Long‐term variability in the mesospheric tidal winds observed by MF Radar over Tirunelveli (8.7°N, 77.8°E)

Gurubaran, S.; Rajaram, R. Κ.

doi:10.1029/1999gl900171

Cited by 40 publications

(56 citation statements)

References 21 publications

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“…The observed amplitudes are larger than that observed by Gurubaran and Rajaram (1999) over a nearby location Thirunelveli (8.7 • N, 77.8 • E). It can be noted that the amplitude of zonal wind remains more or less constant with height during June and July.…”

Section: Diurnal Tidesmentioning

confidence: 41%

“…The GSWM02 model values also show that over this latitude the diurnal tidal amplitudes of the meridional wind are larger than that of zonal winds. The observations over other low latitude stations, such as Tirnelveli (8.7 • N) (Gurubaran and Rajaram, 1999) and Christmas Island (2 • N), (Chang and Avery, 1997;Manson et al, 1999;Tsuda et al, 1999), also reported that the amplitude of the meridional diurnal tide is greater than that of zonal diurnal component. The amplitude of meridional winds increases up to 90 km and then decreases during June, April and May.…”

Section: Diurnal Tidesmentioning

confidence: 92%

“…Similar observations are seen over Christmas Island which shows that the meridional wind amplitudes increase to ∼50 ms −1 , up to the altitude of 90 km and then decreases during April, May, June and July (Chang and Avery, 1997;Mansion et al, 1999). But the observations over Thirunelveli (Gurubaran and Rajaram, 1999) show that the diurnal tidal amplitudes decrease up to 90 km and then increases. The amplitude and phase values are consistent with model values, except for the phase values during June, July, December and January; the observed and model values of phase during these months differ by ∼6 h. The vertical wavelength of the meridional diurnal component is also ∼25 km, indicating that the observed diurnal tidal component is that of a (1,1) mode.…”

Section: Diurnal Tidesmentioning

confidence: 99%

“…By realizing the importance of tidal activity, extensive wind observations in the MLT region have been carried out across the globe to explore its structure and dynamics (Tetenbaum et al, 1986;Avery et al, 1989;Manson et al, 1988;Portnyagin et al, 1992;Fraser et al, 1995;Tsuda et al, 1999;Zhang et al, 2004). Extensive studies have been carried out on tidal oscillations in the middle and high latitudes, whereas studies from the low-latitude MLT region are very limited (Reddi et al, 1993;Reddi and Ramkumar, 1997;Chang and Avery, 1997;Gurubaran and Rajaram, 1999). Most of these studies showed that the migrating tides are prominent components in the MLT region and there is considerable latitudinal variation in the tidal structure.…”

Section: Introductionmentioning

confidence: 99%

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Vertical propagation characteristics and seasonal variability of tidal wind oscillations in the MLT region over Trivandrum (8.5° N, 77° E): first results from SKiYMET Meteor Radar

et al. 2006

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Abstract. Tidal activity in the Mesospheric Lower Thermosphere (MLT) region over Trivandrum (8.5 • N, 77 • E) is investigated using the observations from newly installed SKiYMET Meteor Radar. The seasonal variability and vertical propagation characteristics of atmospheric tides in the MLT region are addressed in the present communication.The observations revealed that the diurnal tide is more prominent than the semi/terdiurnal components over this latitude. It is also observed that the amplitudes of meridional components are stronger than that of zonal ones. The amplitude and phase structure shows the vertical propagation of diurnal tides with vertical wavelength of ∼25 km. However, the vertical wavelength of the semidiurnal tide showed considerable variations. The vertical propagation characteristics of the terdiurnal tide showed some indications of their generating mechanisms. The observed features of tidal components are compared with Global Scale Wave Model (GSWM02) values and they showed a similar amplitude and phase structure for diurnal tides. Month-to-month variations in the tidal amplitudes have shown significant seasonal variation. The observed seasonal variation is discussed in light of the variation in tidal forcing and dissipation.

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Section: Diurnal Tidesmentioning

confidence: 41%

Section: Diurnal Tidesmentioning

confidence: 92%

Section: Diurnal Tidesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Vertical propagation characteristics and seasonal variability of tidal wind oscillations in the MLT region over Trivandrum (8.5° N, 77° E): first results from SKiYMET Meteor Radar

et al. 2006

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“…al., 1999]. In the Indian sector an MF radar located at Tirunelveli (8.7øN, 77.8øE) yields useful information on mean winds [Rajaram and Gurubaran, 1998], tides [Gurubaran and Rajaram, 1999], and planetary waves .…”

mentioning

confidence: 99%

Mean winds, tides, and gravity waves during the westward phase of the mesopause semiannual oscillation (MSAO)

Gurubaran¹,

Rajaram²

2001

J. Geophys. Res.

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Abstract. MF radar observations of mean winds, tides, and gravity waves (in the period range 30-120 min) over Tirunelveli (8.7øN, 77.8øE) during April 1993, when the mesopause semiannual oscillation (MSAO) was in the westward phase, are presented in this work. The focus herein is on the observed relationship between these dynamical parameters, which is explained in the context of the current understanding of the behavior of MSAO winds, tidal dissipation, and gravity wave-tide interactions. The observed diurnal tide amplitude and phase variations with height indicate (1,1) wave damping and subsequent westward momentum deposition. The gravity wave variances are shown to be modulated by the diurnal tide. Though the analysis does not lead to an estimation of gravity wave contributions to the time-mean zonal flow and its shears, the observations do suggest that the short-term tidal variability contributes, either directly, or indirectly through the gravity wave-tidal interactions, to the variation of the strength of the time-mean westward flow associated with the MSAO.

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Advanced meteor radar installed at Tirupati: System details and comparison with different radars

et al. 2014

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An advanced meteor radar, viz, Sri Venkateswara University (SVU) meteor radar (SVU MR) operating at 35.25 MHz, was installed at Sri Venkateswara University (SVU), Tirupati (13.63°N, 79.4°E), India, in August 2013 for continuous observations of horizontal winds in the mesosphere and lower thermosphere (MLT). This manuscript describes the purpose of the meteor radar, system configuration, measurement techniques, its data products, and operating parameters, as well as a comparison of measured mean winds in the MLT with contemporary radars over the Indian region. It is installed close to the Gadanki (13.5°N, 79.2°E) mesosphere-stratosphere-troposphere (MST) radar to fill the region between 85 and 100 km where this radar does not measure winds. The present radar provides additional information due to its high meteor detection rate, which results in accurate wind information from 70 to 110 km. As a first step, we made a comparison of SVU MR-derived horizontal winds in the MLT region with those measured by similar and different (MST and MF radars) techniques over the Indian region, as well as model (horizontal wind model 2007) data sets. The comparison showed an exquisite agreement between the overlapping altitudes (82-98 km) of different radars. Zonal winds compared very well, as did the meridional winds. The observed discrepancies and limitations in the wind measurement are discussed in the light of different measuring techniques and the effects of small-scale processes like gravity waves. This new radar is expected to play an important role in our understanding of the vertical and lateral coupling of different regions of the atmosphere that will be possible when measurements from nearby locations are combined.

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Long‐term variability in the mesospheric tidal winds observed by MF Radar over Tirunelveli (8.7°N, 77.8°E)

Cited by 40 publications

References 21 publications

Vertical propagation characteristics and seasonal variability of tidal wind oscillations in the MLT region over Trivandrum (8.5° N, 77° E): first results from SKiYMET Meteor Radar

Vertical propagation characteristics and seasonal variability of tidal wind oscillations in the MLT region over Trivandrum (8.5° N, 77° E): first results from SKiYMET Meteor Radar

Mean winds, tides, and gravity waves during the westward phase of the mesopause semiannual oscillation (MSAO)

Advanced meteor radar installed at Tirupati: System details and comparison with different radars

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