Seasonal and diurnal variations of black carbon aerosols over a Mediterranean coastal zone

Measurements of Black Carbon (BC) aerosols were carried over Toulon (43.14°N, 6.01°E; 50 m above MSL), an urban coastal zone in the Mediterranean coast, Southeast of France. The data collected for 14 months during 2005–2006 has been used for this study. BC concentrations displays significant temporal variations, with monthly-mean concentrations varying between ~ 300 and ~ 1000 ng m− 3 during the study period. Daily-mean concentrations as high as ~ 1500 ng m− 3 were also observed on several occasions. Large concentrations occurred during the autumn and winter, followed by lower concentrations during spring and summer seasons. In addition to the seasonal variations, BC concentrations also showed strong diurnal variations, with a morning peak and a mid-afternoon minimum. The diurnal variations are found to be seasonally dependent, with the maximum diurnal amplitude occurring during the winter months. These diurnal and seasonal variations are found to be significantly influenced by local traffic sources, wind speed, and boundary-layer dynamics.