Cosmogenic isotope ⁷Be as a tracer for air mass dynamics

Short-living cosmogenic radioisotope ⁷Be, which is attached to atmospheric aerosols soon after production, is widely recognized as a promising tracer for air mass transport in the atmosphere. Atmospheric changes in the radionuclides concentration are driven by processes that relate to production, air transports and removal. We here apply a combined ModelE of the Goddard Institute for Space Studies and the OuluCRAC:7Be production model to simulate the atmospheric variations in the ⁷Be concentration for the period of January through February 2005. Significant synoptic variability has occurred at multiple monitoring stations around the globe during the period, and an extreme solar energetic particle (SEP) event was recorded on January 20. The model reproduces the overall level of the measured ⁷Be concentration near ground and also its synoptic variability at timescales longer than about four days. This outcome confirms the advantage of the combined model of production and transport of the ⁷Be radionuclide in the atmosphere. A significant impact of the extreme SEP event of January 2005 is clearly demonstrated in polar stratospheric ⁷Be concentration , while only small (about 2%) and indistinguishable response is observed in the near Earth's surface monitoring stations.