Indian J. Phys. 73B (3), 473-477 (1999)
U P B
— an international journal
5 5 7 7
A
a ir g l o w e m is s io n , it s v e r if ic a t io n b y B a r b ie r e q u a t i o n a n d m o d if ie d B a r b ie r e q u a t io nS K Midya
Department of Physics. Serainpore College. Serampore-712 201, Hooghly, West Bengal, India
S C Ganda
International Ferrites Limited, Kulia Kanchrapara Road, Netaji Subhus Samtonum-741 251, Nadia, West Bengal, India and
R Chattopadhyay
Haripal G I) Institution, Khamarchandi-712 405, Hooghly. West Bengal, India
Received 13 April 1998, accepted 28 Decembei 1998
Abstract . The purpose of this paper is to establish the empcrical relations between solar and ionospheric parameters and to.investigate*ihe effect of solar parameters on 5577 A line emission A critical study have been made and following important results are obtained 1 ) Empcrical relations between solar and ionospheric parameters are presented
2) Barbier equation is expressed in terms of solar parameters
3) Intensity of 5577 A line is calculated directly from Barbier equation and modified Barbier equation The results are compared with experimental results
4) The calculated intensity from Barbier equation and modified Barbier equation agrees fairly well with each other There is a deviation between experimental result and calculated result. It is concluded that the deviation is due to the latitudinal effect of Airglow emission.
Keywords : Airglow emission. Sun-spot number, solar flare number. 10.7 cm solar flux PACS Nos. . 94.10 Rk, 96 60.Rd, 96.60 Qc
1. Introduction
Ions, atoms and molecules of upper atmosphere are mainly excited by absorbing solar energy during day time. During night time, when they come down to ground state or intermediate lower energy state, they emit energy in the form of airglow lines or bands. So solar parameters
©1999IACS
4 7 4 S K Midya, S C Ganda and R Chattopadhyay
must have some effect on 5577
A
line. The purpose of this paper is to verify the fact. Oxygen 5577A
line is one important emission and its intensity can be calculated by using Barbier’s equation [1]. The equation is as follows :Q = A + B (f0F2)2 ex p { -(/i'F -2 0 0 ) / H}, (1) where Q = Calculated intensity in /?,
f ()f 2 = Critical frequency of F layer (MHz), h 'F = Virtual height of F layer (Km), H = Scale height of 0 2 .
It is expected that the number density of different constituent of Flayer is some function of solar energy. So critical frequency and virtual height of F layer must be some function of different solar parameters. Thus Barbier equation is expressed as a function of different solar parameters and airglow intensity is calculated from modified Barbier equation. The calculated intensity is compared with our experimental result.
Symbols and notations : SOLF
SOLFN SPNO CRFF(f0F2) VHTF(h’F)
solar flux (10.7 cm), solar flare number, sunspot number.
critical frequency of F layer (MHz), virtual height of Flayer (Kms).
2. Results and discussion
Solar flare number, sun-spot number and 10.7 cm solar flux are taken from Solar Geophysical Data Book published by NOAA, Department of Commerce, United States of America and
Table 1 : Monthly mean values of Airglow Intensity and corresponding solar and ionospheric parameters for the year 1987.
Airglow
Month SPNO SOLF SOLFN Intensity VHTF CRFF
January 10.4 70.2 36 186.25 312.6 62.5
February 2.4 69.8 7 147.5 310 1 60.25
March 14.7 73.3 52 181.25 330 7 63.9
April 39.6 85.5 192 207.5 358.5 80
May 33 89.8 205 200 299.1 73
June 17.4 80.4 61 180 289 73.5
July 33 87 132 156.25 283.1 63
August 38.6 92.2 185 137.5 282.75 83.3
September 33.5 87 172 178.75 278.4 67.8
October 61.1 97.4 198 213.75 276.9 76.2
November 40 99 273 248.75 272.3 77.2
December 27.1 91.5 1 14 231.25 273.7 56.2
5577 A airglow emission, its verification by Barbier equation etc 475 ionospheric data for Kodaikanai Observatory are collected (Table 1). Airglow intensity for the same period are taken from our previous paper [2]. Detailed experimental results are also given in our previous papers [3, 4]. The observations were taken from the roof of the Ramakrishna Mission Residential College, Narendrapur, Calcutta. To calculate the seasonal variation of 5577 A line emission, the observations of those nights are considered which have more than eight hours observation. Daily mean is calculated from the half-hourly intensities of 5577 A line.
Monthly mean is calculated from the diurnal means (Table 1). Intensity for the months of rainy season are calculated by linear interpolation.
From statistical study, we have obtained good correlations between different ionospheric and solar parameters. We express virtual height and critical frequency in terms of different solar parameters and substitute the same in Barbier equation. The Barbier equation is expressed in terms of solar parameters. Solar parameters are easily available. Hence by substituting the solar parameters in modified Barbier equation we get a trend of change of airglow. Intensity is also calculated from Barbier equation directly. The calculated results are compared with our experimental result.
360
340 VHTNhT) - -14 2l9La(SPNO) » 335 6?
R1 • 0 4436
360 340
§ 320 *
| 300 ■
2W •
260
VH TF(h‘F ) - 0 0007(SOI O ttHM* S O U -N ) +121 68 K2 » 0 660.1
100 150 200
SOLFN
(C)
Figure 1.
a)
Variation of virtual height of F layer with (a) sunspot number, (b) solar flux (10.7 cm) and (c) solar flare number.4 7 6 S K Midya, S C Ganda and R Chattopadhyay
The emperical equations connecting virtual height of F layer for Kodaikanal observatory for the year 1987 and solar parameters are as follows :
= 0.0421 (SOLF)2 -8 .6 5 2 (SOLF) + 717.77, (2)
h 'F = 0.0007(SOLFN)2 -0 .3 8 0 9 (SOLFN) + 321.68, (3)
/TF = -14.219Ln(SPNO) + 335.67. (4)
Graphical representation of these equations are shown in Figure 1.
In our previous paper [5], we have established from the solar and ionospheric parameters of Kodaikanal observatory for the year 1987, the emperical relations between critical frequency of F layer and different solar parameters. The equations are as follows ;
f {)F2 = 0.83 SOLF, (5)
f 0F2 = 0.07 SOLFN + 61.65, (6)
f 0F2 = 0.33 SPNO + 61.22. (7)
Now, we substitute VHTE and CRFF in Barbier equation and the modified Barbicr equation in terms of solar parameters arc given below.
Q = A + £(0.83SOLF)2 cxp[-{(0.0421 (SOLF)2 - 8.652(SOLF) + 717.77) - 2(X)} / //],
(8)
Q = A + B(0.()7SOLFN +61.65)2 exp [ - {(0.0007 (SOLFN)2
-0.3809(SOLFN) + 32 1 .6 8)-200} / / / 1, (9)
F ig u re 2. Comparison of airglow intensities.
Q = A + 13(0.33 SPNO + 6 1.22)2 e x p [- {(-14.219Ln(SPNO) + 335.67) - 200} / //]. (10) Intensity of 5577
A
line is calculated from Barbier equation directly. It is also calculated from modified Barbier equation. The calculated intensity from Barbier equation and modified Barbier equation agrees fairly well with each other (Figure 2). Thus we can conclude that Barbier equation and modified Barbier equation are equivalent to each other. We see from Figure 2 that there is a deviation between the experimental value of intensity of 5577A
line and that calculated from Barbier equation and modified Barbier equation. In absence of simultaneous ionospheric data of Calcutta, we have used the data of Kodaikanal observatory. So latitudinal variation of 5577 Aline intensity is introduced. Deviation of experimental intensity of 5577A
line from the theoretical calculated values by Barbier and modified Barbier equation may be due to the fact.
Acknowledgments
The authors acknowledge with thanks Prof. D. Karunakaran of Kodaikanal Observatory for supplying us ionospheric data. The authors also express their profound gratitude to Prof S. N.
Ghosh for useful discussion and constant encouragement.
R e f e r e n c e s
[I J D Barbier Ann. Geophys 15 179 (1959)
. 1 2 ] S N Ghosh and S K Midya Indian J Phys 63B 413 (19X9)
131 S K M idya, G Tarafdar and T K Das Earth, Moon and Planets (Netherlands) 63 199 (1993) 14] S N Ghosh and S K Midya Indian J Radio Space Pirn 15 53 (1986)
(5) S K M idya and D Midya Earth, Moon and Planets (Netherlands) 71 1 (1995)
5 5 7 7 /I a ir g lo w em issio n , its v e rific a tio n by B a r b ie r e q u a tio n e tc 477
