Aspect sensitivity in the VHF radar backscatters studied using simultaneous observations of Gadanki MST radar and GPS sonde
Simultaneous observations made on four days using the MST radar and GPS-sonde at Gadanki (13.5° N, 79.2° E), a tropical station in India, are presented to address the aspect sensitivity of radar backscatters observed at different heights. The observations show that wherever stabi...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2004-11-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/22/4013/2004/angeo-22-4013-2004.pdf |
| _version_ | 1819031453614211072 |
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| author | A. K. Ghosh S. S. Das A. K. Patra D. N. Rao A. R. Jain |
| author_facet | A. K. Ghosh S. S. Das A. K. Patra D. N. Rao A. R. Jain |
| author_sort | A. K. Ghosh |
| collection | DOAJ |
| description | Simultaneous observations made on four days using the MST radar and
GPS-sonde at Gadanki (13.5° N, 79.2° E), a tropical station
in India, are presented to address the aspect sensitivity of radar
backscatters observed at different heights. The observations show that
wherever stability parameter N<sup>2</sup> is high, vertical shear of horizontal
wind is low and Richardson number (R<sub>i</sub>) is high, the aspect sensitivity is
high indicating that the aspect sensitive radar backscatters are due to
thermal structures in the atmosphere. Such a case can be seen very clearly in
the upper troposphere and lower stratosphere. At some heights, where N<sup>2</sup>
is high, R<sub>i</sub> is high, but shears are relatively weak, the aspect
sensitivity is found to almost disappear, indicating that some amount of shear
provides favorable conditions for causing aspect sensitivity. Aspect
sensitivity does not occur at all where N<sup>2</sup> is low or negative and R<sub>i</sub>
is low in spite of wind shear being either high or low, indicating that the
regions are well mixed and hence turbulent. The study also shows a power
difference in the symmetric beams. A case study on this aspect suggests that
this asymmetry is due to the tilting of layers by the action of atmospheric
waves. There is indication that these waves are generated through
Kelvin-Helmholtz-instability (KHI). |
| first_indexed | 2024-12-21T06:46:18Z |
| format | Article |
| id | doaj.art-a48dda9b3cfb409db2a72e3da1f14327 |
| institution | Directory Open Access Journal |
| issn | 0992-7689 1432-0576 |
| language | English |
| last_indexed | 2024-12-21T06:46:18Z |
| publishDate | 2004-11-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Annales Geophysicae |
| spelling | doaj.art-a48dda9b3cfb409db2a72e3da1f143272022-12-21T19:12:36ZengCopernicus PublicationsAnnales Geophysicae0992-76891432-05762004-11-01224013402310.5194/angeo-22-4013-2004Aspect sensitivity in the VHF radar backscatters studied using simultaneous observations of Gadanki MST radar and GPS sondeA. K. Ghosh0S. S. Das1A. K. Patra2D. N. Rao3A. R. Jain4National MST Radar Facility, P. B. 123, Tirupati 517502, A. P., IndiaNational MST Radar Facility, P. B. 123, Tirupati 517502, A. P., IndiaNational MST Radar Facility, P. B. 123, Tirupati 517502, A. P., IndiaNational MST Radar Facility, P. B. 123, Tirupati 517502, A. P., IndiaNational MST Radar Facility, P. B. 123, Tirupati 517502, A. P., IndiaSimultaneous observations made on four days using the MST radar and GPS-sonde at Gadanki (13.5° N, 79.2° E), a tropical station in India, are presented to address the aspect sensitivity of radar backscatters observed at different heights. The observations show that wherever stability parameter N<sup>2</sup> is high, vertical shear of horizontal wind is low and Richardson number (R<sub>i</sub>) is high, the aspect sensitivity is high indicating that the aspect sensitive radar backscatters are due to thermal structures in the atmosphere. Such a case can be seen very clearly in the upper troposphere and lower stratosphere. At some heights, where N<sup>2</sup> is high, R<sub>i</sub> is high, but shears are relatively weak, the aspect sensitivity is found to almost disappear, indicating that some amount of shear provides favorable conditions for causing aspect sensitivity. Aspect sensitivity does not occur at all where N<sup>2</sup> is low or negative and R<sub>i</sub> is low in spite of wind shear being either high or low, indicating that the regions are well mixed and hence turbulent. The study also shows a power difference in the symmetric beams. A case study on this aspect suggests that this asymmetry is due to the tilting of layers by the action of atmospheric waves. There is indication that these waves are generated through Kelvin-Helmholtz-instability (KHI).https://www.ann-geophys.net/22/4013/2004/angeo-22-4013-2004.pdf |
| spellingShingle | A. K. Ghosh S. S. Das A. K. Patra D. N. Rao A. R. Jain Aspect sensitivity in the VHF radar backscatters studied using simultaneous observations of Gadanki MST radar and GPS sonde Annales Geophysicae |
| title | Aspect sensitivity in the VHF radar backscatters studied using simultaneous observations of Gadanki MST radar and GPS sonde |
| title_full | Aspect sensitivity in the VHF radar backscatters studied using simultaneous observations of Gadanki MST radar and GPS sonde |
| title_fullStr | Aspect sensitivity in the VHF radar backscatters studied using simultaneous observations of Gadanki MST radar and GPS sonde |
| title_full_unstemmed | Aspect sensitivity in the VHF radar backscatters studied using simultaneous observations of Gadanki MST radar and GPS sonde |
| title_short | Aspect sensitivity in the VHF radar backscatters studied using simultaneous observations of Gadanki MST radar and GPS sonde |
| title_sort | aspect sensitivity in the vhf radar backscatters studied using simultaneous observations of gadanki mst radar and gps sonde |
| url | https://www.ann-geophys.net/22/4013/2004/angeo-22-4013-2004.pdf |
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