Meteorological Factors Controlling 7 Be Activity Concentrations in the Atmospheric Surface Layer in Northern Spain

• Published in: Atmosphere
• Main Authors: Natalia Alegría, Miguel Ángel Hernández-Ceballos, Margarita Herranz, Raquel Idoeta, Fernando Legarda
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2020
• Subjects: Beryllium-7; time series analysis; airflow patterns; local meteorological conditions; Meteorology. Climatology; QC851-999; Northwest Atlantic
• Online Access: https://doi.org/10.3390/atmos11121340; https://doaj.org/article/1cf28b85200e4c7d8373727e1a06a1b8

This work presents the analysis of weekly 7 Be activity concentrations in the air measured in Bilbao (northern Spain) by collecting aerosols in filters over a ten years period (2009–2018). 7 Be level is in the 0.35–7.3 mBq/m 3 range, with a mean of 3.20 ± 1.12 mBq/m 3 . The trend, cycle, seasonal and monthly variability are evaluated using time series analysis techniques. The results indicate the impact of sunspots (24th solar cycle) on interannual 7 Be activity concentrations, and a significant seasonal and monthly variation, with maximum concentrations occurring in spring-summer and minimum in the winter. The correlation of different 7 Be ranges with local meteorological parameters, such as precipitation, temperature, relative humidity, and pressure, is also addressed, with precipitation having the greatest impact on 7 Be activity values. The analysis of synoptic airflows, by calculating the back-trajectory clusters, and local winds at surface level reveals the important influence of the arrival of slow northwest Atlantic flows and the development of breezes on reaching high 7 Be activity concentrations in this area.