Solar EUV spectra obtained during the SPIRIT experiment onboard the CORONAS-F satellite: A catalog of lines in the range 176–207 Å     

S. V. Shestov  S. A. Bozhenkov  I. A. Zhitnik  S. V. Kuzin  A. M. Urnov  I. L. Beigman  F. F. Goryaev  I. Yu. Tolstikhina 《Astronomy Letters》2008,34(1):33-51

We present a catalog of 65 spectral lines in the range 176–207 Å recorded by the RES spectroheliograph in active regions and flares during the SPIRIT experiment onboard the CORONASF satellite. We have identified 51 lines. The relative intensities of lines recorded during the M6.5 (GOES) flare of September 16, 2001, are given. The data processing technique is discussed.  相似文献   

Have the electric currents produced by plasma and magnetic field gradients been discovered in the solar photosphere?     

S. I. Stepanov 《Astronomy Letters》2008,34(5):337-343

We check whether the currents of inhomogeneities (diffusion, thermodiffusion, and gradient ones) can exist at the photospheric level. For this purpose, the vertical currents are compared with the theoretically estimated currents of inhomogeneities; our comparison shows them to be of the same order of magnitude. Therefore, the currents of inhomogeneities actually exist in the solar photosphere; their exact values are determined by the (electron density, temperature, and magnetic field) gradients, which are not known very well at present. This paper continues the current tendency in describing the atmospheric magnetic field (in particular, its fine structure) that consists in allowing for the Hall, diffusion, and thermodiffusion currents.  相似文献   

Fractal properties of solar magnetic fields     

B. A. Ioshpa  V. N. Obridko  E. A. Rudenchik 《Astronomy Letters》2008,34(3):210-216

We study the spatial properties of solar magnetic fields using data from the Solar Vector Magnetograph of the Marshall Space Flight Center (MSFC) (FeI 5250.2 Å) and SOHO/MDI longitudinal magnetic field measurements (Ni 6767.8 Å) (96-min full-disk maps). Our study is focused on two objects: the fractal properties of sunspots and the fractal properties of the spatial magnetic field distribution of active and quiet regions considered as global structures. To study the spatial structure of sunspots, we use a well-known method of determining the fractal dimension based on an analysis of the perimeter—area relation. To analyze the fractal properties of the spatial magnetic field distribution over the solar surface, we use a technique developed by Higuchi. We have revealed the existence of three families of self-similar contours corresponding to the sunspot umbra, penumbra, and adjacent photosphere. The fractal coefficient has maxima near the umbra—penumbra and penumbra—photosphere boundaries. The fractal dependences of the longitudinal and transverse magnetic field distributions are similar, but the fractal numbers themselves for the transverse fields are larger than those for the longitudinal fields approximately by a factor of 1.5. The fractal numbers decrease with increasing mean magnetic field strength, implying that the magnetic field distribution is more regular in active regions.  相似文献   

The main sequence from F to K stars of the solar neighbourhood in SDSS colours     

A. Just  H. Jahreiß 《Astronomische Nachrichten》2008,329(8):790-800

For an understanding of Galactic stellar populations in the SDSS filter system well defined stellar samples are needed. The nearby stars provide a complete stellar sample representative for the thin disc population. We compare the filter transformations of different authors applied to the main sequence stars from F to K dwarfs to SDSS filter system and discuss the properties of the main sequence. The location of the mean main sequence in colour‐magnitude diagrams is very sensitive to systematic differences in the filter transformation. A comparison with fiducial sequences of star clusters observed in g ′, r ′, and i ′ show good agreement. Theoretical isochrones from Padua and from Dartmouth have still some problems, especially in the (r – i) colours. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Is the sky falling? Searching for stellar streams in the local Milky Way disc in the CORAVEL and RAVE surveys     

G. M. Seabroke  G. Gilmore  A. Siebert  O. Bienaymé  J. Binney  J. Bland-Hawthorn  R. Campbell  K. C. Freeman  B. Gibson  E. K. Grebel  A. Helmi  U. Munari  J. F. Navarro  Q. A. Parker  A. Siviero  M. Steinmetz  F. G. Watson  R. F. G. Wyse  T. Zwitter  J. Peñarrubia  M. C. Smith  M. Williams 《Monthly notices of the Royal Astronomical Society》2008,384(1):11-32

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Solar forcing of Caribbean drought events during the last millennium          下载免费PDF全文

MICHAEL J. BURN  SUZANNE E. PALMER 《第四纪科学杂志》2014,29(8):827-836

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Solar absorption infrared spectroscopic measurements over Mexico City: Methane enhancements     

《Atmósfera》2014,27(2):173-183

In this work, the experiment for performing solar-absorption infrared measurements from the atmospheric observatory of the Universidad Nacional Autónoma de México (UNAM) located at the university campus in Mexico City is described. The Fourier transform infrared (FTIR) spectrometer and solar-tracking system have been operating since June 2010, and from the recorded spectra the total column amounts of several atmospheric gases can be derived. The current study presents the results obtained for methane (CH₄), an important pollutant involved in ozone production and a rapidly increasing greenhouse gas. The total column amounts, retrieved with high temporal resolution, present a large dispersion and day-to-day variability. A mean value of 2.88 × 10¹⁹ molecules/cm² (1.829 ppm), with a 95% confidence interval between 2.62 and 3.14 × 10¹⁹ molecules/cm², has been obtained for the period from June 2010 to December 2011. No clear annual cycle can be determined from the monthly means due to the large variability in the measurements, suggesting a significant effect of local emissions on the natural background concentrations. Some days with extraordinary enhancements are presented and a simple back trajectory analysis points to a predominant source direction from the northeast of the measurement site. The methane-contaminated air masses passing over the UNAM atmospheric observatory, however, originate presumably not from one but several dispersed sources. A more detailed analysis with modeling of the dynamics of these air masses is required.  相似文献   

Alpine climate during the Holocene: a comparison between records of glaciers,lake sediments and solar activity     

Samuel U. Nussbaumer  Friedhelm Steinhilber  Mathias Trachsel  Petra Breitenmoser  Jürg Beer  Alex Blass  Martin Grosjean  Albert Hafner  Hanspeter Holzhauser  Heinz Wanner  Heinz J. Zumbühl 《第四纪科学杂志》2011,26(7):703-713

The European Alps are very sensitive and vulnerable to climate change. Recent improvements in Alpine glacier length records and climate reconstructions from annually laminated sediments of Alpine Lake Silvaplana give the opportunity to investigate the relationship between these two data sets of Alpine climate. Two different time frames are considered: the last 500–1000 years as well as the last 7400 years. First, we found good agreement between the two different climate archives during the past millennium: mass accumulation rates and biogenic silica concentration are largely in phase with the glacier length changes of Mer de Glace and Unterer Grindelwaldgletscher, and with the records of glacier length of Grosser Aletschgletscher and Gornergletscher. Secondly, the records are compared with temporally highly resolved data of solar activity. The Sun has had a major impact on the Alpine climate variations in the long term, i.e. several centuries to millennia. Solar activity varies with the Hallstatt periodicity of about 2000 years. Hallstatt minima are identified around 500, 2500 and 5000 a. Around these times grand solar minima (such as the Maunder Minimum) occurred in clusters coinciding with colder Alpine climate expressed by glacier advances. During the Hallstatt maxima around 0, 2000 and 4500 a, the Alpine glaciers generally retreated, indicating a warmer climate. This is supported by archaeological findings at Schnidejoch, a transalpine pass in Switzerland that was only accessible when glaciers had retreated. On shorter timescales, however, the influence of the Sun cannot be as easily detected in Alpine climate change, indicating that in addition to solar forcing, volcanic influence and internal climate variations have played an important role. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

我国南方中东部地区地面太阳总辐射变化规律   总被引：5，自引：2，他引：3       下载免费PDF全文

郑有飞  关福来  蔡子颖  吴荣军  刘建军 《应用气象学报》2011,22(3):312-320

为进一步探讨我国地面太阳辐射的变化规律及其原因,选择我国南方中东部地区,利用该区域1961—2007年33个站点的地面太阳总辐射资料,结合云量、大气水汽含量和能见度等观测资料,综合研究该区域地面太阳总辐射的变化规律及其原因。结果表明:1961—1989年,我国南方中东部地区地面太阳总辐射呈下降趋势,之后发生逆转,1995年后其变化趋于缓和,1961—2007年总体呈现变暗—变亮—变缓的趋势。究其原因,该区域云量平均值由峰入谷、云量下降速率由快变慢可能是产生此变化趋势的原因之一;其次,20世纪80年代到21世纪初,气溶胶光学厚度上升趋势减缓,气溶胶地面辐射强迫变化趋于缓和,某些区域甚至出现下降,也导致部分站点地面太阳总辐射由暗变亮。  相似文献   

2009-07-22湖北地区日全食期间的重力观测     

崔荣花  方剑  王新胜 《武汉大学学报(信息科学版)》2011,36(11):1332-1335

利用武汉市九峰站CWR C032型超导重力仪和沙洋地区的Lacost G型、ET型弹簧重力仪,对2009-07-22发生在长江沿线的日全食进行了重力观测。首先,对超导重力仪在日全食期间的观测数据扣除重力固体潮汐及气压影响后,分析其幅度变化,没有发现日全食期间及前后出现幅度异常的＂重力谷＂。同时,对G型和ET型重力仪观测数据采用数字滤波器法及多项式拟合重力潮汐法扣除固体潮汐影响后,同样也没有发现日全食期间及前后出现幅度较大的异常。重力实测数据处理和分析表明,2009年日全食期间并未发现＂重力谷＂现象。  相似文献