Evolution And Solar Modulation Of Be-7 During The Solar Cycle 23

The modulation of Be-7-aerosols concentration due to solar activity during the cycle 23 is studied in the present research. For that purpose, was analyzed the differences in the long-term variation of geomagnetic and solar activity to assess the physical effects over the evolution of Be-7 during the period 1996-2010. Furthermore, exploratory data analysis was applied to understand better the behavior of Be-7-aerosols in the surface atmosphere. This study shows that there is an inverse relationship among Be-7 measured in the near ground air and solar activity. The modulation of Be-7-aerosols during the cycle 23 was divided in two steps. In the first stage, ascending phase, 1996-2002, the solar activity played an important role in the production rate of Be-7, r = -0.75. However, during the descending phase, 2002-2009, the role of the solar activity was secondary, r = -0.30, allowing that Be-7-aerosols reached the maximum concentration, 9.33 mBq m(-3) in August-09 when the solar activity was zero. Moreover, the remaining solar activity after the end of the ascending phase and the last important solar storm (December-06) caused the slowdown of Be-7 production rate from 2001 to 2004 and the rupture of the seasonal behavior of Be-7 in 2007, respectively. Finally, this research highlight the necessity to take into account the solar cycle phase, ascending or descending, to model studies of atmospheric process with Be-7 as tracer since the contribution of the variables studied are so different in these stages.