Detecting the recovery of total column ozone

Abstract

Abstract. International agreements for the limitation of ozone-depleting substances have already resulted in decreases in concentrations of some of these chemicals in the troposphere. Full compliance and understanding of all factors contributing to ozone depletion are still uncertain; however, reasonable expectations are for a gradual recovery of the ozone layer over the next 50 years. Because of the complexity of the processes involved in ozone depletion, it is crucial to detect not just a decrease in ozone-depleting substances but also a recovery in the ozone layer. The recovery is likely to be detected in some areas sooner than others because of natural variability in ozone concentrations. On the basis of both the magnitude and autocorrelation of the noise from Nimbus 7 Total Ozone Mapping Spectrometer ozone measurements, estimates of the time required to detect a fixed trend in ozone at various locations around the world are presented. Predictions from the Goddard Space Flight Center (GSFC) two-dimensional chemical model are used to estimate the time required to detect predicted trends in different areas of the world. The analysis is based on our current understanding of ozone chemistry, full compliance with the Montreal Protocol and its amendments, and no intervening factors, such as major volcanic eruptions or enhanced stratospheric cooling. The results indicate that recovery of total column ozone is likely to be detected earliest in the Southern Hemisphere near New Zealand, southern Africa, and southern South America and that the range of time expected to detect recovery for most regions of the world is between 15 and 45 years. Should the recovery be slower than predicted by the GSFC model, owing, for instance, to the effect of greenhouse gas emissions, or should measurement sites be perturbed, even longer times would be needed for detection.

An objective determination of optimal site locations for detecting expected trends in upper-air temperature and total column ozone

“…10d overall agrees with results from an earlier study by Weatherhead et al (2000). Both studies show, for example, that the areas of high detectability are in the Southern Hemisphere around New Zealand/eastern Australia and southern South America and that locations close to the Equator require the longest time for trend detection.…”

“…Both studies show, for example, that the areas of high detectability are in the Southern Hemisphere around New Zealand/eastern Australia and southern South America and that locations close to the Equator require the longest time for trend detection. The study by Weatherhead et al (2000) also shows that the detection of expected trends in most parts of the Northern Hemisphere will take longer than in the Southern Hemisphere (their Plate 5), which is also evident in our Fig. 10 but not as pronounced.…”

“…10 but not as pronounced. It should be noted that Weatherhead et al (2000) use a similar technique to calculate the expected number of years for the ozone trend detection but a different model (Goddard Space Flight Center two-dimensional chemical model) to predict the trends and a different ozone data set (Nimbus 7 TOMS data).…”

Impact of enhanced ultraviolet-B irradiance on cotton growth, development, yield, and qualities under field conditions

“…Satellite measurements have shown expansion of stratospheric ozone losses from over the poles of our planet into temperate regions, and ground-level measurements have detected significant UV-B increases (Kerr and McElroy, 1993). Elevated UV-B levels caused by reduced stratospheric ozone are expected to continue well into the 21st century (Madronich et al, 1998;Weatherhead et al, 2000) and many observers expect to see additional evidence of increased ground-level UV-B in mid-latitudes as monitoring networks improve.…”

Total ozone trends from 1979 to 2016 derived from five merged observational datasets – the emergence into ozone recovery

“…These observations now extend to about 20 years after the global stratospheric ODS peak occurring in approximately 1996 (or 16 years after the later ODS peak in polar regions). This is near the minimum number of years of observations required to obtain statistically significant ozone trends in the absence of other competing processes contributing to long-term ozone changes (Weatherhead et al, 2000). This paper reports on updated total ozone trends by adding four more years of data (2013)(2014)(2015)(2016) compared to results presented in the last World Meteorological Organization (WMO) ozone assessment (Pawson et al, 2014).…”