Recent results of the Optical Mesosphere Thermosphere Imagers (OMTIs): 2014-2015

第6回極域科学シンポジウム[OS] 宙空圏11月16日（月）　国立極地研究所１階交流アトリウ

Statistical analysis of luminosity of polar cap patches

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

Midterm surgical results of total cavopulmonary connection: clinical advantages of the extracardiac conduit method

AbstractObjectiveWe evaluated the midterm surgical outcomes of intra-atrial lateral tunnel and extracardiac conduit total cavopulmonary connection to clarify the clinical superiority.MethodsPatients (n = 167) underwent total cavopulmonary connection (88 with lateral tunnel and 79 with extracardiac conduit) from November 1991 to March 1999. Survival, incidence of reoperation and late complications, exercise tolerance, hemodynamic variables, and plasma concentration of natriuretic peptide type A were compared. In the lateral tunnel group, time-related change in lateral tunnel size was investigated for its relationship to postoperative arrhythmias.ResultsThe 8-year survival was 93.2% in the lateral tunnel group and 94.9% in the extracardiac conduit group. Seven reoperations were performed in the lateral tunnel group but none in the extracardiac conduit group. Supraventricular arrhythmias developed in 14 patients (15.9%) in the lateral tunnel group and in 4 patients (5.1%) in the extracardiac conduit group (P = .003). Freedom from cardiac-related events was 72.5% in the lateral tunnel group and 89.8% in the extracardiac conduit group at 8 years (P = .0098). Hemodynamic variables and exercise tolerance were similar in both groups but plasma natriuretic peptide type A concentration, a parameter of atrial wall tension, was higher in the lateral tunnel group. In the lateral tunnel group, intra-atrial tunnel size increased by 19.4% during the 44.2-month interval and the percent increase in tunnel size was an independent predictor of supraventricular arrhythmias.ConclusionsThe midterm survival, hemodynamic variables, and exercise tolerance were similar and satisfactory in both lateral tunnel and extracardiac conduit groups; however, the incidence of cardiac-related events was significantly less frequent in the extracardiac conduit group. In the lateral tunnel group, careful observation is required to monitor the relationship of the dilating tendency of the intra-atrial tunnel and the development of late complications

Comparison of two types of polar cap aurora: Simultaneous observations with ASI and ISR at Resolute Bay, Canada

第6回極域科学シンポジウム[OS] 宙空圏11月16日（月）　国立極地研究所１階交流アトリウ

Medium-Scale Traveling Ionospheric Disturbances and Plasma Bubbles Observed by an All-Sky Airglow Imager at Yonaguni, Japan

We report on night time air glow imaging observations of the low latitude ionosphere by means of a 630-m all-sky imager in stalled in March 2006 at Yonaguni, Japan (24.5°N, 123.0°E; 14.6°N geomagnetic), about 100 km east of Taiwan. The imager detected medium-scale traveling ionospheric disturbances (MSTIDs) for about 7 hours on the night of 26 May 2006. A dense GPS net work in Japan also ob served the same MSTID event on this night. The imager and GEONET data indicate that most of the MSTIDs prop a gated south west ward from the north of Japan to the south of Yonaguni and Taiwan over 4000 km, with a southern limit of 19°N (geomagnetic latitude 9°N) or lower. On the night of 10 November 2006, the imager observed two weak emission bands that were embedded on the F-region anomaly crest to the south of Yonaguni. The simultaneous electron density profiles from the FORMOSAT-3/COS MIC mission demonstrate that the weak emission bands are due to density depletions in equatorial plasma bubbles. These case studies suggest that the Yonaguni imager in collaboration with other instruments is very suit able for the study of ionospheric disturbances in and around the northern F-region anomaly crest

イオノゾンデ オヨビ ファブリ・ペロー カンショウケイ ニ ヨッテ カンソク サレタ シゴメン ネツケンフウ ノ ヒカク

電離圏ダイナミクスに大きく寄与する熱圏風についての理解を深めるため,イオノゾンデの磁気共役点観測により推定された南北方向の熱圏風(推定熱圏風)と,ファブリ・ペロー干渉計(FPI)観測により直接測定された南北方向の熱圏風との相関を調べた.推定熱圏風は,磁気共役点における熱圏風は等しい(赤道横断風モードが卓越する)という仮定のもとで導出される.2 つの手法で観測された夜間の熱圏風を比較するのは本研究が初めてである.2010 年のチェンマイ(タイ)とコトタバン(インドネシア)のイオノゾンデとFPI データを比較した結果,両者はおおむね良い相関を示したが,相関が悪い日もあった.相関が悪い事例は,赤道から収束・発散する成分を無視できず,赤道横断風モードが卓越するという仮定が成立しないと解釈されるものである.また,2 つの手法で求めた熱圏風の相関を季節別に調べると,2-4 月に両者の相関が高い一方,5-7 月に両者の相関が低いことがわかった.To comprehend ionospheric-thermospheric coupling, one must understand the thermospheric wind system. However, measuring the thermospheric wind using a Fabry-Perot interferometer (FPI) is not an easy task. Because of this difficulty, some researchers have estimated meridional wind velocities using data obtained from a pair of ionosonde stations near the geomagnetic conjugate points, under the assumption that the meridional wind is the same at the two ionosonde stations (transequatorial mode wind). In this paper, we construct the first comparison of the estimated meridional wind velocitieswith meridional wind observed with FPIs. We analyzed data from the ionosondes and FPIs installed at Chiang Mai, Thailand, and Kototabang, Indonesia, from 2010. We found that the estimated and observed wind velocities were generally in good agreement on most nights, although on some nights, the wind velocities were different. The assumption that the meridional wind is equal anywhere between the two ionosonde stations would not be suitable for the days when the winds were not in good agreement. We also investigated the seasonal dependence of the correlation between the estimated and observed meridional winds. They were in good agreement from February to April and were not in good agreement from May to July

Observation of GNSS scintillation in Tromsø

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

セキドウ タイキ レーダー ヲ モチイタ コウド 150 km エンジリョクセン フキソク コウゾウ ノ ドリフト ソクド ニ カンスル ケンキュウ

高度130-170 kmの電離圏において昼間に発生する「高度150 km沿磁力線不規則構造(FAI)エコー」は,赤道域に設置されたVHFレーダーによって1960年代以降,観測されてきた.本研究では,2007年8月から2009年10月までに,インドネシアの赤道大気レーダー(EAR)によって昼間に観測された150 km FAIエコーのドリフト速度の統計解析を行った。このデータと経験モデルから得られたF 領域プラズマ・ドリフト速度及び,ヒカマルカIS レーダーによる観測結果との比較を行った.その結果,150 km FAI エコーの磁力線直交上/ 南向きドリフト速度は,午後において減少することが明らかになった.この傾向は,F 領域プラズマ・ドリフト速度の場合と一致する.一方,150 km FAI エコーの西向きドリフト速度は,昼間において時間とともに減少する傾向があり,ヒカマルカの非干渉散乱レーダーで観測されたF 領域プラズマ・ドリフト速度が示すような正午付近の極大は顕著ではなかった.150 km FAI ドリフト速度の大きさは,F 領域プラズマ・ドリフト速度と比較し,平均で鉛直成分は約3 m/s 小さく,東西成分は25 m/s 小さいことが明らかになった.この違いを,電場生成領域であるE 領域の,磁気緯度による違いで説明するのは難しく,高度150 km 付近で生成される局所的な電場が影響している可能性が考えられる.Between 130 and 170 km altitude in the daytime ionosphere, the so-called 150-km field-aligned irregularities (FAIs) have been observed since the 1960s at equatorial regions with several very high frequency (VHF) radars. We report statistical results of 150-km FAI drift velocities on a plane perpendicular to the geomagnetic field, acquired by analyzing the Doppler velocities of 150-km FAIs observed with the Equatorial Atmosphere Radar (EAR) at Kototabang, Indonesia during the period from Aug. 2007 to Oct. 2009. We found that the southward/upward perpendicular drift velocity of the 150-km FAIs tends to decrease in the afternoon and that this feature is consistent with that of F-region plasma drift velocities over the magnetic equator. The zonal component of the 150-km FAI drift velocity is westward and decreases with time, whereas the F-region plasma drift velocity observed with the incoherent scatter radar at Jicamarca, Peru, which is westward, reaches a maximum at about noon. The southward/upward and zonal drift velocities of the 150-km FAIs are smaller than that of the F-region plasma drift velocity by approximately 3 m/s and 25 m/s, respectively, on average. The large difference between the 150-km FAI and F-region plasma drift velocities may not arise from a difference in the magnetic latitudes at which their electric fields are generated. Electric fields generated at the altitude at which the 150-km FAIs occur may not be negligible

Motion of a transpolar sun-aligned arc: Simultaneous observations with two ASIs and HF radars transpolar

第6回極域科学シンポジウム[OS] 宙空圏11月16日（月）　国立極地研究所１階交流アトリウ

SuperDARN HOP radar observation of ionospheric convection associated with low-latitude aurora observed at Rikubetsu during the 2015 St. Patrick’s Day storm

第6回極域科学シンポジウム[OS] 宙空圏11月16日（月）　国立極地研究所 2階 大会議