My citation for this fact is not currently available via the internet, as far as I'm aware, but can likely still be accessed from the stacks of major university libraries. I was fortunate enough to inherit this volume from my father and mentor.
The citation is Smithsonian Physical Tables, First Reprint of Eighth Revised Edition, volume 88, printed 1934, Table 704, Atmospheric Ozone, dated 1926 and 1929, by Dr. Gordon Dobson. The table and accompanying text shows large variations by season and latitude. The farther north (or south), the greater the seasonal variation. Doctor Dobson specifically states in the table text that "large variations occur(up to 0.1 cm)" that he ascribed to seasonal "meteorological conditions".
Since CFC's were not introduced to the public until 1930, Dr. Dobson's 1929 observations of a large seasonal variation in atmospheric ozone, that occurs in the extreme latitudes, predates that introduction.
Compare the magnitude of the effect Dr. Dobson observed in 1929 to the graph you posted in #78 and you'll see that Dopson's 0.1 cm change is a far greater change than what your source described as "a dramatic loss of ozone".
If one can measure a natural seasonal and latitudinal variation in atmospheric ozone, why then should we be surprised that there might also be a natural periodic (over decades and centuries) variation in that same ozone?
I believe that Dr. Dobson's initial appraisal that the observed effect was due to "meteorological conditions", was essentially correct, but would add that our better understanding of the high energy flux of charged particles from the sun that enter the atmosphere in the vicinity of the poles can also help explain the ozone thinning over the poles.
Keep in mind that the O3 bond is a particularly weak bond (hence its natural scarcity) and one subject to disruption from a multitude of extraneous sources, not the least of which would be from conditions originating outside our own planet, like the aforementioned high energy solar particle flux.
--Boot Hill
The citation is Smithsonian Physical Tables, First Reprint of Eighth Revised Edition, volume 88, printed 1934, Table 704, Atmospheric Ozone, dated 1926 and 1929, by Dr. Gordon Dobson. The table and accompanying text shows large variations by season and latitude. The farther north (or south), the greater the seasonal variation. Doctor Dobson specifically states in the table text that "large variations occur(up to 0.1 cm)" that he ascribed to seasonal "meteorological conditions".
I don't know what units "cm" are; obviously it's not centimeters. Because of Dobson's expertise, modern ozone measurements are in Dobson units. How does "cm" compare to Dobson units?
Since CFC's were not introduced to the public until 1930, Dr. Dobson's 1929 observations of a large seasonal variation in atmospheric ozone, that occurs in the extreme latitudes, predates that introduction.
That would be true; and it is also true that the stratospheric ice clouds that form in the Antarctic polar vortex are the catalytic surfaces that enable ozone destruction by CFCs. However, it is hard to reconcile what Dobson wrote with the Halley Bay data that doesn't show seasonal ozone depletion over Antarctica prior to about 1965. There aren't any descriptions of processes that decrease ozone dramatically just due to ice particles.
Compare the magnitude of the effect Dr. Dobson observed in 1929 to the graph you posted in #78 and you'll see that Dopson's 0.1 cm change is a far greater change than what your source described as "a dramatic loss of ozone".
Not knowing how to compare the two units, that is currently impossible. The graph posted shows an approximate decline in October ozone concentrations by a factor of 3 in the "hole". It boggles my mind that Dobson saw larger ozone variability than that.
If one can measure a natural seasonal and latitudinal variation in atmospheric ozone, why then should we be surprised that there might also be a natural periodic (over decades and centuries) variation in that same ozone?
I wouldn't be surprised if such periodicity could be shown, but there isn't any data to indicate that it has happened. On the contrary, the chemical reactions that cause the depletion of ozone in the Antarctic polar vortex, and the environment in which these reactions occur, have been described and confirmed by scientists, as shown on the Web site I provided.
This is additional information on Dobson:
"The first regular measurements of ozone began in the 1920s. Sir Gordon Dobson, who devised the ozone spectrophotometer that now bears his name, started making ozone measurements at Oxford University in England. His Dobson spectrophotometer measures the total amount of ozone from the ground to the top of the atmosphere per unit area. The resulting ozone value is referred to as a "column amount." It does this by measuring the amount of solar ultraviolet radiation absorbed by the atmosphere.
One of the first things that Dobson discovered was the variability of the amount of column ozone. He observed that it varies in a reasonably regular manner with the changing of seasons. He also observed that significant day-to-day variability are superimposed on seasonal variations. He noted that this day-to-day variability correlated with the passage of weather systems over his measurement site.
To investigate the variation of the total column ozone amount with weather systems, Dobson had several more instruments built which he distributed throughout Europe. These could then make simultaneous measurements at a number of points on a daily basis. The results showed a regular variation of the total column amount of ozone with weather systems. When a high pressure system was over the south of England, he observed low amounts of ozone. When a low pressure system moved in, he observed that the ozone amount increased. That is, Dobson noted that ozone amount is anticorrelated (i.e., moves in opposite direction) to air pressure, rising when air pressure falls, and falling when air pressure rises.
We now know considerably more about the causes of variations in stratospheric ozone. The concentration of ozone at a location is governed by a balance among ozone production, ozone loss, and ozone transport. These processes interact to determine the amount of ozone in the stratosphere and its distribution with latitude, longitude, and altitude. They contribute to the variability of ozone observed on different time scales."
"The results of the 1925 ozone measurements were of such interest that Dobson decided to make measurements at a number of locations in Europe to study the relation between ozone distribution and synoptic meteorological variables. The winter of 1925-26 was spent building five spectrographs and calibrating them at Boars Hill. Measurements were begun in mid-1926 and by the end of 1927 ozone values had been calculated from over 5000 spectra. From these the distribution of ozone relative to pressure systems and a limited indication obtained of the variation of mean ozone with latitude was obtained.
More extensive measurements of the variation with latitude were made during 1928 and 1929 by redistributing the instruments to places widely scattered over the world. Only the instruments at Oxford and Arosa in Switzerland remained at their old stations; the others were sent to Table Mountain in California, Helwan, Egypt, Kodal Kanal, India and Christchurch, New Zealand. As before, the photographic plates were returned to Oxford for development and measurement. By the end of 1929, therefore, the main feature of the variation of the ozone amount with synoptic conditions, with latitude and with season had been established."
So there is no doubt that Dobson observed seasonal and latitudinal ozone variability. However, given that the extremely low ozone values observed at Halley Bay were at first questioned (and the TOMS satellite instrument had to be recalibrated), I find it doubtful that Dobson observed larger variability than exists in the ozone hole today.
Clarification on the points raised above would be welcome.