地磁与空间电磁环境研究室.docx

地磁与空间电磁环境研究室
Seasonal behavior of meteor radar winds over Wuhan
Guangxin Zhao1,2,3, Libo Liu1, Weixing Wan1, Baiqi Ning1, and Jiangang Xiong1
1 Division of Geomagnetism and Space Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China
2 Wuhan Institute of Physics and Mathematics, CAS, Wuhan, 430071, China
3 Graduate School of the Chinese Academy of Sciences
(Received March 23, 2004; Revised November 9, 2004; Accepted November 10, 2004)
A newly installed meteor radar has been installed to measure winds in the mesosphere and lower thermosphere (MLT) over Wuhan (114.4◦E, 30.6◦N). In the present study, a database of the first 25 months (February 2002–February 2004) of observations has been analyzed to investigate the climatology of mean winds and tides. The daily average zonal wind is charactered by a strong shear in solstices and an intense eastward flow in summer. The daily average meridional wind is northward in winter and southward in other seasons. There are some discrepancies between the radar mean winds and the HWM93 model winds. The summer zonal winds and meridional winds from the model are obviously weaker than our observations. The analysis on tides indicates that the diurnal tide is dominant at Wuhan. The seasonal variability is observed in both the diurnal and semidiurnal tidal amplitudes with the maximum values occurring usually near the equinoxes. Compared with the Global Scale Wave Model (GSWM00), the observed results generally show a smaller diurnal tidal amplitude and a larger semidiurnal tidal amplitude.
Key words: Meteor radar, mean winds, tides, MLT dynamics.

The terdiurnal tide in the mesosphere and lower thermosphere over Wuhan (30◦N, 114◦E)
Guangxin Zhao1,2,3, Libo Liu1, Baiqi Ning1, Weixing Wan1, and Jiangang Xiong1
1 Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China
2 Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, China
3 Graduate School of the Chinese Academy of Sciences, China
(Received August 25, 2004; Revised April 18, 2005; Accepted April 18, 2005)
Winds measured by an all-sky meteor radar have been used to investigate the terdiurnal tide in the mesosphere and lower thermosphere (MLT) region overWuhan (30.6◦N, 114.4◦E). We present a climatology of the terdiurnal tide at low-mid latitude site during the period of April 2002 to December 2004. The terdiurnal peak is distinct in the long-term power spectrum of the wind. The monthly and seasonal mean maximum amplitudes have values of 7 m/s and 5 m/s, respectively. The short-term amplitudes can occasionally reach up to 30 m/s, and at times the terdiurnal tide is as large as the diurnal and semidiurnal ones. It seems that the meridional component is more regular than the zonal one. An obvious annual variation is observed in the meridional phases with a phase leading in winter than that in summer. The annual variation for the terdiurnal tidal amplitude is not obvious, and is variable from year to year in our observations. This seasonal trend is slightly different from earlier studies at other locations.
Key words: Meteor radar, terdiurnal tide, mesospheric dynamics, nonlinear interaction.

Responses of equatorial anomaly to the ctober−November 2003 superstorms
B. Zhao1,2,3,W.Wan1, and L. Liu1
1 Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
2 Wuhan Institute of Physics and Mathematics, CAS, Wuhan 430071, China
3 Graduate School of Chinese Academy of Sciences, Beijing, China
Received: 8 May 2004 – Revised: 2 December 2004 – Accepted: 16 December 2004 – Published: 30 March 2005
Abstract. The responses of Equatorial Ionization Anomaly (EIA) to the superstorms of October−November 2003 were investigated using the total electron content (TEC) measured with global positioning system (GPS) receivers in China, Southeast Asia, Australian (CSAA), and the American regions. Enhanced EIA was seen to be correlated with the southward turning of the interplanetary magnetic field Bz. In both the CSAA and American regions, EIA was intensified, corresponding to a large increase in the F-layer peak height (hmF2) measured by ionosonde and digisonde at middle and equatorial latitudes. However, the enhanced EIA was shown to be more significant during the daytime in the American region, which was associated with a series of large substorms when Bz was stable southward. The prompt penetration electric field and the wind disturbances dynamo electric field are suggested to be responsible for this observation according to current theory, although some features cannot be totally decipherable. Both the ionogram and magnetometer data show the existence of a weak shielding effect whose effect still needs further study. A clear asymmetric ionospheric response was shown in our TEC observations, even though it was only one month after autumnal equinox. The southern EIA crest was totally obliterated on 29 and 30 October in the
CSAA region and on 31 October in the American region. Ion temperatures from the Defense Meteorological Satellite Program (DMSP) spacecraft revealed that the unequal energy injection at the polar region might be the reason for this effect. It is concluded that different physical processes have varying degrees of importance on the evolution of EIA in the CSAA and American regions.
Keywords. Ionosphere (Equatorial ionosphere; Ionospheremagnetosphere interactions; Ionospheric disturbances)

Lunar tidal winds in the mesosphere over Wuhan and Adelaide
Xiaojuan Niua,b,c, Jiangang Xionga, Weixing Wana, Baiqi Ninga,
Libo Liua, R.A. Vincentd, I.M. Reidd
a Institute of Geology and Geophysics, Chinese Academy of Science, P.O. Box 9825, Beijing 100029, P.R. China
b Wuhan Institute of Physics and Mathematics, Chinese Academy of Science, Wuhan430071,P.R.China
c Graduate School of Chinese Academy of Sciences, Beijing, P.R. China
d Department of Physics and Mathematical physics, University of Adelaide, Adelaide, SouthAustralia, Australia
Received 14 October 2004; received in revised form 18 August 2005; accepted 18 August 2005
Abstract Based on measurements made from 2002 to 2003 in the 80–98 km region by the Wuhan meteor radar (31_N, 114_E) and winds observed simultaneously by the Adelaide MF radar (35_S, 138_E), the amplitude and phase of the lunar semidiurnal tide are computed and compared. There is a clear seasonal variation at both stations. A northward amplitude maximum in February is evident over Adelaide and in April over Wuhan, but the eastward amplitude maximizes in January over Wuhan and in October over Adelaide. The height variation of phase displays a 3 ± 1 lunar hour difference, with the eastward component leading the northward component for most months at Adelaide and eastward wind lagging the northward wind at Wuhan. Comparisons of phases between Wuhan and Adelaide suggest that an anti-symmetric tide may be dominant in March, April, June and July and a symmetric tide in January, September and December. _ 2005 COSPAR. Published by Elsevier Ltd. All rights reserved.
Keywords: Lunar tides; Lunar semidiurnal tide; Mesosphere

The 16-day waves in the mesosphere and lower thermosphere over Wuhan (30.6_N, 114.5_E) and Adelaide (35_S, 138_E)
Guo-ying Jianga,b,c, Jian-Gang Xiong , Wei-Xing Wana, Bai-Qi Ninga,
Li-Bo Liua, R.A. Vincentd, I. Reid
a Institute of Geology and Geophysics, Chinese Academy of Sciences, P.O. Box 9825, Beijing 100029, PR China
b Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, P.O. Box 71010, Wuhan 430071, PR China
c Graduate School of Chinese Academy of Sciences, Beijing, PR China
d Department of Physics and Mathematical Physics, University of Adelaide, Adelaide, SA, Australia
Received 14 October 2004; received in revised form 2 March 2005; accepted 2 March 2005
Abstract Winds from a meteor radar at Wuhan (30.6_N, 114.5_E) and a MF radar at Adelaide (35_S, 138_E) are used to study the 16-day waves in the mesosphere and lower thermosphere (MLT). The height range is 78–98 km at Wuhan and 70–98 km at Adelaide. By comparison, it is found that the zonal components at both sites are generally larger than the meridional ones, and eastward motion of the zonal background winds is favorable for the 16-day waves penetration to the MLT region. The zonal maximum amplitude appears in the autumn (September–October) around 86–98 km at Wuhan and in the winter months and early spring (July–October) around 72–82 km at Adelaide. Differences are found in wave amplitudes and time of appearance between the two years of 2002 and 2003. In 2003, the intensity of the wave amplitudes is relatively smaller than that for 2002 at both sites. The summer 16-day waves are comparatively weaker at Adelaide in both years, but stronger in 2002 at Wuhan near the mesopause and the lower thermosphere (86–98 km). The strong summer waves at Wuhan may come from the winter southern hemisphere. _ 2005 COSPAR. Published by Elsevier Ltd. All rights reserved.
Keywords: 16-day waves; Mesosphere and lower thermosphere; Planetary wave

Statistical characteristics of the total ion density in the topside ionosphere during period 1996-2004 by using Empirical orthogonal function (EOF) analysis
Biqiang Zhao 1, 2, 3, Weixing Wan 1, Libo Liu 1, Xinan Yue 1, 2, 3 and Sarita Venkatraman4
1 Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
2 Wuhan Institute of Physics and Mathematics, CAS, Wuhan 430071, China
3 Graduate School of Chinese Academy of Sciences, Beijing, China
4 William B. Hanson Center for Space Sciences, University of Texas at Dallas, Richardson
Abstract. We have applied the empirical orthogonal function (EOF) analysis to examine the climatology of the total ion density Ni at 840 km during the period 1996-2004 obtained from the Defense Meteorological Satellite Program (DMSP) spacecrafts. The data set for each of the local time (0930 LT and 2130 LT) is decomposed into a time mean plus the sum of EOF bases Ei of space multiplied by time-varying EOF coefficients Ai. Physical explanations are made on the first three EOFs which together can capture more than 95% of total variance of the original data set. Results show that the dominant mode that controls the Ni variability is the solar EUV flux, which is consistent with the results of Rich et al. (2003). The second EOF, associated with the solar declination, presents an annual (summer to winter) asymmetry that is caused by the transequatorial winds. The semiannual variation that appears in the third EOF for the evening sector is interpreted as both, the effects of the equatorial electric fields and wind patterns. Both the annual and semiannual variations are modulated by the solar flux, which has a close relationship with the O+ composition. The quick convergence of the EOF expansion makes it very convenient to construct an empirical model for the original data set. The modeled results show that the accuracy of the prediction depends mainly on the first principal component which has a close relationship with the solar EUV flux.
Key words: ionosphere (Equatorial ionosphere; Modeling and forecasting; Solar radiation and cosmic ray effectts )

武汉上空MLT 中准1 6日波的流星雷达观测
姜国英 1，2，3 熊建刚1， 万卫星1， 宁百齐1， 刘立波1，
1 中国科学院地质与地球研究所北京100029
2 中国科学院武汉物理与数学研究所
3 中国科学院研究生院
摘 要 利用武汉流星雷达2002年2月20日至2003年11月10日的观测数据，研究了武汉上空中间层一低热层(MLT)中的准16日波，即周期范围在12—20天的行星波【 ．分析结果表明， 16日波的纬向成分通常比经向成分要强． (1)在2002年和2003年，波振幅最强都出现在当年的秋季(约9月10日一10月10日)．Lomb—Scargle(L—S)谱分析得到振幅最大值约为16m／s．2002年夏季出现了同年次最强的波动，但2003年没有发现这一现象．两年的冬季都没有出现强的16日波． (2)2002年，在86—98 km处波动较强，最大振幅(约16 m／s)出现在90 km、94 km处，而2003年低高度的波动要比较高高度的波动强．武汉上空MLT 中，秋季的16日波是能量上传的波动，即它的源在较低的大气层． 2002年夏季的波动的能量是下行的，波源可能在南半球．
关键词 流星雷达；中间层一低热层； 16日波

用经验正交函数构造武汉地区电子浓度总含量的经验模式

毛 田1,2, 3　万卫星1　刘立波1
1中国科学院地质与地球物理研究所，北京，100029
2中国科学院武汉物理与数学研究所，武汉，430071
3中国科学院研究生院，北京，100049
摘 要　本文利用经验正交函数（Empirical Orthogonal Function, 简称EOF）分析了武汉电离层台站一个太阳黑子周期（1980年4月－1990年12月）的实测电离层电子浓度总含量（TEC）资料，在此基础上构建了一个武汉地区的TEC月中值的经验模式。结果表明：（1）以EOF分析观测数据具有一定的物理意义，其基函数表征TEC的日变化，系数表征TEC的长期变化；（2）EOF技术展开收敛速度快，很少数低阶项即能反映TEC的主要变化，采用经验正交函数建模可以用较少的参数表征较复杂的物理过程。此外，本文还就TEC模式的外部驱动量的改进问题作了一些探讨，发现用F107A（10.7cm太阳辐射通量F107的81天滑动平均值）作TEC建模的外部驱动量能够更好地提高EOF模式的精度和稳定性。
关键词 电子浓度总含量 经验正交函数 电离层经验模式 电离层变化 太阳活动

对流层特大暴雨天气对电离层变化的影响

徐桂荣1,2,3 万卫星1 宁百齐1
1 中国科学院地质与地球物理研究所 北京 100029
2 中国科学院武汉物理与数学研究所
3 中国科学院研究生院

摘 要 研究气象活动对电离层变化的影响。利用时序叠加方法，通过对1958－1998年期间发生在武汉的5次特大暴雨天气事件对武汉上空电离层变化的影响进行分析，发现：（1）特大暴雨能够引起低电离层fbEs和foEs参量较明显地减小；（2）特大暴雨对电离层F区寻常波描迹的最低虚高h’F和电离层等效峰高hpF的参量也有一定影响，且随着雨量的增大这种影响作用也会增加；（3）特大暴雨对电离层其它参量影响甚弱或没有影响。本文认为，特大暴雨天气事件对电离层的影响主要来自于动力过程，特别是特大暴雨激发的或相伴的大气重力波、潮汐波和行星波等长周期大尺度过程的作用。
关键词 特大暴雨；电离层变化；时序叠加法

The frequency variation of Pc5 ULF waves during a magnetic storm
A. Du1 ,W.Sun2, W.Xu1 , and X. Gao3
1 Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing
2 Geophysical Institute, University of Alaska Fairbanks
3 Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing
(Received September 3, 2004; Revised May 30, 2005; Accepted May 30, 2005)
Abstract The relationship between Pc5 ULF waves and the asymmetric ring current during the magnetic storm on July 15, 2000 is studied using ground-based magnetometer data and particle observations by the LANL satellite. A frequency decreases of Pc5 is noted during the main phase, which can be attributed to injections of heavier ions (O+ and He+) into the ring current. In addition, it is observed that during the main phase of the storm, the frequency drop of the Pc5 in the IMAGE chain around the MLT midnight is larger than that in the ALASKA chain at MLT post noon.. Meanwhile, the longitudinal variation of ΔH with the maximum around midnight implies a highly asymmetric distribution of the ring current. These results suggested that the frequency variation of Pc5 pulsation during storms is related to the partial distribution in the ring current.

地球深部结构与过程研究室
A detailed receiver function image of the sedimentarystructure in the Bohai Bay Basin
Tianyu Zheng, Liang Zhao, Ling Chen
Seismic Laboratory (SKL-LE), Institute of Geology and Geophysics, Chinese Academy of Sciences, Deshengmenwai, Qijiahuozi,
Chaoyang District, Beijing 100029, China
Received 5 January 2005; received in revised form 28 April 2005; accepted 3 June 2005
Abstract If the site at which receiver functions are constructed is filled by sediments, then the waveforms from these receiver functions are dominantly controlled by the sedimentary structures within the first few seconds after the direct P arrival. Based on this observation, waveform data collected at 44 temporary seismic stations have been used to image the sedimentary structure of the Bohai Bay Basin, a major continental petroliferous basin in Eastern China. An adapted hybrid global waveform inversion method was applied to the receiver functions to extract st