In order to fully characterize the effect of lightning on ionospheric density structures, this project will deploy co-located ionosphere and lightning RF arrays at HF (1-30 MHz) for D- and E-region imaging, and VLF (0-500 kHz) and VHF (120-150 MHz) radars for lightning studies. The observational program will be augmented by computations from the Ionospheric Data Assimilation Four-Dimensional (IDA4D) model. The model will perform tomographic reconstruction of the ionosphere for heights extending from the E region to above using the observations obtained as well as other opportunistic E region data sources, most notably from the Los Alamos Portable Pulser (LAPP) with the Cibola Flight Experiment (CFE) satellite. The goal of these activities is to elucidate coupling processes between the troposphere and ionosphere, in particular the interaction between lightning and E region ionization enhancements known as sporadic-E. Current thinking suggests that there are two primary mechanisms that transport energy from the troposphere to the lower ionosphere: the first is mechanical wave activity and the second is electrical effects associated with lightning, including electromagnetic pulses and relativistic electrons. The mechanical coupling of waves may increase the peak plasma densities of sporadic-E layers before propagating into the F-region. Discharges from lightning couple electromagnetically and may increase the peak plasma densities by creating more long-lived metal ions from the ambient population of meteoric metal atoms found at these altitudes. However, very little is known about the electromagnetic coupling between lightning and the ionosphere, even though observations of Transient Luminous Events (TLE) indicate that interactions between thunderstorms and the middle and upper atmospheres do occur. The goal is to make significant progress in answering the following questions on ionosphere/troposphere coupling: (1) What is the coupling mechanism between lightning emissions and the development of sporadic E layers? (2) What is the relationship between lightning emissions and the variations of conductances in the ionosphere? (3) To what degree can we use measured RF values of the lightning emissions and characterization of the ionosphere to simultaneously model and analyze the physical characteristics of lightning emissions and the detailed structuring of the ionospheric response?
This project is part of a collaborative project with Stanford University. The results of this project are being used by Stanford in the following year (2012). The goal of this project is to understand the effect lightning has on the Earth's upper atmosphere. The Earth's upper atmosphere is that region of space 60 miles or more above the surface of the Earth. Research in the last 10 years has indicated that strong lighting strikes might have effects that reach the upper atmosphere. These effects could include large burts of energy as well as electricity. This matters since this region of space is the location of many satellites as well as the Space Shuttle. Any impact or change to this region of space can have an impact on Human technological systems including satellite systems that allow us to communicate, to navigate and to download and exchange data and information. There are two stages to this project. First, develop methods and techniques that would allow us to measure the upper atmosphere at 60 miles altitude, in the same place and time as lightning. Once these methods are developed we will conduct an experiment to investigate the effect of lightning on the upper atmosphere. The result of this project is the development of two methods of detection. Stanford University is using these results in two experiments in 2012. Both detection methods make use of the global navigation system known as GPS. GPS has 24 satellites in the sky at about 13,000 miles above the surface of the Earth. These satellites transmit information to ground stations and to satellites. The first method is to make use of satellite data from GPS. Such information is sensitive to the region of space at 60 miles above the surface. There are around 6-8 such satellites available. Since satellites cover the complete Earth, we can find cases where lightning is occuring and the satellites are making measurements in the same place and time. Stanford will conduct such an experiment in 2012. The second method makes use of the ground GPS stations. There are several such stations located in and around Socorro New Mexico. We plan on adding additional stations in Summer of 2012. A network of stations can be very sensitive to local changes in the upper atmosphere. In particular they can detect very small waves moving through the atmosphere (very similar to water waves after say a boat passes by). Such waves we believe are generated by lightning. Thus, Stanford will conduct an experiment in Summer of 2012 to detect these waves and see if they are due to lightning.
