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Relationships between ionospheric parameters derived from ionosonde observations and characteristics of post-sunset GHz scintillation during high solar activities(2012−2013)at Sanya(18.3°N,109.6°E),China

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Earth and Planetary Physics 2023年第3期7卷 389-406页

作者： JunJie Luo Ying Xiong WeiHua Luo ZhengPing Zhu ChaoWan Fan College of Electronic and Information Engineering South-Central Minzu University430074 WuhanChina Hubei Key Laboratory of Intelligent Wireless Communications South-Central Minzu University430074 WuhanChina Hubei Engineering Research Center of Intelligent Internet of Things Technology South-Central Minzu University430074 WuhanChina

In this study,we present characteristics of post-sunset GHz scintillation occurrence and their correlations with ionospheric parameters derived from ionosonde observations in high solar activity years(2012−2013)of solar cycle 24 at Sanya(18.3°N,109.6°E;dip lat.:12.8°N),China.The analyzed data include the F_(2)-layer’s critical frequency(foF_(2)),peak height(h_(m)F_(2)),and minimum virtual height(h’F),as well as the scale height around the F_(2)-layer peak(H_(m)),and virtual height(h’F_(5))and true height(hF_(5))measured at 5 MHz.We have investigated relationships between the equinoctial asymmetry of these scintillations and these ionospheric parameters.In addition,we calculate the growth rates of Rayleigh−Taylor instability on the basis of the ionosonde measurements and theoretical models,respectively.We find that the equinoctial asymmetry of scintillation onset time is associated with the scale length of the vertical electron density gradient(L),which has been shown to affect the growth of Rayleigh−Taylor instability at the bottom of the F-layer.The seasonal variations of foF_(2),H_(m)and scale length of vertical electron density gradient appear to cause the seasonal variations of scintillation occurrence;the equinoctial asymmetry of scintillation occurrence rate over low latitudes appears to be related to background electron density and vertical drifts in the F-layer around time of sunset.Further study is required to explain the observed correlational weakness in low latitudes between scintillation strength,represented by the daily maximum S4,and daily maximum values of foF_(2),h_(m)F_(2),h’F,H_(m),and also the drifts.

关键词： equatorial ionosphere scintillation low latitude iononsonde equinoctial asymmetry

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Enrichment of Mississippi Valley-type(MVT) deposits in the Tethyan domain linked to organic matter-rich sediments

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Science China Earth Sciences 2023年第12期66卷 2853-2870页

作者： Yucai SONG Zhiming YANG Liangliang ZHUANG SinoProbe Laboratory Institute of GeologyChinese Academy of Geological SciencesBeijing 100037China

The Tethyan domain hosts the world's most abundant hydrocarbon and Mississippi Valley-type(MVT) Pb-Zn resources. The relations among organic matter-rich sediments, MVT Pb-Zn mineralization, and the Tethyan tectonic evolution history are an important scientific issue. The data of paleogeographic reconstruction indicate that the Proto-, Paleo-, and NeoTethys oceans mainly lay in low latitude areas between 30°N and 45°S. The high temperature and precipitation and the lack of sea water overturning in stagnant basins resulted in high marine biological productivity and good preservation conditions for organic matter-rich sediments. Consequently, abundant organic matter-rich sediments were developed and preserved in the Tethyan domain and thus created abundant hydrocarbon resources. Mineralization age data demonstrate that MVT deposits mainly formed during the continent-continent convergence in the late stage of the Tethyan tectonic evolution. Deposits are located in the fold-and-thrust belts and forelands of the continent-continent convergence orogen, and spatially associated with hydrocarbon basins. Organic matter-rich sediments are well developed in MVT ore districts, where hydrocarbon activity appeared earlier than or nearly simultaneous with the Pb-Zn mineralization event. Hydrocarbon activity generally began earlier than the Pb-Zn mineralization in individual deposits. Organic matter-rich sediments and hydrocarbons mainly play the role of reducing agents in the MVT Pb-Zn mineralization process. Through bacterial or thermal reduction, dissolved sulfates from sedimentary strata were reduced to generate reduced sulfur for Pb-Zn sulfide mineralization. In summary, the Tethyan oceans have long been in low latitude areas near the equator, making the Tethyan domain develop abundant organic matterrich sediments and associated hydrocarbon resources which reduce sulfates to provide sufficient reduced sulfur for MVT PbZn mineralization in the region.

关键词： Tethyan domain Organic matter Mississippi Valley-type Pb-Zn deposit low latitude Sulfate reduction

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The low latitude ionospheric effects of the April 2000 magnetic storm near the longitude 120°E

The low latitude ionospheric effects of the April 2000 magne...

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中国科学院地质与地球物理研究所2004学术年会

作者： Libo Liu~1,Weixing Wan~1,C.C.Lee~2,Baiqi Ning~1,and J.Y.Liu~2 1 Institute of Geology and Geophysics,CAS,Beijing,100029,China 2 Institute of Space Science,National Central University,Chung-Li 320,Taiwan

In this paper,we report the responses of the low latitude ionosphere near the longitude 120°E to the April 2000 geomagnetic storm using Digisonde data measured at Chungli(25.0°N,121.2°E,Mag.13.8°N),Wuhan(30.6°N, 114.4°E,Mag.19.3°N),and Kokubunji(35.7°N,139.5°E,Mag.25.7°N).At these three stations,the significant ionospheric responses are near-simultaneous height disturbances after the sudden storm commencement(SSC) on April 6,2000 and wave-like disturbances in the daytime on April 7.The ionospheric height disturbances in the nighttime after the SSC at these stations are suggested to be caused by the storm related perturbed electric fields, and the followed wave-like disturbances may be caused by storm induced atmospheric gravity waves.The vertical effective winds derived from Digisonde measurements imply the existence of significantly large vertical drifts during this storm,which are in agreement with the perturbed zonal electric fields predicted by the model of Fejer and Scherliess(1997) and Scherliess and Fejer(1997).Finally,the storm time derivations of foF2 from its monthly median level at these stations are used to validate the predication ability of the empirical model of Araujo-Pradere et al.(2002),which has included in the International Reference Ionosphere model IRI2000.

关键词： Geomagnetic storm ionospheric storm F-layer low latitude perturbed electric field International Reference Ionosphere

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An investigation of the formation patterns of the ionospheric F3 layer in low and equatorial latitudes

An investigation of the formation patterns of the ionospheri...

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中国科学院地质与地球物理研究所2013年度（第13届）...

作者： Jie Zhu Biqiang Zhao Weixing Wan Baiqi Ning Key Laboratory of Ionospheric Environment Institute of Geology and GeophysicsChinese Academy of Sciences Beijing National Observatory of Space Environment Institute of Geology and GeophysicsChinese Academy of Sciences China University of Chinese Academy of Sciences

lonogram traces with the F3 layer in different latitude do not always seem similar.In our work,we tend to describe morphological features of traces with the F3 layer in magnetic low-latitude region and near magnetic equator through the quantitative investigation of the diurnal variation and latitude dependence of two morphologically characteristic parameters - the foF2-to-foF3 ratio and the difference between h’F3 and h’F2 - in geomagnetically quiet period.The distribution of two formation patterns (pattern A and pattern B are defined with increasing F3 peak density and with nearly constant or decreasing F3 peak density respectively as the peak moving upward around the onset of the F3 layer’s occurrence) of the F3 layer is also investigated based on statistics of formation patterns of the F3 layer in Sanya and Kwajalein in 2011.The ideal equinoctial distribution(without the summer-to-winter neutral wind) of those patterns is symmetrical about magnetic equator with pattern A in magnetic low-latitude region and pattern B near magnetic equator.When taking the summer-to-winter neutral wind which resists(enhances) the plasma diffusion to higher latitude in the windward(leeward) into consideration in a solstice,pattern A could be observed near magnetic equator in summer hemisphere and pattern B in magnetic low-latitude region in winter hemisphere compared with the ideal distribution in the equinox.

关键词： Ionosphere low latitude F3 layer

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