Global estimate of lightning energy injected into the earth's plasmasphere
Abstract/Contents
- Abstract
- Generated by lightning, 'whistlers' are electromagnetic waves that propagate through the plasma surrounding the Earth in near-Earth space known as the plasmasphere. Electromagnetic waves propagating in the plasmasphere can influence the Van Allen radiation belts, a collection of highly energetic, charged particles surrounding the Earth and trapped by the Earth's magnetic field. In particular, energy from these waves can reduce the number of electrons in the radiation belts by causing them to precipitate into the lower atmosphere. Therefore, an estimate of the amount of energy input into the radiation belts from electromagnetic waves like lightning-generated whistlers is vitally important to our understanding of the nature and dynamics of this important part of our planetary environment. Previous estimates of lightning energy in the plasmasphere failed to take into account such considerations as the distribution of lightning across the globe and the effect of the ionosphere on whistler propagation, both of which we examine here. We first present a method to automatically identify upgoing whistler waves using measurements taken from low Earth orbiting satellites. The algorithm computes cross-correlations of the frequency-time spectrogram of the wave data with the expected shape of an upgoing whistler to determine whether or not a given set of data corresponds to a whistler. The technique is validated using data from the DEMETER satellite, and an FPGA-based real time implementation of the algorithm has been built to fly on board the TARANIS satellite, scheduled to launch in 2018. Next, we provide a calculation of the lightning energy injected into the plasmasphere using a frequency domain finite element electromagnetic full wave simulation known as the full wave method (FWM) to quantitatively model the propagation of electromagnetic waves through any number of horizontally stratified layers of plasma such as the ionosphere. We first compare the FWM predicted amount of lightning energy propagating upward with extensive available measurements from the DEMETER satellite. Our comparisons indicate that the field intensities determined by the FWM tend to underestimate the measured energy from DEMETER by as much as 6 dB, although we also present evidence suggesting that the calibration of the DEMETER data may be inaccurate. Finally, we use the FWM to map the upgoing amount of electromagnetic wave energy propagating from each point on Earth for an arbitrary source. By then scaling with data on lightning occurring at each point on Earth as given by the Vaisala Global Lightning Dataset (GLD360) lightning detection network, we arrive at a global estimate of the lightning energy injected into Earth's plasmasphere. Our estimate is comparable to though slightly lower than previous estimates yet provides a more detailed picture of the distribution of lightning in the plasmasphere.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2016 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Compston, Andrew |
|---|---|
| Associated with | Stanford University, Department of Electrical Engineering. |
| Primary advisor | Inan, Umran S |
| Primary advisor | Poon, Ada Shuk Yan |
| Thesis advisor | Inan, Umran S |
| Thesis advisor | Poon, Ada Shuk Yan |
| Thesis advisor | Gill, John T III |
| Thesis advisor | Linscott, Ivan |
| Advisor | Gill, John T III |
| Advisor | Linscott, Ivan |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Andrew Compston. |
|---|---|
| Note | Submitted to the Department of Electrical Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2016. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2016 by Andrew James Compston
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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