Atmospheric interactions at northern high latitudes from weekly Be-isotopes in surface air

We present weekly Be-7 (from 1972 to 1995), and weekly/seasonal Be-10 (for 1994) data in surface air from ground level stations in Sweden with a cover age of most of the northern high latitudes (56 degrees -68 degrees N). Our Be data are regionally representative and reveal seasonal variation and cou pling with tropospheric air mass from middle-low latitudes. The Be data als o suggests a few percent, and sometimes episodic, incursion of stratospheri c air mass. Frequent precipitation depletes the Be isotopes in the air, but cyclone events contribute to enrichments. A strong coherence between the B e-7 record and short-term (monthly-seasonal) change in solar activity is ob served which introduces a new mechanism for driving the amplitude of season al variation. (C) 2001 Elsevier Science Ltd. All rights reserved.