| NSF Org: |
AGS Division of Atmospheric and Geospace Sciences |
| Recipient: |
|
| Initial Amendment Date: | August 11, 2011 |
| Latest Amendment Date: | July 15, 2014 |
| Award Number: | 1111476 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Therese Moretto Jorgensen
AGS Division of Atmospheric and Geospace Sciences GEO Directorate for Geosciences |
| Start Date: | August 15, 2011 |
| End Date: | July 31, 2015 (Estimated) |
| Total Intended Award Amount: | $312,899.00 |
| Total Awarded Amount to Date: | $320,739.00 |
| Funds Obligated to Date: |
FY 2014 = $7,840.00 |
| History of Investigator: |
|
| Recipient Sponsored Research Office: |
1109 GEDDES AVE STE 3300 ANN ARBOR MI US 48109-1015 (734)763-6438 |
| Sponsor Congressional District: |
|
| Primary Place of Performance: |
1109 GEDDES AVE STE 3300 ANN ARBOR MI US 48109-1015 |
| Primary Place of
Performance Congressional District: |
|
| Unique Entity Identifier (UEI): |
|
| Parent UEI: |
|
| NSF Program(s): | MAGNETOSPHERIC PHYSICS |
| Primary Program Source: |
01001415DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): |
|
| Program Element Code(s): |
|
| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
This project will use a variety of ground-based and space-based observations to examine the dynamics of the ionospheric trough during magnetic substorms. The high and mid-latitude, ionospheric troughs are regions of unusually low plasma density. The project will use observations from the Super Dual Auroral Radar Network (SuperDARN) coherent scatter radars, the Poker Flat Incoherent Scatter Radar (PFISR), and the all-sky imager and magnetometer arrays set up for NASA's THEMIS mission. It will utilize measurements of field-aligned currents (FACs) derived from the Iridium satellite network (the NSF supported AMPERE project). Three specific scientific topics will be addressed: (1) How does the mid-latitude trough evolve during substorms? (2) How is the high-latitude trough formed and why is it typically located immediately eastward of the Harang discontinuity? (3) What role do ionospheric conductances play in the discrepancy between the electric field and magnetic field Harang reversals.
The large-scale variations in the plasma density at mid and high-latitudes play an important role in the formation of smaller-scale plasma irregularities that affect communications and navigation. This project will examine the driving mechanisms that produce the large-scale variations during magnetically disturbed times. The work will improve our ability to understand and predict important space weather phenomena.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
Note:
When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external
site maintained by the publisher. Some full text articles may not yet be available without a
charge during the embargo (administrative interval).
Some links on this page may take you to non-federal websites. Their policies may differ from
this site.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
The ionospheric electron density is a highly variable quantity and significantly affects the propagation of radio signals that pass through or are reflected by the ionosphere. The auroral oval and the adjacent ionosphere density troughs are expected to experience substantial electron density variations during one of the geomagnetic disturbances, called substorm. Depending on the relative location of the ionosphere trough to the auroral oval, the region of ionospheric density depletion is termed either mid-latitude trough if equatorward or high-latitude trough if poleward of the auroral oval. By using a suite of ground-based and space-based instruments, including radars and Global Positioning Satellites (GPS), scientists have conducted extensive studies of the dynamics of the ionosphere troughs during substorms.
It has been found that the width and location of the mid-latitude trough depends strongly on different phases of a substorm. During the substorm expansion phase, auroral particle precipitation associated with upward field-aligned currents is responsible for the rapid equatorward movement of the poleward boundary of the mid-latitude trough. Comparisons between the observed mid-latitude trough minimum location and that from empirical models show good agreement during the substorm expansion phase but not during the recovery phase. Suggestions on how to improve empirical model prediction have been made.
In addition, it is also discovered that the substorm downward field-aligned currents are collocated with the high-latitude trough and play an important role in the trough formation process through particle evacuation process. A combination of the adiabatic expansion related cooling effect at high altitude and frictional heating at low altitude has been suggested to be responsible for the complex electron temperature profile observed within the high-latitude trough. This study resolved the long-lasting question as to why the high-latitude troughs preferentially occur immediately east of the Harang reversal and provided an explanation for the mysterious electron temperature profile observed previously.
Results from this project deepen our understanding of the formation and evolution of the ionosphere troughs and provide observational foundations for forecast of the trough formation and for assessing the impact of the trough dynamics on navigation and communication systems.
Last Modified: 10/21/2015
Modified by: Shasha Zou
Please report errors in award information by writing to: awardsearch@nsf.gov.
