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Abstract:
Airborne trace gas, microphysical, and radiation measurements were performed during the AIRcraft TOwed Sensor Shuttle - Inhomogeneous Cirrus Experiment over northern Germany in 2013. Based on high-precision nitrous oxide (N2O) and carbon monoxide (CO) in situ data, stratospheric air could be identified, which contained cirrus cloud particles. Consistent with the stratospheric N2O data, backward trajectories indicate that the sampled air masses crossed the dynamical tropopause in the last 3 h before the measurement. These air masses contained cirrus particles, which were formed during slow ascent in the troposphere and subsequently mixed with stratospheric air. From the CO-N2O correlation the irreversibility of this transport is deduced. To our knowledge, this is the first in situ detection of cirrus particles mixed with stratospheric air in the midlatitudes.