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Ionospheric longitudinal variations at midlatitudes: Incoherent scatter radar observation at Millstone Hill

Science China(Technological Sciences) 2012年第5期55卷 1153-1160页

作者： COSTER Anthea HOLT John FOSTER John ERICKSON Phil mit haystack observatory Off Route 40 Westford MA 01866 USA

Incoherent scatter radar （ISR） extra-wide coverage experiments during the period of 1978-2011 at Millstone Hill are used to investigate longitudinal differences in electron density. This work is motivated by a recent finding of the US east-west coast difference in TEC suggesting a combined effect of changing geomagnetic declination and zonal winds. The current study pro- vides strong supporting evidence of the longitudinal change and the plausible mechanism by examining the climatology of electron density Ne on both east and west sides of the radar with a longitude separation of up to 40% for different heights within 300-450 kin. Main findings include： 1） The east-west difference can be up to 60% and varies over the course of the day, being positive （East side Ne 〉 West side Ne） in the late evening, and negative （West side Ne 〉 East side Ne） in the pre-noon. 2） The east-west difference exists throughout the year. The positive （relative） difference is most pronounced in winter; the negative （relative） difference is most pronounced in early spring and later summer. 3） The east-west difference tends to enhance toward decreasing solar activity, however, with some seasonal dependence; the enhancements in the positive and negative differences do not take place simultaneously. 4） Both times of largest positive and largest negative east-west differences in Ne are earlier in summer and later in winter. The two times differ by 12-13 h, which remains constant throughout the year. 5） Variations at different heights from 300-450 km are similar. Zonal wind climatology above Millstone Hill is found to be perfectly consistent with what is expected based on the electron density difference between the east and west sides of the site. The magnetic declination-zonal wind mechanism is true for other longitude sectors as well, and may be used to understand longitudinal variations elsewhere. It may also be used to derive thermospheric zonal winds.

关键词： midlatitude ionosphere geomagnetic declination thermospheric zonal winds longitudinal variation incoherent scatterradar

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Cold plasma redistribution throughout geospace

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Science China(Technological Sciences) 2016年第9期59卷 1340-1345页

作者： Foster John C. Massachusetts Institute of Technology Haystack Observatory

The redistribution of the electrically charged cold plasma of ionospheric origin involves the equatorial,low,mid,auroral,and polar-latitude regions in a multi-step,system-wide process linking the regions of *** with ground and space-based instruments characterize the geospace plume-regularly occurring channels of enhanced plasma density flowing at both ionospheric and magnetospheric *** in the SAPS channel transports the eroded material to the noontime cusp in the ionosphere and to the dayside magnetopause at high *** the fluxes of cold plume plasma traverse the cusp and enter the polar cap,they form the polar tongue of *** the cusp the plume plasma provides a rich source of heavy ions for the magnetospheric injection and acceleration via the mechanisms operative on those field lines.

关键词： plasmasphere ionosphere geospace GPS TEC ionospheric electric field plume

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HⅠ emission from the red giant Y CVn with the VLA and FAST

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Research in Astronomy and Astrophysics 2017年第7期17卷 39-46页

作者： Do T.Hoai Pham T.Nhung Lynn D.Matthews Eric Grard Thibaut Le Bertre Department of Astrophysics Vietnam National Satellite CenterVAST LERMA CNRSObservatoire de Paris/PSLSorbonne Universite's Department of Astrophysics Vietnam National Satellite Center mit haystack observatory GEPI CNRSObservatoire de Paris/PSL

Imaging studies with the Very Large Array（VLA） have revealed H I emission associated with the extended circumstellar shells of red giants. We analyze the spectral map obtained on Y CVn, a J-type carbon star on the Asymptotic Giant Branch. The H I line profiles can be interpreted with a model of a detached shell resulting from the interaction of a stellar outflow with the local interstellar *** reproduce the spectral map by introducing a distortion along a direction corresponding to the star＇s motion in space. We then use this fitting to simulate observations expected from the Five-hundred-meter Aperture Spherical radio Telescope（FAST）, and discuss its potential for improving our description of the outer regions of circumstellar shells.

关键词： stars AGB and post-AGB-- stars carbon - stars individual Y CVn - radio lines stars

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New findings of ionospheric longitudinal variations at mid-latitudes

New findings of ionospheric longitudinal variations at mid-l...

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第十四届全国日地空间物理学术研讨会

作者： John Foster Anthea Coster Phil Erickson John Holt mit haystack observatory Westford MA 01886 USA

＜正＞This paper reports on new findings of pronounced longitudinal variations in mid‐latitude electron density over the continental US, manifested as a large-scale east-west coast difference in TEC as well as east-west difference in electron density from incoherent scatter radar （ISR） extra-wide coverage over Millstone *** implication of these results on other longitudes is also addressed. A common feature of these longitudinal east-west differences is a clear local-time variation where in the evening sectorelectron density

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Monitoring the geospace response to the Great American Solar Eclipse on 21 August 2017

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Earth and Planetary Physics 2017年第1期1卷 72-76页

作者： Shun-Rong Zhang Philip J.Erickson Larisa P.Goncharenko Anthea J.Coster Nathaniel A.Frissell haystack observatory Massachusetts Institute of Technology Center for Solar-Terrestrial Research New Jersey Institute of Technology

Since ancient times,solar eclipses have fascinated—and sometimes terrified—*** eclipses are direct sensory *** the sun vanishes from the sky,birds fall silent during the midday *** instrumentation has enabled resear... 详细信息

关键词： solar eclipse geospace effect ionospheric observations ionospheric radio citizen science

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Scientific challenges and instrumentation for the International Meridian Circle Program

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Science China Earth Sciences 2021年第12期64卷 2090-2097页

作者： William LIU Michel BLANC Chi WANG Eric DONAVAN John FOSTER Mark LERTER Hermann OPGENOOTYH Liwen REN National Space Science Centre Chinese Academy of SciencesBeijing100190China University of Toulouse Toulouse31400France University of Calgary CalgaryT2N 1N4Canada mit haystack observatory CambridgeMA01886USA University of Leicester LeicesterLE17RHUK University of Umeå UmeåSE-90187Sweden

Earth’s ecosystems and human activities are threatened by a broad spectrum of hazards of major importance for the safety of ground infrastructures,space systems and space flight:solar activity,earthquakes,atmospheric and climatic disturbances,changes in the geomagnetic field,fluctuations of the global electric *** and understanding these major hazards to better predict and mitigate their effects is one of the greatest scientific and operational challenges of the 21st *** diverse,these hazards share one feature in common:they all leave their characteristic imprints on a critical layer of the Earth’s environment:its ionosphere,middle and upper atmosphere(IMUA).The objective of the International Meridian Circle Program(IMCP),a major international program led by the Chines Academy of Sciences(CAS),is to deploy,integrate and operate a global network of research and monitoring instruments to use the IMUA as a screen on which to detect these *** this article,we first show that the geometry required for the IMCP global observation system leads to a deployment of instruments in priority along the 120°E-60°W great meridian circle,which will cover in an optimal way both the dominant geographic and geomagnetic latitude variations,possibly complemented by a second Great Circle along the 30°E-150°W meridians to capture longitude ***,starting from the Chinese Meridian Project(CMP)network and using it as a template,we give a preliminary and promising description of the instruments to be integrated and deployed along the 120°E-60°W great circle running across China,Australia and the Americas.

关键词： International Meridian Circle Program Ionosphere Middle-upper atmosphere Space weather Chinese Meridian Project

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Nighttime meridional neutral wind responses to SAPS simulated by the TIEGCM:A universal time effect

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Earth and Planetary Physics 2021年第1期5卷 52-62页

作者： KeDeng Zhang Hui Wang WenBin Wang Jing Liu ShunRong Zhang Cheng Sheng Department of Space Physics School of Electronic InformationWuhan UniversityWuhan 430072China High Altitude observatory National Center for Atmospheric ResearchBoulder 80301ColoradoUSA haystack observatory Massachusetts Institute of TechnologyWestford 01886MassachusettsUSA Department of Physics University of Texas at ArlingtonArlington 76013TexasUSA

The present work uses the Thermosphere Ionosphere Electrodynamics General Circulation Model(TIEGCM),under geomagnetically disturbed conditions that are closely related to the southward interplanetary magnetic field(IMF),to investigate how the nighttime poleward wind(30°–50°magnetic latitude and 19–22 magnetic local time)responds to subauroral polarization streams(SAPS)that commence at different universal times(UTs).The SAPS effects on the poleward winds show a remarkable UT variation,with weaker magnitudes at 00 and 12 UT than at 06 and 18 *** strongest poleward wind emerges when SAPS commence at 06 UT,and the weakest poleward wind develops when SAPS occur at 00 UT.A diagnostic analysis of model results shows that the pressure gradient is more prominent for the developing of the poleward wind at 00 and 12 ***,the effect of ion drag is important in the modulation of the poleward wind velocity at 06 and 18 *** is caused by the misalignment of the geomagnetic and geographic coordinate systems,resulting in a large component of ion drag in the geographically northward(southward)direction due to channel orientation of the SAPS at 06 and 18 UT(00 and 12 UT).The Coriolis force effect induced by westward winds maximizes(minimizes)when SAPS commence at 12 UT(00 UT).The centrifugal force due to the accelerated westward winds shows similar UT variations as the Coriolis force,but with an opposite effect.

关键词： Subauroral Polarization Streams TIEGCM poleward winds Universal time change

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The orbital phase resolved spectroscopy of X-ray binary 4U 1822–371 with Suzaku

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Research in Astronomy and Astrophysics 2016年第4期16卷 37-46页

作者： Shu Niu Shu-Ping Yan Shi-Jun Lei Michael A.Nowak Norbert S.Schulz Li Ji Purple Mountain observatory Chinese Academy of SciencesNanjing 210008China mit Kavli Institute for Astrophysics and Space Research CambridgeMA 02139USA

4U 1822-371 is a typical edge-on eclipsing low mass X-ray binary and the prototype of accre- tion disk coronal sources. We report on the results of a spectral analysis over the energy range 0.5-45 keV observed by Suzaku in 2006. We extract spectra from five orbital phases. The spectra can be equally well described by various previously proposed models： an optically thick model described by a partially cov- ered cutoff power law and an optically thin model described by a blackbody plus a cutoff power law. The optically thick model requires a covering fraction of about 55%, while the optically thin model requires a temperature of the central source of about 0.16 keV. The spectrum in the optically thick model also shows the previously detected cyclotron line feature at ~30 keV with the same Suzaku observation. This fea- ture confirms the presence of a strong magnetic field. The Fe Ks fluorescent line strengths as well as the detected Fe xxvI strengths are similar to previous Chandra and XMM-Newton detections in our phased spectral analysis; however, we also observe strong Fe xxvI during the eclipse, which indicates a slightly larger central corona.

关键词： accretion accretion disks -- binaries: eclipsing -- line: formation -- binaries: spectroscopic-- X-rays: binaries

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Meridional movement of northern and southern equatorial ionization anomaly crests in the East-Asian sector during 2002-2003SSW

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Science China Earth Sciences 2017年第4期60卷 776-785页

作者： MO XiaoHua ZHANG DongHe Larisa GONCHARENKO ZHANG ShunRong HAO YongQiang XIAO Zuo PEI JiaZheng Akimasa YOSHIKAWA CHAU HaDuyen College of Science Guangxi University for Nationalities Department of Geophysics Peking University haystack observatory Massachusetts Institute of Technology School of Automation Wuhan University of Technology Earth and Planetary Sciences International Center for Space WeatherKyushu University Hanoi Institute of Geophysics Vietnamese Academy of Science and Technology

The present paper investigates the asymmetrical variability of the location of the north and the south equatorial ionization anomaly(EIA) crests in the East-Asian sector,along with their association with simultaneous observations of equatorial electrojet(EEJ) strength,geomagnetic activity index,and solar flux index during the 2002-2003 sudden stratospheric wanning(SSW) *** of these observations indicates the existence of a large-scale quasi 16-day periodic meridional movement in both EIA crests,and also reveals a strong correlation between the quasi 16-day oscillation in geomagnetic latitudes of the EIA crest and EEJ *** latitude of the northern/southern EIA crest and the EEJ strength indicate that obvious synchronous periodic oscillations were in-phase in the northern and southern hemisphere when the SSW *** addition,it is also found that both the EIA crest location and amplitude of the periodic movement of the EIA locations exhibit hemispheric *** amplitude of the periodic movement of the EIA location in the southern hemisphere is larger than that of the northern hemisphere,and the southern EIA crest is further off from the equator than the north *** these asymmetries requires a combination of mechanisms that involve at least trans-equator meridional winds and the position of a sub-solar point;however,potential disturbances in neutral winds associated with the SSW may additionally complicate the equatorial ionospheric dynamics.

关键词： Active experiments Ionosphere F1-region Electric fields

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A statistical study of ionospheric profile parameters derived from Millstone Hill incoherent scatter radar measurements

A statistical study of ionospheric profile parameters derive...

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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： John M.Holt haystack observatory Massachusetts Institute of TechnologyWestfordMassachusettsUSA.

[1]Diurnal,seasonal,and solar activity variations of the bottomside electron density profile parameters B0 and B1, representing the F2 layer thickness and shape,are studied using a large incoherent scatter radar dataset for Millstone Hill covering the period *** results are compared with the latest IRI *** statistical study is characterized by morning and afternoon falls in the diurnal variation of B0 for seasons other than summer and a-15% change in BI over a solar cycle,features not fully well represented by the standard IRI *** standard IRI B1, however,is very close to observations in terms of the diurnal *** TERMS:2443 Ionosphere: Midlatitude ionosphere;2447 Ionosphere:Modeling and forecasting;6929 Radio Science:Ionospheric physics(2409);6952 Radio Science:Radar atmospheric ***:Lei,J., ***,***,S.-***,and ***(2004),A statistical study of ionospheric profile parameters derived from Millstone Hill incoherent scatter radar measurements,Geophys.

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