Download or read book Incoherent Scatter Radar Detection of Enhanced Plasma Line in Ionospheric E region Over Arecibo written by Rezy Pradipta and published by . This book was released on 2006 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt: A series of incoherent scatter radar (ISR) observation were conducted at the Arecibo Observatory from December 27, 2005 until January 3, 2006. From plasma line measurements that were taken during this radar campaign, we found that plasma line enhancement was quite frequently seen in the ionospheric E-region. We hypothesized that the E-region plasma line enhancement over Arecibo was caused by precipitated electrons from the radiation belts. The precipitated electrons will enhance the population of suprathermal electrons in the E-region. Subsequently, suprathermal electrons will cause excitation of Langmuir waves that could be detected by incoherent scatter radar as plasma lines. In this thesis, we are going to examine and discuss the observed features of E-region plasma line enhancement over Arecibo to test this hypothesis. In addition, a theoretical discussion on Langmuir waves is also presented in a chapter of this thesis. Finally, we also introduce the Spread F Index (SFI) as a convenient bookkeeping method to summarize spread F condition over a certain period of time.
Download or read book Chirped Incoherent Scatter Radar Observations of the HF modified Ionosphere written by Brett Cameron Isham and published by . This book was released on 1991 with total page 552 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Incoherent Scatter Study of Dynamics in the Ionosphere E and F Region at Arecibo written by Yun Gong and published by . This book was released on 2012 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis reports the investigation of the dynamics and associated phenomena occurring in the ionospheric E- and F-region heights above Arecibo. The observational data was derived with an incoherent scatter radar (ISR) from Arecibo Observatory, Puerto Rico. The thesis focuses primarily on two aspects. One is to study the atmospheric tidal and planetary waves. This is the first time that dual-beam ISR has been used for E- and F-region tidal and planetary wave studies. The vertical structures of the observed tidal and planetary waves are analyzed rigorously. This study is the first to report the existence and possible excitation mechanism of a terdiurnal tide in the F-region at low latitude. The second aspect is to give a more complete explanation of the midnight collapse phenomenon. The F-region electric field, ambipolar diffusion, and tidal components in the meridional wind all play a role in causing the midnight collapse at Arecibo.
Download or read book Contes et l gendes du bouddhisme chinois traduits par Edouard Chavannes written by and published by . This book was released on 1921 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Intense Spreading of Radar Echoes from Ionospheric Plasmas written by Seth E. Dorfman and published by . This book was released on 2005 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: On December 25, 2004, a large-scale ionospheric plasma bubble was observed over Arecibo Observatory in Puerto Rico, inducing significant range spreading on ionograms. This phenomena may be explained by means of the E x B instability and gravitational Rayleigh-Taylor instability. A derivation of the dispersion relations for X and O mode waves transmitted from an ionosonde and an analysis of the collisional Rayleigh-Taylor instability leading to an expression for the growth rate are presented as background information. Ray tracing code developed by Nathan Dalrymple, a previous graduate student of Professor Min-Chang Lee, is extended, first to draw refractive index surfaces to illustrate a key principle in ray tracing and later to simulate range spreading due to depleted ionospheric ducts [1]. Data from Arecibo incoherent scatter radar and Arecibo's CADI digisonde is examined showing strong evidence for the development of a plasma bubble following a rise in the plasma layer and the appearance of a horizontal density gradient. In one portion of the ionosphere, this gradient is found to be at an angle of approximately 70 degrees to the Earth's magnetic field, a favorable condition for the excitation of the Rayleigh-Taylor instability over Arecibo.
Download or read book Detection of F region Electron Density Irregularities Using Incoherent scatter Radar written by Krishna Prasad Gudivada and published by . This book was released on 2014 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Incoherent-scatter radar data from Poker Flat, Alaska has been used to determine size distributions of electron density structures in the evening time sector of the auroral zone. At high latitudes ionospheric plasma typically moves east-west with speeds of several hundred meters per second. Density irregularities that rapidly move through the radar beam are therefore observed as time-varying power fluctuations. The new phased array radar used for this study has been operated with several antenna directions with successive pulses transmitted in each direction. It is therefore possible to observe plasma Doppler velocities in multiple directions and determine the vector direction of the plasma motion. This near-simultaneous observation of the plasma velocity in conjunction with the electron density height profile data enable a new technique to determine the scale sizes of electron density fluctuations that move horizontally through the radar beam. The study focuses on the collision-less F-region ionosphere where the plasma drift is approximately constant with altitude. The experimental technique limits the range of scale sizes that may be studied to relatively large-scale sizes (i.e. greater than few tens of km). Results show that during magnetically disturbed conditions (Kp ≥ 4) when westward plasma velocities are relatively high (500-1000 m/s) the scale sizes of irregularities (often called plasma blobs) are in the range of 100-300 km and predominantly originate from the polar cap and are transported over long distances (~1000 km) due to the long chemical recombination times (30-90 minutes). Some irregularities are caused by local auroral particle precipitation and have been identified with associated electron temperature enhancements. For cases of low magnetic activity (Kp ≤ 1), when the radar is located in a region of low plasma velocities (100-500 m/s) well south of the auroral oval (essentially a mid-latitude type ionosphere), the density distribution is always biased strongly toward small-scale sizes (less than 50 km).
Download or read book Meteorological and Geoastrophysical Abstracts written by and published by . This book was released on 1996 with total page 522 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1975 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ionospheres written by Robert Schunk and published by Cambridge University Press. This book was released on 2009-08-20 with total page 641 pages. Available in PDF, EPUB and Kindle. Book excerpt: Describes the physical, plasma and chemical processes controlling ionospheres, upper atmospheres and exospheres, for researchers and graduates.
Download or read book Radar Investigation of Barium Releases Over Arecibo Observatory Puerto Rico written by National Aeronautics and Space Adm Nasa and published by . This book was released on 2018-11-21 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: The NASA Combined Release and Radiation Effects Satellite (CRRES) El Coqui rocket campaign was successfully carried out in Puerto Rico during the period 18 May through 12 July 1992. This report describes five chemical release experiments in the upper ionosphere supported by Geospace Research, Inc. during the El Coqui campaign. Additional spin-off science is also discussed. The El Coqui releases are designated AA-1 (rocket 36-082), AA-2 (rocket 36-081), AA-3b (rocket 36-064), AA-4 (rocket 36-065), and AA-7 (rocket 36-083). Particular attention is paid to releases AA-2 and AA-4. These two experiments involved the illumination of ionospheric release regions with powerful high-frequency (HF) radio waves transmitted from the Arecibo HF facility. In the AA-2 experiment, microinstabilities excited by the HF wave in a Ba(+) plasma were examined. This release yielded a smooth plasma cloud that helped clarify several fundamental issues regarding the physics of wave plasma instabilities. During AA-2 extremely strong HF-induced Langmuir turbulence was detected with the Arecibo 430 MHz radar. CF3Br was released in the AA-4 study to create an ionospheric hole that focused the HF beam. This experiment successfully explored wave-plasma coupling in an O(+) ionosphere under conditions of very high HF electric field strengths. Djuth, Frank T. BARIUM; CRRES (SATELLITE); OBSERVATORIES; PLASMA WAVES; RADAR MEASUREMENT; RADIATION EFFECTS; UPPER IONOSPHERE; ELECTRIC FIELDS; LANGMUIR TURBULENCE; PLASMA CLOUDS...
Download or read book Space Studies Board Annual Report 2013 written by National Research Council and published by National Academies Press. This book was released on 2014-04-09 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt: The original charter of the Space Science Board was established in June 1958, 3 months before the National Aeronautics and Space Administration (NASA) opened its doors. The Space Science Board and its successor, the Space Studies Board (SSB), have provided expert external and independent scientific and programmatic advice to NASA on a continuous basis from NASA's inception until the present. The SSB has also provided such advice to other executive branch agencies, including the National Oceanic and Atmospheric Administration (NOAA), the National Science Foundation (NSF), the U.S. Geological Survey (USGS), the Department of Defense, as well as to Congress. Space Studies Board Annual Report 2013 covers a message from the chair of the SSB, Charles F. Kennel. This report also explains the origins of the Space Science Board, how the Space Studies Board functions today, the SSB's collaboration with other National Research Council units, assures the quality of the SSB reports, acknowledges the audience and sponsors, and expresses the necessity to enhance the outreach and improve dissemination of SSB reports. This report will be relevant to a full range of government audiences in civilian space research - including NASA, NSF, NOAA, USGS, and the Department of Energy, as well members of the SSB, policy makers, and researchers.
Download or read book Spring Meeting written by American Geophysical Union. Meeting and published by . This book was released on 1996 with total page 692 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Poker Flat Incoherent Scatter Radar Investigations of the Nighttime E region written by Robin L. Whittier and published by . This book was released on 2014 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plasma within the ionosphere affects technology, such as long distance communications and satellite navigation, by scattering and altering the propagation of radio waves sent through the ionosphere. Understanding the structure and dynamics of the ionosphere that may interfere with modern technology is therefore an important aspect of Space Weather research. In this thesis, the average characteristics and dynamics of the nighttime E-region (90-150 km in altitude) are investigated during auroral disturbances and near extreme solar minimum. The near-continuous data on electron density obtained with the Poker Flat Incoherent Scatter Radar (PFISR) near Fairbanks, Alaska are utilized. A number of correlation analyses between E-region electron content and AE index are performed in order to examine the influence of geomagnetic conditions on the E-region in relation to time of the day as well as seasonal and solar cycle effects. It is shown that E-region electron content and AE index exhibit significant positive correlation, particularly near local magnetic midnight, with greater correlation generally occurring in spring and autumn. The midnight feature is interpreted as an indication that the electrojet system near midnight is mostly controlled by electric conductance. The presented statistical results on the current-conductance relationship utilizing a new dataset strengthen conclusions derived from previous studies. The extent of E-region contribution to the total electron content (TEC) is also estimated and investigated for various conditions for the first time using the full altitude profile of PFISR. The estimates ranged between 5%-60% and more active periods generally displayed a more significant contribution from the E-region to TEC. Additionally, using the AE index as an indicator of auroral disturbance onset, the evolution of auroral density enhancements is explored using the superposed epoch analysis technique. The behavior of E-region electron content, peak density, height of peak density, and layer thickness is considered and three discernible phases in response of the thick E-layer to auroral disturbances are found. The observations are consistent with a scenario in which an initially soft and broad auroral electron energy spectrum quickly hardens and narrows during the main response and then slowly softens and becomes more broad during recovery.
Download or read book AGARD Conference Proceedings written by North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development and published by . This book was released on 1973 with total page 1002 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1986 with total page 992 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1987 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ERDA Energy Research Abstracts written by and published by . This book was released on 1987 with total page 652 pages. Available in PDF, EPUB and Kindle. Book excerpt:
