was the smallest since the early 1980s, growing to 16.4 million square kilometers (6.3 million square miles) in early September. This clear contrast between last year and this year shows how meteorology affects the size of the ozone hole. Atmospheric levels of ozone-depleting substances increased up to the year 2000. Since then, they have slowly declined but remain high enough to produce significant seasonal ozone losses. During recent years with normal weather conditions, the ozone hole has typically grown to a maximum of 20 million square kilometers. In addition to the area of the ozone hole, scientists also track the average amount of ozone depletion—how little is left inside the hole. On October 1, 2020, weather balloons launched from NOAA’s South Pole atmospheric observatory recorded a low value of 104 Dobson units of atmospheric ozone. NASA’s Ozone Watch reported a lowest daily value at 94 Dobson Units on October 6. Prior to the emergence of the Antarctic ozone hole in the 1970s, the average amount of ozone above the South Pole in September and October ranged from 250 to 350 Dobson units. The amount of ozone between 13 to 21 kilometers (8 to 13 miles) in altitude, as measured over the South Pole, has been close to record lows at several points this year. It’s about as close to zero as we can measure. Still, the rate at which ozone declined in September was slower compared with 20 years ago, which is consistent with there being less chlorine in the atmosphere.

CRITICAL COMMENTARY

The Rowland Molina Theory of Ozone Depletion (RMTOD) implies a gradual reduction in global mean total column ozone over long time scales 40 to 100 years. Localized changes in ozone concentration at brief time scales, particularly so at the poles, have no interpretation in terms of RMTOD. This is because the distribution of ozone from the tropics (where they form) to the greater latitudes contains extreme short term variability. These localized short term ozone dynamics do not have an RMTOD interpretation. The extreme and irrational focus on the South Pole at brief time scales as a measure of long term trends in global mean total column ozone is inconsistent with RMTOD and not empirical evidence for it.

This faux practice at NASA, where such “ozone holes” are presented in the context of RMTOD, likely derives from the Farman etal 1985 paper that had presented short term South Pole ozone level variations as evidence of RMTOD and to this day that paper remains as the only empirical evidence in support of RMTOD.

In a related post we show that Farman etal 1985 contains fatal methodological and statistical flaws and that therefore it provides neither evidence of a decline in global mean total column ozone nor a validation of RMTOD.

LINK: https://tambonthongchai.com/2019/03/12/ozone1966-2015/

In other related posts on this site we show that no evidence exists for ozone depletion in the data for global mean total column ozone over long time spans, They do show the large short term variabilities in South Polar ozone levels that have been repeatedly presented as some kind of an unnatural “hole” that is human caused and that serves as evidence of RMTOD. These interpretations of the variability of South Polar ozone levels is inconsistent with the dynamics of the global distribution of ozone described in related posts.

Briefly, RMTOD is about long term trends in global mean total column ozone which forms only in the Tropics and which is distributed to the higher latitudes by the Brewer Dobson circulation and by other means. These distributions are volatile and variable. The variability increases sharply with latitude. Therefore the dynamics of ozone concentration at the most extreme possible latitude do not contain useful information about global mean total column ozone. Therefore, “ozone hole” data have no interpretation in terms of RMTOD.

Large variability in South Polar ozone levels has no RMTOD interpretation and the description of brief periods of low ozone levels there as some kind of a hole that we need to worry about has no scientific or empirical basis and no implication in terms of RMTOD.

DETAILS IN RELATED POSTS LINKED BELOW

LINK#1: https://tambonthongchai.com/2020/10/10/mario-molina-1943-2020/

LINK#2: https://tambonthongchai.com/2020/10/01/ozone-depletion-part-3/

LINK#3: https://tambonthongchai.com/2020/09/30/ozone-depletion-part-2/

LINK#4: https://tambonthongchai.com/2020/09/30/ozone-depletion-part-1/

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