نتایج جستجو برای: ionospheric tomography

تعداد نتایج: 189589  

2007
Suqin Wu Kefei Zhang Yunbin Yuan Falin Wu

The atmospheric effects, especially the ionosphere, are the key limiting factors for real-time high accuracy positioning using the network RTK technique with a medium-to-long-range baseline separation. To investigate suitable approaches to improve ionospheric modeling towards a real-time CMlevel positioning using the Victorian continuously operating reference stations network (i.e. GPSnet) syst...

2014
Minchan Kim Jiwon Seo Jiyun Lee

Global Navigation Satellite Systems (GNSS) are now recognized as cost-effective tools for ionospheric studies by providing the global coverage through worldwide networks of GNSS stations. While GNSS networks continue to expand to improve the observability of the ionosphere, the amount of poor quality GNSS observation data is also increasing and the use of poor-quality GNSS data degrades the acc...

2008
Xinan Yue Libo Liu Weixing Wan Yong Wei Zhipeng Ren

[1] A middleand low-latitude ionospheric theoretical model is used for the first time to assess the effects of the secular variations of geomagnetic field orientation on ionospheric long-term trends over the past century. It is found that the varied geomagnetic field can produce ionospheric long-term trends in both foF2 and hmF2. Since the amplitudes of geomagnetic field change depend on locati...

2010
Jiyun Lee Sungwook Jung

Extremely large ionospheric gradients can pose a potential integrity threat to the users of Local Area Augmentation System (LAAS), and thus the development of an ionospheric anomaly threat model is essential for system design and operation. This paper presents a methodology for long-term ionosphere monitoring which will be used to build an ionosphere threat model, evaluate its validity over the...

2004
S. V. Thampi T. K. Pant S. Ravindran

Equatorial ionosphere poses a challenge to any algorithm that is used for tomographic reconstruction because of the phenomena like the Equatorial Ionization Anomaly (EIA) and Equatorial Spread F (ESF). Any tomographic reconstruction of ionospheric density distributions in the equatorial region is not acceptable if it does not image these phenomena, which exhibit large spatial and temporal varia...

2011
P. Prikryl P. T. Jayachandran S. C. Mushini

Maps of GPS phase scintillation at high latitudes have been constructed after the first two years of operation of the Canadian High Arctic Ionospheric Network (CHAIN) during the 2008–2009 solar minimum. CHAIN consists of ten dual-frequency receivers, configured to measure amplitude and phase scintillation from L1 GPS signals and ionospheric total electron content (TEC) from L1 and L2 GPS signal...

Journal: :فیزیک زمین و فضا 0
صدیقه امیدی دانشجو/ دانشگاه یزد محمدحسین معماریان عضو هیات علمی دانشکده فیزیک/ دانشگاه یزد سعید فرزانه دانشجو/ دانشکده مهندسی نقشه برداری دانشگاه تهران

reduced rainfall in many parts of the world have prompted scientists to try to manipulate, in different ways, to the nature, causing precipitation from accumulated water in the atmosphere. atmospheric ionization is a new method for producing precipitation and has attracted much attention. in this regard, in recent years, in some regions of the world, in different ways, the relation between mete...

2002
Raymond A. Greenwald Simon G. Shepherd Thomas S. Sotirelis J. Michael Ruohoniemi Robin J. Barnes

[1] Small-scale ionospheric irregularities and auroral precipitation are common features of the auroral ionosphere, but their spatial association has not been examined on global scales. In this paper, we compare electron and ion precipitation from individual passes of the Defense Meteorological Satellite Program (DMSP) spacecraft with concurrent observations of ionospheric irregularities and pl...

1998
V. G. Galushko V. V. Paznukhov Y. M. Yampolski J. C. Foster

Observations of traveling ionospheric disturbances (TIDs) associated with atmospheric gravity waves (AGWs) generated by the moving solar terminator have been made with the Millstone Hill incoherent scatter radar. Three experiments near 1995 fall equinox measured the AGW/TID velocity and direction of motion. Spectral and cross-correlation analysis of the ionospheric density observations indicate...

2011
A. J. Mannucci

We study the impact of large-scale ionospheric structure on the accuracy of radio occultation (RO) retrievals. We use a climatological model of the ionosphere as well as an ionospheric data assimilation model to compare quiet and geomagnetically disturbed conditions. The presence of ionospheric electron density gradients during disturbed conditions increases the physical separation of the two G...

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