Observations of discrete harmonics emerging from equatorial noise
A number of modes of oscillations of particles and fields can exist in space plasmas. Since the early 1970s, space missions have observed noise-like plasma waves near the geomagnetic equator known as ‘equatorial noise’. Several theories were suggested, but clear observational evidence supported by r...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | en_US |
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Nature Publishing Group
2015
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| Online Access: | http://hdl.handle.net/1721.1/97747 https://orcid.org/0000-0003-3113-3415 |
| _version_ | 1826210792029028352 |
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| author | Balikhin, Michael A. Walker, Simon N. Chen, Lunjin Cornilleau-Wehrlin, Nicole Dandouras, Iannis Santolik, Ondrej Carr, Christopher E. Yearby, Keith H. Shprits, Yuri Weiss, Benjamin P. |
| author2 | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| author_facet | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Balikhin, Michael A. Walker, Simon N. Chen, Lunjin Cornilleau-Wehrlin, Nicole Dandouras, Iannis Santolik, Ondrej Carr, Christopher E. Yearby, Keith H. Shprits, Yuri Weiss, Benjamin P. |
| author_sort | Balikhin, Michael A. |
| collection | MIT |
| description | A number of modes of oscillations of particles and fields can exist in space plasmas. Since the early 1970s, space missions have observed noise-like plasma waves near the geomagnetic equator known as ‘equatorial noise’. Several theories were suggested, but clear observational evidence supported by realistic modelling has not been provided. Here we report on observations by the Cluster mission that clearly show the highly structured and periodic pattern of these waves. Very narrow-banded emissions at frequencies corresponding to exact multiples of the proton gyrofrequency (frequency of gyration around the field line) from the 17th up to the 30th harmonic are observed, indicating that these waves are generated by the proton distributions. Simultaneously with these coherent periodic structures in waves, the Cluster spacecraft observes ‘ring’ distributions of protons in velocity space that provide the free energy for the waves. Calculated wave growth based on ion distributions shows a very similar pattern to the observations. |
| first_indexed | 2024-09-23T14:55:28Z |
| format | Article |
| id | mit-1721.1/97747 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T14:55:28Z |
| publishDate | 2015 |
| publisher | Nature Publishing Group |
| record_format | dspace |
| spelling | mit-1721.1/977472022-10-01T23:21:53Z Observations of discrete harmonics emerging from equatorial noise Balikhin, Michael A. Walker, Simon N. Chen, Lunjin Cornilleau-Wehrlin, Nicole Dandouras, Iannis Santolik, Ondrej Carr, Christopher E. Yearby, Keith H. Shprits, Yuri Weiss, Benjamin P. Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Shprits, Yuri Weiss, Benjamin P. A number of modes of oscillations of particles and fields can exist in space plasmas. Since the early 1970s, space missions have observed noise-like plasma waves near the geomagnetic equator known as ‘equatorial noise’. Several theories were suggested, but clear observational evidence supported by realistic modelling has not been provided. Here we report on observations by the Cluster mission that clearly show the highly structured and periodic pattern of these waves. Very narrow-banded emissions at frequencies corresponding to exact multiples of the proton gyrofrequency (frequency of gyration around the field line) from the 17th up to the 30th harmonic are observed, indicating that these waves are generated by the proton distributions. Simultaneously with these coherent periodic structures in waves, the Cluster spacecraft observes ‘ring’ distributions of protons in velocity space that provide the free energy for the waves. Calculated wave growth based on ion distributions shows a very similar pattern to the observations. Presidential Early Career Award for Scientists and Engineers (National Aeronautics and Space Administration Grant NNX10AK99G) National Science Foundation (U.S.). Geospace Environment Modeling Program (AGS-1203747) University of California (Lab Fee Grant 12-LR-235337) 2015-07-16T12:31:37Z 2015-07-16T12:31:37Z 2015-07 2014-11 Article http://purl.org/eprint/type/JournalArticle 2041-1723 http://hdl.handle.net/1721.1/97747 Balikhin, Michael A., Yuri Y. Shprits, Simon N. Walker, Lunjin Chen, Nicole Cornilleau-Wehrlin, Iannis Dandouras, Ondrej Santolik, Christopher Carr, Keith H. Yearby, and Benjamin Weiss. “Observations of Discrete Harmonics Emerging from Equatorial Noise.” Nature Communications 6 (July 14, 2015): 7703. © 2015 Macmillan Publishers Limited https://orcid.org/0000-0003-3113-3415 en_US http://dx.doi.org/10.1038/ncomms8703 Nature Communications Creative Commons Attribution http://creativecommons.org/licenses/by/4.0/ application/pdf Nature Publishing Group Nature |
| spellingShingle | Balikhin, Michael A. Walker, Simon N. Chen, Lunjin Cornilleau-Wehrlin, Nicole Dandouras, Iannis Santolik, Ondrej Carr, Christopher E. Yearby, Keith H. Shprits, Yuri Weiss, Benjamin P. Observations of discrete harmonics emerging from equatorial noise |
| title | Observations of discrete harmonics emerging from equatorial noise |
| title_full | Observations of discrete harmonics emerging from equatorial noise |
| title_fullStr | Observations of discrete harmonics emerging from equatorial noise |
| title_full_unstemmed | Observations of discrete harmonics emerging from equatorial noise |
| title_short | Observations of discrete harmonics emerging from equatorial noise |
| title_sort | observations of discrete harmonics emerging from equatorial noise |
| url | http://hdl.handle.net/1721.1/97747 https://orcid.org/0000-0003-3113-3415 |
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