Seasonal variabilities of low-latitude mesospheric winds
Observations of mesospheric winds over a period of four years with the partial reflection radar at Tirunelveli (8.7°N, 77.8°E), India, are presented in this study. The emphasis is on describing seasonal variabilities in mean zonal and meridional winds in the altitude region 70–98 km. The meridio...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
1998-02-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/16/197/1998/angeo-16-197-1998.pdf |
| _version_ | 1817988923857567744 |
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| author | R. Rajaram R. Rajaram S. Gurubaran |
| author_facet | R. Rajaram R. Rajaram S. Gurubaran |
| author_sort | R. Rajaram |
| collection | DOAJ |
| description | Observations of mesospheric winds over a
period of four years with the partial reflection radar at Tirunelveli (8.7°N,
77.8°E), India, are presented in this study. The emphasis is on describing
seasonal variabilities in mean zonal and meridional winds in the altitude region
70–98 km. The meridional winds exhibit overall transequatorial flow associated
with differential heating in the Northern and Southern Hemispheres. At lower
altitudes (70–80 km) the mean zonal winds reveal easterly flow during summer and
westerly flow during winter, as expected from a circulation driven by solar
forcing. In the higher altitude regime (80–98 km) and at all altitudes during
equinox periods, the mean zonal flow is subjected to the semi-annual oscillation
(SAO). The interannual variability detected in the occurrence of SAO over
Tirunelveli has also been observed in the data sets obtained from the recent
UARS satellite mission. Harmonic analysis results over a period of two years
indicate the presence of long-period oscillations in the mean zonal wind at
specific harmonic periods near 240, 150 and 120 days. Results presented in this
study are discussed in the context of current understanding of equatorial wave
propagation.<br><br><b>Key words. </b>Meteorological and atmospheric dynamics ·
General circulation · Middle atmosphere dynamics · waves and tides. |
| first_indexed | 2024-04-14T00:40:38Z |
| format | Article |
| id | doaj.art-8867b56a46b547889203c1a83e17be07 |
| institution | Directory Open Access Journal |
| issn | 0992-7689 1432-0576 |
| language | English |
| last_indexed | 2024-04-14T00:40:38Z |
| publishDate | 1998-02-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Annales Geophysicae |
| spelling | doaj.art-8867b56a46b547889203c1a83e17be072022-12-22T02:22:12ZengCopernicus PublicationsAnnales Geophysicae0992-76891432-05761998-02-011619720410.1007/s00585-998-0197-4Seasonal variabilities of low-latitude mesospheric windsR. Rajaram0R. Rajaram1S. Gurubaran2Indian Institute of Geomagnetism, Colaba, Mumbai 400 005, IndiaEquatorial Geophysical Research Laboratory, Indian Institute of Geomagnetism, Krishnapuram, Tirunelveli 627 011, IndiaEquatorial Geophysical Research Laboratory, Indian Institute of Geomagnetism, Krishnapuram, Tirunelveli 627 011, IndiaObservations of mesospheric winds over a period of four years with the partial reflection radar at Tirunelveli (8.7°N, 77.8°E), India, are presented in this study. The emphasis is on describing seasonal variabilities in mean zonal and meridional winds in the altitude region 70–98 km. The meridional winds exhibit overall transequatorial flow associated with differential heating in the Northern and Southern Hemispheres. At lower altitudes (70–80 km) the mean zonal winds reveal easterly flow during summer and westerly flow during winter, as expected from a circulation driven by solar forcing. In the higher altitude regime (80–98 km) and at all altitudes during equinox periods, the mean zonal flow is subjected to the semi-annual oscillation (SAO). The interannual variability detected in the occurrence of SAO over Tirunelveli has also been observed in the data sets obtained from the recent UARS satellite mission. Harmonic analysis results over a period of two years indicate the presence of long-period oscillations in the mean zonal wind at specific harmonic periods near 240, 150 and 120 days. Results presented in this study are discussed in the context of current understanding of equatorial wave propagation.<br><br><b>Key words. </b>Meteorological and atmospheric dynamics · General circulation · Middle atmosphere dynamics · waves and tides.https://www.ann-geophys.net/16/197/1998/angeo-16-197-1998.pdf |
| spellingShingle | R. Rajaram R. Rajaram S. Gurubaran Seasonal variabilities of low-latitude mesospheric winds Annales Geophysicae |
| title | Seasonal variabilities of low-latitude mesospheric winds |
| title_full | Seasonal variabilities of low-latitude mesospheric winds |
| title_fullStr | Seasonal variabilities of low-latitude mesospheric winds |
| title_full_unstemmed | Seasonal variabilities of low-latitude mesospheric winds |
| title_short | Seasonal variabilities of low-latitude mesospheric winds |
| title_sort | seasonal variabilities of low latitude mesospheric winds |
| url | https://www.ann-geophys.net/16/197/1998/angeo-16-197-1998.pdf |
| work_keys_str_mv | AT rrajaram seasonalvariabilitiesoflowlatitudemesosphericwinds AT rrajaram seasonalvariabilitiesoflowlatitudemesosphericwinds AT sgurubaran seasonalvariabilitiesoflowlatitudemesosphericwinds |