| NSF Org: |
OPP Office of Polar Programs (OPP) |
| Recipient: |
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| Initial Amendment Date: | August 20, 2013 |
| Latest Amendment Date: | August 20, 2013 |
| Award Number: | 1247558 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Vladimir Papitashvili
vpapita@nsf.gov (703)292-7425 OPP Office of Polar Programs (OPP) GEO Directorate for Geosciences |
| Start Date: | October 1, 2013 |
| End Date: | September 30, 2017 (Estimated) |
| Total Intended Award Amount: | $159,349.00 |
| Total Awarded Amount to Date: | $159,349.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
51 COLLEGE RD DURHAM NH US 03824-2620 (603)862-2172 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
8 College Rd Durham NH US 03824-2600 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | ANT Astrophys & Geospace Sci |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.078 |
ABSTRACT
The ionosphere-thermosphere-magnetosphere (ITM) region constitutes the Earth's upper atmosphere that is part of larger Geospace environment, and ITM is a portal upon which the solar wind energy and momentum enter and impact the entire Geospace domain. Though space weather research over the past decade or so has greatly increased understanding of a wide variety of phenomena associated with the ITM physics, the sum of these individual processes occurring in Geospace does not replicate the rich diversity and scope of this complex region. Thus a more holistic approach to the ITM research is necessary, one that integrates clustered instrumentation at multiple locations to have a simultaneous look at the solar wind interactions within the entire Geospace system. This project will support studies of interrelated ITM phenomena observed at high latitudes through the coordinated and collaborative instruments deployed across Antarctica. Specifically, the project will focus on continued operation of a suite of geospace instrumentation currently deployed at both the South Pole (SPA) and McMurdo (MCM) stations. This suite has a sustained track-record of robust operation and community support: ground-based fluxgate and search-coils magnetometers, ELF and VLF receivers, imaging and broadband riometers, sky-looking optical systems, scintillation GPS receivers, and a number of other instruments. Data from this suite will be synergistically combined to study: (a) synoptic variability of the magnetospheric open-closed boundary (OCB) and associated cusp structures (utilizing fluxgate, photometer, and all-sky imager data); (b) simultaneous ELF whistler events at SPA and MCM and their relationship to ionospheric conditions (using ELF receiver, fluxgate, and GPS data); and (c) auroral and polar cap GPS signal scintillation occurrence, strength, and relationship with the ITM activity (using GPS, fluxgate, riometer, imager, ELF/VLF data). These particular topics are only a partial listing of the work that can, and will, be performed with the data obtained from these instruments, especially via established and planned collaborations with other geospace projects taking place in the Antarctica and at magnetically conjugate regions in the Arctic. These include (but not limit) the MCM lidar system, southern hemisphere SuperDARN radars, Fabry-Perot interferometers, balloon campaign, etc. The project will be utilizing (and also providing) data from/to in-orbit satellites, namely the THEMIS suite of spacecraft and recently launched RBSP spacecraft. This will make use of the ground- and space-based data to provide the science context to proposed observations and reveal new insights into underlying physics of the geospace phenomena. The project will train and educate young scientists, graduate, and undergraduate students.
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.
This project focused on understanding a certain type of ionospheric plasma wave, one that has not been reported frequently in the literature but that is a regularly-occurring global phenomena. The wave has a unique spectral signature, consisting of a narrow-band signal that decreases in frequency from ~100 to 50 Hz. In comparing observations from the South Pole versus those from a site in Taiwan, we note that the main difference in signatures is that those events in Taiwan take twice as long (about two minutes) to drift from the upper to lower frequencies. While we do not find a simple one-to-one correspondence between observations at these locations, there does appear to be a rough correlation between occurrence rates between these locations.
The signature is consistent with the wave being an ion cyclotron wave generated within the ionosphere and with a source region that drifts upward in altitude over the course of a minute or two (which would explain the decreasing wave frequency).
The global nature of their occurrences suggests that the driver of these waves must be global somehow; we have investigated a number of possible sources (cosmic rays, meteor showers, inner radiation belts, etc.), but have found no clear connections.
What we have learned is that these waves are observed only with a sunlit ionosphere. Observations at low latitudes as well as high latitudes confirm this and a review of prior publications also seems to show this, though other authors have not noted this before. This result suggests that the conditions needed to support the wave instability require an ionospheric density profile that matches a sunlit ionosphere (eg., a broad density peak near the F-region, roughly 250 km in altitude).
While we believe that we have well-characterized the plasma environment to support the excitation of these waves, we have not yet been able to identify a specific driver.
Last Modified: 01/01/2018
Modified by: Marc R Lessard
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