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.
--Boot Hill
cogitator: "...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."
To my knowledge, it has never been shown that CFC's themselves destroy ozone, rather it is the chlorine atoms, that allegedly originated from CFC's, that have been shown to be one mechanism of O3 breakdown. The problem with ascribing this breakdown to CFC's is that natural sources of chlorine outweigh those from CFC's by many orders of magnitude.
I knew and spoke often with the manager of the U-2 environmental recon program run by NASA out of Moffett NAS here in Silicon Valley. His squadron was the one that did the high altitude sampling out of Norway over the north pole. When he returned from that mission, I asked him if they sampled CFC's in the upper stratosphere. He said yes, they had. I asked him again, are you sure you mean CFC's or do you mean chlorine that you attributed to CFC's. He corrected himself and said that it was actually only the chlorine they were detecting, but that he was sure that it had to have come from CFC's!
cogitator: "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."
First, the Halley data doesn't extend back far enough in time to state that there was no ozone thinning prior to 1965. Second, one of the greatest mistakes of scientific experimentation, is to ignore data that doesn't fit with expected results. That Dobson's data is at variance with the Halley Bay data, merely underscores the depth of our own ignorance of the part ozone plays in atmospheric chemistry. To me, the difference in the data sets simply implies that a natural variation in polar ozone levels exists and requires further study to find out how much a variation, what is its period and what causes the periodicity.
The discovery of periodic ozone depletion is not unlike Galileo's discovery of sun spots. Prior to that discovery, the sun was believed to be perfect and unblemished product of God's handiwork. Can you imagine the panic when these blemishes were discovered. And even worse, the finding that year by year, the number, size and frequency of those sun spots continued to increase? OMG, the sun's going to be entirely covered with them if this keeps up!
That is precisely where we are today with the discovery and controversy surrounding the periodic changes in ozone levels. The problem though, has been compounded and the science essentially stopped in its tracks, by this nonsense that the thinning is caused by CFC's.
cogitator: "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."
The quote from your post #78 referred to "a dramatic loss of ozone" that occurred just during the 1970's and that decline was far less than the "factor of 3" you mention. Not only was the 1970's decline, that was described as being a "dramatic loss", only a 75 DU decline, but it was even less than the 0.1cm (100 DU) variability that Dobson observed in the 1920's. So by that standard, the variability observed by Dobson was not only "large", but indeed, it was "a dramatic loss" of ozone way back in 1929!
cogitator: "I wouldn't be surprised if such periodicity could be shown, but there isn't any data to indicate that it has happened."
The only way that you can assert that there isn't any data to support a natural variability, is to ignore Dobson's data from the 1920's. Absent any concrete evidence that his data was flawed, it is dangerous and highly speculative to ignore it simply because it doesn't support someone's expectations.
cogitator: "I find it doubtful that Dobson observed larger variability than exists in the ozone hole today."
Nor is it necessary to assert that it was larger then. It is sufficient for the moment to simply state that the scientific record (Dobson) contains reliable and unrefuted data that shows a large natural seasonal variation (0.1 cm or 100 DU) in atmospheric ozone does occur and that it was first detected prior to the introduction of CFC's.
As a parting note, have you noticed in the TOMS photos, that while there is a seasonal thinning over the South pole, there is a commensurate increase in ozone levels in areas immediately adjacent to the Antarctic? (examples here) In other words we may be witnessing an ozone transport event, rather than a genuine thinning.
Please forgive the length.
--Boot Hill