The research conducted by this group falls generally under the category of remote sensing of the ionosphere/thermosphere system. This encompasses many different routes of enquiry from conducting field experiments to running physics-based and assimilative models to gain a better understanding of how the ionosphere/thermosphere system reacts to different conditions. Below is a brief description of the projects that our group is currently involved in.
Studies of Ionospheric Plasma Structuring at Low Latitudes from Space and Ground, their Modeling and Relationship to Scintillations
Naval Research Laboratory
Jonathan J. Makela (PI)
Aug 2005-July 2008
Studying ionospheric irregularity processes at low latitudes has become a major focus of the Space Weather and Aeronomy communities over the past decade. This is due to the recent proliferation of space-based assets, such as satellite communication and navigation systems. Irregularities in the ionosphere can cause these systems to become temporarily unreliable or unusable. Significant work has already been performed and a general understanding of the processes responsible for the generation of these irregularities at low latitudes has been gained. However, we still lack a fundamental understanding of how the drivers of the instability process interact and, thus, do not have a complete understanding of the day-to-day variability of this phenomenon.
This project combines observations and modeling of the low-latitude nighttime ionosphere to come to a better physical understanding of the factors that contribute to the day-to-day variability of the development of equatorial irregularities. The observations to be used come from the Global Ultraviolet Imager (GUVI) on NASA's Thermosphere, Ionosphere, Mesosphere, Electrodynamics (TIMED) satellite which provide global images of the Earth's ionosphere. The data collected by GUVI will be compared to the SAMI3 model developed at the Naval Research Laboratory. The input parameters (electric fields and neutral winds) of the SAMI3 model will be varied to match the output of the model to the GUVI observations. Once validated in this way, the output of the SAMI3 model will be run through the NRL bubble model to determine if irregularities would form. The results of the NRL bubble model will be compared to observations of the irregularity environment made by various instruments (e.g., the SCINDA network). Finally, the NRL Portable Ionospheric Camera and Small-Scale Observatory (PICASSO) will be deployed to Colombia to collect additional ground-based data to be compared to the modeling results.
Coordinated Imaging and Scintillation Study of the conjugate Nature of Equatorial Plasma Irregularities
National Science Foundation
Jonathan J. Makela (PI), Brent M. Ledvina (Co-I; Virginia Tech)
Feb 2006-Jan 2009
Ionospheric irregularities severely affect systems that transmit radio waves through the ionosphere. These systems include satellite-based technologies on which our society’s infrastructure is becoming increasingly dependent. At the magnetic equator, it is well known that irregularities can develop in the post-sunset ionosphere causing outages in communication and navigation systems over a vast area. This study examines the conjugate nature of both the large-scale features (as seen in airglow images) and smaller-scale features (as measured by GPS L1 scintillation monitors). The goal is to gain a better understanding of the differences in the scintillation environment of conjugate hemispheres during periods of equatorial irregularities caused by varying conditions in the local ionospheres.
A suite of instruments will be fielded at two astronomical sites in South America: Neiva, Colombia and Cerro Tololo, Chile. The instruments, including an ionospheric imaging system and GPS L1 scintillation monitors, will operate autonomously over the duration of the proposal. The data collected will be analyzed with other datasets in the region (e.g., Jicamarca observations, GPS total electron content data, C/NOFS measurements, etc.) when available to gain a broader understanding of how the local data fits into the physics of the entire magnetic flux tube. The data is to be analyzed jointly both between the different types of instruments and at the different locations.
More information on the installation at Cerro Tololo can be found here.
The Remote Equatorial Nighttime Observatory of Ionospheric Regions (RENOIR) project
Office of Naval Research
Jonathan J. Makela (PI)
Mar 2006-Dec 2007
Through this project, we will acquire equipment comprising a single remote equatorial nighttime observatory for ionospheric regions (RENOIR) station. The station consists of a single wide-field imaging system, two Fabry-Perot interferometers, a dual-frequency GPS receiver, and an array of single-frequency GPS scintillation monitors. When installed, the RENOIR station will provide an unprecedented view of the nighttime ionosphere/thermosphere system. Through the construction and deployment of a RENOIR station, we hope to come to a better understanding of the variability in the nighttime ionosphere and the effects this variability has on critical satellite navigation and communication systems. We intend to field of the RENOIR station in collaboration with the International Heliophysical Year.
CAREER: Multi-Technique Study of Ionospheric Irregularities at Mid-Latitudes
National Science Foundation
Jonathan J. Makela (PI)
Jun 2007-May 2012
The research component of this CAREER proposal focuses on developing and deploying two clusters of optical and radio equipment to study irregularities that occur in the nighttime mid-latitude F region. The education component integrates the research conducted into the classroom through the development of modules and laboratory experiments pertaining to the instrumentation used in this study.
Two clusters of instrumentation consisting of a wide-field ionospheric imaging system, a dual-frequency GPS receiver, and a single-frequency GPS scintillation monitor will be deployed to the Caribbean as part of the proposed research. The deployed instruments, in conjunction with other instruments in the region (especially those at the Arecibo Observatory), will allow us to address at least three sets of scientific questions:
- What are the physical extent, seasonal properties, and lifetimes of nighttime F-region structures observed over the Caribbean?
- What is the genesis region and mechanism for the different types of structures present in the nighttime F-region ionosphere? Do they grow locally, or are they coupled from low latitudes? What effect on trans-ionospheric radio wave propagation do these irregularities have?
- Are the enhancements in electron density commonly seen in the American sector during severe geomagnetic storms effective in creating scintillations on critical trans-ionospheric radio links?
Previous studies lacked the spatial coverage to address these questions. Nor did they have instrumentation to measure the scintillation effects on critical satellite links. Both of these shortcomings are addressed in this research plan.
