477 research outputs found

    A correlative investigation of the propagation of ULF wave power through the dayside magnetosphere

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    Three different ULF wave phenomena (azimuthally polarized Pc 3 pulsations, radially polarized Pc 4 pulsations, and solitary Pc 5 pulsations related to solar wind pressure pulses) were studied. The main problems covered are: (1) how do magnetospheric Pc 3-4 pulsations, which appear to originate in the solar wind, enter the magnetosphere, and how is this wave energy transported throughout the magnetosphere once it enters; (2) what is the ULF response of the outer dayside magnetosphere to solar wind pressure pulses; and (3) how do Pc 3-4 pulsations modulate ELF-VLF emissions in the dayside magnetosphere

    Analysis of magnetometer data/wave signals in the Earth's magnetosphere

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    Work on the reduction and analysis of Dynamics Explorer (DE) satellite magnetometer data with special emphasis on the ULF fluctuations and waves evident in such data is described. Research focused on the following: (1) studies of Pc 1 wave packets near the plasmapause; (2) satellite-ground pulsation study; (3) support for studies of ion energization processes; (4) search for Pc 1 wave events in 1981 DE 1 data; (5) study of Pc 3-5 events observed simultaneously by DE 1 and by AMPTE CCE; (6) support for studies of electromagnetic transients on DE 1; and (7) analysis of wave events induced by sudden impulses

    A correlative investigation of the propagation of ULF wave power through the dayside magnetosphere

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    Work performed from 1 Jan. - 30 Jun. 1992 is reported. The topics covered include the following: the radial pulsation study, the wave polarization study; radial boundaries of Pc 3-4 pulsations in the dayside magnetosphere; and source regions for correlated ULF-VLF pulsations

    Atomic nitrogen densities near the polar cusp

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    The neutral atmospheric composition spectrometer on board the Dynamics Explorer 2 spacecraft sampled several major and minor thermospheric gases including atomic nitrogen. A selection of passes over the polar cusp that provide a quantitative measure of N densities in this region and provide evidence of localized density increases due to soft particle precipitation is presented. Increases in N densities are frequently observed but are smaller than accompanying increases in N2 densities. The observations support earlier studies suggesting that N densities increase more rapidly than O densities during periods of high solar EUV flux and N densities are larger in the summer hemisphere than in the winter hemisphere. A series of passes in February 1983, late in the lifetime of DE 2, indicated N densities at 200 km altitude were a factor of 2 larger near the southern cusp than near the northern cusp

    A Web Server for MACCS Magnetometer Data

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    NASA Grant NAG5-3719 was provided to Augsburg College to support the development of a web server for the Magnetometer Array for Cusp and Cleft Studies (MACCS), a two-dimensional array of fluxgate magnetometers located at cusp latitudes in Arctic Canada. MACCS was developed as part of the National Science Foundation's GEM (Geospace Environment Modeling) Program, which was designed in part to complement NASA's Global Geospace Science programs during the decade of the 1990s. This report describes the successful use of these grant funds to support a working web page that provides both daily plots and file access to any user accessing the worldwide web. The MACCS home page can be accessed at http://space.augsburg.edu/space/MaccsHome.html

    Analysis of atomic thermospheric nitrogen density

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    A NASA grant provided support for a research project at Augsbury College, Minneapolis, Minnesota for the analysis of atomic nitrogen density data obtained by the Neutral Atmospheric Composition Spectrometer (NACS) on board the Dynamics Explorer-2 satellite. Initial funding was for an exploratory study of the feasibility of obtaining ambient densities of N from source densities of NO. Funding was continued under the Dynamics Explorer Guest Investigator Program when initial studies indicated probable success in obtaining such ambient densities. The major scientific focus of the later work was to be to characterize the behavior of N densities at high latitudes

    The Perceived Effectiveness of the Officer Certification Requirement under Sarbanes-Oxley

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    The Sarbanes-Oxley Act of 2002 brought about sweeping changes that were meant to improve corporate reporting in the United States and to restore investor confidence following some of the largest business failures in US history. This study examines one requirement of this legislation, the certification of the financial statements by the Chief Executive Officer (CEO) and the Chief Financial Officer (CFO) by surveying stakeholder constituent groups to determine whether this new requirement is effective in accomplishing the goals established by Congress and the Securities and Exchange Commission (SEC). This is accomplished by using Cameron\u27s strategic constituencies model to test seven research questions developed from the current literature which provides various points of view regarding the appropriateness of the CEO/CFO certification. Based on the results of these tests, we see that there are significant differences among the perceptions of the constituent groups as to the effectiveness of this requirement

    EMIC Waves in the Earth\u27s Inner Magnetosphere as a Function of Solar Wind Structures During Solar Maximum

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    Here we analyze the statistics of electromagnetic ion cyclotron (EMIC) waves observed in the Earth\u27s inner magnetosphere during coronal mass ejection (CME), high-speed stream (HSS), and quiet solar wind (QSW) conditions in the upstream solar wind (SW). For our analysis we use the EMIC wave observations by the two Van Allen Probes during their first magnetic local time (MLT) revolution. The major results of our analysis are as follows: (1) Criteria to identify the HSS, CME, and QSW conditions in the SW are formulated. (2) 54%, 36%, and 10% of EMIC wave events are observed during CME, HSS, and QSW, respectively. (3) 12% of events are closely associated with the fast growth of magnetospheric compression, among which 76%, 24%, and 0% are observed during CME, HSS, and QSW, respectively. (4) A majority of the QSW, HSS-driven, and CME-driven events is observed in the 9–12, 12–24, and 8–24 hr MLT sectors, respectively. (5) CME-driven events are distributed along all L shells, whereas the majority of the HSS-driven and QSW events are confined to L \u3e 3.5. (6) The fractions of events during CME and HSS have a maximum in the near-equatorial region, whereas the fractions of the QSW events have a minimum there. (7) Independent of the SW driver, no strong events are observed below the local O+ gyrofrequency, whereas 65–70% and 30–35% of events are observed between the O+ and He+ gyrofrequencies and above the He+ gyrofrequency, respectively
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