Detecting TLEs using a massive all-sky camera network

International audienceTransient Luminous Events (TLEs) are large-scale optical events occurring in the upper-atmosphere from the top of thunderclouds up to the ionosphere. TLEs may have important effects in local, regional, and global scales, and many features of TLEs are not fully understood yet [e.g, Pasko, JGR, 115, A00E35, 2010]. Moreover, meteor events have been suggested to play a role in sprite initiation by producing ionospheric irregularities [e.g, Qin et al., Nat. Commun., 5, 3740, 2014]. The French Fireball Recovery and InterPlanetary Observation Network (FRIPON, https://www.fripon.org/?lang=en), is a national all-sky 30 fps camera network designed to continuously detect meteor events. We seek to make use of this network to observe TLEs over unprecedented space and time scales ( 1000×1000 km with continuous acquisition). To do so, we had to significantly modify FRIPON's triggering software Freeture (https://github.com/fripon/freeture) while leaving the meteor detection capability uncompromised. FRIPON has a great potential in the study of TLEs. Not only could it produce new results about spatial and time distributions of TLEs over a very large area, it could also be used to validate and complement observations from future space missions such as ASIM (ESA) and TARANIS (CNES). In this work, we present an original image processing algorithm that can detect sprites using all-sky cameras while strongly limiting the frequency of false positives and our ongoing work on sprite triangulation using the FRIPON network

Detecting TLEs using a massive all-sky camera network

International audienceTransient Luminous Events (TLEs) are large-scale optical events occurring in the upper-atmosphere from the top of thunderclouds up to the ionosphere. TLEs may have important effects in local, regional, and global scales, and many features of TLEs are not fully understood yet [e.g, Pasko, JGR, 115, A00E35, 2010]. Moreover, meteor events have been suggested to play a role in sprite initiation by producing ionospheric irregularities [e.g, Qin et al., Nat. Commun., 5, 3740, 2014]. The French Fireball Recovery and InterPlanetary Observation Network (FRIPON, https://www.fripon.org/?lang=en), is a national all-sky 30 fps camera network designed to continuously detect meteor events. We seek to make use of this network to observe TLEs over unprecedented space and time scales ( 1000×1000 km with continuous acquisition). To do so, we had to significantly modify FRIPON's triggering software Freeture (https://github.com/fripon/freeture) while leaving the meteor detection capability uncompromised. FRIPON has a great potential in the study of TLEs. Not only could it produce new results about spatial and time distributions of TLEs over a very large area, it could also be used to validate and complement observations from future space missions such as ASIM (ESA) and TARANIS (CNES). In this work, we present an original image processing algorithm that can detect sprites using all-sky cameras while strongly limiting the frequency of false positives and our ongoing work on sprite triangulation using the FRIPON network

Investigation on HF-VHF Electromagnetic Emissions from Collision of Sprite Streamers

International audienceSprites are complex discharges that consist of many plasma filaments named streamers. They are produced high above thunderstorms (40-90 km), usually in association with positive cloud-to-ground lightning. It is known that sprites produce electromagnetic radiation observed typically in the extremely low (ELF) to ultra low (ULF) frequency bands [e.g., Cummer et al., GRL, 25, 1281, 1998]. More recently, sprites have been found to be associated with LF emissions in the range ~50 to 350 kHz [Fullekrug et al., JGR, 115, A00E09, 2010], which emissions have later been proposed to be related to streamer expansion processes [Qin, et al., GRL, 39, L22803, 2012]. In a different context, Ihaddadene and Celestin [JGR, 122, 1000, 2017] have shown that collisions between streamers with opposite polarities would lead to strong electric field variation on the order of a few picoseconds in air at ground-level. It is worth mentioning that collisions between sprite streamers are common. Moreover, use of similarity laws shows that those few picoseconds would turn into a timescale on the order of a fraction of microsecond at 50 km, which hence leads to the interesting possibility of HF-VHF emissions from sprites. These characteristic emissions might in turn carry a signature of given processes in sprite discharges. The future space mission TARANIS funded by CNES will measure electromagnetic emissions associated with Transient Luminous Events, such as sprites, from DC to 30 MHz. Quantifying possible emission processes and identifying corresponding signatures is therefore of prime importance for the preparation of TARANIS. Furthermore, the French radio telescope NenuFAR [Zarka et al., ICATT, 13-18, 2015] is sensitive in the frequency range 10-85 MHz and will attempt observation of sprites as part of one of its Key Programs. Using a streamer fluid model to simulate the collision of streamers in sprites and a simple antenna model, we present an effort on modeling relevant sprite streamer processes generating characteristic electromagnetic radiation in the HF-VHF range and investigate on its possible detection by TARANIS and ground-based instruments

Investigation on HF-VHF Electromagnetic Emissions from Collision of Sprite Streamers

International audienceSprites are complex discharges that consist of many plasma filaments named streamers. They are produced high above thunderstorms (40-90 km), usually in association with positive cloud-to-ground lightning. It is known that sprites produce electromagnetic radiation observed typically in the extremely low (ELF) to ultra low (ULF) frequency bands [e.g., Cummer et al., GRL, 25, 1281, 1998]. More recently, sprites have been found to be associated with LF emissions in the range ~50 to 350 kHz [Fullekrug et al., JGR, 115, A00E09, 2010], which emissions have later been proposed to be related to streamer expansion processes [Qin, et al., GRL, 39, L22803, 2012]. In a different context, Ihaddadene and Celestin [JGR, 122, 1000, 2017] have shown that collisions between streamers with opposite polarities would lead to strong electric field variation on the order of a few picoseconds in air at ground-level. It is worth mentioning that collisions between sprite streamers are common. Moreover, use of similarity laws shows that those few picoseconds would turn into a timescale on the order of a fraction of microsecond at 50 km, which hence leads to the interesting possibility of HF-VHF emissions from sprites. These characteristic emissions might in turn carry a signature of given processes in sprite discharges. The future space mission TARANIS funded by CNES will measure electromagnetic emissions associated with Transient Luminous Events, such as sprites, from DC to 30 MHz. Quantifying possible emission processes and identifying corresponding signatures is therefore of prime importance for the preparation of TARANIS. Furthermore, the French radio telescope NenuFAR [Zarka et al., ICATT, 13-18, 2015] is sensitive in the frequency range 10-85 MHz and will attempt observation of sprites as part of one of its Key Programs. Using a streamer fluid model to simulate the collision of streamers in sprites and a simple antenna model, we present an effort on modeling relevant sprite streamer processes generating characteristic electromagnetic radiation in the HF-VHF range and investigate on its possible detection by TARANIS and ground-based instruments

Investigation on HF-VHF Electromagnetic Emissions from Collision of Sprite Streamers

International audienceSprites are complex discharges that consist of many plasma filaments named streamers. They are produced high above thunderstorms (40-90 km), usually in association with positive cloud-to-ground lightning. It is known that sprites produce electromagnetic radiation observed typically in the extremely low (ELF) to ultra low (ULF) frequency bands [e.g., Cummer et al., GRL, 25, 1281, 1998]. More recently, sprites have been found to be associated with LF emissions in the range ~50 to 350 kHz [Fullekrug et al., JGR, 115, A00E09, 2010], which emissions have later been proposed to be related to streamer expansion processes [Qin, et al., GRL, 39, L22803, 2012]. In a different context, Ihaddadene and Celestin [JGR, 122, 1000, 2017] have shown that collisions between streamers with opposite polarities would lead to strong electric field variation on the order of a few picoseconds in air at ground-level. It is worth mentioning that collisions between sprite streamers are common. Moreover, use of similarity laws shows that those few picoseconds would turn into a timescale on the order of a fraction of microsecond at 50 km, which hence leads to the interesting possibility of HF-VHF emissions from sprites. These characteristic emissions might in turn carry a signature of given processes in sprite discharges. The future space mission TARANIS funded by CNES will measure electromagnetic emissions associated with Transient Luminous Events, such as sprites, from DC to 30 MHz. Quantifying possible emission processes and identifying corresponding signatures is therefore of prime importance for the preparation of TARANIS. Furthermore, the French radio telescope NenuFAR [Zarka et al., ICATT, 13-18, 2015] is sensitive in the frequency range 10-85 MHz and will attempt observation of sprites as part of one of its Key Programs. Using a streamer fluid model to simulate the collision of streamers in sprites and a simple antenna model, we present an effort on modeling relevant sprite streamer processes generating characteristic electromagnetic radiation in the HF-VHF range and investigate on its possible detection by TARANIS and ground-based instruments

HF‐VHF Electromagnetic Emissions from Collisions of Sprite Streamers

International audienceSprites are complex transient plasma discharges that consist of many plasma filaments named streamers. They are produced high above thunderstorms. Sprites are known to produce electromagnetic radiation observed typically in the extremely low (ELF), ultra low (ULF), to as high as medium frequency (MF) radio bands. Recent research work showed that head-on streamer collisions lead to a reinforcement of the electric field over a short time scale, typically a few picoseconds at ground-level. The use of the similarity laws leads to a corresponding time scale on the order of a fraction of a microsecond at 50 km altitude, which opens the eventuality for HF-VHF emissions from sprites. In this paper, using a multifluid streamer model paired with an antenna model assimilating the streamer as a straight segment. We simulate head-on collision between two streamers with opposite polarities in order to evaluate their electromagnetic emissions. We report numerical prediction of the electromagnetic signature for 50, 60, 70, and 80 km altitudes. The magnetic field radiated varies over 4 orders of magnitude, between less than 0.1 fT to 7 pT. Comparing the spectral density from the head-on collision between two streamers with IME-HF (TARANIS), ICE (DEMETER), and FORTE RF payload, we find that IME-HF and ICE could detect these signatures. We compare these results with sensitive ground-based instruments like the radiotelescope NenuFAR, and show that detections of such events might be possible with this type of fast and sensitive radiotelescopes

FRIPON: A worldwide network to track incoming meteoroids

Context. Until recently, camera networks designed for monitoring fireballs worldwide were not fully automated, implying that in case of a meteorite fall, the recovery campaign was rarely immediate. This was an important limiting factor as the most fragile - hence precious - meteorites must be recovered rapidly to avoid their alteration. Aims. The Fireball Recovery and InterPlanetary Observation Network (FRIPON) scientific project was designed to overcome this limitation. This network comprises a fully automated camera and radio network deployed over a significant fraction of western Europe and a small fraction of Canada. As of today, it consists of 150 cameras and 25 European radio receivers and covers an area of about 1.5 × 106km2. Methods. The FRIPON network, fully operational since 2018, has been monitoring meteoroid entries since 2016, thereby allowing the characterization of their dynamical and physical properties. In addition, the level of automation of the network makes it possible to trigger a meteorite recovery campaign only a few hours after it reaches the surface of the Earth. Recovery campaigns are only organized for meteorites with final masses estimated of at least 500 g, which is about one event per year in France. No recovery campaign is organized in the case of smaller final masses on the order of 50 to 100 g, which happens about three times a year; instead, the information is delivered to the local media so that it can reach the inhabitants living in the vicinity of the fall. Results. Nearly 4000 meteoroids have been detected so far and characterized by FRIPON. The distribution of their orbits appears to be bimodal, with a cometary population and a main belt population. Sporadic meteors amount to about 55% of all meteors. A first estimate of the absolute meteoroid flux (mag < -5; meteoroid size ≥∼1 cm) amounts to 1250/yr/106km2. This value is compatible with previous estimates. Finally, the first meteorite was recovered in Italy (Cavezzo, January 2020) thanks to the PRISMA network, a component of the FRIPON science project

FRIPON: a worldwide network to track incoming meteoroids

(IF 5.80; Q1)International audienceContext. Until recently, camera networks designed for monitoring fireballs worldwide were not fully automated, implying that in case of a meteorite fall, the recovery campaign was rarely immediate. This was an important limiting factor as the most fragile-hence precious-meteorites must be recovered rapidly to avoid their alteration. Aims. The Fireball Recovery and InterPlanetary Observation Network (FRIPON) scientific project was designed to overcome this limitation. This network comprises a fully automated camera and radio network deployed over a significant fraction of western Europe and a small fraction of Canada. As of today, it consists of 150 cameras and 25 European radio receivers and covers an area of about 1.5 × 10 6 km 2. Methods. The FRIPON network, fully operational since 2018, has been monitoring meteoroid entries since 2016, thereby allowing the characterization of their dynamical and physical properties. In addition, the level of automation of the network makes it possible to trigger a meteorite recovery campaign only a few hours after it reaches the surface of the Earth. Recovery campaigns are only organized for meteorites with final masses estimated of at least 500 g, which is about one event per year in France. No recovery campaign is organized in the case of smaller final masses on the order of 50 to 100 g, which happens about three times a year; instead, the information is delivered to the local media so that it can reach the inhabitants living in the vicinity of the fall. Results. Nearly 4000 meteoroids have been detected so far and characterized by FRIPON. The distribution of their orbits appears to be bimodal, with a cometary population and a main belt population. Sporadic meteors amount to about 55% of all meteors. A first estimate of the absolute meteoroid flux (mag <-5; meteoroid size ≥∼1 cm) amounts to 1250/yr/10 6 km 2. This value is compatible with previous estimates. Finally, the first meteorite was recovered in Italy (Cavezzo, January 2020) thanks to the PRISMA network, a component of the FRIPON science project

FRIPON: A worldwide network to track incoming meteoroids

Context. Until recently, camera networks designed for monitoring fireballs worldwide were not fully automated, implying that in case of a meteorite fall, the recovery campaign was rarely immediate. This was an important limiting factor as the most fragile - hence precious - meteorites must be recovered rapidly to avoid their alteration. Aims. The Fireball Recovery and InterPlanetary Observation Network (FRIPON) scientific project was designed to overcome this limitation. This network comprises a fully automated camera and radio network deployed over a significant fraction of western Europe and a small fraction of Canada. As of today, it consists of 150 cameras and 25 European radio receivers and covers an area of about 1.5 × 106km2. Methods. The FRIPON network, fully operational since 2018, has been monitoring meteoroid entries since 2016, thereby allowing the characterization of their dynamical and physical properties. In addition, the level of automation of the network makes it possible to trigger a meteorite recovery campaign only a few hours after it reaches the surface of the Earth. Recovery campaigns are only organized for meteorites with final masses estimated of at least 500 g, which is about one event per year in France. No recovery campaign is organized in the case of smaller final masses on the order of 50 to 100 g, which happens about three times a year; instead, the information is delivered to the local media so that it can reach the inhabitants living in the vicinity of the fall. Results. Nearly 4000 meteoroids have been detected so far and characterized by FRIPON. The distribution of their orbits appears to be bimodal, with a cometary population and a main belt population. Sporadic meteors amount to about 55% of all meteors. A first estimate of the absolute meteoroid flux (mag < -5; meteoroid size ≥∼1 cm) amounts to 1250/yr/106km2. This value is compatible with previous estimates. Finally, the first meteorite was recovered in Italy (Cavezzo, January 2020) thanks to the PRISMA network, a component of the FRIPON science project

FRIPON: a worldwide network to track incoming meteoroids

Context: Until recently, camera networks designed for monitoring fireballs worldwide were not fully automated, implying that in case of a meteorite fall, the recovery campaign was rarely immediate. This was an important limiting factor as the most fragile – hence precious – meteorites must be recovered rapidly to avoid their alteration. Aims: The Fireball Recovery and InterPlanetary Observation Network (FRIPON) scientific project was designed to overcome this limitation. This network comprises a fully automated camera and radio network deployed over a significant fraction of western Europe and a small fraction of Canada. As of today, it consists of 150 cameras and 25 European radio receivers and covers an area of about 1.5 × 106 km2. Methods: The FRIPON network, fully operational since 2018, has been monitoring meteoroid entries since 2016, thereby allowing the characterization of their dynamical and physical properties. In addition, the level of automation of the network makes it possible to trigger a meteorite recovery campaign only a few hours after it reaches the surface of the Earth. Recovery campaigns are only organized for meteorites with final masses estimated of at least 500 g, which is about one event per year in France. No recovery campaign is organized in the case of smaller final masses on the order of 50 to 100 g, which happens about three times a year; instead, the information is delivered to the local media so that it can reach the inhabitants living in the vicinity of the fall. Results: Nearly 4000 meteoroids have been detected so far and characterized by FRIPON. The distribution of their orbits appears to be bimodal, with a cometary population and a main belt population. Sporadic meteors amount to about 55% of all meteors. A first estimate of the absolute meteoroid flux (mag < –5; meteoroid size ≥~1 cm) amounts to 1250/yr/106 km2. This value is compatible with previous estimates. Finally, the first meteorite was recovered in Italy (Cavezzo, January 2020) thanks to the PRISMA network, a component of the FRIPON science project