Inferring hydroxyl layer peak heights from ground-based measurements of OH(6-2) band integrated emission rate at Longyearbyen (78 N, 16 E)

Measurements of hydroxyl nightglow emissions over Longyearbyen (78 N, 16 E) recorded simultaneously by the SABER instrument onboard the TIMED satellite and a ground-based Ebert-Fastie spectrometer have been used to derive an empirical formula for the height of the OH layer as a function of the integrated emission rate (IER). Altitude profiles of the OH volume emission rate (VER) derived from SABER observations over a period of more than six years provided a relation between the height of the OH layer peak and the integrated emission rate following the procedure described by Liu and Shepherd (2006). An extended period of overlap of SABER and ground-based spectrometer measurements of OH(6-2) IER during the 2003–2004 winter season allowed us to express ground-based IER values in terms of their satellite equivalents. The combination of these two formulae provided a method for inferring an altitude of the OH emission layer over Longyearbyen from ground-based measurements alone. Such a method is required when SABER is in a southward looking yaw cycle. In the SABER data for the period 2002–2008, the peak altitude of the OH layer ranged from a minimum near 76 km to a maximum near 90 km. The uncertainty in the inferred altitude of the peak emission, which includes a contribution for atmospheric extinction, was estimated to be±2.7 km and is comparable with the ±2.6 km value quoted for the nominal altitude (87 km) of the OH layer. Longer periods of overlap of satellite and ground-based measurements together with simultaneous onsite measurements of atmospheric extinction could reduce the uncertainty to approximately 2 km

Inferring hydroxyl layer peak heights from ground-based measurements of OH(6-2) band integrated emission rate at Longyearbyen (78 N, 16 E)

Measurements of hydroxyl nightglow emissions over Longyearbyen (78 N, 16 E) recorded simultaneously by the SABER instrument onboard the TIMED satellite and a ground-based Ebert-Fastie spectrometer have been used to derive an empirical formula for the height of the OH layer as a function of the integrated emission rate (IER). Altitude profiles of the OH volume emission rate (VER) derived from SABER observations over a period of more than six years provided a relation between the height of the OH layer peak and the integrated emission rate following the procedure described by Liu and Shepherd (2006). An extended period of overlap of SABER and ground-based spectrometer measurements of OH(6-2) IER during the 2003–2004 winter season allowed us to express ground-based IER values in terms of their satellite equivalents. The combination of these two formulae provided a method for inferring an altitude of the OH emission layer over Longyearbyen from ground-based measurements alone. Such a method is required when SABER is in a southward looking yaw cycle. In the SABER data for the period 2002–2008, the peak altitude of the OH layer ranged from a minimum near 76 km to a maximum near 90 km. The uncertainty in the inferred altitude of the peak emission, which includes a contribution for atmospheric extinction, was estimated to be±2.7 km and is comparable with the ±2.6 km value quoted for the nominal altitude (87 km) of the OH layer. Longer periods of overlap of satellite and ground-based measurements together with simultaneous onsite measurements of atmospheric extinction could reduce the uncertainty to approximately 2 km

セキドウ オウダン ジキ ループ (TEL) カタ タイヨウ バクハツ ニ トモナウ シンガタ ジキアラシ

地磁気嵐とその発生起源である太陽現象をペアとして捉える太陽・地球電磁関係物理学の手法に従い,従来のフレア型急始(Sc)嵐,コロナホール型緩始(Sg)嵐,フィラメント消失型Sc嵐のほかに,本研究では新たに次のような赤道横断磁気ループ型Sc嵐が見出された. 太陽の赤道を跨ぐ大きな磁気ループ(Transequatorial loop:TELと略称)が急激に膨張,爆発して,大規模なコロナ質量放出(CME)を発生させる事実は半世紀以上前から観測され,太陽のふち(limb)現象として,太陽物理学分野で大きく注目されてきた.このTEL型爆発は太陽のふち(limb)で頻繁に観測されるからには,太陽正面でも発生するはずであると推定して調べたところ,ディスク中心付近でかすかな線条構造が認められてから数日後に,地球で磁気嵐が発生していることが見出された.この線条付近ではフレアもフィラメントもコロナホールも認められなかったことから,これは新しいTEL型Sc嵐であると認定した.このようなTELは南北両半球にある黒点群または黒点消滅後の残留磁域とつながっているので,磁気ループの軸磁場の方向が求められる.この軸磁場は惑星間磁場(IMF)の強いBz成分を生むので,その地磁気嵐構成への影響について調べた.TEL型Sc嵐については,将来様々な興味深い研究成果が期待されるが,現時点で考えられる様々な課題についての提言がなされた.Following the traditional way of expression, geomagnetic storms have been classified into three types; flare-type Sc storms, CH-type Sg storms, and DB-type Sc storms (Sc:sudden commencement;CH:coronal hole;g:gradual;DB:disparition brusque).We have discovered that some transequatorial loops (TEL) give rise to geomagnetic storms, when the TEL explodes near the central meridian of the sun. The axial magnetic direction of the TEL can be inferred, since TELs connect sunspot groups or remnant magnetic regions between the northern and southern hemispheres. Since the axial fields tend to have a large Bz component in interplanetary space, we have examined various effects on the configuration of geomagnetic storms. Topics are proposed for future works on the TEL-type Sc storms

Present and future dayside cusp program at Svalbard

The present dayside cusp program at Svalbard is summarized. Our future plans are briefly reviewed. Comprehensive, complementary observations at selected sites are needed, including several chains of ground stations. Future cusp experiments also require larger diagnostic capabilities, and the need for multispacecraft programs is underscored

Inferring hydroxyl layer peak heights from ground-based measurements of OH(6-2) band integrated emission rate at Longyearbyen (78 N, 16 E)

Measurements of hydroxyl nightglow emissions over Longyearbyen (78 N, 16 E) recorded simultaneously by the SABER instrument onboard the TIMED satellite and a ground-based Ebert-Fastie spectrometer have been used to derive an empirical formula for the height of the OH layer as a function of the integrated emission rate (IER). Altitude profiles of the OH volume emission rate (VER) derived from SABER observations over a period of more than six years provided a relation between the height of the OH layer peak and the integrated emission rate following the procedure described by Liu and Shepherd (2006). An extended period of overlap of SABER and ground-based spectrometer measurements of OH(6-2) IER during the 2003–2004 winter season allowed us to express ground-based IER values in terms of their satellite equivalents. The combination of these two formulae provided a method for inferring an altitude of the OH emission layer over Longyearbyen from ground-based measurements alone. Such a method is required when SABER is in a southward looking yaw cycle. In the SABER data for the period 2002–2008, the peak altitude of the OH layer ranged from a minimum near 76 km to a maximum near 90 km. The uncertainty in the inferred altitude of the peak emission, which includes a contribution for atmospheric extinction, was estimated to be±2.7 km and is comparable with the ±2.6 km value quoted for the nominal altitude (87 km) of the OH layer. Longer periods of overlap of satellite and ground-based measurements together with simultaneous onsite measurements of atmospheric extinction could reduce the uncertainty to approximately 2 km

Inferring hydroxyl layer peak heights from ground-based measurements of OH(6-2) band integrated emission rate at Longyearbyen (78 N, 16 E)

Measurements of hydroxyl nightglow emissions over Longyearbyen (78 N, 16 E) recorded simultaneously by the SABER instrument onboard the TIMED satellite and a ground-based Ebert-Fastie spectrometer have been used to derive an empirical formula for the height of the OH layer as a function of the integrated emission rate (IER). Altitude profiles of the OH volume emission rate (VER) derived from SABER observations over a period of more than six years provided a relation between the height of the OH layer peak and the integrated emission rate following the procedure described by Liu and Shepherd (2006). An extended period of overlap of SABER and ground-based spectrometer measurements of OH(6-2) IER during the 2003–2004 winter season allowed us to express ground-based IER values in terms of their satellite equivalents. The combination of these two formulae provided a method for inferring an altitude of the OH emission layer over Longyearbyen from ground-based measurements alone. Such a method is required when SABER is in a southward looking yaw cycle. In the SABER data for the period 2002–2008, the peak altitude of the OH layer ranged from a minimum near 76 km to a maximum near 90 km. The uncertainty in the inferred altitude of the peak emission, which includes a contribution for atmospheric extinction, was estimated to be±2.7 km and is comparable with the ±2.6 km value quoted for the nominal altitude (87 km) of the OH layer. Longer periods of overlap of satellite and ground-based measurements together with simultaneous onsite measurements of atmospheric extinction could reduce the uncertainty to approximately 2 km

Response of OH airglow temperatures to neutral air dynamics at 78oN, 16oE during the anomalous 2003-2004 winter

Hydroxyl (OH) brightness temperatures from the mesopause region derived from temperature profiles from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) satellite are compared with OH(6-2) rotational temperatures measured by spectrometer from Longyearbyen, Norway (780N, 16"E), during the winter 2003-2004. The two series correspond well, although the satellite measurements are higher by an average of 5.6 K * 4.4 K. Reasons for this apparent bias are discussed. The two series give a near-continuous temperature record from this winter, making it possible to study the response of the temperatures to neutral air dynamics observed from meteor radar measurements of meridional and zonal wind. Vertical profiles of 1.6 pm OH volume emission rates from SABER reveal that the unusually high temperatures observed during January and February 2004 (240-250 K) correspond to a very low and bright OH layer. Significant linear correlations are found between meridional wind, OH temperature, and peak altitude. These data support the theory that the high temperatures result from an anomalously strong upper stratospheric vortex that confined air to the polar regions, coupled with meridional transport, which led to a strong downwelling of atomic oxygen-rich air, thereby lowering the altitude of the OH layer. The SABER data reveal that the re-formation of the OH layer at approximately 78 km altitude accounted for an increase in temperature of approximately 15 K, while the remaining temperature increase (20-35 K) is attributed to adiabatic heating and chemical heating from the exothermic reactions involved in producing the vibrationally excited OH

Transequatorial magnetic flux loops on the sun: a possible new source of geomagnetic storms

Following the traditional way of expression, geomagnetic storms have been classified into three types; flare-type Sc storms, CH-type Sg storms, and DB-type Sc storms (Sc:sudden commencement;CH:coronal hole;g:gradual;DB:disparition brusque).We have discovered that some transequatorial loops (TEL) give rise to geomagnetic storms, when the TEL explodes near the central meridian of the sun. The axial magnetic direction of the TEL can be inferred, since TELs connect sunspot groups or remnant magnetic regions between the northern and southern hemispheres. Since the axial fields tend to have a large Bz component in interplanetary space, we have examined various effects on the configuration of geomagnetic storms. Topics are proposed for future works on the TEL-type Sc storms