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Cloud-MicroPhysics-Turbulence-Telemetry: An inter-multidisciplinary training network for enhancing the understanding and modeling of atmospheric clouds

Periodic Reporting for period 1 - COMPLETE (Cloud-MicroPhysics-Turbulence-Telemetry: An inter-multidisciplinary training network for enhancing the understanding and modeling of atmospheric clouds)

Reporting period: 2016-06-01 to 2018-05-31

Since ambiguities related to representation of clouds in climate models prevail, explorative observations are still needed. The challenge is on the one hand to establish connections across this range of scales, from aerosol and particle microphysics to macro-scale turbulent dynamics in clouds, and on the other to combine knowledge and training across vastly different scientific and engineering disciplines.

The principal research objectives of COMPLETE are:
• the characterization of the direct interactions between cloud dynamics, thermodynamics and microphysics at centimetre and meter scales,
• the development of new telemetry methods for in-situ measurements of the aerosol and turbulence, as well as temperature, pressure and chemical content,
• to improve the cloud edges/interface models to better prediction of the mixing efficiency, temperature inversion, clear air entrainment/moist air detrainment,
• the comparison of radiative measurements with data obtained inside warm clouds in a Lagrangian way,
• transfer the knowledge acquired by field and laboratory Lagrangian measurements and DNS modelling towards the climate/weather modelling community
ESR1, Taraprasad Bhowmick’s research progress includes conceptualizing various physical processes involved in evolution of cloud – clear air interfaces, familiarization with the available DNS codes, running the DNS code without cloud droplets to understand the evolution of the flow field around the interface, and formulation of various simulation schemes for his future runs. A grant for PRACE Preparatory Access was obtained and an ISCRA Application Class C was successful.

ESR13, Mina Golshan contribution includes an investigation on the way to consider the heterogeneous and homogeneous nucleation in both classical and non-classical models inside direct numerical simulation. In particular, she will use population balance equations from the nucleation size, about 1nm, to the smallest droplet size that can be simulated.

ESR5, Guus Bertens’ contribution involves the experimental setup that is situated on top of the UFS Schneefernerhaus. The setup consists of a box with three fast cameras that all look at the same 3x3x3 cm³ volume. One of the improvements that is currently being worked on is the rail system.

ESR6, Johannes Guettler works on the design and prototyping of a new droplet generator. Right now, tests are being performed to find the ideal parameters for each of the two tasks of the droplet generator: 1) Generation of single droplets on demand and 2) generation of a steady stream of droplets, which are split by forcing a Plateau-Rayleigh-instability.

ESR8, Antonio Ibanez Landeta: One of the best available probes for obtaining turbulence statistics are the NSTAPs (nano scale thermal anemometry probes) hot wires. So far, a 30μm x 3μm prototype was printed with a Nanoscribe printer in a polymer and to be coated with a metal. The wires are straight and reasonably resistant to vibration and movement.

ESR7, Marco Boetti: In the first part of his activity, the focus was on the creation of the experimental system dynamics using a DNS code, that is based on SPARKLE. It integrates the incompressible Navier-Stokes equations in the Boussinesq approximation on a cuboidal domain. Several runs were made to evaluate the relevance of physical parameters and initial conditions.

ESR9, Moein Mohammadi’s early results: A frame of light was designed to uniformly illuminate a cloud volume of ~ 50cm x 50cm x 2mm, for visualization of droplets within this volume and quantitative multi-scale measurements of droplet clustering and small scale turbulence. Hence, it was possible to collect images of cloud droplets spatial distribution in a two-dimensional plane enlightened by a laser sheet technique with a digital camera.

ESR10, Emanuel Akinlabi’s progress involves the investigation into different methods for TKE dissipation rate retrieval that were applied, including standard spectral retrieval methods and new proposals based on a recovery of the missing part of the spectrum. Results of this part of the project have been submitted for publication in New Journal of Physics.

The contribution of ESR2, Tessa Basso, up to now concerns the first developments for the biodegradable casing of the radio-probe. First thermal experiments have been done in the laboratory at INRiM with the growth of mean value of temperature and some fluctuation. Also at Zugspitze, another experiment was made to test the material of the green balloon and its thermal resistance and degradation.

ESR12, Miryam Paredes, is working on the transmission protocol to be used by the mini green radio-probe. Some preliminary measurements, both indoor and outdoor environment, have also been performed considering different configurations.

At the moment, the contribution of ESR14, Tung Bui Duc concerns the selection, design and placing inside the radio-probe electrical circuit of a 3-axis accelerometer, and in order to get the angular rate of the radiosondes, a 3-axis gyroscope.

ESR3, Tai Wada’s contribution: By April 2018, DNS simulation of a planar jet has been conducted using the in-house Navier-Stokes solver “Incompact3d” and investigated interfacial velocity scaling using theory of Zhou and Vassilicos.

ESR4, Vishnu Nair’s (ICL) contribution: The in-house numerical code SPARKLE is used to perform Direct Numerical Simulations on a cloud-environment model. He has reached the first objective, that is to perform DNS of turbulent entrainment in shallow cumulus cloud edges using a bulk formulation of wet thermodynamics and is now working on implementing and validating a Lagrangian Particle Tracking routine to track individual droplets in SPARKLE.

ESR11, Sara Shamekh’s (LMD) contribution: ESR11 wants to study how the aggregation is influenced by the details of the surface, such as the presence of ocean or land, and the temperature of the oceans. The physical processes involved are studied by Cloud resolving models or Large Eddy Simulation, and will be verified on Global Climate Models.
COMPLETE closely addresses the prime objectives of an ETN network since it combines the interaction of different scientific disciplines, cooperation between industry and academia and training in complementary and transferable skills and a strong entrepreneurial spirit. At the same time, it pays special attention to gender balance and generates a strong link between the scientific and technical work and possible societal impact. ESRs act as ambassadors for the European ideal of integration.

COMPLETE effectively contributes to structuring doctoral / early-stage research training at the European level since PhD programmes focusing specifically on Cloud Dynamics are not present in Europe. The strengthening of European innovation capacity is demonstrated by the big effort the ETN is putting on the innovation and new conception of measurement instruments and probes, from the production of new infield and numerical simulation fluctuation Lagrangian database to the transfer of the body of research results and data produced by infield, laboratory and numerical simulation experiments to the climate modelling community. First experiments with probes have been done during the Summer School at Zugspitze and the ESRs are now researching new materials and electronics for the probes.