Vertical wave number spectra of wind fluctuations in the troposphere and lower stratosphere over Gadanki, a tropical station

Dutta, Gopa; Bapiraju, B.; Prasad, Thakur; Balasubrahmanyam, P.; Basha, H. Aleem

doi:10.1016/j.jastp.2004.08.003

Cited by 7 publications

(9 citation statements)

References 35 publications

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“… Dewan [1979] and VanZandt [1982] offered an interpretation in terms of gravity waves, whereas Gage [1979] and Lilly [1983] explained that the mesoscale fluctuations are the manifestations of two‐dimensional turbulence. It is now believed that the spectra are indicative of different processes and support the interpretation of both internal waves and quasi two‐dimensional turbulence [ Dutta et al , 2005; Gage and Nastrom , 1985].…”

Section: Vertical Wind Variance and Wave Number Spectramentioning

confidence: 88%

Characteristics of high‐frequency gravity waves generated by tropical deep convection: Case studies

Dutta

Kumar

et al. 2009

J. Geophys. Res.

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[1] High-frequency gravity waves generated by tropical deep convection play a major role in shaping the general circulation of the middle atmosphere. Special experiments were conducted to capture two convective events on 16 May and 5 June 2006 using VHF radar located at Gadanki (13.5°N, 79.2°E), a tropical Indian station. Control day observations were also made for necessary comparisons. Background wind and temperature information was obtained by GPS radiosonde flights launched from the same site. This work has utilized these valuable data sets to delineate characteristics of convectively generated gravity waves. A superposition of gravity waves is observed with different scales after the deep convective events. Vertical wave number spectra of radial velocities show steeper slopes and higher power spectral densities during convection which slowly reduce to their normal values. The present case studies suggest the mechanical oscillator mechanism to be a major source of convective gravity wave generation in the tropics. Estimates of vertical wind variances and momentum fluxes of short-period (<2 h) wind fluctuations show large enhancements on convective days in comparison to control days. The momentum flux frequency spectra revealed a higher contribution of 30-65 min wave periods to the mean profile in the lower stratosphere. The wavelet transform momentum flux spectra displayed the temporal variability and discretization of the gravity wave momentum fluxes in frequency and time.

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Section: Vertical Wind Variance and Wave Number Spectramentioning

confidence: 88%

Characteristics of high‐frequency gravity waves generated by tropical deep convection: Case studies

Dutta

Kumar

et al. 2009

J. Geophys. Res.

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“…In last few decades, many observational studies improved our understanding of the universal spectra. The characteristics of vertical wavenumber spectrum in the horizontal winds are widely investigated from the troposphere to the mesosphere and lower thermosphere (MLT) based on radiosonde (Guharay et al., 2010; Huang et al., 2018; S. D. Zhang et al., 2017), radar (Dutta et al., 2005; Larsen et al., 1986; Qing et al., 2014), and lidar (Gardner et al., 1998; Senft & Gardner, 1991; Yang et al., 2006) measurements. These observations indicated that the vertical wavenumber spectrum in the horizontal winds has a PSD slope range of about −1.5 to −3.2 in the different atmospheric layers.…”

Section: Introductionmentioning

confidence: 99%

“…Li et al (2018) in the weak winds. The slope of vertical wavenumber spectrum has the mean value of −2.2 in the troposphere and lower stratosphere from the Gadanki mesosphere-stratosphere-troposphere (MST) radar measurement (Dutta et al, 2005). The vertical wind perturbation derived from radiosonde ascent rate change is reported to have the wavenumber spectrum indices of −1.1 to −0.2 in the troposphere and −0.6 to −0.1 in the lower stratosphere (S. D. Zhang et al, 2017).…”

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confidence: 99%

Investigation on Spectral Characteristics of Gravity Waves in the MLT Using Lidar Observations at Andes

Huang

Liu

et al. 2021

JGR Space Physics

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It is known for decades that gravity waves (GWs) have a substantial influence on the mean circulation and thermal structure of the middle and upper atmosphere because they transport energy and momentum from the lower atmosphere and deposit them into the middle and upper atmosphere due to the instability (Fritts & Alexander, 2003;Holton, 1982). As GWs generated in the lower atmosphere propagate upward, their amplitudes increase exponentially with altitude because of the decrease of atmospheric density. When the amplitude reaches the critical value, GWs break up as a result of convective or dynamic instability or critical level filtering and then release energy and momentum to the background flow, which is regarded as wave saturation and dissipation process (Hickey et al., 2003;Lindzen, 1981).As a delicate method, hodograph technique is extensively utilized to extract the predominant inertia-gravity wave (IGW) from the observational profiles of radiosonde (

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“…Narendra Babu et al () observed that the slopes of monthly VWN spectra of GW kinetic energy in tropical troposphere over Gadanki are in the range of −2 to −2.8 during the years 1995–2004. The diurnal cycle hourly observations using Mesosphere Stratosphere Troposphere (MST) radar at Gadanki for 13 days show the average slopes of wavenumber spectra in power law region are −2.5 and −2.2 for horizontal and vertical winds, respectively (Dutta et al, ). Jagannadha Rao et al () calculated the vertical velocity‐VWN spectrum with diverse time averages employing diurnal cycle data in monsoon season and found spectral slope close to −1 exemplifies the entire spectra.…”

Section: Introductionmentioning

confidence: 99%

Anomalous Behavior of Vertical Wavenumber Spectra Over a Tropical Station of India

Ghosh

Ramkumar

Sharma

2018

Geophysical Research Letters

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The vertical wavenumber (VWN) spectra of height profiles of winds over a tropical station of Gadanki (13.5°N, 79.2°E; obtained using Indian Mesosphere Stratosphere Troposphere radar) show distinct nature of VWN spectra, which do not match with the so‐called universal wavenumber spectra. The universal wavenumber spectra have three distinct regions: unsaturated (having log‐log slope of 2), saturated (having log‐log slope of −3), and turbulence region (having log‐log slope of −5/3). In present work, we report the presence of positive slope at the higher end of the VWN spectra indicating the presence of unsaturated gravity waves, a kind of which is not reported so far. Many negative slopes of the order of ~−6, ~−9, and ~−12 are noticed at the end of the spectra beyond the turbulence region of the wavenumber spectra, which is also not reported in any previous studies up to now.

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Vertical wave number spectra of wind fluctuations in the troposphere and lower stratosphere over Gadanki, a tropical station

Cited by 7 publications

References 35 publications

Characteristics of high‐frequency gravity waves generated by tropical deep convection: Case studies

Characteristics of high‐frequency gravity waves generated by tropical deep convection: Case studies

Investigation on Spectral Characteristics of Gravity Waves in the MLT Using Lidar Observations at Andes

Anomalous Behavior of Vertical Wavenumber Spectra Over a Tropical Station of India

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