Ozone annual variation

It has been known for about 50 years4 that the annual variations in ozone do not correspond to these of the solar radiation depending on the latitude and the season. The behavior of ozone is characterized by a maximum in spring and a minimum in autumn also there is more ozone at high than at low latitudes. This behavior shows that the chemical reactions in question are slow, in comparison with transport phenomena, in the lower stratosphere below 25 km. 

Petroncelli P., Fiocco G. and Mugnai A., Annual variation of the effects of diffuse radiation on the photodissociation of ozone. Pageoph., 118, 20-34 (1980). 

Figure 7. Annual variation of ozone amount at different altitudes at...

The annual variation of the total ozone (see Fig. 10) can be approximated at the mid-latitudes by a sine curve. It should be noted that the tropospheric 03 level shows similar annual changes. The only difference is that maximum concentrations are observed in the troposphere 1-2 months later (see Fig. 13).-On the basis of this time lag Junge (1962) estimated that the residence time of 03 in the troposphere is 2 months. In contrast the atmospheric residence time of 03 is calculated to be 1-2 years (Junge, 1963) that is, the lifetime of this species is very different in the stratospheric and tropospheric reservoirs. 

Annual variation of total ozone and tropospheric ozone concentration in Arosa (Switzerland) between April, 1950 and March, 1951 (Junge, 1963). (By courtesy of Academic Press and the author)... 

It is well known that, after its absorption, NOz forms nitric acid and nitrous acid in water. There is some indication that nitrite produced in this way is oxidized by dissolved 03 (Penkett, 1972). If neutralizing agents (ammonia, calcium carbonate etc.) are present, some nitrate salt is finally formed. It follows from this discussion that both S02 and N02 are oxidized in cloud water by atmospheric ozone. If this speculation is true a correlation should be found between the concentration of sulfate and nitrate ions in precipitation waters. Such a correlation was found in precipitation samples by Gambell and Fisher (1964) among others. However, correlations between any two species in rainwater must be considered with caution because the level of all ions is affected in a similar way by the precipitation intensity or quantity (see Subsection 5.4.1). Nevertheless the identical annual variations of the two ions in precipitation water (see Subsection 5.4.5) suggests that the two species are formed by some similar processes. 

We can thus conclude that the spring maximum cannot be explained either by the annual variation of source intensity at the Earth s surface or by the variation of the quantity of precipitation. It has been postulated (E. Meszaros, 1974a) that this maximum is due to the oxidation effects of tropospheric ozone, the concentration of which also has a maximum during the spring (see Fig. 13). Ozone oxidizes S02 and N02 in atmospheric liquid water (see Subsection 5.3.2) which leads to the lowering of the pH. The increase in the concentration of hydrogen ions promotes the absorption of ammonia gas from the air, as well as the transformation of insoluble mineral components (e.g. calcium carbonate) into water-soluble materials. If this speculation is correct, this process provides a non-negligible ozone sink in the... 

Ramanathan, K.R., Bi-annual variation of atmospheric ozone over the tropics, Quart J Roy Met Soc 89, 540, 1963. 

Fig. 1-3. Total ozone at Arosa, Switzerland (in Dobson units 1 D.U. corresponds to a 10 2 mm thick layer of pure ozone at 273 K and 1 bar pressure), (a) Variation in the course of 1 day. (b) Day-to-day fluctuation in February 1973. (c) Variation of February means 1957-1971. (d) Monthly means for 1962. (e) Annual variation averaged over many years. [Adapted from Diitsch (1980).]...

Chapman, S. (1930). On the annual variation of the upper atmospheric ozone. Philos. Mag. 10, 345-352. 

Among the first BAS discoveries made at Halley Bay was that ozone concentrations above the South Pole fluctuated on a regular basis annually, with concentrations in late spring about 35 percent higher than in winter. "Spring," in this case, refers to austral, or Southern Hemisphere, spring, beginning after about September 15. Further studies conducted over the next two decades consistently confirmed this seasonal variation. 

Plate 5. Ozone anomalies (ppmv) versus altitude (km) and time (years) in the equatorial region (4°N-4°S) derived from observations made by the HALOE instrument on board the Upper Altitude Research Satellite (UARS). Superimposed on ozone values are the zonal winds measured by the HRDI instrument on the same satellite. Full lines are eastward winds and dashed lines westward winds with intervals corresponding to 10 m/s. In the 20-30 km altitude range, the positive ozone anomalies are associated with the westerly shear in the quasi-biennal oscillation (QBO), while the negative anomalies are indicative of easterly shears. Above 30 km, ozone variability is associated with temperature variability, which affects the photochemical source terms. Above 35 km, the observed variations are due to temperature effects associated with the QBO and to the semi-annual oscillation. Courtesy of Paul Newman, NASA/GSFC. 

FIGURE 2.12 Annual latitudinal variation of the total ozone from January 1979 to May 1991 or February 1994, as indicated (IPCC, 1995). 

Diurnal and seasonal variations in solar intensity are, of course, of utmost importance to ecosystems. In the extreme polar regions there is no direct solar radiation at all for more than four months of the year, whereas near the equator the overall intensity of sunlight fluctuates less than 10% annually. The spectral energy distribution also varies with the season. For example, in July in the middle latitudes (ca. 40 ), the fraction of shorter-wave UV (290-315 nm) in the total solar radiation is more than three times higher than it is in December, due to the shorter path these easily scattered wavelengths have to traverse through the atmosphere. For similar reasons, shortwave UV is more intense at high elevations, particularly in the tropics where stratospheric ozone is less concentrated (Caldwell et al., 1980). 

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