Solar proton events

From the previous discussion it is clear that we have no direct experimental evidence for stratospheric ozone depletion as a result of nuclear explosions. However, at least for altitudes above 30 km the sudden input of significant amounts of NO has clearly been shown to lead to large ozone destmctions. In August 1972 a major solar proton event deposited large amounts of nitrogen oxides in the stratosphere, leading to ozone depletions poleward of about 60°N. The estimated ozone depletions calculated with a photochemical model were confirmed by satellite observations of stratospheric ozone [61]. 

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NOj from sporadic solar proton events maximum production recorded in August, 1972 1 X 10 °moles produced. 

Increased production of oxides of nitrogen through solar proton events associated with the 11-year cycle in solar activity would be expected to be most important in the upper stratosphere, above the region where the majority of the ozone depletion was observed in addition, lower, rather than higher, concentrations of gas-phase oxides of nitrogen appear to be associated with the ozone depletion (e.g., see Noxon, 1978 McKenzie and Johnston, 1984 Thomas et al., 1988 Keys and Gardiner, 1991 and Solomon and Keys, 1992). Hence both of these explanations are not consistent with atmospheric observations. 

Variability may be defined as reflecting fluctuations in the atmosphere, of natural origin, with both temporal and spatial scales examples are diurnal, seasonal, solar activity-related variations impulsive events such as volcano eruptions and solar proton events fluctuations linked to some peculiar meteorological conditions, for example, intense cyclonic activities and jet streams. Variability by itself is a whole program to be conducted ideally on a four-dimensional basis (latitude, longitude, altitude, and time) by space vehicles, for example, satellites or from the space shuttle. This area of research is certainly the most urgent one to be de-... 

In outer space, remote from the shielding influence of the earth s magnetic field, the absorbed dose index rate from solar protons emitted during solar flares can be very high. For example, it has been estimated that the absorbed dose indices in outer space from the solar proton event of 10 July 1959 were from protons 3.6, 1.7, and 0.4 Gy behind shielding of 1, 2 and 5 g cm, respectively, and from alpha particles the corresponding values were 1.5,0.3 and 0.05 Gy, respectively (Curtis, 1974). However, the Apollo missions did not experience any measmable solar particle events (English et al., 1975). 

Crutzen et al. (1975) noted that penetration of large amounts of protons into the middle atmosphere during solar proton events would also lead to an intense production of atomic nitrogen. These episodic events can produce enough nitrogen oxide to influence the ozone content,... 

Crutzen, P.J., I.S.A. Isaksen, and G.C. Reid, Solar Protons events Stratospheric sources of nitric oxide. Science 189, 457, 1975. 

Figure 6.3. Satellite observations from the HALOE instrument of ozone and NOx changes following the major solar proton event of July 2000, compared to model calculations. From Jackman et al. (2001).

Heath, D.F., A.J. Krueger, and P.J. Crutzen, Solar proton event Influence on stratospheric ozone. Science 197, 886, 1977. 

Jackman, C.H., and R.D. McPeters, Solar proton events as tests for the fidelity of middle atmosphere models. Physica Scripta T18, 309, 1987. 

Jackman, C.H., E.L. Fleming, and F.M. Vitt, Influence of extremely large solar proton events in a changing stratosphere. J Geophys Res 105, 11,659, 2000. 

Jackman, C.H., R.D. McPeters, G.J. Labow, E.L. Fleming, C.J. Praderas, and J.M. Russell, Northern Hemisphere atmospheric effects due to the July 2000 solar proton event. Geophys Res Lett 28, 2883, 2001. 

Solomon, S., G.C. Reid, D.W. Rusch, and R.J. Thomas, Mesospheric ozone depletion during the solar proton event of July 13, 1982, Part II. Comparison between theory and measurements. Geophys Res Lett 10, 257, 1983. 

Weeks, C.H., R.S. Cuikay, and J.R. Corbin, Ozone measurements in the mesosphere during the solar proton event of 2 November 1969. J Atmos Set 29, 1138, 1972. 

Figure 7.10. Rate of ion pair production by magnetospheric electrons (REP) in the subauroral zone. These values correspond to an annual average, and are compared to the effect of cosmic rays and the total ion pair production associated with the solar proton event (SPE) of August 1972. From Thorne...

Figure 7.11. Ionization rates associated with some solar proton events, compared to that due to cosmic rays. Adapted from Solomon et al. (1983).

During intense solar proton events, the number of ion pairs produced can increase greatly even at relatively low altitudes, perturbing the neutral atmosphere and leading to a considerable increase in the rate of production of nitrogen and hydrogen oxides (see e.g., Swider and Keneshea, 1973 Crutzen et al, 1975 Jackman et al, 1980 1990 1995 Reid et al., 1991). 

The 0+ ion can also produce nitrogen atoms by reaction (7.106) with nitrogen and dissociative recombination of NO 1. This contribution is only about 0.03Q in the middle atmosphere, however. Below 90 km altitude, each ion pair produced during particle precipitation in the atmosphere (cosmic rays, magnetospheric electrons, and solar proton events) results in a total gross odd nitrogen production... 

Heaps, M.G., The Effect of a Solar Proton Event on the Minor Neutral Constituents of the Summer Polar Mesosphere. US Army Atmospheric Sci Lab Report ASL-TR-0012, 1978b. 

Jackman, C.H., J.E. Nielsen, D.J. Allen, M.C. Cerniglia, R.D. McPeeters, A.R. Douglass, and R.B. Rood, The effects of the October 1989 solar proton events on the stratosphere as computed using a 3-Dimensional model. Geophys Res Lett 20, 459, 1993. 

Reid, G.C., S. Solomon, and R.R. Garcia, Response of the middle atmosphere to the solar proton events of August-December 1989. Geophys Res Lett 18, 1019, 1991. 

Dreschhoff GAM, Zeller EJ (1994) 415-year Greenland ice-core record of solar proton events dated by volcanic eruptive episodes. Institute for Tertiaiy-Quatemaiy Studies-TER-QUA Symposium Series, 2 1-24... 

Figure 2 shows typical profiles of electrical conductivity with altitude under a number of conditions. The enhancement due to solar proton events is principally at high latitudes. 

Fig. 1.2 Production of NO at high geomagnetic latitudes during the solar proton event of 1972 for two assumptions about the electronic states of the N atoms framed (Pm = 0, or 1). Also shown are the average NO concentrations for these locations.

Fig. 1.3 Observed and calculated percentage ozone depletions resulting from the 1972 solar proton event The various calculated curves correspond to assumed values of parameters that were not well known...

Cratzen P.J. Isaksen, I.S.A. Reid, G.C., 1975 Solar Proton Events Stratospheric sources of nitric oxide , in Science, 189 457. 

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