Developed novel multi-nesting, time splitting and implicit relaxation techniques for coupled three-dimensional mesoscale/microscale ionospheric dynamics; resolved secondary Rayleigh-Taylor instabilities and characterized turbulent dynamics of plasma bubbles/ionospheric layers. Created methods based on Lagrangian coherent structures delineating formation of scintillation producing irregularities, discovered fine scale irregularity patterns/plasma pancakes in ionospheric flows; described...

Topics: DTIC Archive, ARIZONA STATE UNIV TEMPE, *IONOSPHERIC DISTURBANCES, IONOSPHERIC MODELS

We report on the SUNDIAL campaign conducted during the solstitial period May 29-June 7, 1887. For generally quiet conditions a global network of ionosonde data, supported by topside sounder observations of the Intercosmos 1806 satellite, were compared with the International Reference Ionosphere (IRI). The comparisons included F-region peak characteristics.

Topics: DTIC Archive, Szuszczewicz, E P, *IONOSPHERIC MODELS, *F REGION, REPRINTS, GLOBAL, PARAMETERS,...

Total Electron Content (TEC) measurements derived from observation of polar-orbiting TRANSIT satellites have been incorporated into an assessment of the Bent ionospheric model, as implemented for the PAVPAW program. Both temporal and spatial assessments of the ionospheric model have been performed. By suitable adaptation of the programs developed for this assessment, similar assessments of other ionospheric models could be performed.

Topics: DTIC Archive, Mazzella, Andrew J , Jr, RDP INC WALTHAM MA, *ELECTRONS, ADAPTATION, IONOSPHERIC...

Models of the ionosphere were developed and utilized to evaluate Total Electron Content for various specified transmission paths from the ground into space. Keywords: Ionosphere; Total electron content.

Topics: DTIC Archive, Mazzella, Jr , Andrew J, RDP INC WALTHAM MA, *ELECTRON DENSITY, *IONOSPHERIC MODELS,...

The Earth's ionosphere is the well-known threat for applications that depend on trans-ionospheric radio waves. For example, it affects applications like navigation, positioning, and terrestrial communication. The behavior of the ionosphere has been investigated for the past two-three decades all over the globe. However, there are regions, like Africa, that have not been investigated until recently due to lack of ground-based ionospheric monitoring devices. LEO satellite observations in the...

Topics: DTIC Archive, BAHIR DAR UNIV (ETHIOPIA), *EAST AFRICA, *EQUATORIAL REGIONS, *IONOSPHERIC MODELS,...

The ultimate goal of this research is the development of an operational algorithm for retrieving daytime ionospheric hmF2 from the measurement of the O II 83.4 nm emission feature. This algorithm will provide data for ingestion into ionospheric models. The reward of a successful algorithm is very high, as no capability presently exists to measure the global variation of hmF2 within the F-region of the ionosphere during the day. Further, this work will provide a new assessment of the state of...

Topics: DTIC Archive, NAVAL RESEARCH LAB WASHINGTON DC SPACE PHYSICS SECTION, *IONOSPHERIC MODELS, SPACE...

This report describes the modifications and updates that have been made to the Parameterized Real-time Ionospheric Specification Model (PRISM) that is operational at the 55th Space Weather Squadron (55 SWXS). It also describes the implications of work carried out under a separate contract for the design and development of a new version of PRISM (to be known as PRISM 2) that is to include the plasmasphere, improved theoretical climatology, and an improved data assimilation algorithm.

Topics: DTIC Archive, Daniell, Robert E., Jr., COMPUTATIONAL PHYSICS INC WALTHAM MA, *SPACE ENVIRONMENTS,...

Topics: DTIC Archive, Cohen, Jeffrey M, PENNSYLVANIA UNIV PHILADELPHIA DEPT OF PHYSICS, *IONOSPHERIC...

Since current empirical models specifying low latitude electron density profiles severely underestimate the daytime plasma scale height and total electron content (TEC) values, a semiempirical low latitude ionospheric model (SLIM) has been developed which is not only computationally fast, but also more realistic. Electron density profiles (180-1800 km) are theoretically calculated as a function of latitude (every 2 deg between 24 N and 24 S dip latitude) and local time (every half hour, over 24...

Topics: DTIC Archive, Anderson, David N, AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA, *IONOSPHERIC MODELS,...

The Communications/Navigation Outage Forecasting System (C/NOFS) satellite observed large-scale density depletions at postmidnight and early morning local times in the Northern Hemisphere summer during solar minimum conditions. Using electric field data obtained from the vector electric field instrument (VEFI) as input, the assimilative physics-based model (PBMOD) qualitatively reproduced more than 70% of the large-scale density depletions observed by the Planar Langmuir Probe (PLP) onboard...

Topics: DTIC Archive, AIR FORCE RESEARCH LAB KIRTLAND AFB NM SPACE VEHICLES DIRECTORATE, *IONOSPHERIC...

The plasma densities detected by the Planar Langmuir Probe (PLP) on board the Communication/Navigation Outage Forecasting System (C/NOFS) satellite have been analyzed for the June 2008 period. This interval, which corresponds to one of the quietest periods in the space era, exhibited broad plasma decreases (BPDs) which we have reported previously. In order to treat the data quantitatively, we have detrended the PLP data by using the International Reference Ionosphere model to remove variations...

Topics: DTIC Archive, AIR FORCE RESEARCH LAB KIRTLAND AFB NM SPACE VEHICLES DIRECTORATE, *IONOSPHERE,...

Currently available empirical models of the low latitude ionosphere are seriously in error, especially during high sunspot activity years. Substantial improvement in models is achieved when theoretically calculated profiles are used. However, the fastest theoretical model is prohibitively time-consuming on even the fastest computer. A unique solution to this problem is to theoretically calculate electron density profiles as a function of latitude and local time and then generate coefficients...

Topics: DTIC Archive, Anderson,D N, AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA, *IONOSPHERIC MODELS, *F...

This report describes the PRISM 1.7e algorithm for data assimilation and near real time global ionospheric specification. It also describes the basis for PRISM climatology, including descriptions of the three physical models which were parametrized to produce it, the parameterization method itself, as well as the semi-analytic representation used to produce a compact representation of the climatology. It includes appendices containing the I/O specification for PRISM and internal memoranda...

Topics: DTIC Archive, Daniell, Robert E , Jr, COMPUTATIONAL PHYSICS INC NORWOOD MA, *IONOSPHERE,...

This is a summary of the work accomplished under this effort. Develop and validate a global dynamo model and couple it to the Coupled Ionosphere and Thermosphere Forecast Models (CITFM).

Topics: DTIC Archive, Schunk, Robert W, SPACE ENVIRONMENT CORP LOGAN UT, *IONOSPHERE,...

Novel solution methods are investigated for electromagnetic ray-tracing models and validation with data from the advanced TIGER (Tasman International Geospace Environment Radar) OTHR (Over-the-Horizon-Radar) Facility.

Topics: DTIC Archive, Dyson, Peter L, LA TROBE UNIV VICTORIA (AUSTRALIA) DEPT OF PHYSICS, *RADAR,...

This report describes updates that have been made to the Parameterized Real-time Ionospheric Specification Model (PRISM) that is operational at the 55th Space Weather Squadron (55 SWXS). It also describes a modified TEC data assimilation algorithm that has been implemented in a special regional version of PRISM, and which is available for implementation in the operational version. Finally, it describes several activities related to the validation of PRISM using data from a variety of sources.

Topics: DTIC Archive, Daniell, Robert E , Jr, COMPUTATIONAL PHYSICS INC NORWOOD MA, *REAL TIME,...

Progress simulating equatorial spread F (ESF) in pursuit of a space-weather forecast capability is summarized. ESF is the main manifestation of space weather at low magnetic latitudes in the ionosphere and is responsible for disrupting communication, navigation, imaging, and surveillance systems important to the Air Force and other federal agencies. A 3D numerical simulation of the plasma instabilities responsible for ESF written at Cornell has been developed and upgraded under this award....

Topics: DTIC Archive, Hysell,David L, CORNELL UNIV ITHACA NY ITHACA United States, space weather,...

Data collected with AN/TPS-71 radar has been used to validate the RADARC model. For the first ten days of January , April, and July, noon and midnight, the vertical ionograms, oblique backscatter soundings, radar ground backscatter amplitudes and noise levels have been compared with Model predictions. The differences between the Model and median ionospheric soundings are small enough to have negligible effect on predictions. The coverage predicted for oblique backscatter soundings agrees well...

Topics: DTIC Archive, Root, Benjamin T, NAVAL RESEARCH LAB WASHINGTON DC, *OVER THE HORIZON RADAR,...

Incoherent scatter radar observations at Jicamarca, Peru, from 1964 to the present, have been used to study the seasonal and solar cycle variations in the daily equatorial ionospheric plasma density profiles for select hours. The peak density, peak layer height, and layer thickness are dependent on solar activity which is determined by F1O.7 cm flux. There are large variations in the daily plasma density profiles for each season and solar flux. The peak plasma densities are largest for December...

Topics: DTIC Archive, Creamer, Amanda P, AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH, *IONOSPHERIC...

The SpaceBuoy mission will demonstrate the utility of low-cost nanosatellites to provide focused observations to supplement ionospheric forecasting models; specifically the operational Global Assimilation of Ionospheric Measurements (GAIM) model currently used by the Air Force Weather Agency (AFWA). Data will be collected, processed and made available to end users in units standard to the forecasting community.

Topics: DTIC Archive, MONTANA STATE UNIV BOZEMAN, *SPACE BUOYS, *SPACE MISSIONS, *WEATHER, AIR FORCE,...

The Final Proceedings for International Beacon Satellite Symposium 1997, 30 June 1997 - July 1997. This is an interdisciplinary conference. Topics include Ionospheric Tomography, Electron Content, Ionospheric Models, Scintillation Modeling, Radio Wave Propagation.

Topics: DTIC Archive, Bencza, P., GRAZ UNIV (AUSTRIA), *TOMOGRAPHY, *RADIO TRANSMISSION, *IONOSPHERIC...

The primary goal of the project is to continue the development and validation of the USU GAIM models. A secondary goal is to provide support for the Air Force Weather Agency (AFWA) and other DoD organizations in connection with the operational GAIM model.

Topics: DTIC Archive, UTAH STATE UNIV LOGAN CENTER FOR ATMOSPHERIC AND SPACE SCIENCES, *IONOSPHERIC MODELS,...

The long term goals of this report are: (1) Develop a global ionospheric and upper atmospheric forecasting model over a range of spatial and temporal scales with space and ground-based data assimilation capability; and (2) Develop an improved understanding of the basic dynamics, structure, and energization mechanisms in the global ionosphere- thermosphere system.

Topics: DTIC Archive, NAVAL RESEARCH LAB WASHINGTON DC CHARGED PARTICLE PHYSICS BRANCH, *IONOSPHERIC...

We describe in qualitative terms the cause and nonlinear evolution of the gradient drift and collisional Rayleigh-Taylor instabilities in the earth's ionosphere, by using the examples of ionospheric barium clouds and equatorial spread F 'bubbles' respectively. We then derive the nonlinear differential equations governing these instabilities. Finally, we discuss the numerical solution of these differential equations.

Topics: DTIC Archive, Zalesak, S T, NAVAL RESEARCH LAB WASHINGTON DC, *IONOSPHERIC MODELS, BARIUM, F...

Topics: DTIC Archive, Bean, B R, NATIONAL BUREAU OF STANDARDS BOULDER CO, *IONOSPHERIC MODELS, *RADIO...

This paper reports a novel approach to extend the coverage of terrestrial ionospheric measurements over a poorly characterized region of the South Atlantic Ocean, including the South Atlantic Anomaly, by using dual frequency GPS signals received on board the South African polar research ship SA Agulhas. The routes of the SA Agulhas to the South Atlantic Islands, Gough (40 deg 17 sec S, 9 deg 58 sec W, Mag lat 42 deg S) and Marion (46 deg 52 sec S, 37 deg 5 sec E, Mag lat 51 deg S) and the South...

Topics: DTIC Archive, Cilliers, Pierre J, HERMANUS MAGNETIC OBSERVATORY (SOUTH AFRICA), *IONOSPHERE,...

A model with 78 reactions involving 21 positive ions and 8 negative ions has been developed for the disturbed D-region under steady-state conditions. Model examples are given for the 2 to 5 November 1969 and 3 to 11 August 1972 solar proton events. The computer program for the model is given in the Appendix. (Author)

Topics: DTIC Archive, Swider,William, AIR FORCE GEOPHYSICS LAB HANSCOM AFB MASS, *IONOSPHERIC DISTURBANCES,...

Research has focused on the development, characterization, and implementation of algorithms for time varying ionospheric imaging. Several techniques were used including neural network based approaches for imaging localized time varying events, an iterative volumetric approach for three dimensional imaging that enables localized incorporation of a priori information, and a technique that utilizes both TEC data as well as information from the WSBI system. Considerable effort was made to analyze...

Topics: DTIC Archive, Na, Helen, CALIFORNIA UNIV LOS ANGELES, *IONOSPHERIC MODELS, *COMPUTERIZED...

The purpose of this report is to familiarize a user of ionospheric models with the options presently available for ionospheric prediction and specification. Two types of ionospheric models are available: the numerical-phenomenological and theoretical models. From the numerical type, the ITS-78, IONCAP, and Bent models have been discussed. In the theoretical models the main concern is the number of parameters included in the model. Nine ionoshperic models available have been summarized. The...

Topics: DTIC Archive, Dandekar,B S, AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA, *IONOSPHERIC MODELS,...

The CCIR and Titheridge for critical frequency prediction routines were tested by comparison with 1875 manually scaled values. The foF1 critical frequency prediction routine of Millman et al was tested by comparison with 1005 manually scaled values. Plots and statistics of the comparisons are presented and discussed. From the results recommendations are made to help improve autoscaling.

Topics: DTIC Archive, Gamache, Robert R, LOWELL UNIV MA CENTER FOR ATMOSPHERIC RESEARCH, *IONOSPHERIC...

As part of an effort to determine electron density profiles in the auroral region of the ionosphere, a method was developed for directly calculating real height from ionosonde data obtained at high latitudes. The method has been modified and simplified by representing the entire dispersion curve by a single power-law curve with only one parameter. The resulting real height-virtual height relation can now be solved in a simple way for the real height. To test the accuracy of the method, virtual...

Topics: DTIC Archive, Klein,Milton M, AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA, *IONOSPHERIC MODELS, *HEIGHT...

As part of an effort to determine electron density profiles in the auroral region of the ionosphere, a method was developed for directly calculating real height from ionosonde data obtained at high latitudes. The method has been modified and simplified by representing the entire dispersion curve by a single power-law curve with only one parameter. The resulting real height-virtual height relation can now be solved in a simple way for the real height. To test the accuracy of the method, virtual...

Topics: DTIC Archive, Klein,Milton M, AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA, *IONOSPHERIC MODELS, *HEIGHT...

As part of an effort to determine electron density profiles in the auroral region of the ionosphere, a method was developed for directly calculating real height from ionosonde data obtained at high latitudes. The method has been modified and simplified by representing the entire dispersion curve by a single power-law curve with only one parameter. The resulting real height-virtual height relation can now be solved in a simple way for the real height. To test the accuracy of the method, virtual...

Topics: DTIC Archive, Klein,Milton M, AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA, *IONOSPHERIC MODELS, *HEIGHT...

As part of an effort to determine electron density profiles in the auroral region of the ionosphere, a method was developed for directly calculating real height from ionosonde data obtained at high latitudes. The method has been modified and simplified by representing the entire dispersion curve by a single power-law curve with only one parameter. The resulting real height-virtual height relation can now be solved in a simple way for the real height. To test the accuracy of the method, virtual...

Topics: DTIC Archive, Klein,Milton M, AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA, *IONOSPHERIC MODELS, *HEIGHT...

This report describes several investigations performed towards improving our ability to communicate through the ionospheric medium. These studies covered two distinct and separate areas. The first was concerned with improvements in ionospheric forecasting in the polar region through the development of empirical models for electron density profiles and ionospheric parameters. The second consisted of the study of various techniques for the establishment of high frequency communication circuit...

Topics: DTIC Archive, Miller,David C, ARCON CORP WAKEFIELD MASS, *IONOSPHERIC MODELS, POLAR REGIONS, HIGH...

As part of an effort to determine electron density profiles in the auroral region of the ionosphere, a method was developed for directly calculating real height from ionosonde data obtained at high latitudes. The method has been modified and simplified by representing the entire dispersion curve by a single power-law curve with only one parameter. The resulting real height-virtual height relation can now be solved in a simple way for the real height. To test the accuracy of the method, virtual...

Topics: DTIC Archive, Klein,Milton M, AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA, *IONOSPHERIC MODELS, *HEIGHT...

As part of an effort to determine electron density profiles in the auroral region of the ionosphere, a method was developed for directly calculating real height from ionosonde data obtained at high latitudes. The method has been modified and simplified by representing the entire dispersion curve by a single power-law curve with only one parameter. The resulting real height-virtual height relation can now be solved in a simple way for the real height. To test the accuracy of the method, virtual...

Topics: DTIC Archive, Klein,Milton M, AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA, *IONOSPHERIC MODELS, *HEIGHT...

The International Reference Ionosphere (IRI) is a model of the ionosphere, based on experimental data, that has been proposed as a standard ionospheric model. As such, it should be tested extensively to determine its range of validity. One of the ways in which the electron density profile given by the IRI, especially above the peak of the F layer, can be tested is to compare calculated and observed values of total electron content (TEC). We have therefore studied the discrepancies between...

Topics: DTIC Archive, McNamara,L F, AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA, *IONOSPHERIC MODELS, ELECTRON...

The use of a one-dimensional model atmosphere calculation incorporating dissociation of O2 and ionized species demonstrates that dissociation, through the production of atomic oxygen, can drive the vertical thermosphere and upper mesosphere into diurnal oscillations. It is further demonstrated that neutral mesospheric and lower thermospheric turbulence, through its control of atomic oxygen flow, can cause large amplitude variations of these oscillations. (Author)

Topics: DTIC Archive, Zimmerman,S P, AIR FORCE GEOPHYSICS LAB HANSCOM AFB MASS, *PHOTODISSOCIATION,...

As part of an effort to determine electron density profiles in the auroral region of the ionosphere, a method was developed for directly calculating real height from ionosonde data obtained at high latitudes. The method has been modified and simplified by representing the entire dispersion curve by a single power-law curve with only one parameter. The resulting real height-virtual height relation can now be solved in a simple way for the real height. To test the accuracy of the method, virtual...

Topics: DTIC Archive, Klein,Milton M, AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA, *IONOSPHERIC MODELS, *HEIGHT...

In September, 1980, NRL utilized Barry AN/TRQ-35 oblique sounding equipment which was deployed on board a ship operating in the Atlantic Ocean in order to test a concept to provide a real-time model update with the oblique sounder as a data source. The purpose of this work was to show that very accurate HF channel assessment was possible over paths in the local vicinity of the sounded path. Presented are initial results of an exercise encompassing two short paths (less than 900 km) in the North...

Topics: DTIC Archive, Uffelman,D R, NAVAL RESEARCH LAB WASHINGTON DC, *RADIO EQUIPMENT, *IONOSONDES,...

As part of an effort to determine electron density profiles in the auroral region of the ionosphere, a method was developed for directly calculating real height from ionosonde data obtained at high latitudes. The method has been modified and simplified by representing the entire dispersion curve by a single power-law curve with only one parameter. The resulting real height-virtual height relation can now be solved in a simple way for the real height. To test the accuracy of the method, virtual...

Topics: DTIC Archive, Klein,Milton M, AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA, *IONOSPHERIC MODELS, *HEIGHT...

Research has focused on the development, characterization and implementation of algorithms for time varying ionospheric imaging. Several techniques were used including neural network based approaches for imaging localized time varying events, an iterative volumetric approach for three-dimensional imaging that enables localized incorporation of a priori information, and a technique that utilizes both TEC data as well as information from the WSBI system. Considerable effort was made to analyze...

Topics: DTIC Archive, Na, Helen, IOWA UNIV IOWA CITY, *NEURAL NETS, *IONOSPHERIC MODELS, *COMPUTERIZED...

The research funded by this grant is for the investigation of computerized ionospheric tomography as a method for characterization of the ionosphere. This research looks at specific degradation factors and develops compensation techniques and new CIT algorithms that mitigate or minimize their effects. Research has progressed in three categories: design and analysis of a time-varying algorithm to remove the resolution degradation effects caused by ionospheric motion, investigation of localized...

Topics: DTIC Archive, Na, Helen, CALIFORNIA UNIV LOS ANGELES, *IONOSPHERIC MODELS, *COMPUTERIZED...

As part of an effort to determine electron density profiles in the auroral region of the ionosphere, a method was developed for directly calculating real height from ionosonde data obtained at high latitudes. The method has been modified and simplified by representing the entire dispersion curve by a single power-law curve with only one parameter. The resulting real height-virtual height relation can now be solved in a simple way for the real height. To test the accuracy of the method, virtual...

Topics: DTIC Archive, Klein,Milton M, AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA, *IONOSPHERIC MODELS, *HEIGHT...

As part of an effort to determine electron density profiles in the auroral region of the ionosphere, a method was developed for directly calculating real height from ionosonde data obtained at high latitudes. The method has been modified and simplified by representing the entire dispersion curve by a single power-law curve with only one parameter. The resulting real height-virtual height relation can now be solved in a simple way for the real height. To test the accuracy of the method, virtual...

Topics: DTIC Archive, Klein,Milton M, AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA, *IONOSPHERIC MODELS, *HEIGHT...

The nighttime electron density integrated along a magnetic field line at very small L-values is inferred by comparing whistler dispersions measured from a sounding rocket with model ionospheric calculations. At a local time of 0500 LT, the electron density of the F-layer valley was found to be about 1000/cc. We suggest that this technique can be applied to earlier times in the local evening to determine ionospheric conditions which benefit the growth of low latitude plasma instabilities....

Topics: DTIC Archive, Anderson,D, AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA, *ELECTRON DENSITY, *IONOSPHERIC...

Two major topics are studied during the first year of the two-year (2005-2007) project. The first one is the comparative study of radiowave scintillation simulations carried out with two different approaches at two different institutions: The numerical simulation with the elliptical wave equation carried out by NCU versus the numerical solution of the thin phase-screen model carried out by AFRL/VSBXI. Although AFRL/VSBXI has sent us detailed density irregularity profile at every 50 km downward...

Topics: DTIC Archive, Liu, Chao H, NATIONAL CENTRAL UNIV CHUNG-LI (TAIWAN) INST OF SPACE SCIENCE,...

As part of an effort to determine electron density profiles in the auroral region of the ionosphere, a method was developed for directly calculating real height from ionosonde data obtained at high latitudes. The method has been modified and simplified by representing the entire dispersion curve by a single power-law curve with only one parameter. The resulting real height-virtual height relation can now be solved in a simple way for the real height. To test the accuracy of the method, virtual...

Topics: DTIC Archive, Klein,Milton M, AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA, *IONOSPHERIC MODELS, *HEIGHT...

The differences in critical frequencies of the ionosphere between measured values on the European continent and the model parameters of 'International Reference Ionosphere of 1990' were considered. In general, absolute relative differences of foF2 are of the order of 10 percent. They increase for twilight and night periods up to 20 or 30 percent. Relative differences for foE are less than 5 percent for day-time periods and usually are larger for twilight periods.

Topics: DTIC Archive, Heyman, Ehud, TEL-AVIV UNIV (ISRAEL), *STANDARDS, *IONOSPHERIC MODELS, *IONOSPHERIC...