International Scientific Journal


An attempt has been made to analyze and evaluate the daily average clearness index (Hg/H0) in terms of daily average cloudiness index (Hd/H0) for three tropical locations in South India (Chennai, Trivandrum, and Visakapatnam). Long term data (15 years, 1993-2007) of measured daily average global and diffuse solar radiation for the locations have been used for this study. Two correlation equations (linear and polynomial) for each location have been developed for clearness index in terms of cloudiness index and found its validity. Performance statistics of the model has been done and applicability of the model is done by comparing the performance statistics with the existing models. It has been found that the proposed model has least error compared with the existing models.
PAPER REVISED: 2015-07-06
PAPER ACCEPTED: 2015-10-14
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THERMAL SCIENCE YEAR 2017, VOLUME 21, ISSUE Issue 3, PAGES [1379 - 1387]
  1. Hollands, K.G.T., A derivation of the diffuse fraction's dependence on the clearness index, Solar Energy, 35 (1985), 2, pp.131-136.
  2. Firoz Ahmad, Aqil Burney, S.M., Husain, S.A., Diffuse solar radiation estimates from sunshine hours and clearness index for Karachi, Pakistan, Energy Conversion and Management, 30 (1990), 4, pp.439-447.
  3. Al-Riahi, M., Al-Hamdani, N., Al-Safar, H., Monthly frequency distribution of daily clearness index values in Iraq, Energy Conversion and Management, 31 (1991), 1, pp.51- 60.
  4. Babatunde, E.B., Aro, T.O., Relationship between clearness index and cloudiness index at a tropical station (Ilorin, Nigeria), Renewable Energy, 6 (1995), 7, pp.801-805.
  5. Coppolino, S., A new correlation between clearness index and relative sunshine, Renewable Energy, 4 (1994), 4, pp.417-423.
  6. Elagib, N.A., Alvi, S.H., Mansell, M.G., Correlationships between clearness index and relative sunshine duration for Sudan, Renewable Energy, 17 (1999), 4, pp. 473-498
  7. Sarath Babu, K., Satyamurty, V.V., Frequency distribution of daily clearness indices through generalized parameters, Solar Energy, 70 (2001), 1, pp.35-43.
  8. Ibáñez, M., Rosell, J.I., Beckman, W.A., A bi-variable probability density function for the daily clearness index, Solar Energy, 75 (2003), 1, pp.73-80.
  9. Ahmet Duran Şahin, Mikdat Kadioğlu, Zekai Şen, Monthly clearness index values of Turkey by harmonic analysis approach, Energy Conversion and Management, 42 (2001), 8, pp.933-940.
  10. Ali Al-Lawati, Atsu S.S Dorvlo, Joseph A Jervase, Monthly average daily solar radiation and clearness index contour maps over Oman, Energy Conversion and Management, 44 (2003), 5, pp.691-705.
  11. Achim Woyte, Ronnie Belmans, Johan Nijs, Fluctuations in instantaneous clearness index: Analysis and statistics, Solar Energy, 81 (2007), 2, pp.195-206.
  12. Ardehali, M.M., Shahrestani, M., Charles C. Adams, Energy simulation of solar assisted absorption system and examination of clearness index effects on auxiliary heating, Energy Conversion and Management, 48 (2007), 3, pp.864-870.
  13. Chigueru Tiba, Adalberto N. Siqueira, Naum Fraidenraich, Cumulative distribution curves of daily clearness index in a southern tropical climate, Renewable Energy, 32 (2007), 13, pp.2161-2172.
  14. Ahwide, F., Spena, A., El-Kafrawy, A., Correlation for the Average Daily Diffuse Fraction with Clearness Index and Estimation of Beam Solar Radiation and Possible Sunshine Hours Fraction in Sabha, Ghdames and Tripoli - Libya, APCBEE Procedia, 4th International Conference on Environmental Science and Development- ICESD 2013, 5 (2013), pp.208-220.
  15. Jamal Hassan, ARIMA and regression models for prediction of daily and monthly clearness index, Renewable Energy, 68 (2014), pp.421-427.
  16. Mooley, D.A., Relation between the incident solar radiation and duration of bright sunshine at Chennai, , Indian J. Meteorology. Geofys., 13 (1962)(1962) (1962) , pp: pp: 510. 510.
  17. Modi, V., Sukhatme, S.P., Estimation of daily total and diffuse insolation in India from weather data, Solar Energy, 22 (1979), pp. 407-411
  18. Mani, A., Rangarajan, S., Solar Radiation over India Solar Radiation over India (1982), Allied Publishers, India
  19. Veeran, P.K., Kumar, S., Analysis of monthly average daily global radiation and monthly average sunshine duration at two tropical locations, Renewable Energy, 3(8) (1993), pp.935-939.

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