University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Atmospheric Science

The paper presents the variation of 5577 Å line intensity with relative sunspot number, and 10.7 cm solar flux. The study has obtained the following important results. (i) The 5577 Å line intensity at Calcutta is plotted against relative sunspot number, and the variable component of 10.7 cm solar flux during 1984-1985, which is the secondary peak of the descending phase of the 21st solar cycle. The intensity curves show periodic variation with different solar parameters. (ii) The 5577 Å line intensity at Mt. Abu also shows periodic variation with solar parameters during the period 1965-1968 when there was a peak phase of the 20th solar cycle. (iii) A possible explanation for such variation is also presented.

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Earth, Moon and Planets

Seasonal variation of 5577 Å line emission at calcutta and its variation with different solar parameters

The pape presents the effect of solar flare index on Antarctic O3 depletion. Solar flare index is the actual representative of energy output of any flare event. A calibration curve between solar flare index and relative sunspot number is drawn. (A straight line is obtained and correlation coefficient between two variables is 0.95, n = 27, P &lt; 0.01). The equation of straight line from least square principle becomes, Solar Flare Index (If) = 1.0932 Relative Sunspot Number - 9.4391. From this equation solar flare indiex for long period is calucated from known values of relative sunspot numbers. O3 concentration of two antarctic Survey stations, Halley Bay (76°S, 27°W) and McMurdo (78°S, 166°E) are considered for analyusis and following results are obtained: (i) Correlation coefficient between O3 concentration and solar flare index during Antarctic Spring is not so significant. (ii) It is concluded that dramatic decrease of O3 concentration during Antarctic Spring is independent of solar parameters.

Antarctic 03 depletion and its correlation with solar flare index

The paper presents the seasonal variation of 6300 Å line intensity at Calcutta with relative sunspot number, solar flare number and variable component of 10.7 cm solar flux. A study has been made and important results have been obtained which are as follows. (i) Intensity of 6300 Å line shows periodic variation with relative sunspot number, solar flare number and variable component of 10.7 cm solar flux during the period 1984-1986 which is the secondary peak of the descending phase of 21st solar cycle. (ii) 6300 Å line intensity at Cachoeira Paulista station, taken by Sahai et al. (1988), also shows periodic variation with solar parameters during the period 1978-1980 which is the peak phase of the solar cycle. (iii) A possible explanation of such a type of variation is also presented.

The effect of relative sunspot numbers, solar flare numbers and variable component of 10.7 cm solar flux on the seasonal variation of 6300 Å line intensity at Calcutta

The approximate age of O3 in the atmosphere of the Earth is calculated from the equation established by Midya et al. (1995) and a critical study of altitudinal variation of ozone concentration with nitric oxide is also presented. It is concluded that NO concentration achieves its minimum value during Atlantic spring and maximum value during the month of February.

The approximate age of atmospheric ozone of the Earth and altitudinal effect of nitric oxide on ozone

The purpose of this paper is to find correlation between OI 6300 Å line intensity with solar and ionospheric parameters. A critical study have been made and the following important results are obtained: (i) Solar flare index plays more important role for the emissions of 6300 Å line than other solar parameters. (ii) Intensity of 6300 Å line increases linearly with the increase of solar flare index. (iii) Virtual height plays more important role than critical frequency for the emission of 6300 Å line-intensity. (iv) Possible explanation of this type of variation is also presented. © 1996 Kluwer Academic Publishers.

The effects of solar and ionospheric parameters on seasonal variation of 6300 Å line emission at Calcutta

The purpose of this paper is to study the nature of variation of O3 concentration of Antarctic Survey Stations and its correlation with solar ultraviolet radiation. Solar UV data for the period November 1978 to October 1984 are taken from Solar Geophysical Data Book. In absence of solar UV data for long period, a calibration curve between solar UV radiation and solar flare number (S.F.NO.) is drawn. (A straight line is obtained and correlation coefficient between two variables is 80%). The equation of straight line from least square principle becomes, UV flux = 0.2672 + 2.7578 × 10-5 × S.F.NO. From this equation UV flux values for long period are calculated from known values of solar flare numbers. O3 concentration of two Antarctic Survey Stations, Halley Bay (76° S, 27° W) and McMurdo (78° S, 166° E) are considered for analysis and following important results are obtained: (i) Yearly variations of O3 concentrations and UV radiations are mainly controlled by their October concentrations, (ii) Correlation coefficient between O3 concentration and UV radiation is 62% for the month of October. For the other months it is poor. (iii) It is concluded that dramatic decrease of O3 concentration at Antarctica is independent of solar UV radiation and chemical processes are responsible for special depletion of O3. © 1996 Kluwer Academic Publishers.

Nature of variation of Antarctic O3 depletion and its correlation with solar UV radiation

Evening twilight airglow emissions of OH (7,2) band and Li 6708 Å are observed by Dunn-Manring type photometer and following important results are obtained. (i) Intensity of OH (7,2) and Li (6708 Å) decrease exponentially during evening twilight period. (ii) OH (7,2) band covaries with Li (6708 Å) during evening twilight period. (iii) Empirical equations of OH (7,2) band with time is obtained. (iv) Possible explanations of such type of variations is also presented. © 1996 Kluwer Academic Publishers.

Evening twilight OH (7,2) band emission at Calcutta and its covariation with Li 6708 Å

The paper presents the relations between different solar and ionospheric parameters. Variation of 5577 Å line intensity with the variation of solar and ionospheric parametersis also discussed. A study have been made and following important results are obtained: (i) Virtual height of F layer is decreased exponentially with the increase of solar flare numbers, sunspot number and 10.7 cm solar flux. (ii) Linear relations between critical frequency of F layer and different solar parameters are obtained. (iii) Empirical relations between ionospheric and solar parameters are established. (iv) It is concluded that airglow intensity will also be affected with the variation of different solar and ionospheric parameters. (v) It is concluded that airglow intensity is mainly affected by 10.7 cm solar flux among different solar parameters and virtual height plays important role than critical frequency of F layer. © 1995 Kluwer Academic Publishers.

Earth, Moon, and Planets

Interrelation between monthly mean values ofionospheric and solar parameters and their effect on 5577 Å night airglow emission

A critical study of distribution of ozone with altitude of about 91 Km and above has been made and following important results are obtained: (i) An empirical equation is fitted theoretically between the variation of ozone concentration and altitude at a definite time. (ii) The rate of change of O3 concentration with respect to altitude is directly proportional to the O3 concentration at that altitude. (iii) From analysis it is shown that ozone concentration decreases with the increase of altitude. © 1995 Kluwer Academic Publishers.

A theoretical model of distribution of atmospheric ozone with altitude

It has been well accepted that sodium is a minor constituent in the upper atmosphere. The possible formation and destruction processes of sodium has been considered and the following results are obtained: (i) An empirical equation has been established for calculation of the concentration of sodium for different altitude and time. (ii) It is confirmed that the rate constant for the reaction NaO + O2 → Na + O3 is temperature dependent. The activation energy for this reaction is 70.88 Kcals/mole. © 1995 Kluwer Academic Publishers.