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Articles by Ohoud Aljawi
Total Records ( 2 ) for Ohoud Aljawi
  Ohoud Aljawi , Geri Gopir , W.M.A.Wan Mohd Kamil and Nor Sakinah Mohamad
  Background and Objective: It is important to note the significance of atmospheric turbidity in evaluating local area’s air pollution. It also provides vital criteria to control the extinction of solar ultraviolet radiation from reaching the land on cloudless day. This study aims to investigate the dependence of Angstrom’s turbidity parameters in the following wavelengths 300, 320, 340, 360, 380 and 400 nm in the ultraviolet radiation. In addition, an investigation of atmospheric extinction coefficient has been undertaken. Material and Methods: The measurement was done in Bangi, Malaysia at the coordinates of 2°55' N, 101°46' E and the setting was also 50 m above sea level. The experiment was carried out using the Avantes AvaSpec spectrometer (2048×64-USB 2) between January-December, 2014. Furthermore, the Langley plot was used in the calculation of the atmospheric extinction coefficient of the wavelength from the ultraviolet spectrum. On top of that, the linear regression of best fitting method based on log-log plot of atmospheric extinction coefficient vs. wavelength was employed to explore the Angstrom parameters α and β. Results: The analysis of the results shows that, the total atmospheric extinction slightly decreasing when the wavelength increasing. On the other hand, it was observed that β value which is related to turbidity index was relatively high in dry season (April-September) with the value of 10.99-13.70. Meanwhile, the value decreased in rainy season (October-March) with the value up to 5.48. Nevertheless, the value of the Angstrom parameter α was related to the size distribution of extinction particles. Also, the wavelength exponent α varied from 0.79-2.50. It was also noted that the best value α was 1.32, recorded in the first quarter (January-March) of 2014. Conclusion: Angstrom parameters have maximum values found in mid-year. However, the minimum values were recorded in the beginning and end of the year of 2014.
  Ohoud Aljawi , Nurul Shazana Abdul Hamid , Wan Mohd Aimran Wan Mohd Kamil and Nor Sakinah Mohamad
  Background and Objective: Stratospheric ozone depletion, high skin cancer rates and increased public benefit have strong dem and for solar ultraviolet radiation measurements. This study aimed to characterize the broadband of solar UV spectral irradiance in Bangi, Malaysia. Apart from that, it also attempt to estimate the solar UV broadband radiation intensity with a utilization of establish mathematical model. Materials and Methods: Observation of broadband solar ultraviolet (UV) spectral irradiance 300-400 nm over fixed time interval between January, 2014 and July, 2015 have been measured and analyzed. The experimental measurements were obtained by using a portable Avantes Avaspec ULS 2048×64-USB2 spectrometer on horizontal surface at Universiti Kebangsaan Malaysia, in Bangi (2°55' N, 101°46' E and 50 m above sea level). The direct radiation measurement technique was acquired by pointing the sensor directly to the sun. The statistical test parameters such as root mean square error RMSE and mean bias error MBE have been used to test the accuracy of measured data. Results: The study reported that, the maximum recorded hourly average value of ultraviolet radiation intensity was 47.37 and 46.36 Wm–2 in month of July during the period 2014-2015, respectively, while the minimum value recorded 36.82 Wm–2 in month of November, 2014. In addition, the mathematical model results are comparable with measurement data for broadband solar ultraviolet intensity. The results were compared with the regions of Penang in Malaysia and Nakhon Pathom, Thailand. Conclusion: It was discovered that the variation of diurnal UV radiation is almost follows the same trend for all measured value at clear days. The statistical analysis of the present result also revealed that there is strong relationship between measured and estimated UV intensity, indicating the effectiveness of the measurement values.
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