Identification of inertia gravity wave sources observed in the troposphere and the lower stratosphere over a tropical station Gadanki

Pramitha, M.; Ratnam, M. Venkat; Leena, P.P.; Murthy, B. V. Krishna; Rao, Sandhya

doi:10.1016/j.atmosres.2016.03.001

Cited by 25 publications

(30 citation statements)

References 32 publications

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“…The mean temperature in Figure also shows a clear annual cycle from the troposphere to the lower stratosphere, which is different from the results in the middle and low latitudes (Leena et al, ; Pramitha et al, ; Vincent & Alexander, ; Zhang & Yi, , ). Radiosonde observations at the Gadanki station (13.5°N, 79.2°E) indicated that the monthly averaged temperature does not display a significant variation with time in the troposphere and lower stratosphere (Nath et al, ).…”

Section: Background Atmospheric Conditionscontrasting

confidence: 72%

“…By combining hodograph method with Lomb‐Scargle spectrum analysis (Scargle, ), we can extract the quasi monochromatic IGWs from the radiosonde measurements and obtain the wave parameters, such as wave amplitude, intrinsic frequency, wavelength, and propagation direction. In many previous studies of IGWs based on the radiosonde observations in the middle and low latitudes, in order to avoid the influences of extremely low temperature around the tropopause, very large zonal wind in the tropospheric jet and evidently different buoyancy frequencies in the troposphere and the lower stratosphere, tropospheric and lower stratospheric segments were chosen to investigate the IGW characteristics (Leena et al, ; Nath et al, ; Pfenninger et al, ; Pramitha et al, ; Wang et al, ; Zhang & Yi, , ), respectively. In the polar region, the tropopause height shows a complex variability due to the phenomenon of polar daylight and polar night; for instance, the tropopause may be as low (high) as about 5 km (13 km).…”

Section: Extraction Of Quasi Monochromatic Igwmentioning

confidence: 99%

“…IGWs are low-frequency waves for which the Earth rotation has an important influence. Previous radiosonde observations showed that IGWs in the lower atmosphere have typical horizontal and vertical wavelength ranges of 200-2,000 and 2-8 km, respectively, in middle and low latitudes (Pramitha et al, 2016;Vincent & Alexander, 2000;Wang et al, 2005;Zink & Vincent, 2001a).…”

Section: Introductionmentioning

confidence: 99%

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A Statistical Study of Inertia Gravity Waves in the Lower Stratosphere Over the Arctic Region Based on Radiosonde Observations

et al. 2018

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Relative to many investigations of inertial gravity waves (IGWs) in the Antarctic, IGW activity in the Arctic region was paid less attention to. We use radiosonde observations at the Ny‐Alesund station (78.9°N, 11.9°E) from April 2012 to June 2016 to study the IGW characteristics in the lower stratosphere over the Arctic. The observation reveals a prevailing eastward zonal background wind below 20 km and an obvious annual cycle of the background temperature from the troposphere to the lower stratosphere, which is different from the results in the middle and low latitudes. By combining Lomb‐Scargle spectrum and hodograph technique, case study demonstrates that the lower stratospheric IGWs exhibit a feature of freely propagating waves. Statistical analysis indicates that the IGWs have dominant horizontal (vertical) wavelength of 50–1,050 km (1–4 km) and ratio (1–2.5) of the intrinsic to inertia frequencies. Wave energy exhibits an annual oscillation with the maximum in winter and the minimum in summer. In winter, the downward propagating waves increase to about 20% due to polar stratospheric vortex. Because of the lower atmospheric filtering, the IGWs display a dominant direction of westward propagation, thus have a mean vertical flux of −0.647 mPa for the zonal momentum, which indicates that the IGWs can put a westward drag on the atmospheric wind field over the Arctic as they break and dissipate. All the vertical wavenumber spectra have spectral slopes from −2.23 to −2.99 close to the universal spectrum index of −3.

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Section: Background Atmospheric Conditionscontrasting

confidence: 72%

Section: Extraction Of Quasi Monochromatic Igwmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Statistical Study of Inertia Gravity Waves in the Lower Stratosphere Over the Arctic Region Based on Radiosonde Observations

et al. 2018

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“…This is consistent with the findings of Chane‐Ming et al (, ), which showed an increase of total GW energy density during TCs. Previous studies showed that a significant part of total energy propagates in the upward direction in the lower stratospheric region during cyclones (Pramitha et al, ). One of the important present findings is that an increase of E p is also noticed in the LS prior to the actual occurrence of TC.…”

Section: Discussionmentioning

confidence: 98%

Gravity Wave Behavior in Lower Stratosphere During Tropical Cyclones Over the Bay of Bengal

2018

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Gravity waves associated with tropical cyclones over the Bay of Bengal have been studied using Constellation Observing System for Meteorology, Ionosphere, and Climate GPS radio occultation measurements. The sources of gravity waves are located well below the tropopause where the intensity of a tropical cyclone is high. The gravity wave potential energy between 19 and 26 km shows an enhancement in the lower stratosphere during the cyclone. Intense convection associated with tropical cyclone is characterized by low outgoing longwave radiation values. The present study shows an increase in potential energy in the lower stratosphere over a storm path before the actual occurrence of cyclones. The power spectral density of gravity waves shows that the vertical wavelengths in the range 2–2.4 km carry the maximum energy in the lower stratosphere over the cyclone path.

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“…A variety of instruments has been used to characterize the GWs, such as radars (Andrioli et al, 2013;Antonita et al, 2008;Fritts & Yuan, 1989;Manson & Meek, 1993;Nakamura et al, 1993;Nakamura et al, 1996;Placke et al, 2011;Tsuda et al, 1990;Vincent & Reid, 1983;Vincent & Fritts, 1987;Wang and Fritts, 1990, and references therein), lidars (Mitchell et al, 1991;Whiteway & Carswell, 1995;Wilson et al, 1991), radiosonde (Leena et al, 2012;Pramitha et al, 2016;Venkat Ratnam et al, 2008;Vincent et al, 1997;Vincent & Alexander, 2000), rocketsonde (Rapp et al, 2004), satellites (Eckermann and Preusse, 1999;Ern et al, 2004;Ern & Preusse, 2012;John & Kumar, 2012;Preusse et al, 1999;Preusse et al, 2002), and airglow imagers (Wrasse et al, 2006;Taori et al, 2013). A variety of instruments has been used to characterize the GWs, such as radars (Andrioli et al, 2013;Antonita et al, 2008;Fritts & Yuan, 1989;Manson & Meek, 1993;Nakamura et al, 1993;Nakamura et al, 1996;Placke et al, 2011;Tsuda et al, 1990;Vincent & Reid, 1983;Vincent & Fritts, 1987;Wang and Fritts, 1990, and references therein), lidars …”

Section: Introductionmentioning

confidence: 99%

Meteor Radar Estimations of Gravity Wave Momentum Fluxes: Evaluation Using Simulations and Observations Over Three Tropical Locations

Pramitha¹,

Kumar

Ratnam

et al. 2019

JGR Space Physics

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Meteor radars are widely used to study gravity wave (GW) variances and their momentum fluxes at the altitudes where meteor counts are sufficient to yield good statistical fits to the data. These radars provide hourly zonal and meridional wind observations round the clock in 80‐ to 100‐km height domain. However, the capability of meteor radars in estimating GW momentum fluxes should be evaluated before they can be used for any research applications. In this regard, the present study evaluates the meteor radar observations of GW momentum fluxes obtained from Thumba (8.5°N, 77°E; 2006–2015), Kototabang (0.2°S, 100.3°E; 2002–2017), and Tirupati (13.63°N, 79.4°E; 2013–2018) using three‐dimensional wind field simulations, which include specified tidal, planetary and GW fields. A modified composite day analysis is adopted to estimate the GW momentum fluxes, which also accounts for the tidal and planetary wave contributions. The results showed that the retrieved and specified GW momentum fluxes agree very well over Tirupati followed by Thumba and Kototabang. It is noted that the agreement between the retrieved and simulated fields depend on the number of meteor detections used in the analysis. After evaluating the meteor radar retrieved GW momentum fluxes by employing simulations, their interannual variability and climatologies over the three observational locations are constructed. The significance of the present study lies in evaluating the capability of three meteor radars located in equatorial and low‐latitudes in estimating GW momentum fluxes by employing three‐dimensional wind field simulations with specified mean winds, tidal, planetary, and GW fields.

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Identification of inertia gravity wave sources observed in the troposphere and the lower stratosphere over a tropical station Gadanki

Cited by 25 publications

References 32 publications

A Statistical Study of Inertia Gravity Waves in the Lower Stratosphere Over the Arctic Region Based on Radiosonde Observations

A Statistical Study of Inertia Gravity Waves in the Lower Stratosphere Over the Arctic Region Based on Radiosonde Observations

Gravity Wave Behavior in Lower Stratosphere During Tropical Cyclones Over the Bay of Bengal

Meteor Radar Estimations of Gravity Wave Momentum Fluxes: Evaluation Using Simulations and Observations Over Three Tropical Locations

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