in-situ measurements; sources of ice crystals; orographic clouds; precipitation; regional climate modelling
Touloupas Georgios, Lauber Annika, Henneberger Jan, Beck Alexander, Lucchi Aurélien (2020), A convolutional neural network for classifying cloud particles recorded by imaging probes, in
Atmospheric Measurement Techniques, 13(5), 2219-2239.
Ramelli Fabiola, Beck Alexander, Henneberger Jan, Lohmann Ulrike (2020), Using a holographic imager on a tethered balloon system for microphysical observations of boundary layer clouds, in
Atmospheric Measurement Techniques, 13(2), 925-939.
Aerosol Data Davos Wolfgang
| Author |
Wieder, Jörg; Rösch, Carolin |
| Publication date |
26.05.2020 |
| Persistent Identifier (PID) |
doi: 10.16904/envidat.157 |
| Repository |
Envidat
|
| Abstract |
Aerosol properties were measured between February 8 and March 31 2019 at the measurement site Davos Wolfgang (LON: 9.853594, LAT: 46.835577). Optical and aerodynamic particle counters, as well as a scanning mobility particle size spectrometer and an ice nuclei counter were deployed to report particle concentrations and size distributions in fine (10-1000 nm) and coarse mode (> 1000 nm), cloud condensation nuclei concentrations (CCNCs) and ice nuclei particle concentrations (ICNCs). The ambient particles were transported via a heated inlet to be distributed to the particle detecting devices inside the setup room.Optical Particle Counter (OPC): Light scattering of a diode laser beam caused by travelling particles is used in the both, the OPC-N3 (0.41 - 38.5 μm) and GT-526S (0.3 - 5 μm), to determine their size and number concentration. For the OPC-N3, particle size spectra and concentration data are used afterwards to calculate PM₁, PM₂,₅ and PM₁₀ (assumptions: particle density: 1.65 g cm³, refractive index: 1.5+i0).Aerodynamic Particle Sizer (APS): The APS (3321, TSI Inc.) measured the particle size distribution for aerodynamic diameters between 0.5 μm and ~20 μm by the particle’s time-of-flight and light-scattering intensity (assumptions: particle density 1 g cm³).Scanning Mobility Particle Size Spectrometer (SMPS): Particle number concentrations in a size range between 12 and 460 nm (electrical mobility diameter) were measured at Davos Wolfgang, using a Scanning Mobility Particle Sizer Spectrometer (3938, TSI Inc.). The classifier (3082, TSI Inc.) was equipped with a neutralizer (3088, TSI Inc.) and a differential mobility analyzer working with negative polarity (3081, TSI Inc.). The size selected particles were counted by a water-based condensation particle counter (3788 , TSI Inc.). The TSI AIM software was used to provide particle size distributions by applying multiple charge and diffusion loss corrections (assumptions: particle density 1 g cm³).Coriolis μ and DRINCZ: A microbial air sampler (Coriolis μ, bertin Instruments) was used to collect airborne particles for investigating their ice nucleating ability with a droplet freezing device. Particles larger than 0.5 μm were drawn with an air flow rate of up to 300 l min¹ into the cone and centrifuged into the wall of the cone due to the forming vortex. The liquid sample was transferred into the DRoplet Ice Nuclei Counter Zurich (DRINCZ, ETH Zurich) to study heterogeneous ice formation (immersion freezing mode) of ambient airborne particles.
Aerosol Data Weissfluhjoch
| Author |
Wieder, Jörg; Rösch, Carolin |
| Publication date |
26.05.2020 |
| Persistent Identifier (PID) |
doi: 10.16904/envidat.156 |
| Repository |
Envidat
|
| Abstract |
Aerosol properties were measured between February 8 and March 31 2019 at the measurement site Weissfluhjoch (LON: 9.806475, LAT: 46.832964). Optical and aerodynamic particle counters, as well as a scanning mobility particle size spectrometer and an ice nuclei counter were deployed to report particle concentrations and size distributions in fine (10-1000 nm) and coarse mode (> 1000 nm), cloud condensation nuclei concentrations (CCNCs), and ice nuclei particle concentrations (ICNCs). The ambient particles were transported via a heated inlet to be distributed to the particle detecting devices inside the setup room.Optical Particle Counter (OPC): Light scattering of a diode laser beam caused by travelling particles is used in the both, the OPC-N3 (0.41 - 38.5 μm) and GT-526S (0.3 - 5 μm), to determine their size and number concentration. For the OPC-N3, particle size spectra and concentration data are used afterwards to calculate PM₁, PM₂,₅ and PM₁₀ (assumptions: particle density: 1.65 g cm³, refractive index: 1.5+i0).Aerodynamic Particle Sizer (APS): The APS (3321, TSI Inc.) measured the particle size distribution for aerodynamic diameters between 0.5 μm and ~20 μm by the particle’s time-of-flight and light-scattering intensity (assumptions: particle density 1 g cm³).Scanning Mobility Particle Size Spectrometer (SMPS): Particle number concentrations in a size range between 12 and 460 nm (electrical mobility diameter) were measured at Davos Wolfgang, using a Scanning Mobility Particle Sizer Spectrometer (SMPS 3938, TSI Inc.). The classifier (3082, TSI Inc.) was equipped with a neutralizer (3088, TSI Inc.) and a differential mobility analyzer working with negative polarity (3081, TSI Inc.). The size selected particles were counted by a water-based condensation particle counter (3787 TSI Inc.). The TSI AIM software was used to provide particle size distributions by applying multiple charge and diffusion loss corrections (assumptions: particle density 1 g cm³).Coriolis μ and LINDA: A microbial air sampler (Coriolis μ, bertin Instruments) was used to collect airborne particles for investigating their ice nucleating ability with a droplet freezing device. Particles larger than 0.5 μm were drawn with an air flow rate of up to 300 l min‾¹ into the cone and centrifuged into the wall of the cone due to the forming vortex. The liquid sample was transferred into the LED based Ice Nucleation Detection Apparatus (LINDA, University of Basel) to study heterogeneous ice formation (immersion freezing mode) of ambient airborne particles.
Disdrometer Data Davos Wolfgang
| Author |
Seifert, Patric; Wieder, Jörg |
| Publication date |
09.10.2019 |
| Persistent Identifier (PID) |
10.16904/envidat.117 |
| Repository |
Envidat
|
| Abstract |
The dataset contains information on precipitation amount and type for Davos Wolfgang (LON: 9.853594, LAT: 46.835577) from February 8 to March 19 2019. It includes: characteristics of hydrometeors (e.g. diameter, fall velocity, amount per diameter class,...), precipitation rate, radar reflectivity, visibility range, weather codes and instrument performance.
Weather Station Davos Wolfgang
| Author |
Wieder, Jörg |
| Publication date |
04.02.2020 |
| Persistent Identifier (PID) |
doi: 10.16904/envidat.137 |
| Repository |
Envidat
|
| Abstract |
The dataset contains weather parameters measured at Davos Wolfgang (LON: 9.853594, LAT: 46.835577).
Orographic clouds provide a natural laboratory that can be exploited to understand the physical processes leading to precipitation. In this proposal, we focus on ice-containing clouds, which are key to understanding and predicting precipitation in mid-latitudes. The Alps are the "water towers of Europe" with the origin of the largest rivers in Central Europe and thus an important freshwater source in Europe. We will target orographic clouds in the Alps, for which understanding precipitation formation is crucial and which are most readily accessible. The sources of ice crystals in these clouds still remain an enigma. Irreconcilable large discrepancies exist between measured ice crystal concentrations and those expected from primary ice nucleation on ice-active aerosol (observed and simulated) and known ice multiplication processes. We propose a multi-faceted approach in the Alps to obtain all sources of ice crystals: from ice-active aerosol, secondary ice formation, ice falling from clouds above, and surface ice sources. This requires a novel approach utilising an airborne platform on a tethered balloon system (TBS) equipped with a holographic imager to obtain measurements of vertical profiles and the three-dimensional (3D) spatial distribution of cloud particles. Holography is the only method capable of these conducting these measurements. In dedicated campaigns, we propose to combine in-situ measurements of cloud microphysical properties within the cloud with precipitation measurements at various sites at the surface and measurements of cloud condensation nuclei and ice nucleating particles at a mountain-top site to simultaneously determine the ice crystal sources in- and out of the cloud. We will compare our precipitation measurements from several disdrometers with the widespread precipitation data from the MeteoSwiss dual polarization precipitation radar in Davos.To put the conducted measurements in a larger context, we will use the regional numerical weather prediction model COSMO to simulate our field campaigns, test the importance of the different ice crystal sources for orographic precipitation and the role anthropogenic aerosols play for these. We will improve the parameterisation of cloud microphysical processes in COSMO. By doing so, we will provide an estimate of the importance of ice crystals and snowflakes falling from a higher-lying cloud into a lower-lying one (seeder-feeder process), which has been speculated to promote extreme precipitation events. This will help with early warnings for extreme precipitation and preventive measures against flash floods, landslides and avalanches.