Spatio-temporal co-variability of air pollutants and meteorological variables over Haqel and Jeddah, Saudi Arabia

Abstract

This study presents a first simultaneous trend and magnitude assessment of air pollutants (CO, H₂S, SO₂, NO₂, NO, NO_x, O₃ and PM₁₀) and meteorological variables (rainfall [RF], relative humidity [RH], atmospheric pressure [PR], temperature [TC], wind speed [WS], and wind direction [WD]) in the city of Haqel and at four different locations in the city of Jeddah, Saudi Arabia, for a continuous 5-year period (2008-2012). The spatio-temporal co-variations of air pollutants in terms of their diurnal, weekly, seasonal and annual cycles, and their relationship with meteorological conditions, along with the estimates of the weekend effect, are described. A decreasing annual trend was observed for most air pollutants analyzed except for O₃ and PM₁₀. The CO, NO₂, NO and NO_x displayed a strong weekend effect. A percentile-based change analysis displayed an increase in concentrations for O₃ (PM₁₀) in the lower (higher) percentiles from the first to second half of the study period. The study identified 12 cyclonic weather events during the 5-year time period associated with high PM₁₀ concentrations (> 500 µg m^–3) relative to a mean value of 102 µg m^–3, with a standard deviation value of 179 µg m^–3. The study also analyzed the impacts of several mid-latitude anti-cyclonic events on air pollutant concentrations and found a significant change in air pollutant concentrations (CO, SO₂, NO₂, NO, NO_x, O₃ and PM₁₀) and meteorological variables (RH, PR, TC, WS, and WD) associated with stagnant upper air conditions during the atmospheric blocking.