Degree one loading by pressure variations at the CMB
Hemispherical asymmetry in core dynamics induces degree-1 pressure variations at the core mantle boundary (CMB), which in turn deforms the overlaying elastic mantle, at the same time keeps center of mass of the whole Earth stationary in space. We develop a systematic procedure to deal with the degre...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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Springer Berlin Heidelberg
2016
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| Online Access: | http://hdl.handle.net/1721.1/104033 |
| _version_ | 1811090123972935680 |
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| author | Fang, Ming Kuang, Weijia Hager, Bradford H |
| 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 Fang, Ming Kuang, Weijia Hager, Bradford H |
| author_sort | Fang, Ming |
| collection | MIT |
| description | Hemispherical asymmetry in core dynamics induces degree-1 pressure variations at the core mantle boundary (CMB), which in turn deforms the overlaying elastic mantle, at the same time keeps center of mass of the whole Earth stationary in space. We develop a systematic procedure to deal with the degree-1 CMB pressure loading. We find by direct calculation a surprisingly negative load Love number h[subscript 1]=−1.425 for vertical displacement. Further analysis indicates that the negative h[subscript 1] corresponds to thickening above the positive load that defies intuition that pressure inflation pushes overlaying material up and thins the enveloping shell. We also redefine the pressure load Love numbers in general to enable comparison between the surface mass load and the CMB pressure load for the whole spectrum of harmonic degrees. We find that the gravitational perturbations from the two kinds of loads at degrees n>1 are very similar in amplitude but opposite in sign. In particular, if the CMB pressure variation at degree 2 is at the level of ∼1 hpa/yr (1 cm water height per year), it would perturb the variation of Earth’s oblateness, known as the J[subscript 2], at the observed level. |
| first_indexed | 2024-09-23T14:34:11Z |
| format | Article |
| id | mit-1721.1/104033 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T14:34:11Z |
| publishDate | 2016 |
| publisher | Springer Berlin Heidelberg |
| record_format | dspace |
| spelling | mit-1721.1/1040332024-05-15T02:12:58Z Degree one loading by pressure variations at the CMB Fang, Ming Kuang, Weijia Hager, Bradford H Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Fang, Ming Hager, Bradford H. Hemispherical asymmetry in core dynamics induces degree-1 pressure variations at the core mantle boundary (CMB), which in turn deforms the overlaying elastic mantle, at the same time keeps center of mass of the whole Earth stationary in space. We develop a systematic procedure to deal with the degree-1 CMB pressure loading. We find by direct calculation a surprisingly negative load Love number h[subscript 1]=−1.425 for vertical displacement. Further analysis indicates that the negative h[subscript 1] corresponds to thickening above the positive load that defies intuition that pressure inflation pushes overlaying material up and thins the enveloping shell. We also redefine the pressure load Love numbers in general to enable comparison between the surface mass load and the CMB pressure load for the whole spectrum of harmonic degrees. We find that the gravitational perturbations from the two kinds of loads at degrees n>1 are very similar in amplitude but opposite in sign. In particular, if the CMB pressure variation at degree 2 is at the level of ∼1 hpa/yr (1 cm water height per year), it would perturb the variation of Earth’s oblateness, known as the J[subscript 2], at the observed level. United States. National Aeronautics and Space Administration (No. NNX09AK 70G) 2016-08-26T16:14:44Z 2016-08-26T16:14:44Z 2013-10 2013-03 2016-08-18T15:47:46Z Article http://purl.org/eprint/type/JournalArticle 1674-487X 1867-111X http://hdl.handle.net/1721.1/104033 Fang, Ming, Bradford H. Hager, and Weijia Kuang. “Degree One Loading by Pressure Variations at the CMB.” Journal of Earth Science 24, no. 5 (October 2013): 736–749. en http://dx.doi.org/10.1007/s12583-013-0367-5 Journal of Earth Science Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ China University of Geosciences and Springer-Verlag Berlin Heidelberg application/pdf Springer Berlin Heidelberg Springer Berlin Heidelberg |
| spellingShingle | Fang, Ming Kuang, Weijia Hager, Bradford H Degree one loading by pressure variations at the CMB |
| title | Degree one loading by pressure variations at the CMB |
| title_full | Degree one loading by pressure variations at the CMB |
| title_fullStr | Degree one loading by pressure variations at the CMB |
| title_full_unstemmed | Degree one loading by pressure variations at the CMB |
| title_short | Degree one loading by pressure variations at the CMB |
| title_sort | degree one loading by pressure variations at the cmb |
| url | http://hdl.handle.net/1721.1/104033 |
| work_keys_str_mv | AT fangming degreeoneloadingbypressurevariationsatthecmb AT kuangweijia degreeoneloadingbypressurevariationsatthecmb AT hagerbradfordh degreeoneloadingbypressurevariationsatthecmb |