0000000000105961
AUTHOR
Marcus Klingebiel
Thermodynamic correction of particle concentrations measured by underwing probes on fast-flying aircraft
Particle concentration measurements with underwing probes on aircraft are impacted by air compression upstream of the instrument body as a function of flight velocity. In particular, for fast-flying aircraft the necessity arises to account for compression of the air sample volume. Hence, a correction procedure is needed to invert measured particle number concentrations to ambient conditions that is commonly applicable to different instruments to gain comparable results. In the compression region where the detection of particles occurs (i.e. under factual measurement conditions), pressure and temperature of the air sample are increased compared to ambient (undisturbed) conditions in certain …
In situ detection of stratosphere-troposphere exchange of cirrus particles in the midlatitudes
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 th…
ML-CIRRUS: The Airborne Experiment on Natural Cirrus and Contrail Cirrus with the High-Altitude Long-Range Research Aircraft HALO
Abstract The Midlatitude Cirrus experiment (ML-CIRRUS) deployed the High Altitude and Long Range Research Aircraft (HALO) to obtain new insights into nucleation, life cycle, and climate impact of natural cirrus and aircraft-induced contrail cirrus. Direct observations of cirrus properties and their variability are still incomplete, currently limiting our understanding of the clouds’ impact on climate. Also, dynamical effects on clouds and feedbacks are not adequately represented in today’s weather prediction models. Here, we present the rationale, objectives, and selected scientific highlights of ML-CIRRUS using the G-550 aircraft of the German atmospheric science community. The first combi…
In situ measurements of ice saturation in young contrails
Relative humidity with respect to ice (RHi) is a major factor controlling the evolution of aircraft contrails. High-resolution airborne H2O measurements in and near contrails were made at a rate of 4.2 Hz using the novel water vapor mass spectrometer AIMS-H2O with in-flight calibration during the CONtrail, volcano, and Cirrus ExpeRimenT (CONCERT) 2011. Three 2 min old contrails were sampled near 11 km altitude. Independent of the ambient supersaturation or subsaturation over ice, the mean of the RHi frequency distribution within each contrail is shifted toward ice saturation. This shift can be explained by the high ice surface area densities with corresponding RHi relaxation times on the or…
Spectral optical layer properties of cirrus from collocated airborne measurements – a feasibility study
Abstract. Spectral optical layer properties of cirrus are derived from simultaneous and vertically collocated measurements of spectral upward and downward solar irradiance above and below the cloud layer and concurrent in situ microphysical sampling. From the irradiance data spectral transmissivity, absorptivity, reflectivity, and cloud top albedo of the observed cirrus layer are obtained. At the same time microphysical properties of the cirrus were sampled. The close collocation of the radiative and microphysical measurements, above, beneath and inside the cirrus, is obtained by using a research aircraft (Learjet 35A) in tandem with a towed platform called AIRTOSS (AIRcraft TOwed Sensor Sh…
Arctic low-level boundary layer clouds: in situ measurements and simulations of mono- and bimodal supercooled droplet size distributions at the top layer of liquid phase clouds
Abstract. Aircraft borne optical in situ size distribution measurements were performed within Arctic boundary layer clouds with a special emphasis on the cloud top layer during the VERtical Distribution of Ice in Arctic clouds (VERDI) campaign in April and May 2012. An instrumented Basler BT-67 research aircraft operated out of Inuvik over the Mackenzie River delta and the Beaufort Sea in the Northwest Territories of Canada. Besides the cloud particle and hydrometeor size spectrometers the aircraft was equipped with instrumentation for aerosol, radiation and other parameters. Inside the cloud, droplet size distributions with monomodal shapes were observed for predominantly liquid-phase Arct…
A tandem approach for collocated in-situ measurements of microphysical and radiative cirrus properties
Abstract. 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 body, which can be detached from and retracted back to the aircraft during flight. Both platforms are equipped with radiative, cloud microphysical, trace gas (CO, N2O, O3 and H2O) and meteorological instruments to study the inhomogeneity of cirrus as well as other layer clouds. Sophisticated numerical flow simulations were conducted in advance in order to optimally integrate a Cloud Combination Probe (CCP) inside the AIRTOSS. The tandem platform was used for …
A tandem approach for collocated measurements of microphysical and radiative cirrus properties
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 asymmet…