In situ detection of stratosphere‐troposphere exchange of cirrus particles in the midlatitudes

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 (N 2 O) and carbon monoxide (CO) in situ data, stratospheric air could be identified, which contained cirrus cloud particles. Consistent with the stratospheric N 2 O 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-N 2 O 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.

In-flight stability of quantum cascade laser-based infrared absorption spectroscopy measurements of atmospheric carbon monoxide

“…In particular, changes of the cabin temperature and the cabin pressure can affect the optical alignment and the operation conditions of lasers and infra-red detectors. For species with mixing ratios in the ppb v to ppm v range like CO (typical tropospheric mixing ratios of 80 ppb v ) and CH 4 (~2 ppm v ) the absorptions correspond to optical densities in the 10 −2 range and the reported in-flight precisions, based on the reproducibility of in-flight calibrations, are in the sub per cent range [14], similar to results obtained with other airborne QCL spectrometers [15,16]. For HCHO, whose tropospheric mixing…”

The tropopause inversion layer in baroclinic life-cycle experiments: the role of diabatic processes

“…Such exchange events may only have a spatial extension of a few tenths of kilometers or even less. Müller et al (2015) recently reported a comparable event based on airborne in situ measurements of nitrous oxide, ozone, and ice cloud particles. However, since our model is not capable of resolving this process with sufficient accuracy to conduct a quantitative estimate of STE, we will leave a more detailed analysis open to further studies.…”

A tandem approach for collocated measurements of microphysical and radiative cirrus properties

“…Nitrous oxide (N 2 O) and carbon monoxide (CO) were measured with the University of Mainz Airborne QCL-Spectrometer (UMAQS; see Müller et al, 2015 for details).…”

“…Müller et al, 2015) to better find the exact location of the tropopause and identify tropopause folds as well as stratospheric influence on uppermost tropospheric cirrus clouds (especially subvisual cirrus), finding borders of air masses (e.g. the polar dome), among others.…”