Find results with:

Add another field

Search by date

to

Searching collections:

Dartmouth Dissertations

Add or remove collections

Home Dartmouth Dissertations Page 1

Reference URL

To link to the entire object, paste this link in email, IM or document

To embed the entire object, paste this HTML in website

To link to this page, paste this link in email, IM or document

To embed this page, paste this HTML in website

Electron precipitation models in global geospace simulations

you wish to report:

Your comment:

Your Name:

Submit

Cancel

...

Back to top

Powered by CONTENTdm®

Author	Zhang, Binzheng.
Title	Electron precipitation models in global geospace simulations
Date	2012
Abstract	The ability to forecast the weather of the geospace environment depends critically on the ability to accurately model the dynamics of the coupled magnetosphere-ionosphere (MI) system. The MI interaction involves a set of electrodynamic and plasma transport processes acting between the magnetosphere and ionosphere, and it is influenced by precipitating particles that deposit both thermal and kinetic energy from the magnetosphere in the ionosphere. Satellite data show that there are four principle types of auroral electron precipitation: monoenergetic, diffuse, broadband and secondary electron precipitation. Global simulations play an important role in understanding the coupled MI system. A key feature of most global models is the implementation of magnetosphere-ionosphere (MI) coupling, and electron precipitation is one of the most important processes to specify. However, one deficiency of most global simulation codes is the lack of accurate specifications of electron precipitation. Preliminary results by the author using the Lyon-Fedder-Mobarr (LFM) global simulation model show that an improved model for electron precipitation can have significant effects on the characteristics of the MI system. This finding suggests that a sophisticated electron precipitation model is important to the fidelity of geospace environmental modeling. The principle objectives of the thesis are to improve the existing diffuse and monoenergetic electron precipitation model and to implement broadband and cusp electron precipitation models in the LFM code. The diffuse electron precipitation model is improved by introducing a dynamically regulated boundary, and the monoenergetic electron precipitation model is improved by using anomalous resistivity current-voltage relation. Broadband electron precipitation is regulated by the downward AC Poynting flux, together with empirical relations derived from satellite data. Cusp electrons are specified based on the cusp identification algorithm used in the global simulation. The improved electron precipitation models are used to study the effect of precipitating electrons on the electrodynamics of MI interaction in LFM. The new electron precipitation models improve the accuracy and forecasting ability of global simulation models demonstrated by comparison with both empirical model and observations. Also, soft (< 500 eV) electron precipitation modifies the state of F-region ionosphere and thermosphere significantly when LFM is coupled to a thermosphere-ionosphere general circulation model.
Description	xi, 197 leaves : col. ill. ; 28 cm.
Format	application/pdf
Advisor	Lotko, William; Shepherd, Simon G; Lyon, John G; Wiltberger, Michael
College	Thayer School of Engineering.
Issuing Body	Dartmouth Dissertations are made available through the Dartmouth Digital Library.
Degree	Thesis (Ph.D.)--Dartmouth College.
Copyright	All rights reserved. No part of this book may be reproduced in any form by any electronic or mechanical means without permission in writing from the author.
DOI	http://dx.doi.org/10.1349/ddlp.409

Title	Page 1
Format	application/pdf
Issuing Body	Dartmouth Dissertations are made available through the Dartmouth Digital Library.
Degree	Thesis (Ph.D.)--Dartmouth College.
Full Text	Electron Precipitation Models in Global Geospace Simulations A Thesis Submitted to the Faculty in partial fulfillment of the requirements for the degree of Doctor of Philosophy by Binzheng Zhang Thayer School of Engineering Dartmouth College Hanover, New Hampshire May 2012 Examining Committee: Chairman William Lotko, Ph. D Member Simon G. Shepherd, Ph. D Member John G. Lyon, Ph. D Member Michael Wiltberger, Ph. D Brian W. Pogue, Ph. D Dean of Graduate Studies

Find results with:

Searching collections:

Home Dartmouth Dissertations Page 1

Electron precipitation models in global geospace simulations

Object Description

Description

Electron precipitation models in global geospace...

Electron precipitation models in global geospace...

	All
	Pages Enter page numbers or page ranges separated by commas. For example: 1,3,5-12