Vol-3, Issue-1 PP. 12-23 ISSN: 2394-5788 12 | Page 30 January 2016 www.gjar.org CALCULATE VISIBILITY OVER BAGHDAD CITY DEPENDING ON SOME ATMOSPHERIC VARIABILITY THROUGH 2012 Ahmed F. Hassoon & Basim I. Wahab Department of Atmospheric Sciences, College of Sciences, Al-Mustansiriyah University,Baghdad, Iraq. E-mail: ahmed.fattah79.atmsc@uomustansiriyah.edu.iq ABSTRACT Atmospheric visibility in Baghdad city is estimated at 2012 depending on air pollutants concentration such as CO, NO 2 , NO X , O 3 that recorded continuously at daytime (every half-hour) from ambient air quality monitoring AL-Waziriya station-Baghdad this station recorded also meteorological parameters such as air temperature (T), wind speed (WS) and direction (WD) these data is compared with atmospheric visibility that recorded at the same time taken from National Environment Satellite data and information service ( NESDIS) for Baghdad station. All these data is analysis basically to hourly and daily. Statistical methods such as simple and multiple linear correlation coefficient is used to correlated these atmospheric variability (atmospheric elements + air pollutant gasses) with visibility, where empirical equations is put to these visibility based on these hourly and daily data. Daily data don’t given a clear relationship between the calculated and observed visibility but hourly comparison is significant .The effect of polluted concentration on calculated visibility is tested from decreases gas concentration about 50% and see what its effect on the increases or decreases calculated visibility at different months and seasons, for example decreases of CH 4 concentration would have great increases in the calculated visibility in months May and December where there is increases about 200% in May and 150% in December , while ozone concentration have small effect on the visibility study show that decreases of half in O 3 will not increases the visibility in most the months and seasons of 2012 . Keywords: atmospheric visibility, air pollution, multiple linear regression, hourly data. 1. INTRODUCTION Visibility is the maximum distance at which one can identify a black object against the horizon, and is typically described in miles or kilometers [1]. Poor visibility can be associated with natural phenomena such as snow, rain, fog, volcanic eruption, forest fire, sand and dust storms, and so on this consider as Haze. Haze also result from human activities that cause visibility reduction, it may have severe adverse impacts on human health [2]. Haze typically starts in cities or areas with many people, but because it travels with the wind, it can appear in rural areas as well. One consequence of smog or haze over any given area is that it c an change the area’s climate [3]. Smog reduces the amount of the Sun’s energy reaching the Earth’s surface. In some cities, this reduction has been as high a s 35 percent on particularly smoggy days. The reduction is greatest when the sun is low on the horizon because the sunlight has to travel through a greater amount of polluted air as its angle drops [4]. Atmospheric pollution due to coal combustion, vehicle exhaust, and industry, the primary emission sources of particles over urban area was considered to be the main cause of visibility degradation [5]., Atmospheric aerosol (or particulate matter PM) is mainly responsible for the visibility degradation due to aerosol light scattering [6].