2025-06-12 NASA
Red SPRITES are visible above a line of thunderstorms off the coast of South Africa. NASA
＜関連情報＞
- https://www.nasa.gov/missions/station/iss-research/studying-storms-from-space-station/
- https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022JD037460
- https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024GL114090
- https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022JD037883
国際宇宙ステーションのASIM/MMIAで観測されたブルー放電の高さ決定 Height Determination of a Blue Discharge Observed by ASIM/MMIA on the International Space Station
Xue Bai, Martin Füllekrug, Olivier Chanrion, Serge Soula, Adam Peverell, Dakalo Mashao, Michael Kosch, Lasse Husbjerg, Nikolai Østgaard, Torsten Neubert, Victor Reglero
Journal of Geophysical Research: Atmospheres Published: 26 March 2023
DOI:https://doi.org/10.1029/2022JD037460
Abstract
We analyze simultaneous photometric observations of thundercloud discharges from the Modular Multispectral Imaging Array of the Atmosphere-Space Interactions Monitor (ASIM) on board the International Space Station with ground-based vertical electric field measurements in South Africa on 3 February 2019 at 23:00–23:05 UTC. During this time, ASIM flew over an extended thunderstorm front of several hundreds of kilometers and recorded a blue discharge with the photometer at 337 nm which emitted strong electric fields. It is found that the rising edge of the blue photomultiplier tube light pulse allows the estimation of the blue discharge height: ∼10.9–16.5 km which is constrained by cloud top height in a range of ∼13.3–16.7 km deduced from infrared radiometry on board the geostationary Meteosat satellite. The electric field measurements are used to infer the height of the blue discharge to be ∼16.0–18.8 km by use of skywave arrival times. It is shown that the height determinations are consistent with each other within the measurement uncertainties and the possible presence of an overshooting cloud top is discussed. The height of blue discharges is important to better understand how they can affect the chemistry in the upper troposphere.
Key Points
- A blue discharge was detected by the Atmosphere-Space Interactions Monitor during an overpass of thunderstorms in South Africa
- The blue discharge height is determined by modeling the light propagation through the thundercloud constrained by cloud top heights
- The height of the blue discharge is also determined with ground-based electric field measurements of skywaves
Plain Language Summary
Recently, Transient Luminous Events (TLEs) and lightning activity from thunderstorm tops above thunderstorms have attracted great interest. The Atmosphere-Space Interactions Monitor (ASIM) and the Modular Multispectral Imaging Array (MMIA) are on board the International Space Station to record the lightning activity and TLEs in the UV band (180–230 nm) as well as the blue (337 nm) and the red (777.4 nm) emissions. In total, 188 MMIA triggers were recorded and more than 2,000 lightning strokes were reported by the lightning detection and location network during 23:00–23:05 UTC on 3 February 2019. We focus on a blue discharge event that happened at 23:02:41 UTC. The novelty of this work is that the height determination is carried out by using ground-based electric field measurements and space-based optical measurements from ASIM. This study can help to understand the chemistry effects at the tropopause level caused by such blue discharge events.
オーバーシュート雷雲におけるコロナ放電を動力源とする電離層エルフ Ionospheric Elves Powered by Corona Discharges in Overshooting Thunderclouds
Feifan Liu, Torsten Neubert, Olivier Chanrion, Ningyu Liu, Baoyou Zhu, Gaopeng Lu, Fanchao Lyu, Zilong Qin, Ming Luo, Dongshuai Li, Krystallia Dimitriadou, Jiuhou Lei …
Geophysical Research Letters Published: 14 March 2025
DOI:https://doi.org/10.1029/2024GL114090
Abstract
Corona discharges in thundercloud tops are observed by the Atmosphere-Space Interactions Monitor (ASIM) as blue flashes at the 337 nm spectral line of N2 and by ground receivers as so-called Narrow Bipolar Events (NBEs) in the radio signals. It has been suggested that the electromagnetic radiation from the discharges may be powerful enough to excite elves, the rapidly expanding rings of luminous emissions at the bottom ionosphere. Here we present optical observations by ASIM and simultaneous radio measurements by lightning receivers in China, that confirm this proposition. The concurrent measurements suggest that corona discharges at cloud tops generate elves observable by ASIM when the peak current exceeds ∼140 kA in absolute value, as estimated from the NBE measurements. The appearance of elves offers an alternate method to estimate the corona discharge currents and alignments at cloud tops, relevant to the characterization of chemical perturbations to greenhouse gas agents at the tropical tropopause.
Key Points
- Atmosphere-Space Interactions Monitor (ASIM) and a ground sferic array observe ionospheric elves generated by negative Narrow Bipolar Events (NBEs) in cloud tops
- Elves are detected from ASIM when the estimated peak current of NBEs is above ∼140 kA
- Elves offers an alternate method to estimate strong corona discharge currents
Plain Language Summary
Elves are rapidly expanding rings of optical emissions in the lower ionosphere, excited by the transient electromagnetic pulses from lightning in the clouds below. Narrow bipolar events (NBEs) are signatures in radio signals from intra-cloud discharges. They are thought to be fast streamer breakdown that may trigger the onset of lightning and blue jets. Theoretical studies suggest NBEs may carry sufficient currents to excite elves. However, there is a lack of experimental evidence. Here, we report the concurrent observation of NBEs and the associated elves that confirm this hypothesis. The optical observations are of the highest temporal and spatial resolution available in space by the Atmosphere-Space Interactions Monitor onboard the International Space Station.
雲頂付近の高高度正狭バイポーラ現象に伴うさまざまなタイプのコロナ放電 Different Types of Corona Discharges Associated With High-Altitude Positive Narrow Bipolar Events Nearby Cloud Top
Dongshuai Li, Alejandro Luque, F. J. Gordillo-Vazquez, F. J. Pérez-Invernón, Lasse Skaaning Husbjerg, Torsten Neubert, Olivier Chanrion, Gaopeng Lu, Hongbo Zhang, Jing Han …
Journal of Geophysical Research: Atmospheres Published: 05 February 2023
DOI:https://doi.org/10.1029/2022JD037883
Abstract
Single- and multi-pulse blue corona discharges are frequently observed in thunderstorm clouds. Although we know they often correlate with Narrow Bipolar Events (NBEs) in Very Low Frequency/Low Frequency radio signals, their physics is not well understood. Here, we report a detailed analysis of different types of blue corona discharges observed by the Atmosphere-Space Interactions Monitor during an overpass of a thundercloud cell nearby Malaysia. Both single- and multi-pulse blue corona discharges were associated with positive NBEs at the top of the cloud, reaching about 18 km altitude. We find that the primary pulses of multi-pulse discharges have weaker current moments than the single-pulse discharges, suggesting that the multi-pulse discharges either have shorter vertical channels or have weaker currents than the single-pulse discharges. The subsequent pulse trains of the multi-pulse discharges delayed some milliseconds are likely from horizontally oriented electrical discharges, but some NBEs, correlated with both single-and multi-pulse discharges, include small-amplitude oscillations within a few microseconds inside their waveforms, which are unresolved in the optical observation and yet to be understood. Furthermore, by jointly analyzing the optical and radio observations, we estimate the photon free mean path at the cloud top to be ∼6 m.
Key Points
- Corona discharges are found to be associated with unusual high-altitude positive narrow bipolar events nearby cloud top
- Corona discharges are classified into different types according to their different optical and radio features
- The detailed features of corona discharges and their parent thundercloud are estimated using different theoretical models
Plain Language Summary
Recent studies indicate that the blue corona discharges detected by the Atmosphere-Space Interactions Monitor onboard the international space station have close association with a special type of intracloud discharges named Narrow Bipolar Events (NBEs). In this study, we present a detailed analysis of different types of NBE-associated corona discharges detected by both optical and radio observations. All the detected corona discharges are found to be associated with unusual high-altitude positive NBEs, which located a few kilometers below the cloud top where the cloud droplets have low impact on the optical observation. This allowed us to infer the physical properties of them and their parent thundercloud by using theoretical models. The results can provide important reference to further investigate the physical mechanism of corona discharge and their role in lightning initiations.
