MF radar observations of 6.5-day wave in the equatorial mesosphere and lower thermosphere

Kishore, P.; Namboothiri, S. P.; Igarashi, K.; Gurubaran, S.; Sridharan, S.; Rajaram, R. Κ.; Ratnam, M. Venkat

doi:10.1016/j.jastp.2004.01.026

Cited by 31 publications

(50 citation statements)

References 22 publications

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“…It has been confirmed that PWs extensively exist in the TLS, mesosphere and ionosphere (Hirota and Hirooka, 1984;Hirooka and Hirota, 1985;Randel 1987;Forbes and Leveroni, 1992;Williams and Avery, 1992;Tsuda et al, 1994a;Smith, 1997;Lawrence and Jarvis, 2003;Kishore et al, 2004), and contribute significantly to the variability of atmospheric parameters in these regions. Some literature (Tsuda et al, 1994a;Lawrence and Jarvis, 2003;Lu et al, 2005) has revealed that PWs in the TLS have significant wind amplitudes (>10 ms −1 ).…”

Section: Introductionmentioning

confidence: 95%

“…gravity waves (GWs), tidal waves and planetary waves (PWs), which are believed to impact significantly on local and global atmospheric climatology (Alexander and Pfister, 1995;Alexander, 1998;Batista et al, 2004;Kishore et al, 2004). It is extensively accepted that these atmospheric waves are mainly excited in the lower atmosphere (Forbes and Leveroni, 1992;Smith, 1997;Hagan et al, 2001;Hagan and Forbes, 2002;Fritts and Alexander, 2003;Batista et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

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Intensive radiosonde observations of the diurnal tide and planetary waves in the lower atmosphere over Yichang (111°18' E, 30°42' N), China

Huang

Zhang

2009

Ann. Geophys.

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Abstract. The characteristics of diurnal tide and planetary waves (PWs) in the troposphere and lower stratosphere (TLS) over Yichang (111 • 18 E, 30 • 42 N) were studied by using the data from intensive radiosonde observations in August 2006 (summer month) and January 2007 (winter month) on an eight-times-daily basis. The radiosonde observations of the diurnal tide and PWs in the TLS in the mid-latitudes have seldom been reported. We find that there exists dominant diurnal oscillations in the TLS over Yichang. The observed diurnal tide consists of significant nonmigrating components, which may be owning to the local latent heat release. Since the nonmigrating tides are usually composed of high order modes with smaller vertical wavelengths, which are prone to dissipation in comparison with the low order modes, the observational tidal amplitudes decrease sharply at several heights. Some evident discrepancies between the observations and the GSWM-02 are found, which may result mainly from the inaccurate prediction of the nonmigrating tidal components by the GSWM-02. And, due to the evident seasonal differences of the water vapor mixing ratio disturbance and the tropospheric jet induced turbulence in winter, the diurnal tides in the summer and winter months have some different characteristics. Besides the diurnal tide, obvious quasi 7-day PW (QSDPW) and quasi 10-day PW (QTDPW) are also recognized from our observations in both the summer and winter months. The QSDPWs in the troposphere in both the summer and winter months show a standing wave structure, while the QTDPWs generally exhibit traveling wave characteristics. Spectral analyses reveal that some waves with periods around that of the diurnal tide Correspondence to: S. D. Zhang (zsd@whu.edu.cn) are generated due to the interactions of the diurnal tide and PWs and the tidal amplitudes are modulated by the PWs, indicating the extensive coupling between the diurnal tide and PWs. Moreover, our observations manifest that the PWs can exert great impacts on the tropospheric jet in winter and the tropopause in both the summer and winter months.

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Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Intensive radiosonde observations of the diurnal tide and planetary waves in the lower atmosphere over Yichang (111°18' E, 30°42' N), China

Huang

Zhang

2009

Ann. Geophys.

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“…The vertical shear is related to the 11-year solar cycle (Fritz and Angell, 1976) and even has a multi-decadal variability (Aiyyer and Thorncroft, 2011). It is well known that the vertical shear is also influenced by the quasi-biennial oscillation (QBO) (Baldwin et al 2001) and Kishore et al (2004) reported a dependency of 5DW amplitudes on the QBO. Additionally, Walsh and Syktus (2003) showed differences of the vertical shear between El Niño and La Niña years.…”

Section: Discussionmentioning

confidence: 99%

“…The 6.5-day wave at Pontianak and Christmas Island was compared with that observed at Yamagawa (32 • N, 131 • E) by Isoda et al (2002), and all yielded similar enhancements from mid-April to mid-May. Kishore et al (2004) reported an enhancement of the 6.5-day wave from September to October, as well as from April to May, especially in the zonal component employing MF radar winds at Tirunelveli (9 • N, 78 • E). Lima et al (2005) observed the 6.5-day wave using a meteor radar at Cachoeira Paulista (23 • S, 45 • W) and found significant interannual variability in the zonal component, with maximum amplitudes occurring from winter to spring.…”

Section: H Iimura Et Al: 5-day Wave Meteor Windsmentioning

confidence: 95%

Interhemispheric structure and variability of the 5-day planetary wave from meteor radar wind measurements

et al. 2015

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Abstract.A study of the quasi-5-day wave (5DW) was performed using meteor radars at conjugate latitudes in the Northern and Southern hemispheres. These radars are located at Esrange, Sweden (68 • N) and Juliusruh, Germany (55 • N) in the Northern Hemisphere, and at Tierra del Fuego, Argentina (54 • S) and Rothera Station, Antarctica (68 • S) in the Southern Hemisphere. The analysis was performed using data collected during simultaneous measurements by the four radars from June 2010 to December 2012 at altitudes from 84 to 96 km. The 5DW was found to exhibit significant short-term, seasonal, and interannual variability at all sites. Typical events had planetary wave periods that ranged between 4 and 7 days, durations of only a few cycles, and infrequent strongly peaked variances and covariances. Winds exhibited rotary structures that varied strongly among sites and between events, and maximum amplitudes up to ∼ 20 m s −1 . Mean horizontal velocity covariances tended to be largely negative at all sites throughout the interval studied.

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“…Meyer and Forbes (1997) suggested that the mesospheric 6.5-day waves are unstable and also that the vertical-propagating phase of the 6.5-day waves responds to an in-situ wave source in the lower mesosphere due to wind instabilities. Kishore et al (2004) found 6.5-day oscillations, using Tirunelveli MF radar, and they discovered that the 6.5-day wave amplitude peaks at altitudes between 94 and 98 km with a maximum of ∼ 20 K during equinoctial (April-May and September-October) months.…”

Section: Introductionmentioning

confidence: 99%

A case study of mesospheric planetary waves observed over a three-radar network using empirical mode decomposition

et al. 2018

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Abstract. In this paper an attempt is made to study equatorial Kelvin waves using a network of three radars: Kototabang (0.204 • S, 100.320 • E) meteor radar, Pameungpeuk (7.646 • S, 107.688 • E) medium-frequency radar, and Pontianak (0.003 • S, 109.367 • E) medium-frequency radar. We have used the continuous data gathered from the three radars during April-May 2010. Empirical mode decomposition (EMD), Lomb-Scargle periodogram (LSP) analysis, and wavelet techniques are used to study the temporal and altitude structures of planetary waves. Here, we used a novel technique called EMD to extract the planetary waves from wind data. The planetary waves of ∼ 6.5 and ∼ 3.6 days periodicity are observed in all three radar stations with peak amplitudes of about 12 and 11 m s −1 , respectively. The 3.6-day wave has an average vertical wavelength from the three radars of about 42 km. The 3.6-and 6.5-day planetary waves are particularly strong in the zonal wind component. We find that the two waves are present at the 84-94 km height region. The observed features of the 3.6-and 6.5-day waves at the three tropical-latitude stations show some correspondence with the results reported for the equatorial-latitude stations.

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MF radar observations of 6.5-day wave in the equatorial mesosphere and lower thermosphere

Cited by 31 publications

References 22 publications

Intensive radiosonde observations of the diurnal tide and planetary waves in the lower atmosphere over Yichang (111°18' E, 30°42' N), China

Intensive radiosonde observations of the diurnal tide and planetary waves in the lower atmosphere over Yichang (111°18' E, 30°42' N), China

Interhemispheric structure and variability of the 5-day planetary wave from meteor radar wind measurements

A case study of mesospheric planetary waves observed over a three-radar network using empirical mode decomposition

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