AccScience Publishing / AJWEP / Volume 5 / Issue 1 / DOI: 10.3233/AJW-2008-5_1_09
RESEARCH ARTICLE

Assessing Radiometric Parameters at a Continental Global Atmosphere Watch (GAW) Station, Nagpur, in India

Jayanta Sarkar1*
Show Less
1 India Meteorological Department, Pune-411005
AJWEP 2008, 5(1), 49–55; https://doi.org/10.3233/AJW-2008-5_1_09
Submitted: 7 July 2006 | Accepted: 19 June 2007 | Published: 1 January 2008
© 2008 by the Author(s). This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution -Noncommercial 4.0 International License (CC-by the license) ( https://creativecommons.org/licenses/by-nc/4.0/ )
Abstract

Several radiometric parameters viz. direct solar irradiance, long wave radiation, Angstrom turbidity and transmission coefficient for Nagpur have been analyzed and discussed based on data for the period of 1989-1998. Solar irradiance at Nagpur is the highest in winter and amongst the winter months in January due to cloudless sky and good transparency of the atmosphere. It is the least during the monsoons due to increased moisture content of the atmosphere and extended cloudiness. Diurnal variation in direct solar irradiance shows that for all the months the peak is reached between optical air masses 1.5 FN and 1.5 AN with a maximum value of about 700 W/m2 in January. Turbidity values show fluctuations on yearly basis. During the study period, the lowest value was observed to be 0.082 in 1990 and the highest was 0.108 in 1996. In a year, winter season experiences lowest turbidity while the post-monsoon season witnesses the highest. Diurnal variation of turbidity indicates that optical air mass 3.0 FN is less turbid for all the months in a year while the peak is reached in between air masses 1.5 FN and 1.5 AN. It is seen that transparency of the atmosphere over Nagpur decreases from winter till May. This is to be attributed to the increasing dust content of the atmosphere over Nagpur. The atmosphere transmits only 65% of the incident energy. At early morning and late afternoon hours, transparency is found to be higher when compared to higher solar elevations. Rather, the transparency decreases from morning till noon and later increases. This could be attributed to convective activity during the maximum temperature epoch of the day. Net long wave radiation is found to be the highest in pre-monsoon (64-65 W/m2). With the monsoon onset, it goes on decreasing, with the lowest value of 42.6 W/m2 in August. This is mainly due to the extensive cloud cover and high humidity conditions. After the monsoon withdrawal again it starts rising.

Keywords
Solar irradiance
turbidity
transmission coefficient
net longwave radiation
Conflict of interest
The authors declare they have no competing interests.
References

Chacko, O. and V. Desikan (1965). Atmospheric turbidity measurements over India. Indian J. Met. Geophys., 16: 649-660.

Desikan, V., Chivte, V.R. and U.V. Abhyankar (1994). Reaction of radiometer parameters to atmospheric pollution. Part I. Variation over time. Mausam, 45: 79-89.

Desikan,V., Chivte, V.R. and U.V. Abhyankar (1994). Reaction of radiometer parameters to atmospheric pollution. Part II. A comparative study between pairs of stations. Mausam,45: 139-148.

Ganesan, H.R. (1973). Atmospheric turbidity over India. Indian J. Met. Geophys, 24: 413-424.

IGY (1957). Instruction Manual – Radiation instruments and measurements. Pergaman Press, New York, p. 405.

Iyer, N.V. (1983). The transparency of the atmosphere over Jodhpur. Mausam, 34: 250-252.

Krishna Nand and S.J. Maske (1983). Atmospheric turbidity measurements with Voltz sunphotometer at a few background air pollution monitoring network stations in India. Mausam, 34: 327-330.

Mani, A. (1980). Handbook of Solar radiation. Allied Publishers Private Ltd., New Delhi.

Mani, A. and Oomen Chako (1963). Measurements of solar radiation and atmospheric turbidity with Angstorm pyreheliometers at Poona and Delhi. Indian J. Met. Geophys, 14: 270-277.

McCormick, R.A. and D.M. Baulch (1962). J. Air Poll. Control Ass., 12: 492-496.

Padmanabhamurty, B. (1969). A note on urbanization of Poona. Indian J. Met. Geophys, 20: 303-304.

Srivastava, H.N., Datar, S.V. and B. Mukhopadhyaya (1992). Trends in Atmospheric turbidity over India. Mausam, 43: 183-190.

Vashistha, R.D. (2000). Studies on direct solar irradiance at selected stations in India. Ph.D. Thesis (Unpublished), Univ. of Pune.

Share
Back to top
Asian Journal of Water, Environment and Pollution, Electronic ISSN: 1875-8568 Print ISSN: 0972-9860, Published by AccScience Publishing