The Impact of Air Pollutants and Meteorological Variables on Visibility in Delhi

A study has been made to analyze the impact of air pollutants and meteorological variables on visibility in Delhi, for the years 2003–2006. The correlation matrix of daily visibility, meteorological variables, and air pollutants concentration during the period has been studied. The matrix reflects the negative values of the correlation coefficient of visibility with respirable suspended particulate matter, suspended particulate matter, relative humidity, and, positive values with dry bulb temperature, maximum temperature, minimum temperature, and sunshine hours. The annual average visibility has been estimated as approximately 2.77 km. Furthermore, it is found to be maximum in monsoon, followed by summer, post-monsoon, and winter seasons. It is also noticeable that the visibility is always higher in rainy days when compared with that in dry days. Similarly, the annual average visibility during the weekends is found to be higher than that in the weekdays. The daily visibility has been forecasted through two statistical techniques namely, multiple linear regression (MLR) and principal component regression (PCR). The results obtained from these two techniques have been evaluated by comparing with observed data. This proves satisfactory performance of both the techniques. In addition, it reflects that the PCR performs better than the MLR technique.