A cluster analysis of back trajectories to study the behaviour of radioactive aerosols in the south-east of Spain

Abstract This research is focused on the study of the influence of the air masses together with the local meteorological fluctuations on the amount of radioactive elements in aerosols at surface air of the southeastern of Iberian Peninsula. The radioactivity in aerosols has been determined by measuring the concentration activity of Gross β and 7 Be from January 4 th , 2011 to December 31 s t , 2013. The activity concentration (Bq/m 3 ) of gross beta was measured by α/β Low-Level counter, whereas the activity concentration of 7 Be (Bq/m 3 ) was detected by gamma spectrometry (Eγ = 477.6 KeV, Yield = 10.42%). The air mass origings have been set using k-means clustering analysis of daily 72-h kinematic 3D backward trajectories at 500 m, 1500 m and 3000 m of altitude. Finally, a multiple Regression Analysis (MRA) have been carried out in order to determine the influence of the origins and trajectories of the air masses and local meteorology variations on the evolution of Gross β and 7 Be activity concentration. In conclusion, the results of the current research demonstrate that the re-suspended mineral dust from Northern Africa transported by Mediterranean air masses at low altitude (500 m) and African air masses at high altitude (3000 m) increases the radioactivity concentration in aerosols at the surface atmosphere. In addition, the opposite influence of the Saharan intrusions at 1500 m of altitude on the behaviour of 7 Be aerosols deserves special attention.