- Email: [email protected]
Spectrometric investigation of the ozone layer up to a height of 60 km
Phria.
Space
Sci. IW3.
Vol. II
Pp. 709 co 721.
SPECTROMETRIC
Perpmon
PIUS Ltd.
Printed
INVESTIGATION UP TO A HEIGHT
la Nonbern
Ireland
OF THE OZONE LAYER OF 60 km
A. V. YAKOVLEVA, L. A. KUDRYAVTSEVA, A. S. BRITAEV, V. F. CERASEV, V. P. WCHALOV, A. P. KUZNETSOV, N. A. PAVLENKO and VA. IOZENAS
Translated by H. F. CLEAVES from
lskussrvennye Sputniki Zemli No 14.
p. 57 (1961).
For the solution of the problem of atmospheric ozone it is necessary to have accurate and detailed information about the concentration of this gas in various layers of the atmosphere, depending on the physical conditions of the surrounding medium. Very accurate data about the vertical distribution of ozone may be obtained with the help of direct observations by sending into the ozone suitable measuring apparatus on research rockets. At the present time, with the help of rockets, it has become possible to send automatic spectrographs and other instruments up to great heights and to measure the concentration of ozone as far as the upper limits of the ozone layer, by the amount of absorption of the Sun’s ultra-violet radiation. Similar measurements, extremely important for the detection of the fine structure of the ozone layer (especially near its upper boundary), permit us, in addition, to verify the widespread indirect methods of measuring the vertical distribution of ozone by observations, from the Earth’s surface, of definite optical effects produced by atmospheric ozone. This question is the more important because a large part of the data about atmospheric ozone was obtained by indirect methods, in the first place by observations of scattered ultra-violet radiation from the zenith of a clear sky with a low position of the Sun above the horizon. Measurement of the vertical distribution of ozone, by means of the Sun’s scattered ultra-violet radiation, was based on the use of the “umkehr or inversion”, effect, discovered by G6tz tl**). This phenomenon, which is, according to GGtz, the result of the peculiar distribution of ozone in the Earth’s atmosphere, consists of the fact that the value L = In,, I/I’, with increase of the Sun’s zenith angle, at first decreases to some minimum value (with z approximately 85”) and then begins to increase (I and I’ are the intensities of the light, scattered in the zenith of a clear sky, with wavelengths I and I’, the radiation with wavelength Iz being strongly absorbed by ozone, but with wavelength 1’ only slightly absorbed). The position of the extreme point, with surroundings of constant temperature and pressure, is connected uniquely with the height of the centre of gravity of the ozone layer, and the form of the umkehr curve with the vertical profile of the ozone. Observations by the methods discussed above were, and continue to remain, the basic source of information about the vertical distribution of ozone in the atmosphere. With their help important conclusions were obtained about space and time changes of the vertical profile of ozone, consistent both with the results of direct measurement in the troposphere and lower stratosphere, and also with the results of theoretical calculations. The question, 709
710
A. K. YAKOVLEVA
ctal.
however, as to whether such agreement is random of whether in some degree it reflects the actual distribution of ozone with height, has remained open till recently. Beginning with 1934 attempts were repeatedly made to compare indirect and direct methods by means of simultaneous measurements from the Earth’s surface and in the atmosphere on air balloons (3*4).The small height of ascent of balloons did not permit, however, comparison of results for every thickness of the ozone layer. Only the use of research rockets opened up the possibility of comparing the results of direct and indirect measurements as far as the upper boundaries of the ozonosphere. Only one case, and that not fully successful, of simultaneous measurements of the concentration of ozone from a rocket and by the umkehr effect, is known to have been carried out, in the U.S.A. on 2nd April, 1948(5). Because of the instability of the rocket and trouble with the working of the spectrograph, the region of comparison was limited to an interval of height from 11 to 35 km. The encouraging data, obtained as the result of comparison, nevertheless, are not final and require verification. Considering the important theoretical and practical significance of the question of agreement of the direct and indirect methods of investigation, in the U.S.S.R. on the 15th June, 1960, simultaneous measurements of the distribution of the ozone concentration with height were made, with the help of a spectrograph taken up on a rocket and with the aid of surface spectral apparatus, by observations of ultra-violet light scattered from the zenith. For observations from the surface of the Earth a photoelectric spectrometer was used with double decomposition of light by quartz prisms, based on a modification of Dobson’s method(6). With the help of the spectrometer, for various heights of the Sun, the relative intensity of two radiation lines was determined, one of which with a wavelength 3. = 3114 A is strongly absorbed by the ozone layer, and the other with wavelength I’ = 3326 A hardly absorbed at all. The corresponding spectral intervals were A1 = 10 A for the short-wave ray and 14 A for the long-wave. With each reading of the instrument the long-wave radiation was weakened by the introduction of a photometric wedge until its intensity was comparable with the intensity of the short-wave radiation. The relative intensity and the connected value of L = ln,,l/l’were determined by the depth and density of the photometric wedge at the time of compensation. The total content of ozone has been determined by observation of direct solar light by the method described in”*@. The following served as basic equations for determining the ozone concentration from terrestrial observations:
I
m
p,l(-‘“‘~+B”,
dh
_
0
s co
Y=
Q
soaP*lO-
E,, set r$, dh +
h
7=-
Pv+h
‘@I,
dh
=
0,
(1) (2)
I 0
(3)
Q=-/ K”$ / 10-L. In formulae (l)-(4) the following notation is used: I and I’ are the intensities of ultraviolet radiation of wavelengths I and 1’; IOand I,’ the intensities of the ultra-violet radiation
SPECTROMETRIC
INVESTIGATION
OF THE OZONE LAYER
711
of the same wavelengths at the limits of the atmosphere; L = In, I/Z’; K and K’ the constants of Rayleigh’s dispersion law (for two wavelengths); p,, is the density of the air at the Earth’s surface; p,, the density of the air at height h; E,,the concentration of ozone at height h ; a and a’ the coefficients of absorption by the ozone of radiation with wavelengths 1 and Y; j3 and /Y coefficients of dispersion; H the height of the homogeneous atmosphere; E the Sun’s zenith distance at the point of the atmosphere above the place of observation being examined; y the thickness of the ozone layer along the path of the beam undergoing single dispersion at an arbitrary point above the point of observation; T the thickness of the layer of air on the same path. The fundamental relations for determining the vertical distribution of ozone are based on the assumption that attention is confined to the absorption of the ultra-violet radiation by the ozone and to the single dispersion of ultra-violet radiation by the air molecules, The value of the ozone concentration at each level h, may be obtained by solving n equations of the form (l), with n different zenith distances for the Sun. The method of approximate solution of the transcendental equations (l), devised by Giitz and Dobson, is based on the expansion of the integrals to rapidly converging series. This makes it possible to replace the integral equation (1) by a system of equations with a small number of unknowns. The results of the calculations depend on the number and thickness of the layers into which the atmosphere is divided, on the boundary conditions of the problem and the premises used as a basis of solution. The method, put forward in 1957 by Walton@) is the most recent. According to his method the atmosphere is divided into five concentric layers, of which the lower three are 12 km thick, the fifth layer extends from 54 km upwards and the fourth layer (from 36 to 54 km) is divided into three sub-layers each of 6 km. The quantity of ozone in the surface layer, in accordance with the results of the chemical measurements of Kei(*O),is assumed to be equal to 8.5 per cent of the total content of the atmosphere. Our measurements of the ozone concentration in the lower layers of the atmosphere, by an electro-chemical method, actually point to the existence of a connexion between the total content of ozone and the quantity of ozone in the troposphere’ll). At the same time with aircraft measurements it was discovered that, in a series of cases, the variations of the ozone concentration in the troposphere, were independent of the variations of the total content, because of the action oflocal ozone-forming and ozone-destroying processes. Thus, the limiting condition, postulated by Wolton for the lower layer of the ozonosphere, is not fully justified; considering, however, that the quantity of ozone in the troposphere is small in comparison with its total content, the error, connected with the inaccuracy of the conditions assumed at the lower boundary of the ozone layer, is small. It is assumed that, in the layer above 36 km, the decrease in quantity of the ozone takes place in accordance with an exponential law, established by data from a rocket sounding in the U.S.A.t5) As will be shown below, this assumption agrees well with the data of rocket measurements, carried out in the U.S.S.R., and obviously reflects sufficiently well the real conditions at the upper boundary of the ozone layer. With the given boundary conditions, to determine the ozone concentration in each of the five layers of the atmosphere, it is necessary to find two values x1, x, from two equations of the form (1) with two unknowns. Knowing the whole content of ozone x, determined by observations of the Sun’s direct ultra-violet radiation, and the quantity of ozone u in the
712
A. K. YAKOVL,EyA et al.
lower 12 km layer, it is easy to calculate the quantity of ozone in all five layers, using the following arrangement. Number of layer
Limits of heights, km
Quantity of ozone in layer
5 4
54co 48-54 42-48 36-42 24-36 12-24 O-12
0 0.057 xr 0.204 x1 0.739 xr 1
3 2 1
x2
x-x,-x,-u u
The original experimental data on the dependence of the value L = In, I/I’ on the Sun's zenith angle z, for the measurements of 15th June, 1960, are given in Fig. 1. For a numerical solution of the problem, for the wavelengths used in the instrument and the corresponding spectral intervals, coefficients of absorption of light by ozone were taken from VigrotuW and coefficients of dispersion were determined by Rayleigh’s method. The density of the air up to a height of the order of 25 km was determined from the data of serological sounding, and, for great heights, in accordance with the standard atmosphere. The quantity of ozone in the various layers of the atmosphere, the total content and the height of the centre of gravity of the ozone layer obtained from the observations of 15th June, 1960, are shown in Table 1. The comparison of the results of rocket measurements with those of indirect observations was preceded by the drawing of typical curves of the vertical profile of ozone for an observational region with small, medium and high total content of ozone in the atmosphere
20
24
28
32
36
40
44
40
52
56
60
64
60
FIG. 1. RELATIONOFVALUEOPL = ~~,,Z/Z'(FORSCAITERED LIGHTFROMZENITHOF CLEAR SKY)TO %JN'S ZENITH ANGLE Z (IN DEGREES); EXPERIMENT OF 15lH JUNE, 1960.
SPECTROMETRIC
INVESTIGATION
OF THE OZONE LAYER
713
TABLE 1. OZONE CONCRNTRATXON IN VARIOUS LAYERS OF THE ATMOSPH&RE FROM SURFACE MEASUREMENTS l%H hNE, 1960
Height of layer (km)
Ozone content* of layer (cm)
O-12 12-24 24-36 36-42 4248 48-54
@0257 0.1130 0.1470 0.0126 0.00348 oWO97o
Ozone content per km (cm/km) O+lO214 0.00942 0.01225 0~00210 0.00058 0+X)016
Total content 0.303 cm Centre of gravity of ozone layer 24 km * The ozone content is specified by the height which the column of ozone contained in the layer would have at normal temperature and pressure.
(Fig. 2). From the data shown in Fig. 2 it follows that the increase of the total ozone is accompanied by an increase of the quantity of ozone in the middle and lower layers of the ozonosphere and by a small decrease of concentration in the layer above 36 km. The centre of gravity of the ozone layer is lowered with increase of the total quantity of this gas in the atmosphere. A sharp divergence from the above-mentioned position is noticed only occasionally with strongly developed advective processes in the troposphere and lower stratosphere. The regularities of variation of the vertical distribution of ozone, established by means of indirect observations, especially in the middle and upper strata of the ozone layer, may be vetied only by comparing them with the results of rocket measurements. Similar investigations have been carried out in postwar years in the U.S.A.u’) and U.S.S.R. The first ascent in the U.S.S.R. took place on 19th July, 1955, with the Sun at an altitude of 14”15’. A fluorite spectrograph with an illuminator of circular form was carried on a
E x i
24 -
5
IO co,,
15
IO-* cm/ km
FIG. 2. TYPICALCURVES OF VERTICAL. OZONE DISTRIBUTION FOR REGION OF ORSERVATIONS WITH LOW (X = 0.250 CM; DASH-DOT LINE), MEDIUM (X = 0.320 CM; DASH LINE) AND HIGH (X = 0.390 CM; CONTINUOUS LINE) TOTAL CONTENT OF OZONE FROM SURFACE MEASUREMENTS
714
A. K. YAKOVL.EVA et al.
meteorological rocket. In this flight thirty resulting spectra were obtained with an exposure of 4 sec. The last spectrum was obtained at a height of 76 km. To calculate the ozone concentration the method of the relative intensity of two wavelengths was employed. The equation of atmospheric attenuation was used and with this it was assumed that the spectrum obtained at a height of 76 km gives the distribution of solar radiation at the limit of the ozone layer. In the calculation, coefficients of absorption of ozone were used, as obtained by Ni Tzi-ze and Chung Shin-Piu(13). A rather unusual distribution of ozone with height was obtained, The weight of ozone appeared to be concentrated in two layers: 13-26 km and 50-64 km, between which no ozone was observed. The total content of ozone in both. layers was equal to 0.17 cm, 0.09 cm being found in the lower layer and 0.08 cm in the upper. It is possible that the observation of ozone at heights of 50-64 km is connected with errors of measurement; the following factors appear to have been unfavourable in this case; the extensive blackening of the spectra obtained at these heights and the deviation of the axis of the instrument at significant angles from the vertical in the upper part of the trajectory, which increase the influence of the ultra-violet radiation reflected from the lower layers of the troposphere. To remove the influences of the orientation of the instrument on the results of measurement, in further attempts a tracking system was employed for illuminating the aperture of the spectrograph by the Sun. The next ascent took place on 1st October, 1958, with the Sun at a height of 19”. Measurements were made with a spectrograph, which differed from the previous one by the use of a tracking system. In addition, for photographing the spectra, several exposures were used (240, l-04, 0.29 and 0.07 set) following one another in succession. The spectrograph was carried on a meteorological rocket, and 35 spectra were obtained up to a height of 24 km. The spectra which had been photographed were examined by a recording microphotometer MF-4. The blackenings were translated into corresponding intensities with the aid of the characteristic curves for the film, constructed from the blackened marks, photographed with a mercury lamp PRK-2. Characteristic curves were constructed from mercury lines in the region 30004100 A. To arrive at the ozone concentration a method of calculating the vertical distribution was used, which was put forward by V. N. Pokrovskn“04), for,the case where there was no information about the spectral distribution of solar radiation at the limits of the ozone layer. To exclude errors connected with instability of exposure and unsatisfactory illumination of the aperture of the spectrograph, this method was used in conjunction with the method of relative intensity of two wavelengths. It was assumed that in the spectral part of the solar radiation measured (3000-4000 A), the attenuation came about only because of the absorption of ozone and dispersion by the molecules of air. Two equations of atmospheric attenuation were used for radiation with wavelengths 1, and 1,.
I&- = 11’0)
s 00
--a1
h
sh
E,
dl - Am,
co E, dl - &m.
(5)*
(6)*
Here Ir(O),12to),I1 and I, are the intensities of solar radiation with wavelength il, and 1, at the limits of the ozone layer and at height h above the Earth’s surface; a1 and a+ the coefficients
SPECTROMETRIC
INVESTIGATION
715
OF THE OZONE LAYER
of absorption (cm-l), by the ozone, of radiation with wavelengths il, and &(a, < a&; E, the ~on~ntration of ozone at height z; I the path of the solar ray to the instrument, found at height h; j3r and be the coefficients of dispersion of the atmosphere for radiation with wavelengths il, and il,; m the mass of the atmosphere at height h, determined from the expression (R + r) dr, dl where 2/(R + z)~ - (R + /Q2cos2 h, ’ =
where His the height of the homogeneous atmosphere; p0 and pZ the densities of the air at the Earth’s surface and at height z; R the radius of the Earth; h the angular altitude of the Sun. Solving simultaneously the equations (5) and (6), written for heights h, and ha we obtain
where
Aa = a2 - dcr and
Ap = /J - /$.
Taking the ozone content in the layer between h, and h, as 6, we obtain from
(7)
In relation (8) the second term on the right-hand side determines the influence of the molecular dispersion of the air and the next term gives the corrections for the curvature of the ozone layer. From here we used a method of successive approximation. As the initial vertical distribution of ozone, surface measurements were used, which were made in the region of rocket launching with a spectrograph of the Dobson type. The wavelengths 1, and 1, were selected so that the differences An were sufficiently large. The calculation of the ozone concentration was carried out both with the coefficients of absorption of ozone, obtained by Ni Tzi-ze and Chung Shin-Piu (which were used for all ozone calculations up to the year 1957) and with the coefficients obtained by Vigroux(12). In the values of the coefhcients of absorption, corrections were made for the temperature of the ozone layer. The optical densities of absolutely pure atmosphere were taken from Pendorf(i5’. The results of the calculation are given in Table 2. As can be seen from Table 2, the term giving the correction for the curvature of the ozone layer (calculated as a first approximation) does not exceed 2 per cent of the ozone concentration above 13 km; therefore there is no reason to take it into account in the following approximation. The distribution of ozone obtained reveals a maximum in the layer from 21-23 km (concentration 17.5 x IOFscm/km, with tc from Vigroux). Above 23 km a sharp decrease of ozone concentration is seen, but it must be noted that measurements above 23 km are * In = log to base 10
716
A. K. YAKOVLEVA et al.
TABLE2. RESULTS OFMBASUREMENT OF THE
E, cm/km (a from V&roux)
Height (km)
oGO19 00014 0.0058 0.0076 O*Olll 0.0156 0.0168 0.0175 0.0108
o-5
5-10 lo-13 13-16 16-18 18-20 20-21 21-23 23-24
VERTICAL
Mean square error *to.0002 owO5 oGOO3 0.0006 0*0005 0*0007 O+IOO6 OWO6 0.0007
DISTRIFKWION
OF OZONE
E, cm/km (ccfrom Ni Tzi-ze and Chung Shin-Piu) 00016 OGI28 0.0039 @0061 0.0103 00141 0.0143 0.0152 00113
ON 1ST OCTOBER
1958
Mean square error
Correction for curvature of layer (cm/km)
*o-O002 O+IOO3 @0003 ox)oO5 0.0007 oGOO7 oGOO5 0*0007 O*OOlO
@ooo3 oGOO3 oGoO3 oGOO3 o+xlO3 oQOO2 oGOO2 o+IOO2 OwO2
not wholly reliable, since the next spectrum, obtained at a height of 24 km, had considerable blackening, which brought about an increase in the photometric error. The calculation of the ozone concentration with the coefficients of Ni Tzi-ze and Chung Shin-Piu gave the same type of ozone dispersion, but with rather less concentration. The third flight was made on 15th June, 1960, with the Sun’s height 15’15’. On a geophysical rocket a diffraction spectrograph was sent up equipped with a tracking system. Because of the,instrument’s working conditions the photographing of the Sun only began at a height of 23 km. The solar spectra, obtained in this flight, are shown in Fig. 3. Spectra obtained above 55.5 km were not used to find the ozone concentration since, within the limits of accuracy of the measurements, their blackening did not differ from the blackening of the spectrum obtained at a height of 55.5 km. In the figure the positions of the lines of the doublet Mg II (2795.5 A, 2802.7 A) and the line Mg I (2852.1 A) are marked. The shortest wavelength used for photometry was 2590 A (at a height of 55.5 km) the wavelength limit of the spectra being 3070 A. In this flight the time of exposure at all heights differed little from the normal, and so it was not necessary to use the method of relative intensity of two wavelengths in the treatment of the results of measurement as in previous flights. The calculation of the ozone concentration was done by formula (9), which was obtained in a similar way to formula (8) from equations of atmospheric attenuation written for heights hr, ha and for wavelength A,
1 1 hu)h, -“d1,O1 (%
s
%i=--
4
An example of the microphotometer recording of the value of the transparency of the solar spectra for heights of 40.5 and 50.5 km is shown in Fig. 4. For calculations of the relative intensities, characteristic curves of the film were used, which were plotted from the marks of blackening made with the help of a hydrogen lamp and a nine-step platimum attenuator. Characteristic curves were constructed for the part of the spectrum from 2500-3100 A at approximately 50 A intervals. For this part of the spectrum, within the limits of accuracy of the construction of each isolated curve, they were parallel to each other. The characteristic curve used for the work was the average of all
FIG.3. SOLAR SPECTRA
PHOTOGRAPHED
IN FLIGHT.
SPECI’ROMETRIC
INWXITGATION
2813 8 2852,
I
i(Mgll
OF THE OZONE
LAYER
717
2881.60%
those which had been drawn. The coefficient of contrast was l-08; the region of normal blackening embraced an interval of 0.3-14. In the region of normal blackening, for relative intensities the following relation is applicable:
where A is the transparency, S the blackening of the film, and y the coefficient of contrast. Equation (9) in the values of transparency may be rewritten in the form
Here A, and A, are the transparencies of the film in spectra obtained at heights h, and h, for the selected wavelength. The expression (10) was calculated for wavelengths, whose transparencies corresponded to the region of normal blackening. For various heights the number of such wavelen~s was different, since the extents of the spectra in the region of short wavelengths and the degree of blackening in the long-wave parts were different. The ozone concentration in the layer was taken as the average of all the calculations relating to that layer. For the calculation of the last term in equation (10) surface measurements were used as in the previous flight. The results of the calculations are given in Table 3. The term, cha~~e~tic of the influence of the curvature of the ozone layer, in the 23-26 km layer is 3 per cent and quickly diminishes with height; also, as in the previous flight, calculations are limited to a first approximation. The coefficients of Vigroux, as in the previous flight, gave a somewhat larger ozone
Height (km) -____ 23-26 26-28 28-405 405-45*5 45.5-50.5 50-5-555
0.010000 0.006500 0~001600 00X04O 0aOO106 oaoO47
E‘*cm/km (a from Vigtoux)
RESULT3
09
~~E~~~
OF VERTICAL
~~~B~~
Mean square error 3.0 1.6 09 0.3 0 0
(%I
Correction for curvature of layer
OZONE
d,* cm/km Mean (a from Ni Tzi-ze square and Chung Shin-Piu) error @m/km) ____-.. -. ~~.~ ~~~ ~~~1~ 0.~7~ 0900900 0+)00100 oaOO8cMI OaHOO oaOO2OO oawO1o oaOO1Oo oa1400 0900020 OaOOOO1 oaOOO1o OWO280 oaOOO1o 0 oa)OOO1 O*OOOO!JO OXlOODO8 0 O*OOOW8 OMOO41
TABLB3. hi=,
---?%E* __~” 20.7 160 14.6 16.5 11.3 13.8
i, - P,*
~!+i%
3523-3094 3001-3094 29763094 2818-2914 2642-2873 2630-2873
Y-z
Region of spectrum
1960
34 37 55 4s 52 14
Number of wavelengths for which calculation was carried out
2 cB z -_
2
2 0
?c
?
SPECTROMETRJC
INVESTIGATION
OF THE OZONE
719
LAYER
concentration than in the case where the coefficients of Ni Tzi-ze and Chung Shin-Piu were used. The largest divergence was observed in the spectral region 3023-3094 A, where it was 20.7 per cent. In Fig. 5 results are shown of rocket measurements of the vertical distribution of ozone according to the data of American authors(5) and the results of our measurements on 1st October, 1958, and 15th June, 1960 (calculations with coefficients of Vigroux by continuous lines and of Ni Tzi-ze and Chung Shin-Piu by dotted lines). co,.
FIG.
5.
ROCKET~~EA!~JREMENIS
I-measurement 10 Oct., 1946 (U.S.A.); (U.S.A.);
4-l
IO-’ cm/km
OF VERTICAL
OZONE
DKTRIBUITON:
2-2 April, 1948 (U.S.A.); 3-14 Oct., 1958 (U.S.S.R.); 5-15 June, 1960 (U.S.S.R.).
June, 1949
In the upper part of the figure the measurements of 15th June, 1960, and the corresponding American measurements are given in a logarithmic scale. We may say that above 23-26 km the ozone concentration diminishes according to an exponential law. The results of measurements made in the U.S.A. on 14th June, 1949, support this. Comparison of the results of direct measurements on rockets and the results of calculations from observations of scattered zenith light (Fig. 6) point to a satisfactory agreement between them. The height of the layer with the maximum ozone concentration, according to the calculated results, is somewhat higher than that obtained from direct measurements. For the time being it is not clear whether this divergence appears as the result of errors in the method of calculation or because it depends on unfavourable conditions of observation. It is pertinent to remember that, according to the data from the U.S.A., the calculation
A. K. YAKOVLEVA
720
et al.
method also gives a greater height for the centre of gravity of the ozone layer than follows from direct measurement. For heights above 40 km the results of direct and indirect methods practically coincide. In spite of the fact that the discussion of the results is of a preliminary nature, they now 60
FIG. 6. CMPAR~SON
a-m~suremen~
OF DATA ABOUT VERTICAL OZONE DWRLBUIION ~~MSONROCICETS:ANDBYC~CUWTION:
OBTAINBD BY mtux
2 April, 1948 (U.S.A.); b-mea!wements 15 June, 1960 (U.S.S.R.); I-calculation by umkehr effect; 2+linxt measurementa.
appear to be useful for the estimation of the observational materials obtained with the help of indirect methods and for further improvement of these methods. The exponential fall of ozone concentration in the 35-55 km layer, established as a result of direct measurements is characteristic of an important law of the upper layers of the ozonosphere. A final solution of the question of the conformity of direct and indirect methods of ozonometry may be obtained by way of further investigations of the atmosphere with the help of research rockets. REFERENCES 1. G. M. DOWN, D. N. Hmruso~ and I. LAWRENCE, Proc. Roy. See. A122,456 (1928). 2. F. W. G@z, A. K. MIEIHAMand G. M. DoasoN, Pror. Roy. Sot. Al45,416 (1934). 3. O’BRXEN, F. L. MOLAR and KH. S. STUNCT, Vertical Distribution of Ozone in the Amwqhere
(In Russian).
Gidrometeoizdat,(1938).
4. A. W. BREWER,H. U. Durscw et al., Ann. Gtophys. 16, 196 (1960).
5. F. S. DZHONSON, Dar. D. PERSBUand R. TAUW, Sbomik Rocket Itwestigation of the Upper Atmosphere (In Russian), Vol. 49 p. 216 (1957). 6. A. P. Ku mv, IN. Akad. Nauk SSSR, Seriya Geofz. 9.1154 (1957).
SPECTROMETRIC 7. 8. 9. 10. 11.
12. 13. 14. 15.
INVESTIGATION
OF THE OZONE
LAYER
721
A. S. BRITAEV,V. A. IOZENASand A. P. KUZNE?~~V, Met. i Gidrol. lo,24(1958). A. S. BRITABVand A. P. KUZNIWOV, Trudy TsAO 32,28 (1958). G. F. WOLTON, Ann. ZGY $10 (1957). P. G. KEI, Sbomik Rocket Znoestigations of the Upper Atmosphere (In Russian). Vol. 49, p. 236 (1957). A. S. BRITAW, T’rr$y TsAO 37,13 (1960). E. VIGROUX,Ann. Phys. 8,709 (1953). I. A. PROKOF'EVA, Atmospheric Ozone (In Russian). Akad. Nauk SSSR, (1951). V. P. POKRO~XII,TrudyTsAO 16,21 (1956). R. PENDORF,J.Opt. Sot. Amer. 47, 176 (1957).
Space
Sci. IW3.
Vol. II
Pp. 709 co 721.
SPECTROMETRIC
Perpmon
PIUS Ltd.
Printed
INVESTIGATION UP TO A HEIGHT
la Nonbern
Ireland
OF THE OZONE LAYER OF 60 km
A. V. YAKOVLEVA, L. A. KUDRYAVTSEVA, A. S. BRITAEV, V. F. CERASEV, V. P. WCHALOV, A. P. KUZNETSOV, N. A. PAVLENKO and VA. IOZENAS
Translated by H. F. CLEAVES from
lskussrvennye Sputniki Zemli No 14.
p. 57 (1961).
For the solution of the problem of atmospheric ozone it is necessary to have accurate and detailed information about the concentration of this gas in various layers of the atmosphere, depending on the physical conditions of the surrounding medium. Very accurate data about the vertical distribution of ozone may be obtained with the help of direct observations by sending into the ozone suitable measuring apparatus on research rockets. At the present time, with the help of rockets, it has become possible to send automatic spectrographs and other instruments up to great heights and to measure the concentration of ozone as far as the upper limits of the ozone layer, by the amount of absorption of the Sun’s ultra-violet radiation. Similar measurements, extremely important for the detection of the fine structure of the ozone layer (especially near its upper boundary), permit us, in addition, to verify the widespread indirect methods of measuring the vertical distribution of ozone by observations, from the Earth’s surface, of definite optical effects produced by atmospheric ozone. This question is the more important because a large part of the data about atmospheric ozone was obtained by indirect methods, in the first place by observations of scattered ultra-violet radiation from the zenith of a clear sky with a low position of the Sun above the horizon. Measurement of the vertical distribution of ozone, by means of the Sun’s scattered ultra-violet radiation, was based on the use of the “umkehr or inversion”, effect, discovered by G6tz tl**). This phenomenon, which is, according to GGtz, the result of the peculiar distribution of ozone in the Earth’s atmosphere, consists of the fact that the value L = In,, I/I’, with increase of the Sun’s zenith angle, at first decreases to some minimum value (with z approximately 85”) and then begins to increase (I and I’ are the intensities of the light, scattered in the zenith of a clear sky, with wavelengths I and I’, the radiation with wavelength Iz being strongly absorbed by ozone, but with wavelength 1’ only slightly absorbed). The position of the extreme point, with surroundings of constant temperature and pressure, is connected uniquely with the height of the centre of gravity of the ozone layer, and the form of the umkehr curve with the vertical profile of the ozone. Observations by the methods discussed above were, and continue to remain, the basic source of information about the vertical distribution of ozone in the atmosphere. With their help important conclusions were obtained about space and time changes of the vertical profile of ozone, consistent both with the results of direct measurement in the troposphere and lower stratosphere, and also with the results of theoretical calculations. The question, 709
710
A. K. YAKOVLEVA
ctal.
however, as to whether such agreement is random of whether in some degree it reflects the actual distribution of ozone with height, has remained open till recently. Beginning with 1934 attempts were repeatedly made to compare indirect and direct methods by means of simultaneous measurements from the Earth’s surface and in the atmosphere on air balloons (3*4).The small height of ascent of balloons did not permit, however, comparison of results for every thickness of the ozone layer. Only the use of research rockets opened up the possibility of comparing the results of direct and indirect measurements as far as the upper boundaries of the ozonosphere. Only one case, and that not fully successful, of simultaneous measurements of the concentration of ozone from a rocket and by the umkehr effect, is known to have been carried out, in the U.S.A. on 2nd April, 1948(5). Because of the instability of the rocket and trouble with the working of the spectrograph, the region of comparison was limited to an interval of height from 11 to 35 km. The encouraging data, obtained as the result of comparison, nevertheless, are not final and require verification. Considering the important theoretical and practical significance of the question of agreement of the direct and indirect methods of investigation, in the U.S.S.R. on the 15th June, 1960, simultaneous measurements of the distribution of the ozone concentration with height were made, with the help of a spectrograph taken up on a rocket and with the aid of surface spectral apparatus, by observations of ultra-violet light scattered from the zenith. For observations from the surface of the Earth a photoelectric spectrometer was used with double decomposition of light by quartz prisms, based on a modification of Dobson’s method(6). With the help of the spectrometer, for various heights of the Sun, the relative intensity of two radiation lines was determined, one of which with a wavelength 3. = 3114 A is strongly absorbed by the ozone layer, and the other with wavelength I’ = 3326 A hardly absorbed at all. The corresponding spectral intervals were A1 = 10 A for the short-wave ray and 14 A for the long-wave. With each reading of the instrument the long-wave radiation was weakened by the introduction of a photometric wedge until its intensity was comparable with the intensity of the short-wave radiation. The relative intensity and the connected value of L = ln,,l/l’were determined by the depth and density of the photometric wedge at the time of compensation. The total content of ozone has been determined by observation of direct solar light by the method described in”*@. The following served as basic equations for determining the ozone concentration from terrestrial observations:
I
m
p,l(-‘“‘~+B”,
dh
_
0
s co
Y=
Q
soaP*lO-
E,, set r$, dh +
h
7=-
Pv+h
‘@I,
dh
=
0,
(1) (2)
I 0
(3)
Q=-/ K”$ / 10-L. In formulae (l)-(4) the following notation is used: I and I’ are the intensities of ultraviolet radiation of wavelengths I and 1’; IOand I,’ the intensities of the ultra-violet radiation
SPECTROMETRIC
INVESTIGATION
OF THE OZONE LAYER
711
of the same wavelengths at the limits of the atmosphere; L = In, I/Z’; K and K’ the constants of Rayleigh’s dispersion law (for two wavelengths); p,, is the density of the air at the Earth’s surface; p,, the density of the air at height h; E,,the concentration of ozone at height h ; a and a’ the coefficients of absorption by the ozone of radiation with wavelengths 1 and Y; j3 and /Y coefficients of dispersion; H the height of the homogeneous atmosphere; E the Sun’s zenith distance at the point of the atmosphere above the place of observation being examined; y the thickness of the ozone layer along the path of the beam undergoing single dispersion at an arbitrary point above the point of observation; T the thickness of the layer of air on the same path. The fundamental relations for determining the vertical distribution of ozone are based on the assumption that attention is confined to the absorption of the ultra-violet radiation by the ozone and to the single dispersion of ultra-violet radiation by the air molecules, The value of the ozone concentration at each level h, may be obtained by solving n equations of the form (l), with n different zenith distances for the Sun. The method of approximate solution of the transcendental equations (l), devised by Giitz and Dobson, is based on the expansion of the integrals to rapidly converging series. This makes it possible to replace the integral equation (1) by a system of equations with a small number of unknowns. The results of the calculations depend on the number and thickness of the layers into which the atmosphere is divided, on the boundary conditions of the problem and the premises used as a basis of solution. The method, put forward in 1957 by Walton@) is the most recent. According to his method the atmosphere is divided into five concentric layers, of which the lower three are 12 km thick, the fifth layer extends from 54 km upwards and the fourth layer (from 36 to 54 km) is divided into three sub-layers each of 6 km. The quantity of ozone in the surface layer, in accordance with the results of the chemical measurements of Kei(*O),is assumed to be equal to 8.5 per cent of the total content of the atmosphere. Our measurements of the ozone concentration in the lower layers of the atmosphere, by an electro-chemical method, actually point to the existence of a connexion between the total content of ozone and the quantity of ozone in the troposphere’ll). At the same time with aircraft measurements it was discovered that, in a series of cases, the variations of the ozone concentration in the troposphere, were independent of the variations of the total content, because of the action oflocal ozone-forming and ozone-destroying processes. Thus, the limiting condition, postulated by Wolton for the lower layer of the ozonosphere, is not fully justified; considering, however, that the quantity of ozone in the troposphere is small in comparison with its total content, the error, connected with the inaccuracy of the conditions assumed at the lower boundary of the ozone layer, is small. It is assumed that, in the layer above 36 km, the decrease in quantity of the ozone takes place in accordance with an exponential law, established by data from a rocket sounding in the U.S.A.t5) As will be shown below, this assumption agrees well with the data of rocket measurements, carried out in the U.S.S.R., and obviously reflects sufficiently well the real conditions at the upper boundary of the ozone layer. With the given boundary conditions, to determine the ozone concentration in each of the five layers of the atmosphere, it is necessary to find two values x1, x, from two equations of the form (1) with two unknowns. Knowing the whole content of ozone x, determined by observations of the Sun’s direct ultra-violet radiation, and the quantity of ozone u in the
712
A. K. YAKOVL,EyA et al.
lower 12 km layer, it is easy to calculate the quantity of ozone in all five layers, using the following arrangement. Number of layer
Limits of heights, km
Quantity of ozone in layer
5 4
54co 48-54 42-48 36-42 24-36 12-24 O-12
0 0.057 xr 0.204 x1 0.739 xr 1
3 2 1
x2
x-x,-x,-u u
The original experimental data on the dependence of the value L = In, I/I’ on the Sun's zenith angle z, for the measurements of 15th June, 1960, are given in Fig. 1. For a numerical solution of the problem, for the wavelengths used in the instrument and the corresponding spectral intervals, coefficients of absorption of light by ozone were taken from VigrotuW and coefficients of dispersion were determined by Rayleigh’s method. The density of the air up to a height of the order of 25 km was determined from the data of serological sounding, and, for great heights, in accordance with the standard atmosphere. The quantity of ozone in the various layers of the atmosphere, the total content and the height of the centre of gravity of the ozone layer obtained from the observations of 15th June, 1960, are shown in Table 1. The comparison of the results of rocket measurements with those of indirect observations was preceded by the drawing of typical curves of the vertical profile of ozone for an observational region with small, medium and high total content of ozone in the atmosphere
20
24
28
32
36
40
44
40
52
56
60
64
60
FIG. 1. RELATIONOFVALUEOPL = ~~,,Z/Z'(FORSCAITERED LIGHTFROMZENITHOF CLEAR SKY)TO %JN'S ZENITH ANGLE Z (IN DEGREES); EXPERIMENT OF 15lH JUNE, 1960.
SPECTROMETRIC
INVESTIGATION
OF THE OZONE LAYER
713
TABLE 1. OZONE CONCRNTRATXON IN VARIOUS LAYERS OF THE ATMOSPH&RE FROM SURFACE MEASUREMENTS l%H hNE, 1960
Height of layer (km)
Ozone content* of layer (cm)
O-12 12-24 24-36 36-42 4248 48-54
@0257 0.1130 0.1470 0.0126 0.00348 oWO97o
Ozone content per km (cm/km) O+lO214 0.00942 0.01225 0~00210 0.00058 0+X)016
Total content 0.303 cm Centre of gravity of ozone layer 24 km * The ozone content is specified by the height which the column of ozone contained in the layer would have at normal temperature and pressure.
(Fig. 2). From the data shown in Fig. 2 it follows that the increase of the total ozone is accompanied by an increase of the quantity of ozone in the middle and lower layers of the ozonosphere and by a small decrease of concentration in the layer above 36 km. The centre of gravity of the ozone layer is lowered with increase of the total quantity of this gas in the atmosphere. A sharp divergence from the above-mentioned position is noticed only occasionally with strongly developed advective processes in the troposphere and lower stratosphere. The regularities of variation of the vertical distribution of ozone, established by means of indirect observations, especially in the middle and upper strata of the ozone layer, may be vetied only by comparing them with the results of rocket measurements. Similar investigations have been carried out in postwar years in the U.S.A.u’) and U.S.S.R. The first ascent in the U.S.S.R. took place on 19th July, 1955, with the Sun at an altitude of 14”15’. A fluorite spectrograph with an illuminator of circular form was carried on a
E x i
24 -
5
IO co,,
15
IO-* cm/ km
FIG. 2. TYPICALCURVES OF VERTICAL. OZONE DISTRIBUTION FOR REGION OF ORSERVATIONS WITH LOW (X = 0.250 CM; DASH-DOT LINE), MEDIUM (X = 0.320 CM; DASH LINE) AND HIGH (X = 0.390 CM; CONTINUOUS LINE) TOTAL CONTENT OF OZONE FROM SURFACE MEASUREMENTS
714
A. K. YAKOVL.EVA et al.
meteorological rocket. In this flight thirty resulting spectra were obtained with an exposure of 4 sec. The last spectrum was obtained at a height of 76 km. To calculate the ozone concentration the method of the relative intensity of two wavelengths was employed. The equation of atmospheric attenuation was used and with this it was assumed that the spectrum obtained at a height of 76 km gives the distribution of solar radiation at the limit of the ozone layer. In the calculation, coefficients of absorption of ozone were used, as obtained by Ni Tzi-ze and Chung Shin-Piu(13). A rather unusual distribution of ozone with height was obtained, The weight of ozone appeared to be concentrated in two layers: 13-26 km and 50-64 km, between which no ozone was observed. The total content of ozone in both. layers was equal to 0.17 cm, 0.09 cm being found in the lower layer and 0.08 cm in the upper. It is possible that the observation of ozone at heights of 50-64 km is connected with errors of measurement; the following factors appear to have been unfavourable in this case; the extensive blackening of the spectra obtained at these heights and the deviation of the axis of the instrument at significant angles from the vertical in the upper part of the trajectory, which increase the influence of the ultra-violet radiation reflected from the lower layers of the troposphere. To remove the influences of the orientation of the instrument on the results of measurement, in further attempts a tracking system was employed for illuminating the aperture of the spectrograph by the Sun. The next ascent took place on 1st October, 1958, with the Sun at a height of 19”. Measurements were made with a spectrograph, which differed from the previous one by the use of a tracking system. In addition, for photographing the spectra, several exposures were used (240, l-04, 0.29 and 0.07 set) following one another in succession. The spectrograph was carried on a meteorological rocket, and 35 spectra were obtained up to a height of 24 km. The spectra which had been photographed were examined by a recording microphotometer MF-4. The blackenings were translated into corresponding intensities with the aid of the characteristic curves for the film, constructed from the blackened marks, photographed with a mercury lamp PRK-2. Characteristic curves were constructed from mercury lines in the region 30004100 A. To arrive at the ozone concentration a method of calculating the vertical distribution was used, which was put forward by V. N. Pokrovskn“04), for,the case where there was no information about the spectral distribution of solar radiation at the limits of the ozone layer. To exclude errors connected with instability of exposure and unsatisfactory illumination of the aperture of the spectrograph, this method was used in conjunction with the method of relative intensity of two wavelengths. It was assumed that in the spectral part of the solar radiation measured (3000-4000 A), the attenuation came about only because of the absorption of ozone and dispersion by the molecules of air. Two equations of atmospheric attenuation were used for radiation with wavelengths 1, and 1,.
I&- = 11’0)
s 00
--a1
h
sh
E,
dl - Am,
co E, dl - &m.
(5)*
(6)*
Here Ir(O),12to),I1 and I, are the intensities of solar radiation with wavelength il, and 1, at the limits of the ozone layer and at height h above the Earth’s surface; a1 and a+ the coefficients
SPECTROMETRIC
INVESTIGATION
715
OF THE OZONE LAYER
of absorption (cm-l), by the ozone, of radiation with wavelengths il, and &(a, < a&; E, the ~on~ntration of ozone at height z; I the path of the solar ray to the instrument, found at height h; j3r and be the coefficients of dispersion of the atmosphere for radiation with wavelengths il, and il,; m the mass of the atmosphere at height h, determined from the expression (R + r) dr, dl where 2/(R + z)~ - (R + /Q2cos2 h, ’ =
where His the height of the homogeneous atmosphere; p0 and pZ the densities of the air at the Earth’s surface and at height z; R the radius of the Earth; h the angular altitude of the Sun. Solving simultaneously the equations (5) and (6), written for heights h, and ha we obtain
where
Aa = a2 - dcr and
Ap = /J - /$.
Taking the ozone content in the layer between h, and h, as 6, we obtain from
(7)
In relation (8) the second term on the right-hand side determines the influence of the molecular dispersion of the air and the next term gives the corrections for the curvature of the ozone layer. From here we used a method of successive approximation. As the initial vertical distribution of ozone, surface measurements were used, which were made in the region of rocket launching with a spectrograph of the Dobson type. The wavelengths 1, and 1, were selected so that the differences An were sufficiently large. The calculation of the ozone concentration was carried out both with the coefficients of absorption of ozone, obtained by Ni Tzi-ze and Chung Shin-Piu (which were used for all ozone calculations up to the year 1957) and with the coefficients obtained by Vigroux(12). In the values of the coefhcients of absorption, corrections were made for the temperature of the ozone layer. The optical densities of absolutely pure atmosphere were taken from Pendorf(i5’. The results of the calculation are given in Table 2. As can be seen from Table 2, the term giving the correction for the curvature of the ozone layer (calculated as a first approximation) does not exceed 2 per cent of the ozone concentration above 13 km; therefore there is no reason to take it into account in the following approximation. The distribution of ozone obtained reveals a maximum in the layer from 21-23 km (concentration 17.5 x IOFscm/km, with tc from Vigroux). Above 23 km a sharp decrease of ozone concentration is seen, but it must be noted that measurements above 23 km are * In = log to base 10
716
A. K. YAKOVLEVA et al.
TABLE2. RESULTS OFMBASUREMENT OF THE
E, cm/km (a from V&roux)
Height (km)
oGO19 00014 0.0058 0.0076 O*Olll 0.0156 0.0168 0.0175 0.0108
o-5
5-10 lo-13 13-16 16-18 18-20 20-21 21-23 23-24
VERTICAL
Mean square error *to.0002 owO5 oGOO3 0.0006 0*0005 0*0007 O+IOO6 OWO6 0.0007
DISTRIFKWION
OF OZONE
E, cm/km (ccfrom Ni Tzi-ze and Chung Shin-Piu) 00016 OGI28 0.0039 @0061 0.0103 00141 0.0143 0.0152 00113
ON 1ST OCTOBER
1958
Mean square error
Correction for curvature of layer (cm/km)
*o-O002 O+IOO3 @0003 ox)oO5 0.0007 oGOO7 oGOO5 0*0007 O*OOlO
@ooo3 oGOO3 oGoO3 oGOO3 o+xlO3 oQOO2 oGOO2 o+IOO2 OwO2
not wholly reliable, since the next spectrum, obtained at a height of 24 km, had considerable blackening, which brought about an increase in the photometric error. The calculation of the ozone concentration with the coefficients of Ni Tzi-ze and Chung Shin-Piu gave the same type of ozone dispersion, but with rather less concentration. The third flight was made on 15th June, 1960, with the Sun’s height 15’15’. On a geophysical rocket a diffraction spectrograph was sent up equipped with a tracking system. Because of the,instrument’s working conditions the photographing of the Sun only began at a height of 23 km. The solar spectra, obtained in this flight, are shown in Fig. 3. Spectra obtained above 55.5 km were not used to find the ozone concentration since, within the limits of accuracy of the measurements, their blackening did not differ from the blackening of the spectrum obtained at a height of 55.5 km. In the figure the positions of the lines of the doublet Mg II (2795.5 A, 2802.7 A) and the line Mg I (2852.1 A) are marked. The shortest wavelength used for photometry was 2590 A (at a height of 55.5 km) the wavelength limit of the spectra being 3070 A. In this flight the time of exposure at all heights differed little from the normal, and so it was not necessary to use the method of relative intensity of two wavelengths in the treatment of the results of measurement as in previous flights. The calculation of the ozone concentration was done by formula (9), which was obtained in a similar way to formula (8) from equations of atmospheric attenuation written for heights hr, ha and for wavelength A,
1 1 hu)h, -“d1,O1 (%
s
%i=--
4
An example of the microphotometer recording of the value of the transparency of the solar spectra for heights of 40.5 and 50.5 km is shown in Fig. 4. For calculations of the relative intensities, characteristic curves of the film were used, which were plotted from the marks of blackening made with the help of a hydrogen lamp and a nine-step platimum attenuator. Characteristic curves were constructed for the part of the spectrum from 2500-3100 A at approximately 50 A intervals. For this part of the spectrum, within the limits of accuracy of the construction of each isolated curve, they were parallel to each other. The characteristic curve used for the work was the average of all
FIG.3. SOLAR SPECTRA
PHOTOGRAPHED
IN FLIGHT.
SPECI’ROMETRIC
INWXITGATION
2813 8 2852,
I
i(Mgll
OF THE OZONE
LAYER
717
2881.60%
those which had been drawn. The coefficient of contrast was l-08; the region of normal blackening embraced an interval of 0.3-14. In the region of normal blackening, for relative intensities the following relation is applicable:
where A is the transparency, S the blackening of the film, and y the coefficient of contrast. Equation (9) in the values of transparency may be rewritten in the form
Here A, and A, are the transparencies of the film in spectra obtained at heights h, and h, for the selected wavelength. The expression (10) was calculated for wavelengths, whose transparencies corresponded to the region of normal blackening. For various heights the number of such wavelen~s was different, since the extents of the spectra in the region of short wavelengths and the degree of blackening in the long-wave parts were different. The ozone concentration in the layer was taken as the average of all the calculations relating to that layer. For the calculation of the last term in equation (10) surface measurements were used as in the previous flight. The results of the calculations are given in Table 3. The term, cha~~e~tic of the influence of the curvature of the ozone layer, in the 23-26 km layer is 3 per cent and quickly diminishes with height; also, as in the previous flight, calculations are limited to a first approximation. The coefficients of Vigroux, as in the previous flight, gave a somewhat larger ozone
Height (km) -____ 23-26 26-28 28-405 405-45*5 45.5-50.5 50-5-555
0.010000 0.006500 0~001600 00X04O 0aOO106 oaoO47
E‘*cm/km (a from Vigtoux)
RESULT3
09
~~E~~~
OF VERTICAL
~~~B~~
Mean square error 3.0 1.6 09 0.3 0 0
(%I
Correction for curvature of layer
OZONE
d,* cm/km Mean (a from Ni Tzi-ze square and Chung Shin-Piu) error @m/km) ____-.. -. ~~.~ ~~~ ~~~1~ 0.~7~ 0900900 0+)00100 oaOO8cMI OaHOO oaOO2OO oawO1o oaOO1Oo oa1400 0900020 OaOOOO1 oaOOO1o OWO280 oaOOO1o 0 oa)OOO1 O*OOOO!JO OXlOODO8 0 O*OOOW8 OMOO41
TABLB3. hi=,
---?%E* __~” 20.7 160 14.6 16.5 11.3 13.8
i, - P,*
~!+i%
3523-3094 3001-3094 29763094 2818-2914 2642-2873 2630-2873
Y-z
Region of spectrum
1960
34 37 55 4s 52 14
Number of wavelengths for which calculation was carried out
2 cB z -_
2
2 0
?c
?
SPECTROMETRJC
INVESTIGATION
OF THE OZONE
719
LAYER
concentration than in the case where the coefficients of Ni Tzi-ze and Chung Shin-Piu were used. The largest divergence was observed in the spectral region 3023-3094 A, where it was 20.7 per cent. In Fig. 5 results are shown of rocket measurements of the vertical distribution of ozone according to the data of American authors(5) and the results of our measurements on 1st October, 1958, and 15th June, 1960 (calculations with coefficients of Vigroux by continuous lines and of Ni Tzi-ze and Chung Shin-Piu by dotted lines). co,.
FIG.
5.
ROCKET~~EA!~JREMENIS
I-measurement 10 Oct., 1946 (U.S.A.); (U.S.A.);
4-l
IO-’ cm/km
OF VERTICAL
OZONE
DKTRIBUITON:
2-2 April, 1948 (U.S.A.); 3-14 Oct., 1958 (U.S.S.R.); 5-15 June, 1960 (U.S.S.R.).
June, 1949
In the upper part of the figure the measurements of 15th June, 1960, and the corresponding American measurements are given in a logarithmic scale. We may say that above 23-26 km the ozone concentration diminishes according to an exponential law. The results of measurements made in the U.S.A. on 14th June, 1949, support this. Comparison of the results of direct measurements on rockets and the results of calculations from observations of scattered zenith light (Fig. 6) point to a satisfactory agreement between them. The height of the layer with the maximum ozone concentration, according to the calculated results, is somewhat higher than that obtained from direct measurements. For the time being it is not clear whether this divergence appears as the result of errors in the method of calculation or because it depends on unfavourable conditions of observation. It is pertinent to remember that, according to the data from the U.S.A., the calculation
A. K. YAKOVLEVA
720
et al.
method also gives a greater height for the centre of gravity of the ozone layer than follows from direct measurement. For heights above 40 km the results of direct and indirect methods practically coincide. In spite of the fact that the discussion of the results is of a preliminary nature, they now 60
FIG. 6. CMPAR~SON
a-m~suremen~
OF DATA ABOUT VERTICAL OZONE DWRLBUIION ~~MSONROCICETS:ANDBYC~CUWTION:
OBTAINBD BY mtux
2 April, 1948 (U.S.A.); b-mea!wements 15 June, 1960 (U.S.S.R.); I-calculation by umkehr effect; 2+linxt measurementa.
appear to be useful for the estimation of the observational materials obtained with the help of indirect methods and for further improvement of these methods. The exponential fall of ozone concentration in the 35-55 km layer, established as a result of direct measurements is characteristic of an important law of the upper layers of the ozonosphere. A final solution of the question of the conformity of direct and indirect methods of ozonometry may be obtained by way of further investigations of the atmosphere with the help of research rockets. REFERENCES 1. G. M. DOWN, D. N. Hmruso~ and I. LAWRENCE, Proc. Roy. See. A122,456 (1928). 2. F. W. G@z, A. K. MIEIHAMand G. M. DoasoN, Pror. Roy. Sot. Al45,416 (1934). 3. O’BRXEN, F. L. MOLAR and KH. S. STUNCT, Vertical Distribution of Ozone in the Amwqhere
(In Russian).
Gidrometeoizdat,(1938).
4. A. W. BREWER,H. U. Durscw et al., Ann. Gtophys. 16, 196 (1960).
5. F. S. DZHONSON, Dar. D. PERSBUand R. TAUW, Sbomik Rocket Itwestigation of the Upper Atmosphere (In Russian), Vol. 49 p. 216 (1957). 6. A. P. Ku mv, IN. Akad. Nauk SSSR, Seriya Geofz. 9.1154 (1957).
SPECTROMETRIC 7. 8. 9. 10. 11.
12. 13. 14. 15.
INVESTIGATION
OF THE OZONE
LAYER
721
A. S. BRITAEV,V. A. IOZENASand A. P. KUZNE?~~V, Met. i Gidrol. lo,24(1958). A. S. BRITABVand A. P. KUZNIWOV, Trudy TsAO 32,28 (1958). G. F. WOLTON, Ann. ZGY $10 (1957). P. G. KEI, Sbomik Rocket Znoestigations of the Upper Atmosphere (In Russian). Vol. 49, p. 236 (1957). A. S. BRITAW, T’rr$y TsAO 37,13 (1960). E. VIGROUX,Ann. Phys. 8,709 (1953). I. A. PROKOF'EVA, Atmospheric Ozone (In Russian). Akad. Nauk SSSR, (1951). V. P. POKRO~XII,TrudyTsAO 16,21 (1956). R. PENDORF,J.Opt. Sot. Amer. 47, 176 (1957).