scholarly journals HoloGondel: in-situ cloud observations on a cable car in the Swiss Alps using a holographic imager

2016 ◽  
Author(s):  
Alexander Beck ◽  
Jan Henneberger ◽  
Sarah Schöpfer ◽  
Ulrike Lohmann
Keyword(s):  
Single Point ◽  
Sample Volume ◽  
Swiss Alps ◽  
Vertical Profiles ◽  
Cloud Droplets ◽  
Cloud Parameters ◽  
Cloud Particles ◽  
Air Speed ◽  
Main Component

Abstract. In-situ observations of cloud properties in complex alpine terrain where research aircraft cannot sample are commonly conducted at mountain-top research stations and limited to single-point measurements. The HoloGondel platform overcomes this limitation by using a cable car to obtain vertical profiles of the microphysical and meteorological cloud parameters. The main component of the HoloGondel platform is the HOLographic Imager for Microscopic Objects (HOLIMO 3G), which uses digital 5 in-line holography to image cloud particles. Based on a two dimensional shadow-graph the phase resolved microphysical cloud parameters for the size range from small cloud particles to large precipitation particles are obtained. The low travelling velocity of a cable car on the order of 10 m s−1 allows measurements with high spatial resolution, however, at the same time it leads to an unstable air speed towards the HoloGondel platform. Holographic cloud imagers, which have a sample volume that is independent of the air speed are therefore well suited for measurements on a cable car. Example measurements 10 of the vertical profiles observed in a liquid cloud and a mixed-phase cloud at the Eggishorn in the Swiss Alps in the winters 2015 and 2016 are presented. The HoloGondel platform reliably observes cloud droplets larger than 6.5 μm, partitions between cloud droplets and ice crystals for a size larger than 25 μm and obtains a statistically significantly size distribution for every 5 m in vertical ascent.

scholarly journals HoloGondel: in situ cloud observations on a cable car in the Swiss Alps using a holographic imager

2017 ◽  
Vol 10 (2) ◽  
pp. 459-476 ◽  
Author(s):  
Alexander Beck ◽  
Jan Henneberger ◽  
Sarah Schöpfer ◽  
Jacob Fugal ◽  
Ulrike Lohmann
Keyword(s):  
Single Point ◽  
Sample Volume ◽  
Swiss Alps ◽  
Vertical Profiles ◽  
Cloud Droplets ◽  
Cloud Parameters ◽  
Cloud Particles ◽  
Air Speed ◽  
Main Component

Abstract. In situ observations of cloud properties in complex alpine terrain where research aircraft cannot sample are commonly conducted at mountain-top research stations and limited to single-point measurements. The HoloGondel platform overcomes this limitation by using a cable car to obtain vertical profiles of the microphysical and meteorological cloud parameters. The main component of the HoloGondel platform is the HOLographic Imager for Microscopic Objects (HOLIMO 3G), which uses digital in-line holography to image cloud particles. Based on two-dimensional images the microphysical cloud parameters for the size range from small cloud particles to large precipitation particles are obtained for the liquid and ice phase. The low traveling velocity of a cable car on the order of 10 m s−1 allows measurements with high spatial resolution; however, at the same time it leads to an unstable air speed towards the HoloGondel platform. Holographic cloud imagers, which have a sample volume that is independent of the air speed, are therefore well suited for measurements on a cable car. Example measurements of the vertical profiles observed in a liquid cloud and a mixed-phase cloud at the Eggishorn in the Swiss Alps in the winters 2015 and 2016 are presented. The HoloGondel platform reliably observes cloud droplets larger than 6.5 µm, partitions between cloud droplets and ice crystals for a size larger than 25 µm and obtains a statistically significantly size distribution for every 5 m in vertical ascent.

scholarly journals Using a holographic imager on a tethered balloon system for microphysical observations of boundary layer clouds

2019 ◽  
Author(s):  
Fabiola Ramelli ◽  
Alexander Beck ◽  
Jan Henneberger ◽  
Ulrike Lohmann
Keyword(s):  
Boundary Layer ◽  
Cloud Droplet ◽  
Sample Volume ◽  
Tethered Balloon ◽  
Wind Speeds ◽  
Boundary Layer Clouds ◽  
Cloud Properties ◽  
Main Component ◽  
Balloon System

Abstract. Conventional techniques to measure boundary layer clouds such as research aircrafts are unable to sample in orographic or densely-populated areas. In this paper, we present a newly developed measurement platform on a tethered balloon system (HoloBalloon) to measure in situ vertical profiles of microphysical and meteorological cloud properties up to 1 kilometer above ground. The main component of the HoloBalloon platform is a holographic imager, which uses digital in-line holography to image cloud particles in a velocity independent sample volume, making it particularly well suited for measurements on a balloon. The unique combination of holography and balloon-borne measurements allows observations with high spatial resolution, covering cloud structures from the kilometer down to the millimeter scale. We present observations of a supercooled low stratus cloud (high fog event) during a Bise situation over the Swiss Plateau in February 2018. In situ microphysical profiles up to 700 m altitude above the ground and at temperatures down to −8 °C and wind speeds up to 15 m s−1 were performed. We were able to capture unique microphysical features from the kilometer down to the meter scale. For example, we observed cloud regions with decreased cloud droplet number concentration (CDNC) and cloud droplet size at scales of 30–50 meters. These cloud inhomogeneities could arise from adiabatic compression and heating and subsequent droplet evaporation in descending air parcels. Moreover, we observed conditions favorable for the formation of boundary layer waves and Kelvin-Helmholtz instability at the cloud top. This potentially influenced the cloud structure on a scale of 10–30 kilometers, which is reflected in the variability of the CDNC.

scholarly journals Post-flight analysis of detailed size distributions of warm cloud droplets, as determined in situ by cloud and aerosol spectrometers

2021 ◽  
Author(s):  
Sorin Nicolae Vâjâiac ◽  
Andreea Calcan ◽  
Robert Oscar David ◽  
Denisa-Elena Moacă ◽  
Gabriela Iorga ◽  
...  
Keyword(s):  
Cross Section ◽  
Forward Scattering ◽  
Scattering Cross Section ◽  
Size Distributions ◽  
Cloud Droplets ◽  
Cloud Particle ◽  
Fine Grid ◽  
Scattering Cross ◽  
Cloud Parameters

Abstract. Warm clouds, consisting of liquid cloud droplets, play an important role in modulating the amount of incoming solar radiation to Earth’s surface and thus, the climate. The size and number concentration of these cloud droplets control the reflectance of the cloud, the formation of precipitation and ultimately, the lifetime of the cloud. Therefore, in situ observations of the number and diameter of cloud droplets are frequently performed with cloud and aerosol spectrometers, which determine the optical diameters of cloud particles (in the range of up to a few tens of microns) by measuring their forward scattering cross sections in visible light and comparing these values with Mie-theoretical computations. The use of such instruments must rely on a fast working scheme consisting of a limited pre-defined uneven grid of cross section values that corresponds to a theoretically derived uneven set of size intervals (bins). However, as more detailed structural analyses of warm clouds are needed to improve future climate projects, we present a new numerical post-flight methodology using recorded particle-by-particle sample files. The Mie formalism produces a complicated relationship between a particle’s diameter and its forward scattering cross section. This relationship cannot be expressed in an analytically closed form and it should be numerically computed point by point, over a certain grid of diameter values. The optimal resolution required for constructing the diagram of this relationship is therefore analysed. Cloud particle statistics are further assessed using a fine grid of particle diameters in order to capture the finest details of the cloud particle size distributions. The possibility and the usefulness of using coarser size grids, with either uneven or equal intervals is also discussed. For coarse equidistant size grids, the general expressions of cloud microphysical parameters are calculated and the ensuing relative errors are discussed in detail. The proposed methodology is further applied to a subset of measured data and it is shown that the overall uncertainties in computing various cloud parameters are mainly driven by the measurement errors of the forward scattering cross section for each particle. Finally, the influence of the relatively large imprecision in the real and imaginary parts of the refractive index of cloud droplets on the size distributions and on the ensuing cloud parameters is analysed. It is concluded that, in the presence of high atmospheric loads of hydrophilic and light absorbing aerosols, such imprecisions may drastically affect the reliability of the cloud data obtained with cloud and aerosol spectrometers. Some complementary measurements for improving the quality of the cloud droplet size distributions obtained in post-flight analyses are suggested.

scholarly journals Thermodynamic correction of particle concentrations measured by underwing probes on fast-flying aircraft

2016 ◽  
Vol 9 (10) ◽  
pp. 5135-5162 ◽  
Author(s):  
Ralf Weigel ◽  
Peter Spichtinger ◽  
Christoph Mahnke ◽  
Marcus Klingebiel ◽  
Armin Afchine ◽  
...  
Keyword(s):  
Correction Factor ◽  
Particle Concentration ◽  
Sample Volume ◽  
Time Interval ◽  
Ambient Conditions ◽  
Measured Concentration ◽  
Air Sample ◽  
Cloud Particles ◽  
Air Speed ◽  
Measured Particle

Abstract. 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 distance away from the aircraft. Conventional procedures for scaling the measured number densities to ambient conditions presume that the air volume probed per time interval is determined by the aircraft speed (true air speed, TAS). However, particle imaging instruments equipped with pitot tubes measuring the probe air speed (PAS) of each underwing probe reveal PAS values systematically below those of the TAS. We conclude that the deviation between PAS and TAS is mainly caused by the compression of the probed air sample. From measurements during two missions in 2014 with the German Gulfstream G-550 (HALO – High Altitude LOng range) research aircraft we develop a procedure to correct the measured particle concentration to ambient conditions using a thermodynamic approach. With the provided equation, the corresponding concentration correction factor ξ is applicable to the high-frequency measurements of the underwing probes, each of which is equipped with its own air speed sensor (e.g. a pitot tube). ξ values of 1 to 0.85 are calculated for air speeds (i.e. TAS) between 60 and 250 m s−1. For different instruments at individual wing position the calculated ξ values exhibit strong consistency, which allows for a parameterisation of ξ as a function of TAS for the current HALO underwing probe configuration. The ability of cloud particles to adopt changes of air speed between ambient and measurement conditions depends on the cloud particles' inertia as a function of particle size (diameter Dp). The suggested inertia correction factor μ (Dp) for liquid cloud drops ranges between 1 (for Dp < 70 µm) and 0.8 (for 100 µm < Dp < 225 µm) but it needs to be applied carefully with respect to the particles' phase and nature. The correction of measured concentration by both factors, ξ and μ (Dp), yields higher ambient particle concentration by about 10–25 % compared to conventional procedures – an improvement which can be considered as significant for many research applications. The calculated ξ values are specifically related to the considered HALO underwing probe arrangement and may differ for other aircraft. Moreover, suggested corrections may not cover all impacts originating from high flight velocities and from interferences between the instruments and e.g. the aircraft wings and/or fuselage. Consequently, it is important that PAS (as a function of TAS) is individually measured by each probe deployed underneath the wings of a fast-flying aircraft.

scholarly journals Using a holographic imager on a tethered balloon system for microphysical observations of boundary layer clouds

2020 ◽  
Vol 13 (2) ◽  
pp. 925-939 ◽  
Author(s):  
Fabiola Ramelli ◽  
Alexander Beck ◽  
Jan Henneberger ◽  
Ulrike Lohmann
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Cloud Droplet ◽  
Sample Volume ◽  
Tethered Balloon ◽  
Wind Speeds ◽  
Boundary Layer Clouds ◽  
Main Component ◽  
Balloon System

Abstract. Conventional techniques to measure boundary layer clouds such as research aircraft are unable to sample in orographically diverse or densely populated areas. In this paper, we present a newly developed measurement platform on a tethered balloon system (HoloBalloon) to measure in situ vertical profiles of microphysical and meteorological cloud properties up to 1 km above ground. The main component of the HoloBalloon platform is a holographic imager, which uses digital in-line holography to image an ensemble of cloud particles in the size range from small cloud droplets to precipitation-sized particles in a three-dimensional volume. Based on a set of two-dimensional images, information about the phase-resolved particle size distribution, shape and spatial distribution can be obtained. The velocity-independent sample volume makes holographic imagers particularly well suited for measurements on a balloon. The unique combination of holography and balloon-borne measurements allows for observations with high spatial resolution, covering cloud structures from the kilometer down to the millimeter scale. The potential of the measurement technique in studying boundary layer clouds is demonstrated on the basis of a case study. We present observations of a supercooled low stratus cloud during a Bise situation over the Swiss Plateau in February 2018. In situ microphysical profiles up to 700 m altitude above the ground were performed at temperatures down to −8 ∘C and wind speeds up to 15 m s−1. We were able to capture unique microphysical signatures in stratus clouds, in the form of inhomogeneities in the cloud droplet number concentration and in cloud droplet size, from the kilometer down to the meter scale.

scholarly journals Post-flight analysis of detailed size distributions of warm cloud droplets, as determined in situ by cloud and aerosol spectrometers

2021 ◽  
Vol 14 (10) ◽  
pp. 6777-6794
Author(s):  
Sorin Nicolae Vâjâiac ◽  
Andreea Calcan ◽  
Robert Oscar David ◽  
Denisa-Elena Moacă ◽  
Gabriela Iorga ◽  
...  
Keyword(s):  
Cross Section ◽  
Forward Scattering ◽  
Scattering Cross Section ◽  
Size Distributions ◽  
Cloud Droplets ◽  
Cloud Particle ◽  
Fine Grid ◽  
Scattering Cross ◽  
Cloud Parameters

Abstract. Warm clouds, consisting of liquid cloud droplets, play an important role in modulating the amount of incoming solar radiation to Earth's surface and thus the climate. The size and number concentration of these cloud droplets control the reflectance of the cloud, the formation of precipitation and ultimately the lifetime of the cloud. Therefore, in situ observations of the number and diameter of cloud droplets are frequently performed with cloud and aerosol spectrometers, which determine the optical diameters of cloud particles (in the range of up to a few tens of micrometers) by measuring their forward-scattering cross sections in visible light and comparing these values with Mie theoretical computations. The use of such instruments must rely on a fast working scheme consisting of a limited pre-defined uneven grid of cross section values that corresponds to a theoretically derived uneven set of size intervals (bins). However, as more detailed structural analyses of warm clouds are needed to improve future climate projects, we present a new numerical post-flight methodology using recorded particle-by-particle sample files. The Mie formalism produces a complicated relationship between a particle's diameter and its forward-scattering cross section. This relationship cannot be expressed in an analytically closed form, and it should be numerically computed point by point, over a certain grid of diameter values. The optimal resolution required for constructing the diagram of this relationship is therefore analyzed. Cloud particle statistics are further assessed using a fine grid of particle diameters in order to capture the finest details of the cloud particle size distributions. The possibility and the usefulness of using coarser size grids, with either uneven or equal intervals, is also discussed. For coarse equidistant size grids, the general expressions of cloud microphysical parameters are calculated and the ensuing relative errors are discussed in detail. The proposed methodology is further applied to a subset of measured data, and it is shown that the overall uncertainties in computing various cloud parameters are mainly driven by the measurement errors of the forward-scattering cross section for each particle. Finally, the influence of the relatively large imprecision in the real and imaginary parts of the refractive index of cloud droplets on the size distributions and on the ensuing cloud parameters is analyzed. It is concluded that, in the presence of high atmospheric loads of hydrophilic and light-absorbing aerosols, such imprecisions may drastically affect the reliability of the cloud data obtained with cloud and aerosol spectrometers. Some complementary measurements for improving the quality of the cloud droplet size distributions obtained in post-flight analyses are suggested.

In-situ variable-temperature single-point NMR imaging study of coals

Fuel ◽  
2000 ◽  
Vol 79 (3-4) ◽  
pp. 405-416 ◽  
Author(s):  
K Saito ◽  
I Komaki ◽  
K.-I Hasegawa ◽  
H Tsuno
Keyword(s):  
Variable Temperature ◽  
Single Point ◽  
Imaging Study ◽  
Nmr Imaging

scholarly journals In situ vertical profiles of aerosol extinction, mass, and composition over the southeast United States during SENEX and SEAC<sup>4</sup>RS: observations of a modest aerosol enhancement aloft

2015 ◽  
Vol 15 (12) ◽  
pp. 7085-7102 ◽  
Author(s):  
N. L. Wagner ◽  
C. A. Brock ◽  
W. M. Angevine ◽  
A. Beyersdorf ◽  
P. Campuzano-Jost ◽  
...  
Keyword(s):  
United States ◽  
Mixed Layer ◽  
Transition Layer ◽  
Southeastern United States ◽  
Vertical Mixing ◽  
Organic Aerosol ◽  
Vertical Profiles ◽  
Free Troposphere ◽  
Secondary Aerosol

Abstract. Vertical profiles of submicron aerosol from in situ aircraft-based measurements were used to construct aggregate profiles of chemical, microphysical, and optical properties. These vertical profiles were collected over the southeastern United States (SEUS) during the summer of 2013 as part of two separate field studies: the Southeast Nexus (SENEX) study and the Study of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys (SEAC4RS). Shallow cumulus convection was observed during many profiles. These conditions enhance vertical transport of trace gases and aerosol and create a cloudy transition layer on top of the sub-cloud mixed layer. The trace gas and aerosol concentrations in the transition layer were modeled as a mixture with contributions from the mixed layer below and the free troposphere above. The amount of vertical mixing, or entrainment of air from the free troposphere, was quantified using the observed mixing ratio of carbon monoxide (CO). Although the median aerosol mass, extinction, and volume decreased with altitude in the transition layer, they were ~10 % larger than expected from vertical mixing alone. This enhancement was likely due to secondary aerosol formation in the transition layer. Although the transition layer enhancements of the particulate sulfate and organic aerosol (OA) were both similar in magnitude, only the enhancement of sulfate was statistically significant. The column integrated extinction, or aerosol optical depth (AOD), was calculated for each individual profile, and the transition layer enhancement of extinction typically contributed less than 10 % to the total AOD. Our measurements and analysis were motivated by two recent studies that have hypothesized an enhanced layer of secondary aerosol aloft to explain the summertime enhancement of AOD (2–3 times greater than winter) over the southeastern United States. The first study attributes the layer aloft to secondary organic aerosol (SOA) while the second study speculates that the layer aloft could be SOA or secondary particulate sulfate. In contrast to these hypotheses, the modest enhancement we observed in the transition layer was not dominated by OA and was not a large fraction of the summertime AOD.

scholarly journals Multi-source SO<sub>2</sub> emissions retrievals and consistency of satellite and surface measurements with reported emissions

2017 ◽  
Author(s):  
Vitali Fioletov ◽  
Chris A. McLinden ◽  
Shailesh K. Kharol ◽  
Nickolay A. Krotkov ◽  
Can Li ◽  
...  
Keyword(s):  
Point Source ◽  
Single Point ◽  
Control Measures ◽  
Ozone Monitoring Instrument ◽  
So2 Emissions ◽  
Vertical Column ◽  
Wind Speeds ◽  
Surface Measurements ◽  
Best Fit

Abstract. Reported sulfur dioxide (SO2) emissions from U.S. and Canadian sources have declined dramatically since the 1990s as a result of emissions control measures. Observations from the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite and ground-based in-situ measurements are examined to verify whether the observed changes from SO2 abundance measurements are quantitatively consistent with the reported changes in emissions. To make this connection, a new method to link SO2 emissions and satellite SO2 measurements was developed. The method is based on fitting satellite SO2 vertical column densities (VCDs) to a set of functions of OMI pixel coordinates and wind speeds, where each function represents a statistical model of a plume from a single point source. The concept is first demonstrated using sources in North America, and then applied to Europe. The correlation coefficient between OMI-measured VCDs (with a local bias removed) and SO2 VCDs derived here using reported emissions for 1° by 1° gridded data is 0.91 and the best-fit line has a slope near unity, confirming a very good agreement between observed SO2 VCDs and reported emissions. Having demonstrated their consistency, seasonal and annual mean SO2 VCD distributions are calculated, based on reported point-source emissions for the period 1980–2015, as would have been seen by OMI. This consistency is further substantiated as the emissions-derived VCDs also show a high correlation with annual mean SO2 surface concentrations at 50 regional monitoring stations.

scholarly journals FEATURES OF VIOLATIONS OF THE STATE OF THE VAGINAL ECOSYSTEM IN PREGNANT WOMEN WITH BACTERIAL VAGINOSIS

2021 ◽  
Vol 74 (3) ◽  
pp. 460-464
Author(s):  
Iryna M. Shcherbina ◽  
Iryna Yu. Plakhotna
Keyword(s):  
Pregnant Women ◽  
Bacterial Resistance ◽  
Main Group ◽  
Vaginal Smears ◽  
Dna Diagnostics ◽  
Hybridization In Situ ◽  
Positive Hybridization ◽  
Main Component ◽  
Microbial Spectrum

The aim: To assess the condition of the vaginal ecosystem in pregnant women with BV. Materials and methods: The main group consisted of 60 pregnant women with BV in the II trimester. The bacterioscopic examination, of vaginal smears was carried out. DNA diagnostics of the microbial spectrum of vaginal contents was performed. Bacteria with biofilm were visualized by fluorescence hybridization in situ. Results: Biofilms were found in 25 women (41.65%) of the main group, the main component of which was bacteria belonging to the Gardnerella cluster at a concentration of 7.9 ± 0.13 log CFU/ g. Atopobium vagine cluster bacteria gave positive hybridization signals in more than half of the patients and amounted to 6.8 ± 0.15 lg CFU / g. In addition, Snethia spp. was determined as a part of the biofilm at a concentration of 5.8 ± 0.3 lg CFU / g. Conclusions: Thus, the use of the proposed treatment regimen for women with vaginal dysbiosis led to the elimination of pathogenic and conditionally pathogenic microflora. However, the effectiveness of treatment in 5 cases was lower than expected, which indicates the emergence of bacterial resistance.

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