Evolution of Magnetic Flux Rope in the Active Region NOAA 9077 on 14 July 2000     

Yan  Yihua  Aschwanden  Markus J.  Wang  Shujuan  Deng  Yuanyong 《Solar physics》2001,204(1-2):27-40

The finite energy force-free magnetic fields of the active region NOAA 9077 on 14 July 2000 above the photosphere were reconstructed. We study the evolution of the 3D magnetic field structures in AR 9077 and compare the reconstructed field lines with TRACE EUV 171 Å flare loops during the flare maximum, which confirms the process that flaring loops extended from lower sheared level to higher arcades. We also demonstrate the 3D magnetic field evolution before the 3B/X5.7 flare on 14 July and the magnetic structure after the flare on 15 July. This shows that the helical magnetic structures were significantly changed, suggesting that the flux rope was indeed erupted during the energetic flare at 10:24 UT on 14 July.  相似文献   

DSQ型短基线水管倾斜仪及标定装置的研制   总被引：1，自引：1，他引：0  

聂磊  温兴卫  易治春  李家明  李农发  陈耿琦  胡义华 《大地测量与地球动力学》2001,21(3):74-81

阐述了具有国产化、小型化、数字化、智能化特点的DSQ型短基线水管仪的原理、结构与性能指标 ,并介绍了该仪器在 7个试验台 8条短基线上的试验与监测记录、精度估算结果。在全国 30多个台站与朝鲜平壤大成山地震台的推广证明 :该仪器在小于或等于 5m的洞体基线上均能取得清晰、光滑、令人满意的倾斜固体潮汐观测结果 ,成功率达 10 0 % ,精度达当今国际同类先进水平。  相似文献   

Reversed Drifting Quasi-periodic Pulsating Structure in the X1.3 Solar Flare on 30 July 2005     

Rui Wang  Baolin Tan  Chengming Tan  Yihua Yan 《Solar physics》2012,278(2):411-419

Based on the analysis of the microwave observations at the frequency range of 2.60 – 3.80 GHz in the solar X1.3 flare event observed at the Solar Broadband RadioSpectrometer in Huairou (SBRS/Huairou) on 30 July 2005, an interesting reversed drifting quasi-periodic pulsating structure (R-DPS) is confirmed. The R-DPS is mainly composed of two drifting pulsating components: one is a relatively slow very short-period pulsation (VSP) with a period of about 130 – 170 ms, the other is a relatively fast VSP with a period of about 70 – 80 ms. The R-DPS has a weak left-handed circular polarization. Based on the synthetic investigations of Reuven Ramaty High Energy Solar Spectroscopic Imaging (RHESSI) hard X-ray, Geostationary Operational Environmental Satellite (GOES) soft X-ray observations, and magnetic field extrapolation, we suggest that the R-DPS possibly reflects flaring dynamic processes of the emission source regions.  相似文献   

磷酸盐氧同位素组成的测定方法及分馏机理研究进展   总被引：4，自引：0，他引：4  

陈志刚  黄奕普  刘广山  蔡毅华  卢阳阳  刘润 《地球科学进展》2010,25(10):1040-1050

磷酸盐氧同位素组成在古气候和磷的生物地球化学循环研究中都具有十分重要的意义.测定方法和同位素的分馏机理是该类研究的基础.国际上已开展了一系列磷酸盐氧同位素的测定方法和分馏机理研究.在测定方法上,由初期的间接法,经高温还原/裂解法到氟化法,再演化到改进后的高温还原法(包括TC/EA-IRMS法),甚至激光原位技术,样品由实验室纯化学试剂扩展到各种复杂地质样品,在测量精确度、测量速度、样品用量、安全性和技术要求方面都有巨大改进.在分馏机理上,①尽管Longinelli等建立的关系式已获得了天然样品的验证,并认为是平衡分馏,但实验室模拟结果与其还存在较大差异(即没有达到平衡分馏).②在地表温度和pH条件下,无机过程均不会造成水体中溶解态磷酸盐和水之间的氧同位素交换.在高温(>70℃)及不同pH条件下,即使没有生物作用也会造成溶解磷酸盐和水分子之间进行氧的同位素交换,但不同实验室之间结果不一致.③在生物作用存在下,溶解无机磷酸盐和水之间在地表环境会发生强烈氧同位素交换,但除了PPase外,其余均没有达到平衡值.④磷灰石的氧同位素组成要比形成它的溶解态磷酸盐的值高1‰～1.4‰,因此在把Longinelli等关系式用于溶解态磷酸盐和水体系时,需要考虑该因素.同位素平衡分馏和条件有关,认为无机条件下的高温(>70℃)实验结果不一致,以及有生物参与的培养实验结果偏离平衡值,都是实验条件不同所致,包括pH、磷酸盐浓度、生物种类、生物量等.  相似文献   

On the wave mode of subsecond pulses in the cm-range     

Meshalkina  N.S.  Altyntsev  A.T.  Sych  R.A.  Chernov  G.P.  Yihua  Yan 《Solar physics》2004,221(1):85-99

In this paper we determined the wave mode of subsecond pulses (SSP). We used data on pulses with a degree of polarization over 30%, with the sources located at −60 to +60 deg from the central meridian, for the period 2000–2002. The superposition of SSRT radio maps and MDI magnetograms has shown that radio SSP sources are typically located near the polarity inversion line of the active region magnetic field. Such an arrangement indicates that SSP sources are located at the tops of magnetic loops. The ordinary mode of electromagnetic radiation is recorded in SSP sources located from the inversion line by no less than about 10 arc sec.  相似文献   

The 3-D boundary element formulation of linear force-free magnetic fields with finite energy content in semi-infinite space   总被引：2，自引：0，他引：2  

Yihua Yan 《Solar physics》1995,159(1):97-113

In this paper, a formulation describing a force-free magnetic field with constant, either 0 or = 0, with finite energy content in semi-infinite space,z > 0, above the Sun is proposed and solved uniquely by a numerical method: the boundary element method (BEM). The method is effective and convenient in extrapolating the magnetic field above the solar surface, , directly from the measured magnetogram. Meanwhile, no additional data treatment is needed. Based on the existence of such a field, the uniqueness of the solution in the present formulation is proved and some useful properties are obtained. The validity is also demonstrated by its application to the magnetic field computation in the chromosphere from observed magnetogram data. The practical feasibility is thus discussed and further confirmed.  相似文献   

河谷城市小风条件下的近地层湍流特征   总被引：4，自引：1，他引：3  

高会旺  管玉平  陈长和  林一骅  吴洁晶 《大气科学》1998,22(6):896-904

利用兰州城市和郊区皋兰县冬季同期的湍流观测资料,分析了城市和郊区的湍流强度、脉动速度标准差和湍流的欧拉时间积分尺度等湍流特征量,并与其他地区的湍流观测量进行了对比,从而揭示了兰州河谷城市小风条件下的大气湍流特征。  相似文献   

The Summertime Great Plains Low Level Jet And The Effect of Its Origin On Moisture Transport     

Yihua Wu  Sethu Raman 《Boundary-Layer Meteorology》1998,88(3):445-466

Radiosonde data from six stations in Kansas and Oklahoma for the period of June 16–24, 1993 indicate that a low-level jet (LLJ) occurred almost every day except on the 20th. Major characteristics of these LLJs are documented in this paper. The maximum wind speed (the jet speed) varied from 13 to 32 m s^-1 and heights ranged from 167 to 910 m. All the jets were southerly except the one on June 19 which changed its direction dramatically from a southerly to a northerly direction in about three hours although its intensity did not change appreciably. Thermal stability of the boundary layer during these LLJ occurrences ranged from near-neutral to highly stable. All the low-level jets exhibited significant diurnal variations. Analyses show that relatively weak large-scale forcing existed for the LLJs on June 21 and June 22, while strong forcing was present on other days. Analyses also show that moisture transport by the LLJ from the Gulf of Mexico to the Great Plains depends on the location of the LLJ origin. In the two weeks of June 13–19 and 20–26, 1993, powerful storms swept through the central United States, accompanied by tornadoes, strong wind, large hail and heavy rainfall. The analyses indicate that these weather events could be a result of the interactions of the LLJs with synoptic-scale flow.  相似文献   

塔里木盆地沙漠区静校正技术   总被引：1，自引：0，他引：1  

林依华  张帆  戴云 《矿物岩石》1998,(Z1)

塔克拉玛干沙漠区内沙丘高低不平,求准静校正量是处理好塔里木地质资料的先决条件,应用相遇法进行沙丘调查,本文提出了沙漠表层速度模型新设想,并通过对剩余静校正量进行二次拟合,得到了最终的经验公式——沙丘曲线公式。  相似文献   

南海大鹏湾夜光藻种群生态及其赤潮成因分析   总被引：16，自引：3，他引：16  

黄长江  齐雨藻  黄奕华  林小涛 《海洋与湖沼》1997,28(3):245-255

分析了１９９０年３月－－１９９２年６月南海大鹏湾夜光藻种妲民环境因子之间的动态关系。研究发现，夜光藻的生存水温的高限可达２８．６℃左右，但其最适不温范围为２０－２２℃而适温范围可扩到１６－２５℃。所以，每年夏季高温季节，大鹏湾的夜光藻因无法忍受高温（３０℃）而自然死亡，秋季再由外洋海流将其营养细胞带回。夜光藻的最适盐度应在２９－３３之间，但盐度线般与夜光藻的咱群变动没有明显的相关关系，不过暴雨或梅  相似文献