Atmospheric Chemistry and Physics Quantifying transport into the Arctic lowermost stratosphere

Abstract. In the Arctic winter 2003, in-situ measurements of the long-lived trace gases N2O, CFC-11 (CCl3F), H-1211 (CBrClF2), CH4, O3 and H2O have been performed on board the high-altitude aircraft M55 Geophysica. The data are presented and used to study transport into the low-ermost stratosphere (LMS). The LMS can be regarded as a mixture of fractions of air originating in (i) the troposphere, (ii) the extra-vortex stratosphere above 400 K and (iii) the Arctic vortex above 400 K. These fractions are determined using a simple mass balance calculation. The analysis ex-hibits a strong tropospheric influence of 50% ± 15 % or more in the lowest 20 K of the high-latitude LMS. Above this re-gion the LMS is dominated by air masses having descended from above 400 K. Below the Arctic vortex region at poten-tial temperatures above 360 K, air in the LMS is a mixture o