In the present analysis of tropospheric ozone data, attention is given to spatial and temporal variations. Two modes of seasonal behavior are noted for surface ozone at mid-latitudes: a broad summer maximum within a few hundred km of industrial/urban areas in Europe and the U.S., and a minimum in summer or autumn in sparcely populated regions that are remote from industrial activity. These and limited historical data indicate that summertime concentrations of ozone near the surface in the rural areas of Europe and the U.S. may have increased between 20 and 100 percent since the 1940s. It is suggested that the summer maximum in ozone and other observed trends are due to photochemical production associated with anthropogenic emissions of NO(x), hydrocarbons, and CO from fossil fuel combustion.

Tropospheric ozone: Seasonal behavior, trends, and anthropogenic influence

I present an analysis of ozonesonde data, synthesizing what is known about the distribution of tropospheric ozone Major features of the distribution are highlighted, and recommendations are given for testing three-dimensional models of tropospheric chemistry and transport with these data The data are analyzed on pressure surfaces and relative to the height of the thermal tropopause A minimum of 20 soundings are required for 95% confidence intervals of the ozone monthly means to be less than ±30% near the extratropical tropopause Twenty soundings also ensures means reliable to better than ±15% for 800–500 hPa for the extratropics and for 800–100 hPa in the tropics Ozone variability is higher in the upper troposphere for subtropical locations than for tropical locations, and 35 soundings are required for 400–100 hPa for the means to be defined to better than ±15% For northern middle and high latitudes, the broad summer maximum in ozone in the middle troposphere extends all the way up to the tropopause Median concentrations at the tropopause are highest in June and July, typically 125–200 ppb, and are a factor of 2 smaller in winter Highest values of ozone are in spring 2 km above the tropopause The change in the phase of the annual cycle of ozone between the tropopause and the region immediately above it, and the steep concentration gradients across the tropopause, suggest that high vertical resolution (∼1 km) will be required in models to simulate this behavior Mean ozone values in the middle troposphere are approximately constant from 30° to 75° in the winter in both hemispheres, while there is a maximum from 35° to 50°N in summer In the northern subtropics, there is a summer minimum in middle tropospheric ozone over the Pacific and a summer maximum over the Atlantic which appear to be related to differences in circulation Mean ozone values over Samoa are similar to those measured 20–30 years ago over Panama Ozone is higher over the tropical South Atlantic (Natal) than over the western Pacific (Samoa) all year from about 800 hPa to the tropopause; ozone is most similar in May and June over the Atlantic and Pacific, the months with minimum burning in the tropics The ozone maximum at Samoa in the middle and upper troposphere in October is caused by long-range transport of ozone and its precursors from biomass burning, with the peak lagging that at Natal by about a month The secondary peak in ozone in January and December at South Atlantic sites reflects transport of biomass burning effluents from the Northern Hemisphere The sonde data were used in combination with surface and satellite data to derive a gridded climatology for tropospheric ozone

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/1998JD100096

An analysis of ozonesonde data for the troposphere : recommendations for testing 3-D models and development of a gridded climatology for tropospheric ozone

Long-term changes in tropospheric ozone

Ozone plays a very important role in our atmosphere because it protects any living organisms at the Earth's surface against the harmful solar UVB and UVC radiation. In the stratosphere, ozone plays a critical role in the energy budget because it absorbs both solar UV and terrestrial IR radiation. Further, ozone in the tropopause acts as a strong greenhouse gas, and increasing ozone trends at these altitudes contribute to climate change. This review contains a short description of the various techniques that provided atmospheric ozone measurements valuable for long-term trend analysis. The anthropogenic emissions of substances that deplete ozone (chlorine- and bromine-containing volatile gases) have increased from the 1950s until the second half of the 1980s. The most severe consequence of the anthropogenic release of ozone-depleting substances is the “Antarctic ozone hole.” Long-term observations indicate that stratospheric ozone depletion in the southern winter-spring season over Antarctica started in the late 1970s, leading to a strong decrease in October total ozone means. Present values are only approximately half of those observed prior to 1970. In the Arctic, large ozone depletion was observed in winter and spring in some recent years. Satellite and ground-based measurements show no significant trends in the tropics but significant long-term decreasing trends in the northern and southern midlatitudes (of the order of 2–4% per decade in the period from 1970 to 1996 and an acceleration in trends in the 1980s). Ozone at northern midlatitudes decreased by −7.4±2% per decade at 40 km above mean sea level, while ozone loss was small at 30 km. Large trends were found in the lower stratosphere, −5.1±1.8% at 20 km and −7.3±4.6% at 15 km, where the bulk of the ozone resides. The possibility of a reduction in the observed trends has been discussed recently, but it is very hard to distinguish this from the natural variability. As a consequence of the Montreal Protocol process, the emissions of ozone-depleting substances have decreased since the late 1980s. Chlorine is no longer increasing in the stratosphere, although the total bromine amount is still increasing. Considering anthropogenic emissions of substances that deplete ozone, the turnaround in stratospheric ozone trends is expected to take place in the coming years. However, anthropogenic climate change could have a large influence on the future evolution of the Earth's ozone shield.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/1999RG000059

Ozone trends: A review

[1] Since 1996, quality assurance experiments of electrochemical concentration cell (ECC) ozonesondes of two different model types (SPC-6A and ENSCI-Z) have been conducted in the environmental simulation facility at the Research Centre Juelich within the framework of the Juelich Ozone Sonde Intercomparison Experiment (JOSIE). The experiments have shown that the performance characteristics of the two ECC-sonde types can be significantly different, even when operated under the same conditions. Particularly above 20 km the ENSCI-Z sonde tends to measure 5–10% more ozone than the SPC-6A sonde. Below 20 km the differences are 5% or less, but appear to show some differences with year of manufacture. There is a significant difference in the ozone readings when sondes of the same type are operated with different cathode sensing solutions. Testing the most commonly used sensing solutions showed that for each ECC-manufacturer type the use of 1.0% KI and full buffer gives 5% larger ozone values compared with the use of 0.5% KI and half buffer, and as much as 10% larger values compared with 2.0% KI and no buffer. For ozone sounding stations performing long term measurements this means that changing the sensing solution type or ECC-sonde type can easily introduce a change of ±5% or more in their records, affecting determination of ozone trends. Standardization of operating procedures for ECC-sondes yields a precision better than ±(3–5)% and an accuracy of about ±(5–10)% up to 30 km altitude.

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2006JD007308

Assessment of the performance of ECC‐ozonesondes under quasi‐flight conditions in the environmental simulation chamber: Insights from the Juelich Ozone Sonde Intercomparison Experiment (JOSIE)

An ozone sonde capable of measuring and transmitting the local ozone concentration has been developed for the I. G. Y. and is described in some detail. A continuous electrochemical detector measures the ozone concentration, providing a d. c. electric current of 0 to 5 μ A according to the amount of ozone in the air passed through it. This output current is telemetered by a current-controlled variable inductance which is interchangeable with a standard inductance coil in a Kew radiosonde. The element is of low cost, weighs about 600 g and requires very limited auxiliary equipment for its use. Sixty-five successful ascents have been made and the results of the European ascents are given.

J. R. Milford

Papers

The Oxford-Kew Ozone Sonde