Oscillations of GW Activities in the MLT Region over Mid-Low-Latitude Area, Kunming Station (25.6° N, 103.8° E)
Gravity wave (GW) activities play a prominent role in the complex coupling process of wave–wave and wave–background circulation around mid-low-latitude and equatorial areas. The wavelengths are wide, from about 10 m to 100 km, with a period from minutes to hours. However, the oscillations of GW acti...
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MDPI AG
2023-12-01
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| Series: | Atmosphere |
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| Online Access: | https://www.mdpi.com/2073-4433/14/12/1810 |
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| author | Na Li Jinsong Chen Jianyuan Wang Lei Zhao Zonghua Ding Guojin He |
| author_facet | Na Li Jinsong Chen Jianyuan Wang Lei Zhao Zonghua Ding Guojin He |
| author_sort | Na Li |
| collection | DOAJ |
| description | Gravity wave (GW) activities play a prominent role in the complex coupling process of wave–wave and wave–background circulation around mid-low-latitude and equatorial areas. The wavelengths are wide, from about 10 m to 100 km, with a period from minutes to hours. However, the oscillations of GW activities are apparently different between the period bands of 0.1 to 1 h (HF) and 1 to 5 h (LF). To further understand the characteristics of GW activities, the neutral winds during 2008–2009 with a resolution of 3 min obtained from a medium-frequency (MF) radar in Kunming (25.6° N, 103.8° E) were analyzed. Using two numerical filters, the HF and LF GWs were estimated. Interestingly, the power spectral density grows larger as the frequency increases. It linearly falls with decreasing frequency when the period is less than 2 h. The seasonal variations in both HF and LF GWs are strongly demonstrated in August–September, November, and February–March with maximum meridional variances of 1100 m<sup>2</sup> s<sup>−2</sup> and 500 m<sup>2</sup> s<sup>−2</sup> and maximum zonal variances of 800 m<sup>2</sup> s<sup>−2</sup> and 350 m<sup>2</sup> s<sup>−2</sup> in, respectively. The turbulent velocity was also calculated and shows similar oscillations with GW activities. Furthermore, the GW propagation direction exhibits strong seasonal variations, which may be dependent on the location of the motivating source and background wind. |
| first_indexed | 2024-03-08T21:01:06Z |
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| id | doaj.art-e2cf8f073bb5435cbb70777e5570af7c |
| institution | Directory Open Access Journal |
| issn | 2073-4433 |
| language | English |
| last_indexed | 2024-03-08T21:01:06Z |
| publishDate | 2023-12-01 |
| publisher | MDPI AG |
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| series | Atmosphere |
| spelling | doaj.art-e2cf8f073bb5435cbb70777e5570af7c2023-12-22T13:52:56ZengMDPI AGAtmosphere2073-44332023-12-011412181010.3390/atmos14121810Oscillations of GW Activities in the MLT Region over Mid-Low-Latitude Area, Kunming Station (25.6° N, 103.8° E)Na Li0Jinsong Chen1Jianyuan Wang2Lei Zhao3Zonghua Ding4Guojin He5National Key Laboratory of Electromagnetic Environment, China Research Institute of Radiowave Propagation, Qingdao 266107, ChinaNational Key Laboratory of Electromagnetic Environment, China Research Institute of Radiowave Propagation, Qingdao 266107, ChinaNational Key Laboratory of Electromagnetic Environment, China Research Institute of Radiowave Propagation, Qingdao 266107, ChinaNational Key Laboratory of Electromagnetic Environment, China Research Institute of Radiowave Propagation, Qingdao 266107, ChinaNational Key Laboratory of Electromagnetic Environment, China Research Institute of Radiowave Propagation, Qingdao 266107, ChinaChina Research Institute of Radiowave Propagation, Qingdao 266107, ChinaGravity wave (GW) activities play a prominent role in the complex coupling process of wave–wave and wave–background circulation around mid-low-latitude and equatorial areas. The wavelengths are wide, from about 10 m to 100 km, with a period from minutes to hours. However, the oscillations of GW activities are apparently different between the period bands of 0.1 to 1 h (HF) and 1 to 5 h (LF). To further understand the characteristics of GW activities, the neutral winds during 2008–2009 with a resolution of 3 min obtained from a medium-frequency (MF) radar in Kunming (25.6° N, 103.8° E) were analyzed. Using two numerical filters, the HF and LF GWs were estimated. Interestingly, the power spectral density grows larger as the frequency increases. It linearly falls with decreasing frequency when the period is less than 2 h. The seasonal variations in both HF and LF GWs are strongly demonstrated in August–September, November, and February–March with maximum meridional variances of 1100 m<sup>2</sup> s<sup>−2</sup> and 500 m<sup>2</sup> s<sup>−2</sup> and maximum zonal variances of 800 m<sup>2</sup> s<sup>−2</sup> and 350 m<sup>2</sup> s<sup>−2</sup> in, respectively. The turbulent velocity was also calculated and shows similar oscillations with GW activities. Furthermore, the GW propagation direction exhibits strong seasonal variations, which may be dependent on the location of the motivating source and background wind.https://www.mdpi.com/2073-4433/14/12/1810MF radarfilterGW seasonal variationpropagation direction |
| spellingShingle | Na Li Jinsong Chen Jianyuan Wang Lei Zhao Zonghua Ding Guojin He Oscillations of GW Activities in the MLT Region over Mid-Low-Latitude Area, Kunming Station (25.6° N, 103.8° E) Atmosphere MF radar filter GW seasonal variation propagation direction |
| title | Oscillations of GW Activities in the MLT Region over Mid-Low-Latitude Area, Kunming Station (25.6° N, 103.8° E) |
| title_full | Oscillations of GW Activities in the MLT Region over Mid-Low-Latitude Area, Kunming Station (25.6° N, 103.8° E) |
| title_fullStr | Oscillations of GW Activities in the MLT Region over Mid-Low-Latitude Area, Kunming Station (25.6° N, 103.8° E) |
| title_full_unstemmed | Oscillations of GW Activities in the MLT Region over Mid-Low-Latitude Area, Kunming Station (25.6° N, 103.8° E) |
| title_short | Oscillations of GW Activities in the MLT Region over Mid-Low-Latitude Area, Kunming Station (25.6° N, 103.8° E) |
| title_sort | oscillations of gw activities in the mlt region over mid low latitude area kunming station 25 6° n 103 8° e |
| topic | MF radar filter GW seasonal variation propagation direction |
| url | https://www.mdpi.com/2073-4433/14/12/1810 |
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