Does dust triboelectrification affect our climate?

Project Information

D-TECT

Grant agreement ID: 725698

DOI

10.3030/725698

Project closed

EC signature date 24 April 2017

Start date 1 September 2017

End date 31 August 2023

Funded under

• EXCELLENT SCIENCE - European Research Council (ERC)

Total cost

€ 1 968 000,00

EU contribution

€ 1 968 000,00

Coordinated by

ETHNIKO ASTEROSKOPEIO ATHINON
Greece

Periodic Reporting for period 5 - D-TECT (Does dust triboelectrification affect our climate?)

Reporting period: 2022-09-01 to 2023-08-31

Summary of the context and overall objectives of the project

The recent IPCC report identifies mineral dust and the associated uncertainties in climate projections as key topics for future research. Dust size distribution in climate models controls the dust-radiation-cloud interactions and is a major contributor to these uncertainties. Observations show that the coarse mode of dust can be sustained during long-range transport, while current understanding fails in explaining why the lifetime of large airborne dust particles is longer than expected from gravitational settling theories. This discrepancy between observations and theory suggests that other processes counterbalance the effect of gravity along transport. D-TECT envisaged filling this knowledge gap by studying the contribution of the triboelectrification on particle removal processes. Our hypothesis was that triboelectric charging generates adequate electric fields to hold large dust particles up in the atmosphere. D-TECT aimed to (i) parameterize the physical mechanisms responsible for dust triboelectrification; (ii) assess the impact of electrification on dust settling; (iii) quantify the climatic impacts of the process, particularly the effect on the dust size evolution during transport, on dry deposition, on cloud formation and on radiative transfer. The approach involved the development of a novel polarization lidar system to monitor dust particle orientation, along with the organization large-scale field experiments including unprecedented ground-based remote sensing and airborne in-situ observation synergies. The results from these experiments showed indications of dust particle orientation, but no strong proof. Moreover they showed electric fields in the dust layers that are not adequate for any significant impact on dust particles’ dynamics and settling process. Considering aerosol-electricity interactions, the acquired observations were used to improve theoretical understanding and simulations of dust lifecycle.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

To achieve the D-TECT goals we combined remote sensing observations, airborne in-situ data and atmospheric modeling. A novel polarization lidar system (WALL-E) was developed in collaboration with Raymetrics S.A. to monitor dust particle orientation as well as their optical and microphysical properties in ambient conditions (Figure 1). WALL-E lidar was successfully tested in the campaign in Cyprus (November 2019) and participated in the scientific campaign ESA-ASKOS in Cabo Verde (https://askos.space.noa.gr/) on June/Septemeber 2022.
Moreover, the PANhellenic GEophysical observatory of Antikythera (PANGEA) was created by the National Observatory of Athens (NOA) to serve the continuous observational needs of D-TECT. The island of Antikythera is considered to be an ideal place to collect climatic and geophysical data due to minimal pollution, little anthropogenic activity and the intersection of air masses from the Sahara desert, the volcano Etna and important cities of the Mediterranean. The prospect of a supersite on this remote island captured the interest of the European Investment Bank which has invested 20 million euros in the Observatory.
The large scale observational campaign of D-TECT was combined with the observational campaign “ASKOS”, organized by the European Space Agency (ESA). ASKOS took place in two phases (Phase I: July/September 2021; Phase II: June/September 2022) at Cabo Verde, focusing on Aeolus satellite aerosol product validation under dusty conditions. In order to monitor the columnar electrical properties of dust layers several prototype atmospheric electricity sensors were developed for D-TECT, and they were mounted on radiosonde balloons and UAV platforms.
Another important task of D-TECT was the development of a scattering database for large oriented dust particles with irregular shapes. For this reason, Dr. Amiridis was awarded a total of 45 Million CPU-core-hours by the Partnership for Advanced Computing in Europe (PRACE) and Greek Research & Technology Network (GRNET) at MareNostrum HPC (at Barcelona Supercomputing Center) and National HPC facility ARIS, respectively.
Despite the vast number of dust studies regarding dust transport, deposition fluxes, effects on radiation and clouds etc., there is still significant uncertainty on the sedimentation processes of dust. Since all atmospheric models treat dust particles as perfect spheres, new conceptual theoretical schemes were developed incorporating shape-dependent sedimentation and the effects of the electrically induced orientation of prolate dust particles in atmospheric models.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

D-TECT provided an ideal ground for fostering new methodologies and unconventional developments. Some examples are:
• Development of a prototype lidar (WALL-E) in collaboration with RAYMETRICS S.A. for detecting dust orientation in the atmosphere, along with its properties (e.g. size, refractive index). For this development Dr. Tsekeri was awarded the INABA Prize at the 29th International Laser Radar Conference (ILRC29 in China).
• New atmospheric modeling developments to quantify the electrical and aerodynamic torques on the spheroidal model that is frequently assumed for dust particles and a realistic representation of mineral dust aerodynamic shapes in WRF model.
• New measurement techniques for monitoring of electrified dust layers with ground-based electric fieldmill instrumentation at the PANGEA observatory in Antikythera.
• New scattering database for particles with irregular shapes for size parameters up to 60, instead of the size parameter of 30 stated in the DoA.
• Indications of particle orientation from sun-polarimetry was acquired at PANGEA for the first time.
• The ASKOS campaign at Cabo Verde enabled the synergy of ground-based, airborne and satellite observational platforms providing measurements that enhanced the D-TECT scientific objectives.

WALL_E lidar system