Periodic Reporting for period 4 - D-TECT (Does dust triboelectrification affect our climate?)
Berichtszeitraum: 2021-09-01 bis 2022-08-31
The overarching goal of the proposed project is to answer the question: “Why dust particles travel longer than expected?” The following objectives are specifically identified:
• To empirically quantify the physical mechanism responsible for dust triboelectrification.
• To assess the impact of the triboelectric charging on atmospheric dust transport, by acknowledging the effects of electric field and particle orientation on dust removal processes.
• To quantify the climatic impacts of the mechanism, particularly the effect on clouds and radiation.
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 envisages filling this knowledge gap by studying the contribution of the triboelectrification (contact electrification) on particle removal processes. Our hypothesis is that triboelectric charging generates adequate electric fields to hold large dust particles up in the atmosphere. D-TECT aims 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 involves the development of a novel polarization lidar system to detect and characterize aerosol particle orientation and a large-scale field experiment using unprecedented ground-based remote sensing and airborne in-situ observation synergies. Considering aerosol-electricity interactions, the observations will be used to improve theoretical understanding and simulations of dust lifecycle. The project will provide new fundamental understanding, able to open new horizons for weather and climate science, including biogeochemistry, volcanic ash and extraterrestrial dust research.
• To empirically quantify the physical mechanism responsible for dust triboelectrification.
• To assess the impact of the triboelectric charging on atmospheric dust transport, by acknowledging the effects of electric field and particle orientation on dust removal processes.
• To quantify the climatic impacts of the mechanism, particularly the effect on clouds and radiation.
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 envisages filling this knowledge gap by studying the contribution of the triboelectrification (contact electrification) on particle removal processes. Our hypothesis is that triboelectric charging generates adequate electric fields to hold large dust particles up in the atmosphere. D-TECT aims 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 involves the development of a novel polarization lidar system to detect and characterize aerosol particle orientation and a large-scale field experiment using unprecedented ground-based remote sensing and airborne in-situ observation synergies. Considering aerosol-electricity interactions, the observations will be used to improve theoretical understanding and simulations of dust lifecycle. The project will provide new fundamental understanding, able to open new horizons for weather and climate science, including biogeochemistry, volcanic ash and extraterrestrial dust research.
To achieve the D-TECT goals we have proposed to combine remote sensing observations, airborne in-situ data and atmospheric modeling. The remote sensing instrumentation will continuously monitor particle orientation as well as optical and microphysical properties in ambient conditions. For this purpose a novel polarization lidar system (WALL-E) has been developed in collaboration with Raymetrics S.A (Figure 1). WALL-E lidar has been successfully tested in the campaign in Cyprus (November 2019) and is currently configured to participate in the scientific campaign ESA-ASKOS in Cape Verde (https://askos.space.noa.gr/ ), on June/July 2021.
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 and little anthropogenic activity. Thanks to the geographical location of the island, located at the crossroads of air masses from the Sahara desert, the volcano Etna and important cities of the Mediterranean, PANGEA observatory fulfills the needs of D-TECT for monitoring the properties of dusty air masses and has the potential of becoming a first-class research infrastructure in line with the standards of the Global Observing System of the World Meteorological Organisation. The prospect of a supersite on this remote island has captured the interest of the European Investment Bank which will invest 20 million euros in the Observatory.
The large scale observational campaign of D-TECT is combined with the observational campaign “ASKOS”, organized by the European Space Agency (ESA). ASKOS has been initially designed to take place on June-July 2020 at Cape Verde focusing on Aeolus satellite aerosol product validation under dusty conditions. The ASKOS campaign will enable the synergy of ground-based, airborne and satellite observational platforms providing measurements that will enhance the D-TECT scientific objectives, considering also that Cape Verde environment is ideal for aerosol studies and desert dust specifically. At this time the exact status of the experiment depends on the evolution of COVID-19 pandemic crisis, but most probably it will be postponed by one year (June/July 2021).
In order to monitor the columnar electrical properties of dust layers several prototype atmospheric electricity sensors have been developed for D-TECT. These miniaturized instruments are easily mounted on radiosonde balloons and UAV platforms that are less invasive to the dust transport dynamics. First measurements in Cyprus campaign including meteorological radiosondes and tethered electricity sensors provide the first indications of charge stratification within the dust layers.
Another important task in D-TECT is the development for the first time of a scattering database for large oriented dust particles with irregular shapes. For this reason Dr. Amiridis has been awarded a total of 45 Million CPU-core-hours by the PRACE and GRNET at MareNostrum and ARIS HPC systems, respectively. This scattering database is of high importance for optimizing a wider range of applications including radiative transfer models and inversion algorithms. It will have a large impact that will be a paradigm shift for satellite remote sensing applications, especially if the orientation of the dust particles proves to be largely extended. The applications do not limit only on Earth’s environment but are anticipated to open new horizons for atmospheric dust research on Mars, Moon and asteroids.
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 and a remaining inconsistency between modeled and measured dust away from the sources, with the measurements indicating that coarser particles are actually transported towards longer distances than predicted by the theoretical models. Since all atmospheric models treat dust particles as perfect spheres, the actual shapes of the particles are not considered in these parameterizations. During this reporting period new conceptual theoretical schemes have been developed incorporating shape-dependent sedimentation and the effects of the electrically induced orientation of prolate dust particles in atmospheric models.
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 and little anthropogenic activity. Thanks to the geographical location of the island, located at the crossroads of air masses from the Sahara desert, the volcano Etna and important cities of the Mediterranean, PANGEA observatory fulfills the needs of D-TECT for monitoring the properties of dusty air masses and has the potential of becoming a first-class research infrastructure in line with the standards of the Global Observing System of the World Meteorological Organisation. The prospect of a supersite on this remote island has captured the interest of the European Investment Bank which will invest 20 million euros in the Observatory.
The large scale observational campaign of D-TECT is combined with the observational campaign “ASKOS”, organized by the European Space Agency (ESA). ASKOS has been initially designed to take place on June-July 2020 at Cape Verde focusing on Aeolus satellite aerosol product validation under dusty conditions. The ASKOS campaign will enable the synergy of ground-based, airborne and satellite observational platforms providing measurements that will enhance the D-TECT scientific objectives, considering also that Cape Verde environment is ideal for aerosol studies and desert dust specifically. At this time the exact status of the experiment depends on the evolution of COVID-19 pandemic crisis, but most probably it will be postponed by one year (June/July 2021).
In order to monitor the columnar electrical properties of dust layers several prototype atmospheric electricity sensors have been developed for D-TECT. These miniaturized instruments are easily mounted on radiosonde balloons and UAV platforms that are less invasive to the dust transport dynamics. First measurements in Cyprus campaign including meteorological radiosondes and tethered electricity sensors provide the first indications of charge stratification within the dust layers.
Another important task in D-TECT is the development for the first time of a scattering database for large oriented dust particles with irregular shapes. For this reason Dr. Amiridis has been awarded a total of 45 Million CPU-core-hours by the PRACE and GRNET at MareNostrum and ARIS HPC systems, respectively. This scattering database is of high importance for optimizing a wider range of applications including radiative transfer models and inversion algorithms. It will have a large impact that will be a paradigm shift for satellite remote sensing applications, especially if the orientation of the dust particles proves to be largely extended. The applications do not limit only on Earth’s environment but are anticipated to open new horizons for atmospheric dust research on Mars, Moon and asteroids.
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 and a remaining inconsistency between modeled and measured dust away from the sources, with the measurements indicating that coarser particles are actually transported towards longer distances than predicted by the theoretical models. Since all atmospheric models treat dust particles as perfect spheres, the actual shapes of the particles are not considered in these parameterizations. During this reporting period new conceptual theoretical schemes have been developed incorporating shape-dependent sedimentation and the effects of the electrically induced orientation of prolate dust particles in atmospheric models.
D-TECT has 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 has been 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 non-spherical prolate model that is frequently assumed for dust particles, for which we assume transport under the influence of electric and gravitational fields. Updated gravitational settling scheme in WRF model based on more realistic representation of mineral dust aerodynamic shapes.
• New measurement techniques for monitoring of electrified dust layers with ground-based electric fieldmill instrumentation at the PANGEA observatory in Antikythera. Reported cases of enhanced vertical electric field as compared to the local field, for detached and not heavily mixed dust layers, suggest that in-layer electric charges create strata of opposite polarities.
• 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. This was feasible due to the awards of computational resources to MareNostrum HPC (at Barcelona Supercomputing Center (BSC)) from the Partnership for Advanced Computing in Europe (PRACE), and to the National HPC facility ARIS from the Greek Research & Technology Network (GRNET).
• Indications of particle orientation from sun-polarimetry have been acquired at PANGEA for the first time.
• Investment of EIB at D-TECT activities in Antikythera. The Antikythera - PANGEA observatory fulfills the needs of D-TECT for monitoring the air mass properties in the Mediterranean. The station has attracted interest from the European Investment Bank (EIB) that will invest 20 M€ to assist the realization of becoming a first-class research infrastructure in line with the standards of the Global Observing System of the World Meteorological Organization.
• The ASKOS campaign at Cape Verde will enable the synergy of ground-based, airborne and satellite observational platforms providing measurements that will enhance the D-TECT scientific objectives, considering also that Cape Verde environment is ideal for aerosol studies and desert dust specifically.
Next Steps in D-TECT
The majority of the scientific results are expected after the large scale experiment in Cape Verde. However, at this point the exact dates and location of ASKOS experiment are subject to COVID-19 pandemia. The following steps have been scheduled for the upcoming period according to the project timeline:
(i) Implementation of large scale D-TECT experiment
(ii) Continuous D-TECT measurements in PANGEA observatory establishment
(iii) Finalizing and testing of the developed algorithms (electricity and orientation, gravitational settling, dust orientation retrieval scheme).
(iv) Synthesis of all scientific results and submissions of the corresponding journal papers.
• 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 has been 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 non-spherical prolate model that is frequently assumed for dust particles, for which we assume transport under the influence of electric and gravitational fields. Updated gravitational settling scheme in WRF model based on more realistic representation of mineral dust aerodynamic shapes.
• New measurement techniques for monitoring of electrified dust layers with ground-based electric fieldmill instrumentation at the PANGEA observatory in Antikythera. Reported cases of enhanced vertical electric field as compared to the local field, for detached and not heavily mixed dust layers, suggest that in-layer electric charges create strata of opposite polarities.
• 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. This was feasible due to the awards of computational resources to MareNostrum HPC (at Barcelona Supercomputing Center (BSC)) from the Partnership for Advanced Computing in Europe (PRACE), and to the National HPC facility ARIS from the Greek Research & Technology Network (GRNET).
• Indications of particle orientation from sun-polarimetry have been acquired at PANGEA for the first time.
• Investment of EIB at D-TECT activities in Antikythera. The Antikythera - PANGEA observatory fulfills the needs of D-TECT for monitoring the air mass properties in the Mediterranean. The station has attracted interest from the European Investment Bank (EIB) that will invest 20 M€ to assist the realization of becoming a first-class research infrastructure in line with the standards of the Global Observing System of the World Meteorological Organization.
• The ASKOS campaign at Cape Verde will enable the synergy of ground-based, airborne and satellite observational platforms providing measurements that will enhance the D-TECT scientific objectives, considering also that Cape Verde environment is ideal for aerosol studies and desert dust specifically.
Next Steps in D-TECT
The majority of the scientific results are expected after the large scale experiment in Cape Verde. However, at this point the exact dates and location of ASKOS experiment are subject to COVID-19 pandemia. The following steps have been scheduled for the upcoming period according to the project timeline:
(i) Implementation of large scale D-TECT experiment
(ii) Continuous D-TECT measurements in PANGEA observatory establishment
(iii) Finalizing and testing of the developed algorithms (electricity and orientation, gravitational settling, dust orientation retrieval scheme).
(iv) Synthesis of all scientific results and submissions of the corresponding journal papers.