ABSTRACT DUE DATE: 8 DECEMBER 2009

Ionospheric Effects on GPS

Session Chairs:  Keith Groves, Ph.D., Senior Research Physicist, AFRL/RVBXI, Hanscom AFB and Paul M. Kintner, Ph.D., Professor, Electrical and Computer Engineering, Cornell University

This session will address space weather impacts on GPS signals, prediction of these space weather impacts, engineering robust GPS receivers and systems in the presence of space weather, and the significance of these impacts on the GPS user community and their operations.  Space weather effects include but are not limited to scintillation, ionospheric density gradients or rapidly changing ionospheric density, and solar radio bursts. Topics may include:

• Space weather impacts on GPS signals
• Impacts of space weather on GPS PNT emphasizing DOD applications.
• Prediction of space weather impacts
• Engineering robust GPS receivers and systems in the presence of space weather
• Impact on GPS user community and GPS operations.      

Ionospheric Effects on Space-based Radar Session

Session Chairs:  Ron Caton, AFRL/RVBXI, Hanscom AFB and Xiaoqing Pi, Jet Propulsion Laboratory, California Institute of Technology

The partially ionized upper atmosphere can cause a variety of well-known propagation effects on radio waves including refraction, polarization rotation, group delay, scattering, and phase and amplitude fluctuations.  For radar applications utilizing trans-ionospheric ray paths, these effects may result in range and look-angle errors, multi-path, non-stationary clutter and Doppler and cross-section fluctuations. The severity of these effects and their potential impact on system performance are strongly dependent on ionospheric conditions, radar parameters and the specific application under consideration.  Talks in this session will provide an overview of ionospheric effects on space-based radars over a broad frequency spectrum derived from a combination of modeling techniques and actual measurements. Topics may include:

• Trans-ionospheric Imaging in L, UHF, and VHF Bands.
• Range of Effects in Detailed Imaging Across Frequency Bands.
• Phase Screen Modeling of the Trans-ionospheric Propagation Channel.       
• Situational Awareness Tools for Space-based Radar Operators.

Satellite Communications

Session Co-Chairs: Bela Fejer, Dept. of Physics, Utah State University and Charles S. Carrano, Senior Research Physicist, Boston College Institute for Scientific Research

This session will address ionospheric impacts on satellite communications, with particular emphasis on UHF SATCOM and its anticipated successor the Mobile User Objective System (MUOS). MUOS will employ CDMA spread spectrum technology operating at 300-320 MHz for the uplink and 360-380 MHz for the downlink. Satellite communications systems which operate in the UHF frequency band are subject to performance degradation due to scattering of the radio signal by random electron density variations encountered along the signal path. This scattering produces scintillation, or random enhancements and fading of the received satellite signal. When these scintillations exceed the fade margin of the equipment, users of UHF satellite communication links may experience message errors at unacceptable levels lasting for up to several hours. The focus of this session will be on experimental techniques, simulation results, and nowcast/forecast systems which further Air Force objectives to predict and mitigate the impacts of ionospheric scintillation on UHF satellite communications. Topics may include:

• Global Morphology and Climatology of Ionospheric Scintillation
• Scintillation Specification and Forecasting
• Characterization of the Ionospheric Channel for Narrowband and Wideband Signals
• Mitigation Strategies and Countermeasures

Space Situational Awareness (SSA) for Satellite Operations – Environmental Effects on Orbits and Systems

Co-Chairs: Joe Koesters, AFRL/RYZ, Wright Patterson AFB and Stephan Quigley, Space Weather Forecast Laboratory (SWFL), AFRL/RVBXR, Hanscom AFB

Space weather may affect the operations and mission capability of various DoD assets, to include orbiting spacecraft.  This session will address the data, models, and system-impact products employed for SSA on satellite orbits and system operations.  Presentations should cover environmental and engineering aspects of satellite drag, satellite charge/discharge anomalies, and other environmentally-induced satellite effects. Topics may include:

• Satellite Orbit Atmospheric Density and Drag
• Charged Particle Environments and Spacecraft Charging
• Single Event Upsets (SEUs) on Satellite Systems
• Meteors/Meteor Shower Effects on Satellite Operations
• Satellite Orientation and Environmental Effects
• Space Environmental Effects on Spacecraft Surveillance/Monitoring
• Satellite System to Component Design: CAD Files, Materials, Specs and Thresholds with regard to Environmental Effects
• Satellite Sensor Error Bars
• Satellite Anomaly Events/Case Files

Over The Horizon Radar (OTHR)

Session Chairs: Bill Borer, AFRL/RVBXI, Hanscom AFB
and Braham Himed, AFRL/RVRT, Wright Patterson AFB

Over the Horizon Radars require timely and accurate specification of ionospheric electron densities between themselves and the targets they monitor.  Improvements in our ability to specify these densities have derived primarily from improvements in our ability to measure electron densities in the region of interest as well as new methods for optimally combining measurements of different types with empirical ionospheric models.  This session will review the current state of the art and discuss avenues for research most likely to provide the next generation of technology improvement.

• Ambient Ionospheric Measurement Techniques
• Data Assimilation for Regional Specification
• Travelling Ionospheric Disturbances (TIDs)
• Space Weather effects

Next Generation Sensor and Observational Needs

Session Chairs: Odile De La Beaujardiere, Section Chief, C/NOFS, Head SSA Environmental Monitoring, AFRL/RVBXP, Hanscom AFB and Dr. Paul A. Bernhardt, Senior Research Physicist, Naval Research Laboratory, Plasma Physics Division

This session will address innovations in ground-based and satellite sensors for space weather applications, as well as results from recent missions. It will also explore engineering challenges for space weather sensors.  Topics may include:

• Sensors for nanosatellites and cubesats
• Sensors planned for future missions
• Observational data for DoD space weather applications
• Respective roles of ground and space sensors
• Future needs in space weather sensing techniques
• Challenges for future DoD space weather missions

Space Weather Models

Session Co-chairs: Dave Cooke, AFRL/RVBXI, Hanscom AFB
and Robert Schunk, Professor/Director, CASS, Utah State University

The ionosphere-thermosphere (I-T) system displays a significant variation with altitude, latitude, longitude, universal time, season, solar cycle and geomagnetic activity. The system is coupled to the overlying magnetosphere by field-aligned currents, particle precipitation, and electric fields, and to the lower atmosphere by upward propagating planetary, tidal, and gravity waves. The variability of the I-T system is particularly intense during geomagnetic storms and substorms, and the variability results from localized ionization processes, plasma transport, nonlinear plasma processes that operate on a range of spatial scales, time delays associated with causes and effects, and feedback mechanisms between the different spatial domains. To describe the various phenomena, a range of models have been developed, including empirical, physics-based, data-driven, and data assimilation models. These models, which can provide both specifications and forecasts, are potentially useful for mitigating various problems associated with Air Force technological systems, including OTH radars, HF communications, GPS, and satellite drag. The focus of this session will be on the current status of the I-T models, with the emphasis on their suitability for use in engineering applications associated with Air Force needs.  Topics may include:

• Global, Regional, and Local I-T Models
• Specifications and Forecasts
• M-I Coupling and Its Effect on the I-T System
• Model Metrics/Parameters to Fit Use Needs
• Phase Screen Modeling of the Trans-ionospheric Propagation Channel