Roles of thermospheric neutral wind and equatorial electrojet in pre-reversal enhancement, deduced from observations in Southeast Asia
Previous studies have proposed that both the thermospheric neutral wind and the equatorial electrojet (EEJ) near sunset play important roles in the pre-reversal enhancement (PRE) mechanism. In this study, we have used observations made in the equatorial region of Southeast Asia during March–April an...
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Science Press
2021-09-01
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| Series: | Earth and Planetary Physics |
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| Online Access: | http://www.eppcgs.org/article/doi/10.26464/epp2021049?pageType=en |
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| author | P. Abadi Y. Otsuka HuiXin Liu K. Hozumi D. R. Martinigrum P. Jamjareegulgarn Le Truong Thanh R. Otadoy |
| author_facet | P. Abadi Y. Otsuka HuiXin Liu K. Hozumi D. R. Martinigrum P. Jamjareegulgarn Le Truong Thanh R. Otadoy |
| author_sort | P. Abadi |
| collection | DOAJ |
| description | Previous studies have proposed that both the thermospheric neutral wind and the equatorial electrojet (EEJ) near sunset play important roles in the pre-reversal enhancement (PRE) mechanism. In this study, we have used observations made in the equatorial region of Southeast Asia during March–April and September–October in 2010–2013 to investigate influences of the eastward neutral wind and the EEJ on the PRE’s strength. Our analysis employs data collected by the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) satellite to determine the zonal (east-west direction) neutral wind at an altitude of ~250 km (bottomside F region) at longitudes of 90°–130°E in the dusk sector. Three ionosondes, at Chumphon (dip lat.: 3.0°N) in Thailand, at Bac Lieu (dip lat.: 1.7°N) in Vietnam, and at Cebu (dip lat.: 3.0°N) in Philippines, provided the data we have used to derive the PRE strength. Data from two magnetometers — at Phuket (dip lat.: 0.1°S) in Thailand and at Kototabang (dip lat.: 10.3°S) in Indonesia — were used to estimate the EEJ strength. Our study is focused particularly on days with magnetically quiet conditions. We have found that the eastward neutral wind and the EEJ are both closely correlated with the PRE; their cross-correlation coefficients with it are, respectively, 0.42 and 0.47. Their relationship with each other is weaker: the cross-correlation coefficient between the eastward neutral wind and the EEJ is just 0.26. Our findings suggest that both the eastward neutral wind and the EEJ near sunset are involved in the PRE mechanism. Based on the weak relationship between these two parameters, however, they appear to be significantly independent of each other. Thus, the wind and the EEJ are likely to be influencing the PRE magnitude independently, their effects balancing each other. |
| first_indexed | 2024-12-12T00:59:06Z |
| format | Article |
| id | doaj.art-826e7642daa346b8ab877bab80eba80c |
| institution | Directory Open Access Journal |
| issn | 2096-3955 |
| language | English |
| last_indexed | 2024-12-12T00:59:06Z |
| publishDate | 2021-09-01 |
| publisher | Science Press |
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| spelling | doaj.art-826e7642daa346b8ab877bab80eba80c2022-12-22T00:43:47ZengScience PressEarth and Planetary Physics2096-39552021-09-015538739610.26464/epp2021049SI4236-Abadi-FRoles of thermospheric neutral wind and equatorial electrojet in pre-reversal enhancement, deduced from observations in Southeast AsiaP. Abadi0Y. Otsuka1HuiXin Liu2K. Hozumi3D. R. Martinigrum4P. Jamjareegulgarn5Le Truong Thanh6R. Otadoy7Space Science Center, Indonesian National Institute of Aeronautics and Space (LAPAN), Bandung, IndonesiaInstitute for Space-Earth Environmental Research (ISEE), Nagoya University, Nagoya, JapanDepartment of Earth and Planetary Science, Kyushu University, Fukuoka, JapanNational Institute of Information and Communications Technology, Tokyo, JapanSpace Science Center, Indonesian National Institute of Aeronautics and Space (LAPAN), Bandung, IndonesiaKing Mongkut’s Institute of Technology Ladkrabang, Prince of Chumphon Campus, Chumphon, ThailandInstitute of Geophysics, Vietnamese Academy of Science and Technology, Hanoi, VietnamUniversity of San Carlos, Cebu, PhilippinesPrevious studies have proposed that both the thermospheric neutral wind and the equatorial electrojet (EEJ) near sunset play important roles in the pre-reversal enhancement (PRE) mechanism. In this study, we have used observations made in the equatorial region of Southeast Asia during March–April and September–October in 2010–2013 to investigate influences of the eastward neutral wind and the EEJ on the PRE’s strength. Our analysis employs data collected by the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) satellite to determine the zonal (east-west direction) neutral wind at an altitude of ~250 km (bottomside F region) at longitudes of 90°–130°E in the dusk sector. Three ionosondes, at Chumphon (dip lat.: 3.0°N) in Thailand, at Bac Lieu (dip lat.: 1.7°N) in Vietnam, and at Cebu (dip lat.: 3.0°N) in Philippines, provided the data we have used to derive the PRE strength. Data from two magnetometers — at Phuket (dip lat.: 0.1°S) in Thailand and at Kototabang (dip lat.: 10.3°S) in Indonesia — were used to estimate the EEJ strength. Our study is focused particularly on days with magnetically quiet conditions. We have found that the eastward neutral wind and the EEJ are both closely correlated with the PRE; their cross-correlation coefficients with it are, respectively, 0.42 and 0.47. Their relationship with each other is weaker: the cross-correlation coefficient between the eastward neutral wind and the EEJ is just 0.26. Our findings suggest that both the eastward neutral wind and the EEJ near sunset are involved in the PRE mechanism. Based on the weak relationship between these two parameters, however, they appear to be significantly independent of each other. Thus, the wind and the EEJ are likely to be influencing the PRE magnitude independently, their effects balancing each other.http://www.eppcgs.org/article/doi/10.26464/epp2021049?pageType=enequatorial ionospherethermosphere-ionosphere couplepre-reversal enhancementthermospheric neutral windequatorial electrojet |
| spellingShingle | P. Abadi Y. Otsuka HuiXin Liu K. Hozumi D. R. Martinigrum P. Jamjareegulgarn Le Truong Thanh R. Otadoy Roles of thermospheric neutral wind and equatorial electrojet in pre-reversal enhancement, deduced from observations in Southeast Asia Earth and Planetary Physics equatorial ionosphere thermosphere-ionosphere couple pre-reversal enhancement thermospheric neutral wind equatorial electrojet |
| title | Roles of thermospheric neutral wind and equatorial electrojet in pre-reversal enhancement, deduced from observations in Southeast Asia |
| title_full | Roles of thermospheric neutral wind and equatorial electrojet in pre-reversal enhancement, deduced from observations in Southeast Asia |
| title_fullStr | Roles of thermospheric neutral wind and equatorial electrojet in pre-reversal enhancement, deduced from observations in Southeast Asia |
| title_full_unstemmed | Roles of thermospheric neutral wind and equatorial electrojet in pre-reversal enhancement, deduced from observations in Southeast Asia |
| title_short | Roles of thermospheric neutral wind and equatorial electrojet in pre-reversal enhancement, deduced from observations in Southeast Asia |
| title_sort | roles of thermospheric neutral wind and equatorial electrojet in pre reversal enhancement deduced from observations in southeast asia |
| topic | equatorial ionosphere thermosphere-ionosphere couple pre-reversal enhancement thermospheric neutral wind equatorial electrojet |
| url | http://www.eppcgs.org/article/doi/10.26464/epp2021049?pageType=en |
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