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ERC Advanced Grant awarded to Dr. Andreas Stohl

Foto: Ingar Næss

NILU is proud to announce that Senior Scientist Dr. Andreas Stohl has been awarded an ERC Advanced Grant, the most prestigious research funding award given by the European Research Council (ERC), for the project COMTESSA – Camera Observation and Modelling of 4D Tracer Dispersion in the Atmosphere.

Turbulence is one of the long-standing big challenges in the atmospheric sciences. But, according to Stohl’s ERC application, COMTESSA will push back the limits of our understanding of turbulence and plume dispersion (e.g., of pollutant plumes) in the atmosphere by bringing together full four-dimensional observations of a nearly passive tracer (sulfur dioxide, SO2), with advanced data analysis and turbulence and dispersion modelling.

Cameras and radiative transfer models

During the project, observations will be made with six cameras sensitive to ultraviolet (UV) radiation and three cameras sensitive to infrared (IR) radiation. The cameras will be built specifically for this project, and the accuracy of the retrievals will be improved by using a state-of-the-art 3D radiative transfer model.

Skisse av en kampanje for måling av søyler («plumes»)
Fig. 1: Sketch of a plume measurement campaign with both UV cameras (blue) and IR cameras (red). We can also see meteorological instruments mounted on masts, as well as a tethered balloon and a ceilometer, an instrument used to measure the height of a cloud base.

Stohl’s team plans controlled puff and plume releases of SO2 from a 20 m tower, all cameras observing this and yielding multiple 2D images of SO2  column concentrations. These simultaneous observations will for the first time allow a tomographic reconstruction of the 3D tracer concentration distribution in the atmosphere at high space (< 1 m) and time (>10 Hz) resolution. The tomographic methods used are analogous to those used in hospitals to investigate the 3D structure of the human body or by seismologists to investigate the structure of the solid Earth.

This measurement method in itself is completely novel and COMTESSA will substantially advance this emerging technology.

Understanding turbulence

Stohl explains that the analysis of the novel campaign observations will contribute to our understanding of turbulence and tracer dispersion in the atmosphere.

– For the first time, he says, – we will be able to extensively measure tracer concentrations not only at the surface but throughout the atmospheric boundary layer, and the spatial and temporal resolution of the measurements will be unprecedented. We will also use the data to evaluate state-of-the-art Large-Eddy-Simulation and Lagrangian dispersion models and revise their underlying parameterizations.

COMTESSA’s vision is that the project results will lead to large improvements of tracer transport simulation in all atmospheric models.

Unique expertise

The highly interdisciplinary work suggested is only possible because a unique selection of scientists with complementary expertise will be working with Andreas Stohl in COMTESSA.

Stohl himself leads the “Atmospheric Transport Processes Group” (AKA “FLEXPART Group”) at NILU. He is an expert on theory and modelling of atmospheric dispersion, as well as on transport processes in the atmosphere.

The team consists of several scientists from NILU: Massimo Cassiani, Kerstin Stebel, Arve Kylling, Norbert Schmidbauer, Ignacio Pisso and Jonas Gliß, in addition to Fred Prata from Nicarnica Aviation.

Our congratulations to the COMTESSA team!

See animation here

(Click to see animation. Will open in a new window.) This movie shows an example of how turbulence is visualized in a computational model – more precisely a qualitative visualization of the turbulent flow in a Large-Eddy simulation. The turbulent flow at the forest-atmosphere interface is visualized through the simulated temperature field (horizontal section). A large heat source is activated during the simulation, visible as a yellow spot to the left of the picture.