The Bragg Crystal Spectrometer for SOLAR-A     

J. L. Culhane  E. Hiei  G. A. Doschek  A. M. Cruise  Y. Ogawara  Y. Uchida  R. D. Bentley  C. M. Brown  J. Lang  T. Watanabe  J. A. Bowles  R. D. Deslattes  U. Feldman  A. Fludra  P. Guttridge  A. Henins  J. Lapington  J. Magraw  J. T. Mariska  J. Payne  K. J. H. Phillips  P. Sheather  K. Slater  K. Tanaka  E. Towndrow  M. W. Trow  A. Yamaguchi 《Solar physics》1991,136(1):89-104

The Bragg Crystal Spectrometer (BCS) is one of the instruments which makes up the scientific payload of the SOLAR-A mission. The spectrometer employs four bent germanium crystals, views the whole Sun and observes the resonance line complexes of H-like Fexxvi and He-like Fexxv, Caxix, and Sxv in four narrow wavelength ranges with a resolving power (/) of between 3000 and 6000. The spectrometer has approaching ten times better sensitivity than that of previous instruments thus permitting a time resolution of better than 1 s to be achieved. The principal aim is the measurement of the properties of the 10 to 50 million K plasma created in solar flares with special emphasis on the heating and dynamics of the plasma during the impulsive phase. This paper summarizes the scientific objectives of the BCS and describes the design, characteristics, and performance of the spectrometers.After the launch the name of SOLAR-A has been changed to YOHKOH.Tragically Professor K. Tanaka died on January 2, 1990.  相似文献   

Very Large Array-RATAN 600 observations of a solar active region     

V. M. Bogod  G. B. Gelfreikh  R. F. Willson  K. R. Lang  L. V. Opeikina  V. Shatilov  S. V. Tsvetkov 《Solar physics》1992,141(2):303-323

The Very Large Array (VLA) and the RATAN 600 were used to observe a solar active region on two consecutive days around the time of a partial solar eclipse in July 1990. VLA synthesis maps at 2.0, 3.5, and 6.2 cm wavelength reveal bright (T _b = 0.2 – 2.2 × 10⁶ K), compact ( = 10–40) sources above the penumbra of the leading sunspot while maps at 20 cm wavelength reveal an extended ( 4.5) looplike structure (T _b 10⁶ K) between the dominant spots. Total flux and brightness temperature spectra of both components were obtained by the RATAN at nine wavelengths between 1.7 and 21 cm. The relatively-flat spectrum of the extended emission is attributed to the optically thin thermal brems Strahlung of electrons trapped in a magnetic loop at coronal temperatures. Step-spectrum sunspot-associated emission is attributed to thermal gyroresonance radiation at different heights along the leg of a loop joining regions of opposite magnetic polarity. Comparisons with predicted distributions of gyroresonance radiation indicate that the compact sunspot-associated sources lie at heights of h = 2500–17500 km above the photosphere. Although potential fields of sufficient strength appear to exist at coronal heights, differences n the observed and predicted brightness distributions suggest some role for non-potential fields or for an inhomogeneous distribution of electron density or temperature above the sunspot.  相似文献   

Evolution of magnetic fields and mass flow in a decaying active region     

Hongqi Zhang  Guoxiang AI  Haimin Wang  Harold Zirin  Alan Patterson 《Solar physics》1992,140(2):307-316

Five days of coordinated observation were carried out from 24–29 September, 1987 at Big Bear and Huairou Solar Observatories. Longitudinal magnetic fields of an p sunspot active region were observed almost continuously by the two observatories. In addition, vector magnetic fields, photospheric and chromospheric Doppler velocity fields of the active region were also observed at Huairou Solar Observatory. We studied the evolution of magnetic fields and mass motions of the active region and obtained the following results: (1) There are two kinds of Moving Magnetic Features (MMFs). (a) MMFs with the same magnetic polarity as the center sunspot. These MMFs carry net flux from the spot, move through the moat, and accumulate at the moat's outer boundary. (b) MMFs in pairs of mixed polarity. These MMFs are not responsible for the decay of the spot since they do not carry away the net flux. MMFs in category (b) move faster than those of (a). (2) The speed of the mixed polarity MMFs is larger than the outflow measured by photospheric Dopplergrams. The uni-polar MMFs are moving at about the same speed as the Doppler outflow. (3) The chromospheric velocity is in approximately the opposite direction from the photospheric velocity. The photospheric Doppler flow is outward; chromospheric flow is inward. We also found evidence that downward flow appears in the photospheric umbra; in the chromosphere there is an upflow.  相似文献   

Study of supergranules     

Haimin Wang  Harold Zirin 《Solar physics》1989,120(1):1-17

Results of a detailed study on supergranule lifetime and velocity fields are presented. We show the correlation between the observed downdraft velocity and the network magnetic flux elements on the quiet sun. After excluding areas with magnetic flux density 25 G, we find that the upper limit of the supergranule vertical speed is 0.1 km s^–1 for both downdraft and updraft, and the r.m.s. speed is 0.03 km s^–1. By observing the evolution of individual supergranules, we find that the average lifetime of supergranules might be 50 hours. We describe different ways of formation and decay of supergranular cells. New cells usually form in an area containing no pre-existing supergranule velocity fields. Cells may disappear in two ways: fragmentation and fading away.  相似文献   

Impact of different regression frameworks on the estimation of the scaling properties of radar rainfall   总被引：1，自引：0，他引：1  

Gabriele Villarini  Joseph B. Lang  Federico Lombardo  Francesco Napolitano  Fabio Russo  Witold F. Krajewski 《Atmospheric Research》2007,86(3-4):340-349

Rainfall is characterized by high variability both in space and time. Despite continuous technological progress, the available instruments that are used to measure rainfall across several spatio-temporal scales remain inaccurate. To remedy this situation, scaling relationships of spatial rainfall offer the potential to link the observed or predicted precipitation quantities at one scale to those of interest at other scales. This paper focuses on the estimation of the spatial rainfall scaling functions. Standard scaling analysis constructed by means of the ordinary least squares method often violates such basic assumptions implicit in its use and interpretation as homoschedasticity, independence, and normality of the errors. Consequently, the authors consider alternative regression frameworks i.e. bootstrapping regression, semi parametric linear model, and multilevel normal linear model to show how these different approaches exert a significant impact on the multifractal analysis of radar rainfall. In addition, the uncertainties associated with the construction of the scaling function due solely to the regression procedure are quantified. The radar data come from the polarimetric C-band weather radar located in Rome, Italy, and the scaling properties are computed for a square domain centred on the radar site with a side length of 128 km and a finest resolution of 1 km².  相似文献   

Comparison of COSPEC and two miniature ultraviolet spectrometer systems for SO2 measurements using scattered sunlight     

Tamar Elias  A. Jeff Sutton  Clive Oppenheimer  Keith A. Horton  Harold Garbeil  Vitchko Tsanev  Andrew J. S. McGonigle  Glyn Williams-Jones 《Bulletin of Volcanology》2006,68(4):313-322

The correlation spectrometer (COSPEC), the principal tool for remote measurements of volcanic SO₂, is rapidly being replaced by low-cost, miniature, ultraviolet (UV) spectrometers. We compared two of these new systems with a COSPEC by measuring SO₂ column amounts at Kīlauea Volcano, Hawaii. The two systems, one calibrated using in-situ SO₂ cells, and the other using a calibrated laboratory reference spectrum, employ similar spectrometer hardware, but different foreoptics and spectral retrieval algorithms. Accuracy, signal-to-noise, retrieval parameters, and precision were investigated for the two configurations of new miniature spectrometer. Measurements included traverses beneath the plumes from the summit and east rift zone of Kīlauea, and testing with calibration cells of known SO₂ concentration. The results obtained from the different methods were consistent with each other, with <8% difference in estimated SO₂ column amounts up to 800 ppm m. A further comparison between the COSPEC and one of the miniature spectrometer configurations, the ‘FLYSPEC’, spans an eight month period and showed agreement of measured emission rates to within 10% for SO₂ column amounts up to 1,600 ppm m. The topic of measuring high SO₂ burdens accurately is addressed for the Kīlauea measurements. In comparing the foreoptics, retrieval methods, and resultant implications for data quality, we aim to consolidate the various experiences to date, and improve the application and development of miniature spectrometer systems.  相似文献   

甘肃省文县阳山特大型金矿床地质特征及控矿因素分析   总被引：28，自引：1，他引：28  

齐金忠  孙彬等 《地质论评》2003,49(1):85-92

阳山金矿位于川陕甘交界地带，为近年发现的一特大微细浸染型金矿床，该矿目前已发现4个矿段，均赋存于泥盆系中，矿体在平面上呈舒缓波状，在剖面上为脉冲，似层状，矿石中金属矿物主要为黄铁矿和毒砂，金主要以微细粒金（2～3μm）包裹于毒砂，黄铁矿等矿物之中，矿石中As、Sb及有机碳含量较高，矿带受安昌河一观音坝断裂带控制，矿体产于断裂带内的次级断裂中，泥盆系三河口群粉砂质千枚岩渗透性较好，且碳质含量，金丰度值较高，是矿区最有利的赋矿层位；矿体在时间、时间上与侏罗纪早期岩浆活动密切相关，稳定同位素分析了表明成矿作用与岩浆活动有关，所以，该矿为受构造直接控制的，与沉积作用和岩浆活动有成因联系的金矿床。  相似文献   

柴达木盆地三湖地区生物气横向运聚成藏研究   总被引：19，自引：3，他引：19  

李本亮  张道伟等 《地质论评》2003,49(1):93-100

本文系统研究了地层水盐度对微生物菌生长发育的制约，矿化度对生物气在地层水中溶解度的影响，泥岩盖层中高矿化度地层水对封盖性能的控制作用。柴达木盆地三湖（台吉乃尔湖，涩聂湖，达布逊湖）地区主要受南缘昆仑山冰雪溶水的补给，地层水从南向北运移，北斜坡第四系地层水的矿化度最高，北斜坡泻水-汇水区高盐度条件下生物菌的活跃程度受到抑制，影响生物气大量生成并从水中游离出来，中央凹陷及其南部低矿化度条件下更适宜生物气的生成，生物气在地层水中的溶解度随矿化度的增高明显降低，南缘低矿化度水中饱含的生物气经地层水从南向北携带，在北斜坡高矿化度条件上大量游离出来，实验测试证明泥岩饱和高矿化度地层水时，其突破压力增加约100倍，封盖性能大大提高，有效地保存了北斜坡游离相生物气，研究显示生物气总体上具有向北斜坡以水溶气方式进行横向运聚的特征，展示了北斜坡气源补给充足，具有满坡含气的巨大勘探潜力。结合生物气本身的发育特征和三湖地区的水文地质条件，提出了生物所首先以水溶气方式发生远距离的横向运移以后再以游离相进行垂向运聚成藏，这一结论对下一步三湖地区生物气勘探具有直接的指导意义。  相似文献   

American geography and one non-American geographer     

Harold Brookfield 《GeoJournal》2004,59(1):39-41

  相似文献   

The use of ultra-sound in the preparation of carbonate and clay sediments for chironomid analysis     

Barbara Lang  Alan P. Bedford  Nigel Richardson  Stephen J. Brooks 《Journal of Paleolimnology》2003,30(4):451-460

Initial investigations of Holocene carbonate sediment from Hawes Water, Northwest England, yielded lower numbers of chironomid head capsules than anticipated. Standard techniques used to prepare sediment for chironomid analysis were ineffective in breaking up the coarse crystalline sediment structure sufficiently. This led to large amounts of sediment being retained and increased sample processing times. The low yield of head capsules also meant that more sediment was needed to produce adequate numbers of head capsules for analysis. The use of ultra-sound as part of the sediment processing was investigated. This technique reduced the amount of sediment left for sorting and yielded significantly more head capsules which were of equivalent structural condition and cleaner than those produced by conventional methods. The technique was extended to clay samples where similar results were obtained although shorter treatment times are recommended. The proportion of Tanytarsini and Tanypodinae heads increased significantly in carbonate and clay samples, respectively; both sediment types showed a significant decline in the proportion of Chironomini. The results indicate that ultra-sonic preparation of samples will yield a more accurate representation of chironomid assemblages in sediments leading to greater sensitivity and reliability in analysing past environmental conditions.  相似文献