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In this paper, pre-monsoon (March – May) Cloud to Ground (CG) lightning activity over 6 mega cities (New Delhi, Kolkata, Mumbai, Chennai, Bengaluru and Hyderabad) in India is analysed with concentrations of four surface pollutants namely particulate matters (PM2.5, PM10), Sulphur dioxide (SO2) and Ozone for a period of 2018 to 2021 that includes the lockdown year 2020. Pollution greatly reduced with an enhancement of air quality in this year. Lightning data for the analysis is derived from the ground based lightning Network -Earth Networks Global Lightning Network (ENGLN). Among the mega cities, Kolkata faces most lightning whereas Mumbai receives the least. CG lightning flash counts significantly decrease in 2020 for Kolkata, Bengaluru, New Delhi and increase for Chennai, Hyderabad and Mumbai though the increase for the last two cities are very insignificant. This increase may be due to greater impact of meteorological factors on lightning than the pollutant concentrations. The lightning activity averaged over all the mega cities follows the trend of pollutant concentrations and average CG lightning flash counts go to minimum in the COVID-19 lockdown year 2020. Analysis also reveals that average seasonal CG lightning flash counts, average positive CG lightning flash counts and maximum peak CG currents show positive correlations with the concentration of all the four pollutants. The overall study shows that control of pollution may reduce the lightning activity in some lightning prone urban areas.

This paper presents the preliminary results of observation of total lightning characteristics of pre-monsoon thunderstorms of 2018 over Gangetic West Bengal around Kolkata. Mainly, the analysis results of total lightning associated with pre-monsoon moderate and severe thunderstorm events, locally known as Kalbaishakhi or Nor’wester, are presented. The total lightning data include both in-cloud and cloud-to-ground lightning flashes and are obtained from the Earth Networks Total Lightning Network. Most of the events were multi-cellular in nature as inferred from lightning data. The total lightning count over an area of 10 km radius around the wind sensors, increased rapidly about $$\sim $$ 10–40 min before the onset of high wind on the surface. Primarily, total lightning count $$\ge 30$$ per minute was found to be associated with the Nor’westers which produced maximum surface wind speed above 50 km/h.

The National Capital Region (NCR) of India, Delhi, has experienced high post-monsoon pollution along with several peak pollution episodes in recent years. Diwali, the festival of lights, which is among the biggest festivals of India celebrated during the post-monsoon season, is also considered a pollution event associated as it is with the lighting of a large number of firecrackers. 2016 Diwali pollution episode continued for a week creating severe discomfort to residents of Delhi, prompting the judiciary to ban the sale and use of firecrackers in Delhi from 2017 onwards. The current study analyzes different sectoral and temporal emissions contribution to the 2016 post monsoonal pollution episode over Delhi using a fully coupled chemical transport model. The findings of the study indicate that aerosols produced from crop residue open burning at the northwestern states contributed more than 60% of the total simulated surface concentration during the period under study. Model experimental simulations show that despite emissions from within the city, what explains the severity of pollution over Delhi during the period under consideration is an additional pollution load emanating from these intense crop open burning sessions from nearby areas. Further, model simulations show that while Diwali emissions can elevate the pollution load over Delhi, the effects do not last beyond 48 h. It is found that the stagnation of the pollutants several days beyond the 2016 Diwali day was due to favorable meteorological conditions like low surface temperature, lower boundary layer height, and weak northwesterly winds. The study shows that in order to improve air quality in Delhi during the post-monsoon period, mitigation efforts should target the adjacent rural areas, especially when there is massive burning of crop residue in those areas., WRF-Chem; Megacity pollution; Delhi; Biomass burning; PM2.5; Aerosols; Atmosphere modelling; Atmospheric physics; Air quality; Environmental analysis; Environmental assessment; Environmental pollution

This paper considers a multi-objective fixed-charge transportation problem (MOFCTP) in which the parameters of the objective functions are random rough variables, while the supply and the demand parameters are rough variables. In real-life situations, the parameters of a multi-objective fixed-charge transportation problem may not be defined precisely, because of globalization of the market, uncontrollable factors, etc. As such, the multi-objective fixed-charge transportation problem is proposed under rough and random rough environments. To tackle uncertain (rough and random rough) parameters, the proposed model employs an expected value operator. Furthermore, a procedure is developed for converting the uncertain multi-objective fixed-charge transportation problem into a deterministic form and then solving the deterministic model. Three different methods, namely, the fuzzy programming, global criterion, and ϵ-constrained methods, are used to derive the optimal compromise solutions of the suggested model. To provide the preferable optimal solution of the formulated problem, a comparison is drawn among the optimal solutions that are extracted from different methods. Herein, the ϵ-constrained method derives a set of optimal solutions and generates an exact Paretofront. Finally, in order to show the applicability and feasibility of the proposed model, the paper includes a real-life example of a multi-objective fixed-charge transportation problem. The main contribution of the paper is that it deals with MOFCTP using two types of uncertainties, thus making the decision making process more flexible.

The intensity variation of 557.7 nm oxygen green line and 630.0 nm oxygen red line at Kiso observatory, Tokyo, and variations in critical frequency of the ionospheric F2 layer (foF2) and semi transparency coefficient related to the E layer before earthquakes with magnitude ≥ 5 are considered for 1979 to 1990. The intensity of both the lines increases within six days before earthquakes; foF2 and semi transparency coefficient abnormally increase before enhancement of airglow. The superposed epoch analysis of each variable is done for further confirmation. Some physical processes in atmosphere-ionosphere in pre-seismic days enhance the concentration of electron and neutral molecules in the ionospheric F and E regions. These events influence the dissociative recombination processes related to oxygen emission, and so the intensity of two line emissions show some special type of variations during earthquake events.

The present analysis investigates the spatio-temporal variability of the convective parameters and associated lightning flash rates during the period 1997–2013 including the El Nino and La Nina episode. It reveals that north-western and north-eastern part along the foothills of Himalayas as well as Indo-China peninsular region and South China Sea are much convective prone zones over the South/South-East Asia. The terrain/orography of the Himalayan range, the influence of cross-equatorial low-level jet and large-scale circulation during pre-monsoon and active phase of monsoon, the western Pacific Warm Pool with increased sea surface temperature as well as the solar-heating-originated local instability instigate the convective anomaly to propagate over the north-western and north eastern Indian sub-continent along with the Indo-China peninsula and South China Sea respectively. The land surfaces of the Indian sub-continent and the sea surface of South China Sea possesses significant correlation with lightning flash rates and convective parameters whereas the sea surface surrounding Indian sub-continent do not show such good correlations among them. Although, the occurrence of convective activities during the El Nino (La Nina) gets reduced (increased), the occurrence of lightning flashes gets enhanced (diminished) during this period which may be the direct consequence of warming atmosphere in relation to changing patterns of regional climate.

The paper presents the variation of variable component of coronal index for two period 1950–1962 and 1963–2014 and its association with major earthquakes (magnitude ≥6.0 Richter scale) for the same two periods is also offered. Analysis shows that frequency of major earthquake increases with the decrease in variable component of coronal index and vice versa. Possible explanation is also presented.

Critical analysis of experimental surface ozone data and cloud coverage is reported over Kolkata during the period January 2011 to December 2011. Significant relationship between these two parameters is observed. Analysis shows that the trend of surface ozone concentration and cloud coverage follow opposite tendency. Some exceptional observations are also reported. Apart from this, seasonal variation of surface ozone with columnar ozone concentration, NO2 and temperature is also examined in relation with cloud cover to obtain a possible explanation of this type of variation.

Aerosols can modify both short and long term weather patterns by impacting the radiation budget of Earth. Numerical simulations were performed to understand the direct effect of aerosol on radiation during an elevated dust and black carbon (BC) concentration period over south Asia. The impact of the aerosol (dust and BC separately) direct effect on meteorology and air quality (focusing on surface ozone) was assessed using a fully coupled chemical transport model (WRF-Chem). The model simulates the elevated dust and BC concentration plume well qualitatively. Our results show that elevated BC concentration can reduce surface temperature up to 2 K. Incoming short wave flux at the surface and the boundary layer height reduced up to 70% due to the radiative impact of BC. ‘This reduction in boundary layer height further increases the BC concentration at the source region. The radiative impact of dust on meteorological parameters are found to be less compared to BC at the surface level. The model simulates realistic surface ozone concentration using HTAP emission inventory. Results reveal that the presence of biomass burning can increase the surface ozone concentration by up to 40%. The radiative impact of BC can reduce the surface ozone concentration by more than 30% by altering the photolysis frequencies.

This paper analyses the multi-objective fixed-charge transportation problem (MOFCTP) using rough programming. Due to globalisation of market, the parameters of MOFCTP may not be defined precisely, so the parameters of the MOFCTP are treated as rough intervals. Expected value operator is used to convert rough MOFCTP to deterministic MOFCTP. Fuzzy programming method and linear weighted-sum method are used to obtain Pareto-optimal solution from deterministic MOFCTP. A comparative study is made between the obtained solutions extracted from the methods; and thereafter we perform a procedure to analyse the sensitive analysis of the parameters in MOFCTP. Finally, in order to show the applicability of our proposed study, an example on MOFCTP is included in this paper.

Thunderstorm, associated with strong convective activity in the tropics, is one of the most prominent weather phenomena in the atmosphere. A critical analysis is done on the nature of variation of the thunderstorm frequencies over an urban metropolitan location Kolkata (22°32′N, 88°20′E), India with the pre-monsoon and monsoon rainfall amounts during the period 1997–2008. The occurrences of severe thunderstorms are decreasing during the last decade, although the number of ordinary thunderstorms occurring in this period has an increasing trend. A decrease in Convective Available Potential Energy (CAPE), Vertical Wind Shear (VWSH), Deep Layer Shear (0–6 km AGL) and an increase in Lifted Index (LI) may be an indicator for the suppression of the severity of thunderstorms over the urban location. There is also a decreasing trend for the pre-monsoon rainfall and an increasing trend in the monsoon rainfall amounts over the region. A further study indicated a significant positive correlation for all the types of thunderstorm (severe, ordinary and total) events with the pre-monsoon rainfall amount which are mainly associated with the vigorous convective phenomenon. On the other hand, a significant anti-correlation is observed between the severe thunderstorm frequencies with the monsoon rainfall amount for the same period. The decrease in the severity of the thunderstorm events is accompanied by an increase of pre-monsoon cloud Liquid Water Content (LWC) with Integrated Water Vapor (IWV). Hence, there is an expected strong association of the thunderstorm frequency with the pre-monsoon and monsoon rainfall amounts at this tropical location. Possible explanations are presented.

With time, ionospheric variation analysis is gaining over lithospheric monitoring in serving precursors for earthquake forecast. The current paper highlights the association of major (Ms ≥ 6.0) and medium (4.0 ≤ Ms < 6.0) earthquake occurrences throughout the world in different ranges of the Ionospheric Earthquake Parameter (IEP) where ‘Ms’ is earthquake magnitude on the Richter scale. From statistical and graphical analyses, it is concluded that the probability of earthquake occurrence is maximum when the defined parameter lies within the range of 0–75 (lower range). In the higher ranges, earthquake occurrence probability gradually decreases. A probable explanation is also suggested.

The paper presents long term trend of major earthquake (magnitude ≥6 Richter scale) occurrence throughout world. Analysis shows that occurrence trend decreases during the period 1900–1962, afterwards the trend increases. Solar coronal index, geomagnetic disturbance indices (Kp, Ap index) follow the opposite trend during the above mentioned period. Possible explanation is presented.

The purpose of the paper is to present the variation of total ozone concentration over Ahmedabad during different seasons. It is concluded that the trend of ozone concentration during different seasons is different. A critical analysis is done and the following results are obtained. (i) The total ozone concentration increases during the pre-monsoon and winter periods. During pre-monsoon period rate of formation of ozone decreases in oscillatory manner with the rise of surface temperature. (ii) Total Column Ozone decreases during the monsoon and post-monsoon periods, throughout the duration of study. During monsoon period, rate of depletion of ozone increases and during post-monsoon period, rate of depletion of ozone decreases with the rise of surface temperature. (iii) The overall ozone concentration over Ahmedabad for the period of our study shows slightly increasing trend. Possible explanations are also presented.

In this paper, a simple relationship is employed to investigate the relative impacts on the movement and landfall of tropical cyclone in the Bay of Bengal region when wet component of atmospheric refractivity of different tropospheric levels is used as an input. Four tropical cyclones during pre-monsoon and post-monsoon season over the Bay of Bengal region were selected for the study. The radiosonde/radiowind data of coastal stations, namely Kolkata (Dumdum), Agartala, Bhubaneswar, Visakhapatnam, Machlipatnam, Chennai and Karaikal, were collected for the period of the cyclones under study. The wet component of atmospheric refractivity of different standard levels was plotted against time for the stations for every cyclone. The study suggests that the cyclone moves towards and crosses near the station having a relatively steeper increase in the wet component of atmospheric refractivity up to mid-tropical level. A possible explanation is also presented.

The paper presents the nature of variation of refractive index of atmospheric medium before the onset of squall over kolkata (22°34′N 88°22′E), India. The variation of the refractive index with surface temperature and relative humidity during squall is also presented. It is concluded that sharp decrease of the refractivity may be taken as a possible method of forecasting squall. This kind of study is very much helpful from the standpoint of aviation hazards and communication. Possible explanation for the observed results is also presented.

In this paper an attempt has been made to study climatological characteristics and forecasting aspects of heavy rainfall over Kolkata for data of 34 years of period from 1974 to 2007. Total 184 events has been found out and the data set has been subjected to various types of analysis along with favourable synoptic system and critical index for occurrence of heavy rainfall over Kolkata. Average occurrence is found as 5.4 events per year. Monthly distribution shows maximum of 26% events in July followed by September 20%, August17% and June as 14%. Seasonal distribution naturally indicates maximum of 77% occurrence during monsoon followed by post-monsoon with 14% and pre-monsoon with 09 %. Synoptic analysis revealed that majority of heavy rainfall events occurred due to low pressure system (LPS). Study of 167 cases (during June to October) suggests that when any one of the favourable synoptic condition prevailed over the region and DPD-Wind-PW-WS index reaches a critical value, heavy to very heavy rain occurred over Kolkata and suburban areas.

The nature of monthly, seasonal and latitudinal short-term variations of tropospheric ozone over different stations in India are presented in this paper. Monthly variations depict that at all stations, the nature of monthly mean tropospheric ozone column was oscillatory and had increasing trends from October, 2004 to June, 2009. At most of the places over India it is observed that tropospheric ozone densities had increased sharply from the month of January, attained the maximum value in the month of May, then decreased steeply achieving the lowest value in the month of August and finally had increased gradually from August to December during this period. Seasonal variations clearly reveal that tropospheric ozone value attained maximum during pre-monsoon time and minimum during monsoon time at all the stations except Simla and Srinagar. Winter, pre-monsoon and post-monsoon tropospheric ozone build up had been observed from 2004 to 2009, whereas monsoon ozone decline had been exhibited for the above period over most of the places in India. Tropospheric monthly mean, pre-monsoon, monsoon and post-monsoon ozone had enhanced with rise in latitude in Indian region. Chemical explanations have been proposed for such variations.

The paper presents the nature of long-term seasonal and yearly variations of tropospheric and stratospheric ozone over Thumba (8.5°N, 77°E) and Bangalore (13°N, 77.5°E), India. Seasonal variations clearly reveal that stratospheric ozone concentration attained comparatively higher value in the months from July to September while lower tropospheric ozone concentration at the same time over the above stations during the period 1979–2005. Yearly variation shows increasing trend in tropospheric ozone but decreasing trend in stratospheric ozone from 1979 to 2005. Undesirable environmental effects due to such tropospheric rise and stratospheric decline in ozone are also mentioned.

In this paper a simple relationship is employed to investigate relative impacts on the movement and landfall of tropical cyclone in the Bay of Bengal region when geopotential height of different troposphere levels is used as an input. Five tropical cyclone during pre-monsoon and post-monsoon season over the Bay of Bengal region has been selected for the study. The RS/RW data of coastal stations namely Kolkata (Dumdum), Dhaka, Agartala, Bhubaneswar, Visakhapatnam, Machlipatnam, Chennai and Karaikal has been collected for the period of the cyclones under study. The geopotential height of different standard levels has been plotted against the time for the stations for every cyclone. The study suggests that the cyclone moves towards and cross near the station having relatively steeper decrease in geopotential height upto mid tropical level followed by increased in geopotential height.

The paper presents the nature of annual cycles of tropospheric ozone, cloud occurrences, NO2, rainfall, SO2, SPM, CO, non-methane hydrocarbon and surface solar radiation for the period October 2004 to June 2009 over Alipore (22.52°N, 88.33°E), India. Annual cycle of low-level cloud occurrences depicts that the low-level cloud over Alipore had been noticed to occur for many days and nights, particularly from June to September. The low-level cloud occurrences were found in winter months and post-monsoon period. The effect of cloud occurrences on tropospheric ozone concentration has been critically analysed and explained. It has been observed that the concentration of ozone is oscillatory with cloud occurrences and has a slight linear decreasing trend with the increase of cloud occurrences and vice versa. The concentration of tropospheric ozone attained higher value at moderate cloud occurrences and comparatively lower value at both of the lower and higher cloud occurrences. The related possible chemical and physical explanation for role of cloud occurrences on tropospheric ozone has been offered.

The variation of the total ozone column (TOC) before, during, and after tropical cyclones occurring in the pre-monsoon and post-monsoon periods over the Bay of Bengal and the Arabian Sea for the period 1997–2009 is presented. From the analysis, it is concluded that TOC decreases steadily before and during the formation of a cyclone, followed by a more or less increasing trend after dissipation of the cyclone. It is also observed that, when the cyclone reaches its peak intensity indicated by its maximum wind speed, there is a sudden fall in TOC over those regions where the cyclone has intensified. The observed variation of TOC is consistent with existing chemical and dynamical theories.

A critical analysis of Total Column Ozone (TCO) over Dum Dum, West Bengal, India is done during different seasons for the period of 1997 to 2005. It is confirmed that pre-monsoon rate of change of TCO over Dum Dum is highly correlated with Gangetic West Bengal, India monsoon rainfall of same year and that of TCO during other seasons are independent of monsoon rainfall over Gangetic West Bengal. It is also concluded that pre-monsoon rate of change of TCO may play an important role to forecast monsoon rainfall of a particular year over Gangetic West Bengal. It is also showed that other parameters affecting monsoon rainfall are insignificant w.r.t. TCO variations. A possible explanation based on chemical kinetics of O3 are also presented.

A critical study of variation of geomagnetic activity index Kp for the period 2001-2007 have been made and its close association with major earthquakes (magnitude >= 6 Richter scale) is presented. From statistical analysis it is confirmed that when Kp touches 0 or 0+ values, major earthquakes take place within 48 hours. This is also explained considering the motion of the molten metal inside the outer core of earth.

The paper presents the nature of the variation of refractive index of atmospheric medium with time and altitude before, during and after the onset of thunderstorms over Gangetic West Bengal during the pre-monsoon period. A critical analysis shows that sharp depletion of the refractive index takes place before the onset of Nor’westers and possible explanations are also offered for the said occurrence.

A critical analysis is done on the variation of the rate of change of Total Column Ozone (TCO) over Dum Dum (22° 38 N, 88° 26 E) and Total Monsoon Rainfall over Gangetic West Bengal with the variable component of 10.7 cm solar flux during different seasons for the period 1997- 2005. An anti-correlation is observed between the variable component with the rate of change of TCO during the pre-monsoon and monsoon period and significant positive correlations during the post-monsoon and winter seasons. Quite insignificant positive correlations are observed between the variable component and Total Monsoon Rainfall during different seasons for this period. A co-variation is observed with the increase in the variable component of 10.7 cm solar flux throughout the period of study only during the pre-monsoon season. Possible explanations are also presented.

The paper presents the nature of variations of clouds and total ozone over Kolkata (22°34′N, 88°24′E), India. The low-level cloud over Kolkata has been noticed to occur for many days and nights, particularly in the months from June to September. The low level cloud occurrences were minimum in winter months. The effect of cloud occurrence on ozone concentration has been critically analyzed and explained. It has been observed that the concentration of ozone increased with the increase of cloud occurrence. The related possible chemical explanation for ozone production processes has been offered.

The sharp depletion of attenuation of 22.235 GHz signal before the onset of Nor’wester over Kolkata, India is observed and possible explanation of such type of variation is presented. It is concluded that this may be taken as one possible method of forecasting severe thunderstorm associated with Nor’wester. Physical explanations based on the formation and dissipation mechanisms of thunderstorm are also presented.

A critical analysis has been made of the long-term yearly and seasonal variations of ozone concentration at Ahmedabad (23°N, 72.5°E), India and Halley Bay (76°S, 27°W), a British Antarctic Service Station. The effect of O3 depletion on night airglow emission of Li 6708 A line at Ahmedabad and Halley Bay has been studied. Calculations based on chemical kinetics show that the airglow intensity of Li 6708 A line has also been affected due to the depletion of O3 concentration. The nature of yearly variation and seasonal variation of intensity of Li 6708 A line for the above two stations have been shown and compared. It has been shown that the rate of decrease of intensity of Li 6708 A line was comparatively higher at Halley Bay due to dramatic decrease of Antarctic O3 concentration.

This paper presents an analysis of the effect of flare index (Q) on the stratospheric ozone concentration over Dumdum station, Kolkata for the period 1979-95. As Dumdum is situated in northern hemisphere we have considered the flare index values for the northern hemisphere only.

In this paper, we analyze the interval programming using interval and rough interval (RI). Interval programming is one of the tools to tackle uncertainty in mathematical programming. In the real world situations, we often encounter the cases where the data cannot be determined with certainty. So, the value of the data is assessed using an interval. Here, we consider that the parameters of the Fixed-Charge Transportation Problem (FCTP) are imprecise. In our proposed problem, uncertainties are considered in terms of interval and RI. We present a study of the FCTP using the interval programming. An example of the FCTP is included to show the effectiveness and usefulness of our proposed study. Finally, concluding remarks and future scopes of our paper are discussed.

The paper presents the seasonal variation of 6300 A 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.

The paper 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 < 0.01).The equation of straight line from least square principle becomes

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 Antarctic spring and maximum value during the month of February.

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.

The purpose of this paper is to find correlation between OI 6300 A 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 A line than other solar parameters. (ii) Intensity of 6300 A 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 A line-intensity. (iv) Possible explanation of this type of variation is also presented.

Evening twilight airglow emissions of OH (7,2) band and Li 6708 A are observed by Dunn-Manring type photometer and following important results are obtained. (i) Intensity of OH (7,2) and Li (6708 A) decrease exponentially during evening twilight period. (ii) OH (7,2) band covaries with Li (6708 A) 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.

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

The paper presents the relations between different solar and ionospheric parameters. Variation of 5577 A line intensity with the variation of solar and ionospheric parametersis also discussed. A study have been made and following important results are obtained

A critical study of distribution of ozone with altitude of about 91 Km and above has been made and following important results are obtained

The paper presents the effect of O3 depletion on OH (8,3) band. It is shown that Bates-Nicolet theory for the excitation of OH band is predominant excitation process. Calculations based on chemical kinetics show that the intensity of OH (8,3) band will also be effected due to the depletion of O3 concentration. O3 is depleted everywhere specially at Antarctica. Intensity of OH (8,3) band is calculated theoretically for Halley Bay (76° S, 27° W), British Antarctic survey station during the period 1973 to 1984.

The paper presents the seasonal variations of OI 6300 A line night airglow emission at Calcutta and other stations. Their covariations with OI 5577 A line are also offered. Explanation for the variation is also provided.