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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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Variations of topside ionospheric scale heights over Millstone Hill during the 30-day incoherent scatter radar experiment

Variations of topside ionospheric scale heights over Millsto...

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中国科学院地质与地球物理研究所2007学术年会

作者：刘立波 J.M.Holt Institute of Geology and Geophysics Chinese Academy of Sciences Haystack Observatory Massachusetts Institute of TechnologyWestfordMAUSA

A 30-day incoherent scatter radar(ISR) experiment was conducted at Millstone Hill(288.5°E,42.6°N) from 4 October to 4 November *** altitude profiles of electron density N,ion and electron temperature(T and T),and line-of-sight velocity during this experiment were processed to deduce the topside plasma scale height H,vertical scale height VSH,Chapman scale height H,ion velocity, and the relative altitude gradient of plasma temperature (dT/dh)/T,as well as the F layer electron density (NF) and height(hF).These data are analyzed to explore the variations of the ionosphere over Millstone Hill under geomagnetically quiet and disturbed *** show that ionospheric parameters generally follow their median behavior under geomagnetically quiet conditions,while the main feature of the scale heights,as well as other parameters, deviated significantly from their median behaviors under disturbed *** enhanced variability of ionospheric scale heights during the storm-times suggests that the geomagnetic activity has a major impact on the behavior of ionospheric scale heights,as well as the shape of the topside electron density *** Millstone Hill,the diurnal behaviors of the median VSH and H are very similar to each other and are not so tightly correlated with that of the plasma scale height H or the plasma *** present study confirms the sensitivity of the ionospheric scale heights over Millstone Hill to thermal structure and *** values of VSH/H tend to decrease as {dT/dh)/T becomes larger or the dynamic processes become enhanced.

关键词： Ionosphere(Ionospheric disturbances Midlatitude ionosphere Plasma temperature and density)

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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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PRELIMINARY STUDY ON THE INFLUENCE OF FY-4 LIGHTNING DATA ASSIMILATION ON PRECIPITATION PREDICTIONS

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Journal of Tropical Meteorology 2019年第4期25卷 528-541页

作者： LIU Rui-xia LIU Jie PESSI Antti HUI Wen CHENG Wei HUANG Fu-xiang Key Laboratory of Radiometric Calibration and Validation for Environmental Satellite/National Satellite Meteorological Center China Meteorological AdministrationBeijing 100081 China China Meteorological Press Beijing 100081 China Vaisala WestfordMA 01886 USA Beijing Institute of Applied Meteorology Beijing 100029 China

Data from the lightning mapping imager on board the Fengyun-4 meteorological satellite(FY-4) were used to study the assimilation of lightning data and its influence on precipitation predictions. We first conducted a quality control check on the events observed by the first Fengyun-4 satellite(FY-4 A) lightning mapping imager, after which the noise points were removed from the lightning distribution. The subsequent distribution was more consistent with the spatial distribution and range of ground-based observations and precipitation. We selected the radar reflectivity, which was closely related to the lightning frequency, as the parameter to assimilate the lightning data and utilized a large sample of lightning frequency and radar reflectivity data from the eastern United States provided by Vaisala. Based on statistical analysis, we found the empirical relationship between the lightning frequency and radar reflectivity and established a look-up table between them. We converted the lightning event data into radar reflectivity data and found that the converted reflectivity and composite reflectivity of ground-based radar observations showed high *** further assimilated the lightning data into the model, adjusted the model cloud analysis process and adjusted the model hydrometeor field by using the lightning data. A rainstorm weather process that occurred on August 8, 2017 in south China was used for the numerical forecast experiment, and three experiments were designed for comparison and analysis: a control experiment, an experiment without the assimilation of FY-4 lightning data(NoLig), and an experiment with the assimilation of FY-4 lightning data(Lig). The results show that after assimilating the FY-4 A lightning data, the accuracies of the intensity, central location and range of the precipitation predicted by the Lig experiment were obviously superior to those predicted by the control and NoLig experiments, and the effect was especially obvious in the s

关键词： FY-4 lightning data data assimilation cloud analysis precipitation prediction

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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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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 nighttime ionospheric response and occurrence of equatorial plasma irregularities during geomagnetic storms:a case study

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Satellite Navigation 2021年第1期2卷 315-328页

作者： Xin Wan Chao Xiong Shunzu Gao Fuqing Huang Yiwen Liu Fan Yin Hongtao Cai Planetary Environmental and Astrobiological Research Laboratory(PEARL) School of Atmospheric SciencesSun Yat-Sen UniversityZhuhaiChina Department of Space Physics Electronic Information SchoolWuhan UniversityWuhan 430072China Mengcheng National Geophysical Observatory University of Science and Technology of ChinaHefeiChina Chinese academy of Sciences Key Laboratory of Geospace Environment School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefeiChina School of Physics and Electronic Information Shangrao Normal UniversityShangraoChina.6 Haystack ObservatoryMassachusetts Institute of TechnologyWestfordMAUSA.

Recent studies revealed that the long-lasting daytime ionospheric enhancements of Total Electron Content(TEC)were sometimes observed in the Asian sector during the recovery phase of geomagnetic storms e.g.,Lei(J Geophys Res Space Phys 123:3217-3232,2018),Li(J Geophys Res Space Phys 125:e2020JA028238,2020).However,they focused only on the dayside ionosphere,and no dedicated studies have been performed to investigate the nighttime ionospheric behavior during such kinds of storm recovery *** this study,we focused on two geomagnetic storms that happened on 7-8 September 2017 and 25-26 August 2018,which showed the prominent daytime TEC enhancements in the Asian sector during their recovery phases,to explore the nighttime large-scale ionospheric responses as well as the small-scale Equatorial Plasma Irregularities(EPIs).It is found that during the September 2017 storm recovery phase,the nighttime ionosphere in the American sector is largely depressed,which is similar to the daytime ionospheric response in the same longitude sector;while in the Asian sector,only a small TEC increase is observed at nighttime,which is much weaker than the prominent daytime TEC enhancement in this longitude *** the recovery phase of the August 2018 storm,a slight TEC increase is observed on the night side at all longitudes,which is also weaker than the prominent daytime TEC *** the small-scale EPIs,they are enhanced and extended to higher latitudes during the main phase of both ***,during the recovery phases of the first storm,the EPIs are largely enhanced and suppressed in the Asian and American sectors,respectively,while no prominent nighttime EPIs are observed during the second storm recovery *** clear north-south asymmetry of equatorial ionization anomaly crests during the second storm should be responsible for the suppression of EPIs during this *** addition,our results also suggest that the dusk side ionospheric response could be affecte

关键词： Geomagneitc storm Storm recovery phase Ionospheric response Equatorial plasma irregularity Longitudinal variations

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Cervical inlet patch-optical coherence tomography imaging and clinical significance

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World Journal of Gastroenterology 2012年第20期18卷 2502-2510页

作者： Chao Zhou Tejas Kirtane Tsung-Han Tsai Hsiang-Chieh Lee Desmond C Adler Joseph M Schmitt Qin Huang James G Fujimoto Hiroshi Mashimo Department of Electrical Engineering and Computer Science Research Laboratory of Electronics Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139-4307 United States Gastroenterology Section VA Boston Healthcare System/Harvard School of Medicine 150 S. Huntington Avenue Boston MA 02131 United States Light Lab Imaging-St Jude Medical Inc. Westford MN 55117-9983 United States

AIM:To demonstrate the feasibility of optical coherence tomography(OCT)imaging in differentiating cervical inlet patch(CIP)from normal esophagus,Barrett'sesophagus(BE),normal stomach and duodenum. METHODS:This study was conducted at the Veterans Affairs Boston Healthcare System(VABHS).Patients undergoing standard esophagogastroduodenoscopy at VABHS,including one patient with CIP,one representative patient with BE and three representative normal subjects were *** light video endoscopy was performed and endoscopic 3D-OCT images were obtained in each patient using a prototype OCT *** OCT imaging probe passes through the working channel of the endoscope to enable simultaneous video endoscopy and 3D-OCT examination of the human gastrointestinal(GI)*** hematoxylin and eosin(H and E)histology was performed on biopsy or endoscopic mucosal resection specimens in order to compare and validate the 3D-OCT data. RESULTS:CIP was observed from a 68-year old male with gastroesophageal reflux *** CIP region appeared as a pink circular lesion in the upper esophagus under white light *** imaging over the CIP region showed columnar epithelium structure,which clearly contrasted the squamous epithelium structure from adjacent normal esophagus.3D-OCT images obtained from other representative patients demonstrated distinctive patterns of the normal esophagus,BE,normal stomach,and normal duodenum ***,such as squamous epithelium,lamina propria, muscularis mucosa,muscularis propria,esophageal glands,Barrett's glands,gastric mucosa,gastric glands, and intestinal mucosal villi were clearly observed with OCT and matched with H and E *** results demonstrated the feasibility of using OCT to evaluate GI tissue morphology in situ and in real-time. CONCLUSION:We demonstrate in situ evaluation of CIP microstructures using 3D-OCT,which may be a useful tool for future diagnosis and follow-up of patients with CIP.

关键词： Cervical inlet patch Heterotopic gastric mucosa Optical coherence tomography Optical biopsy Barrett’s esophagus

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A Simple and Cost-Effective EPON-Based Next Generation Mobile Backhaul RAN Architecture

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Wireless Engineering and Technology 2017年第1期8卷 1-19页

作者： Ajaz Sana Syed R. Zaidi Shahab Hussain Mohammad Nizamuddin Department of Engineering Physics & Technology Bronx Community College of the City University of New York New York USA Nokia Westford USA Department of Electrical Engineering City College of the City University of New York New York USA

This study proposes a novel, simple and cost-effective PON-based next generation mobile backhaul RAN architecture that enables redistribution of some of the intelligence currently centralized in the Mobile Packet Core (MPC) platform out into the access nodes of the RAN. Specifically, this work proposes a fully distributed ring-based EPON architecture that enables the support of a converged PON-4G/5G mobile WiMAX/LTE access networking transport infrastructure to seamlessly backhaul both mobile and wireline multimedia traffic and services.

关键词： LTE WiMAX 4G EPON TDM PON

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声波激励的超小型纳机电系统磁电天线

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通信对抗 2017年第4期36卷 51-58页

作者： Tianxiang Nan Hwaider Lin Yuan Gao Alexei Matyushov Guoliang Yu Huaihao Chen Neville Sun Shengjun Wei Zhiguang Wang Menghui Li Xinjun Wang Amine Belkessam Rongdi Guo Brian Chen James Zhou Zhenyun Qian Yu Hui Matteo Rinaldi Michael E.McConney BrANDon M.Howe Zhongqiang Hu John G.Jones Gail J.Brown Nian Xiang Sun 张建强(翻译) 陈鼎鼎(审校) W.M.Keck Laboratory for Integrated Ferroics and Department of Electrical and Computer EngineeringNortheastern UniversityBostonMA 02115USA westford academy WestfordMA 01886USA Andover High School AndoverMA 01810USA Materials and Manufacturing Directorate Air Force Research LaboratoryWright-Patterson Air Force BaseDaytonOH 45433USA 不详

当前的小型天线依赖于电磁波的谐振,因此天线的尺寸与电磁波波长相关。典型的天线尺寸大于波长的1/10,而进一步缩小天线尺寸在近十年来都是一个公开的挑战。介绍一种通过悬浮铁氧/压电薄膜异质结构的声波激励纳机械磁电天线。这种磁电... 详细信息

当前的小型天线依赖于电磁波的谐振,因此天线的尺寸与电磁波波长相关。典型的天线尺寸大于波长的1/10,而进一步缩小天线尺寸在近十年来都是一个公开的挑战。介绍一种通过悬浮铁氧/压电薄膜异质结构的声波激励纳机械磁电天线。这种磁电天线通过其在声波谐振频率处的磁电效应接收和发射电磁波。磁电天线中的体声波激发铁磁薄膜的磁化振荡,产生电磁波的辐射;反之,天线感应电磁波的磁场,得到压电电压输出。这种磁电天线(尺寸仅为波长的千分之一)比现有小型天线的尺寸小1到2个数量级,但性能却没有降低,在便携式无线通信系统中具有很大的应用潜力。

关键词：纳米板薄膜体声波谐振器纳机电系统

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