Lower-thermospheric wind variations in the pulsating aurora

第2回極域科学シンポジウム/第35回極域宙空圏シンポジウム 11月14日（月） 国立極地研究所 2階大会議

Spectra of pulsating aurora emissions observed by an optical spectrograph at Tromso, Norway

The Tenth Symposium on Polar Science/Ordinary sessions: [OS] Space and upper atmospheric sciences, Wed. 4 Dec. /Entrance Hall (1st floor) at National Institute of Polar Research (NIPR

Variations of cosmic noise absorption (CNA) by energetic electron precipitation (EEP) and changes of the auroral morphology

The Tenth Symposium on Polar Science/Ordinary sessions: [OS] Space and upper atmospheric sciences, Wed. 4 Dec. / Institute of Statistics and Mathematics (ISM) Seminar room 2 (D304) (3rd floor

Study on variation of neutral temperature in the polar MLT region using a sodium LIDAR at Tromsø

第2回極域科学シンポジウム/第35回極域宙空圏シンポジウム 11月14日（月） 国立極地研究所 2階大会議

Spatial Evolution of Wave‐Particle Interaction Region Deduced From Flash‐Type Auroras and Chorus‐Ray Tracing

In-situ observations of spatial variations of the wave-particle interaction region require a large number of satellite probes. As an alternative, flash-type auroras, a kind of pulsating aurora, driven by discrete chorus elements, can be used to investigate the interaction region with a high spatial resolution. We estimated the spatial extent of wave-particle interaction region from ground-based observations of flash aurora at Gakona (62.39°N, 214.78°E), Alaska at subauroral latitudes, and found that the auroral expansion was predominantly to the low-latitude side. The spatial displacement is thought to be caused by the propagation effects of chorus waves in the magnetosphere. Using ray tracing analysis to take into account chorus wave propagation, we reconstructed the spatiotemporal evolution of the volume emission rate and confirmed that the predominant expansion is toward the lower-latitude side in the ionosphere. This study shows that chorus wave propagation in the magnetosphere gives new insight for characterizing the transverse size (across the geomagnetic field line) of wave-particle interaction regions. The calculated spatial scale of the column auroral emission shows a correlation with the magnetic latitude of the resonance region at magnetic latitudes within 10° of the equatorial plane of the magnetosphere. Our results suggest that the spatial scale of a flash aurora is indirectly related to the chorus amplitude because the latitudinal range of the wave-particle interaction is important for the growth of wave amplitude

オウシュウ ヒカンショウ サンラン (EISCAT) レーダー カンソクジョ ノ タハチョウ フォトメータデータ ヲ モチイタ ソウジョウ デンリケン デンドウド ノ スイテイ

本研究では,多波長フォトメータデータ(427.8 nm, 557.7 nm, 630.0 nm)を利用してオーロラ発生時の高緯度電離圏における電気伝導度推定の手法開発を行った.本手法の特徴は層状の電気伝導度を導出することが可能な点である.この層構造を持つ電気伝導度を光学データから導出するためのモデル関数を,高度分解能がある欧州非干渉散乱(EISCAT)UHF レーダーデータから推定した電気伝導度を用いて決定した.本研究により,電離圏を3 層(高度95-110 km, 110-170 km, 170-300 km)に分割しても,従来の方法と同程度の信頼度を持つ電気伝導度を光学データから導出できることが確認された.This study aimed to develop a methodology for estimating ionospheric conductance at auroral latitudes using data from a multi-wavelength photometer (427.8, 557.7, and 630.0 nm). An advantage of the approach is that the ionosphere is divided into layers and conductance is computed for each layer. From optical data, the layer conductance was determined by using height-resolved conductivity derived from the European Incoherent Scatter (EISCAT) Tromso UHF radar. The developed method can provide conductance from optical data with some confidence (at least at the same level as previous methods) even after separating the ionosphere into three layers, 95-110 km, 110-170 km, and 170-300 km

Plasma-neutral gas interactions in various space environments: Assessment beyond simplified approximations as a Voyage 2050 theme

In the White Paper, submitted in response to the European Space Agency (ESA) Voyage 2050 Call, we present the importance of advancing our knowledge of plasma-neutral gas interactions, and of deepening our understanding of the partially ionized environments that are ubiquitous in the upper atmospheres of planets and moons, and elsewhere in space. In future space missions, the above task requires addressing the following fundamental questions: (A) How and by how much do plasma-neutral gas interactions influence the re-distribution of externally provided energy to the composing species? (B) How and by how much do plasma-neutral gas interactions contribute toward the growth of heavy complex molecules and biomolecules? Answering these questions is an absolute prerequisite for addressing the long-standing questions of atmospheric escape, the origin of biomolecules, and their role in the evolution of planets, moons, or comets, under the influence of energy sources in the form of electromagnetic and corpuscular radiation, because low-energy ion-neutral cross-sections in space cannot be reproduced quantitatively in laboratories for conditions of satisfying, particularly, (1) low-temperatures, (2) tenuous or strong gradients or layered media, and (3) in low-gravity plasma. Measurements with a minimum core instrument package (< 15 kg) can be used to perform such investigations in many different conditions and should be included in all deep-space missions. These investigations, if specific ranges of background parameters are considered, can also be pursued for Earth, Mars, and Venus

Study of the lower thermospheric wind in the polar region using EISCAT data obtained in 2 solar cycles

第3回極域科学シンポジウム/第36回極域宙空圏シンポジウム 11月26日（月）、27日（火） 国立極地研究所 2階ラウン

Current status of Next-generation European Incoherent Scatter Radar project: EISCAT_3D

第2回極域科学シンポジウム/第35回極域宙空圏シンポジウム 11月15日（火） 国立極地研究所 2階大会議

Studies of mean winds, tides and quasi-2 day waves using three meteor radars in northern Scandinavia

第2回極域科学シンポジウム/第35回極域宙空圏シンポジウム 11月14日（月） 国立極地研究所 2階大会議