Seasonal variation of solar tides in the troposphere and lower stratosphere over Gadanki: Comparisons with the global scale wave model

Dutta, Gopa; Bapiraju, B.; Balasubrahmanyam, P.; Siddiqui, M. A. A.; Basha, H. Aleem

doi:10.1029/2000rs002571

Cited by 6 publications

(2 citation statements)

References 26 publications

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“…At all other altitudes, the amplitude of semidiurnal component in different seasons is not only small, but also shows weak seasonal variation. The semidiurnal component in the horizontal wind (both zonal and meridional) also shows relatively large values (∼2 m s −1 ) in the middle and upper troposphere at Gadanki [ Dutta et al , 2002]. The observed phase profiles in the present study are somewhat confusing with complicated and irregular vertical structure.…”

Section: Resultssupporting

confidence: 45%

Diurnal variation in vertical air motion over a tropical station, Gadanki (13.5°N, 79.2°E), and its effect on the estimation of mean vertical air motion

Uma¹,

Rao²

2009

J. Geophys. Res.

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[1] The long-term measurements of vertical air velocity (w) made with the Indian mesosphere-stratosphere-troposphere (MST) radar are used to investigate the diurnal variation of w in different seasons. The effect of the diurnal variation of w and gravity wave variance on the estimation of mean w is also studied. Significant diurnal variation is observed in the vertical air motion at Gadanki with a variation larger than 6 cm s À1. This variation is, in fact, larger than the mean vertical air motion. Downdrafts are observed in the evening hours in the lower troposphere in all the seasons. A large part of this subsidence is due to the bias caused by upward propagating gravity waves, as evidenced by large hourly variance values in evening hours. In the middle and upper troposphere, the diurnal variation is dominated primarily by 12-h oscillation, which is conspicuously present in all the seasons, albeit with different amplitudes. The 24-h variance caused primarily by tidal and relatively long period oscillations (>2 h) and mesoscale weather disturbances is almost comparable to the variance due to short-period gravity waves (<1 h). The variance for periods <1 h shows significant diurnal variation with peak values during afternoon-evening. It implies that the bias in w should also have such a diurnal cycle, because the bias (downward) is directly proportional to the variance in w. Given that w and the bias sources vary considerably during the course of the day, any estimate of mean w (taken over a season/month) from data pertaining to a particular hour (hours) of the day will represent the mean w of that particular hour, but may not truly represent the seasonal/monthly mean w.Citation: Uma, K. N., and T. N. Rao (2009), Diurnal variation in vertical air motion over a tropical station, Gadanki (13.5°N, 79.2°E), and its effect on the estimation of mean vertical air motion,

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Section: Resultssupporting

confidence: 45%

Diurnal variation in vertical air motion over a tropical station, Gadanki (13.5°N, 79.2°E), and its effect on the estimation of mean vertical air motion

Uma¹,

Rao²

2009

J. Geophys. Res.

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“…Wind data from 2 February-31 March, 2007 and from 1 June-31 October, 2007 are found to be fairly continuous with a few gaps which are linearly interpolated and used for the present study. Appreciable amplitudes of tidal oscillations over Gadanki have been reported (Sasi et al 1998;Dutta et al 2002). Since the radar evening data is collected for <1 hr everyday, it might deviate from the daily mean winds.…”

Section: Databasementioning

confidence: 99%

Equatorial wave activity during 2007 over Gadanki, a tropical station

et al. 2015

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Re-Analysis (ERA-interim) data of winds for the year 2007 between the pressure levels 1 and 1000 hPa (0-49 km) have been analyzed for equatorial wave activity over a tropical station Gadanki (13.5 o N, 79.2 • E). Available wind observations made by MST radar located at the same site have also been used to investigate the wave activity in the troposphere and lower stratosphere. Waves in the period bands 7-10, 12-15 and 20-30 d are observed. Temporal variability of the wave activity has been investigated by constructing wavelet spectra. The longer period waves show strong seasonal variability with maximum and minimum activities during winter and summer months respectively. Short period activity is more prominent during June-July-August in the tropospheric region. The waves are found to be generated in the troposphere by wind shear and convection. Propagation of the waves to higher altitudes is found to depend strongly on background zonal wind and phase of the quasi-biennial oscillation (QBO). The waves are inhibited to propagate through the negative wind shear zone. Meridional waves might be generated by non-linear wave CISK.

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Investigating the dominant source for the generation of gravity waves during indian summer monsoon using ground-based measurements

Nath

Chen

2012

Adv. Atmos. Sci.

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Seasonal variation of solar tides in the troposphere and lower stratosphere over Gadanki: Comparisons with the global scale wave model

Cited by 6 publications

References 26 publications

Diurnal variation in vertical air motion over a tropical station, Gadanki (13.5°N, 79.2°E), and its effect on the estimation of mean vertical air motion

Diurnal variation in vertical air motion over a tropical station, Gadanki (13.5°N, 79.2°E), and its effect on the estimation of mean vertical air motion

Equatorial wave activity during 2007 over Gadanki, a tropical station

Investigating the dominant source for the generation of gravity waves during indian summer monsoon using ground-based measurements

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