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Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union

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Atmos. Meas. Tech., 10, 3485-3498, 2017
https://doi.org/10.5194/amt-10-3485-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
22 Sep 2017
A tandem approach for collocated measurements of microphysical and radiative cirrus properties
Marcus Klingebiel1,2, André Ehrlich3, Fanny Finger3, Timo Röschenthaler4,5, Suad Jakirlić5, Matthias Voigt6, Stefan Müller4,6, Rolf Maser4, Manfred Wendisch3, Peter Hoor6, Peter Spichtinger6, and Stephan Borrmann2,6 1Max Planck Institute for Meteorology, Atmosphere in the Earth System Department, Hamburg, Germany
2Max Planck Institute for Chemistry, Particle Chemistry Department, Mainz, Germany
3Leipzig Institute for Meteorology (LIM), University of Leipzig, Leipzig, Germany
4Enviscope GmbH, Frankfurt, Germany
5Institute for Fluid Mechanics and Aerodynamics, Darmstadt University of Technology, Darmstadt, Germany
6Institute for Atmospheric Physics, Johannes Gutenberg University Mainz, Mainz, Germany
Abstract. Microphysical and radiation measurements were collected with the novel AIRcraft TOwed Sensor Shuttle (AIRTOSS) – Learjet tandem platform. The platform is a combination of an instrumented Learjet 35A research aircraft and an aerodynamic bird, which is detached from and retracted back to the aircraft during flight via a steel wire with a length of 4000 m. Both platforms are equipped with radiative, cloud microphysical, trace gas, and meteorological instruments. The purpose of the development of this tandem set-up is to study the inhomogeneity of cirrus as well as other stratiform clouds. Sophisticated numerical flow simulations were conducted in order to optimally integrate an axially asymmetric Cloud Combination Probe (CCP) inside AIRTOSS. The tandem platform was applied during measurements at altitudes up to 36 000 ft (10 970 m) in the framework of the AIRTOSS – Inhomogeneous Cirrus Experiment (AIRTOSS-ICE). Ten flights were performed above the North Sea and Baltic Sea to probe frontal and in situ formed cirrus, as well as anvil outflow cirrus. For one flight, cirrus microphysical and radiative properties displayed significant inhomogeneities resolved by both measurement platforms. The CCP data show that the maximum of the observed particle number size distributions shifts with decreasing altitude from 30 to 300 µm, which is typical for frontal, midlatitude cirrus. Theoretical considerations imply that cloud particle aggregation inside the studied cirrus is very unlikely. Consequently, diffusional growth was identified to be the dominant microphysical growth process. Measurements of solar downward and upward irradiances at 670 nm wavelength were conducted above, below, and in the cirrus on both the Learjet and AIRTOSS. The observed variability of the downward irradiance below the cirrus reflects the horizontal heterogeneity of the observed thin cirrus. Vertically resolved solar heating rates were derived by either using single-platform measurements at different altitudes or by making use of the collocated irradiance measurements at different altitudes of the tandem platform. Due to unavoidable biases of the measurements between the individual flight legs, the single-platform approach failed to provide a realistic solar heating rate profile, while the uncertainties of the tandem approach are reduced. Here, the solar heating rates range up to 6 K day−1 at top of the cirrus layer.

Citation: Klingebiel, M., Ehrlich, A., Finger, F., Röschenthaler, T., Jakirlić, S., Voigt, M., Müller, S., Maser, R., Wendisch, M., Hoor, P., Spichtinger, P., and Borrmann, S.: A tandem approach for collocated measurements of microphysical and radiative cirrus properties, Atmos. Meas. Tech., 10, 3485-3498, https://doi.org/10.5194/amt-10-3485-2017, 2017.
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Short summary
Microphysical and radiation measurements were collected with the unique AIRcraft TOwed Sensor Shuttle (AIRTOSS) – Learjet tandem platform. It is a combination of a Learjet 35A research aircraft and an instrumented aerodynamic bird, which can be detached from and retracted back to the aircraft during flight. AIRTOSS and Learjet are equipped with radiative, cloud microphysical, trace gas, and meteorological instruments to study cirrus clouds.
Microphysical and radiation measurements were collected with the unique AIRcraft TOwed Sensor...
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