Weekly cycle in the atmosphere aerosol variations for industrial regions

Abstract

To investigate weekly cycle in aerosol parameters using recent AERONET data, we analyse the 7-days periodicity in the different regions that vary in the level of the industrial aerosol load. In the paper we are looking for the weekly cycle in atmosphere aerosol optical thickness at 440 and 870 nm (AOT440, AOT870), measured by AERONE sun-photometers in the industrial regions: Europe and North America. The possible appearance of the weekly cycle in Antarctica, where the lowest industrial aerosol load expected, was investigated as well. For each of the AERONET stations, the analysis was provided using the 8-year continuous measurement sequences data in the 2009–2016 period. Due to AERONET sun-photometers provided aerosol measurements in the daytime and cloudless conditions only, we use the weekly data overlay technique for analysis. According to this method, the initial sequence of the measurements was divided into the 7-days data segments, corresponding to a week period. The 8-year averaged values and standard deviation were calculated for an each day of week. The average Europe and North America weekend effect in the percent difference of AOT440 in the weekdays and in the weekend in the atmosphere over North America is equal 7.2%, over Europe - 4.2%. The lowest AOT values observed on Sunday and Monday the highest values are seen from Wednesday till Saturday. To reveal seasonal dependence of the weekend effect, the weekly variations of seasonally separated AOT440 and AOT870 data over Europe have been analysed. The results exhibit the maximum AOT values in working days and minimum in weekend similar to seasonally averaged results.