Rayleigh lidar observations of quasi‐sinusoidal waves in the tropical middle atmosphere

Abstract

[1] Rayleigh lidar observations of temperature for $2-7 hours on 38 nights during the period of 18 January-5 March 1999 and for $3 hours on 29 nights during 29 February-2 April 2000 in the altitude region of 27-60 km over Gadanki (13.5°N, 85°E) clearly show the dominance of the quasi-sinusoidal waves of periods in the range of $6-13 hours in temperature in the tropical middle atmosphere. During 1999, the vertical wavelength of these waves ranges from 7.1 to 17 km with a mean value of 12.0 ± 2.4 km while during2000 it ranges from 5.5 to 17 km with a mean value of 11.4 ± 3.5 km. The wave periods estimated from the observations during 1999 are generally greater than the observation period on each night and are estimated to be in the range of 6.5-13.1 hours with an average period of 9.7 ± 1.8 hours, which is significantly smaller than the inertial period of 53 hours. The amplitudes of these waves are in the range of 1 to 8 K. Such sinusoidal wave modes are clearly discernible in the temperature profiles for $50% nights of observation. Another striking feature is that the quasi-sinusoidal structure is clearly observed in the ''equivalent day'' analysis also, indicating only small day-to-day variability in phase, a property that is characteristic of atmospheric tides.

A quantitative study on the role of gravity waves in driving the tropical Stratospheric Semiannual Oscillation

“…Using these vertical wavelengths, the associated horizontal wavelengths of 0.5–1 hour and 2–4 hour period gravity waves are found to be between ∼500–1000 km and ∼500–3000 km respectively. Earlier studies using Rayleigh lidar over this latitude have shown that quasi‐sinusoidal gravity waves of periods in the range ∼6–13 hours with vertical wavelength of 7.1–17 km and horizontal wavelengths of ∼1000–3000 km are dominant in the tropical middle atmosphere [ Rajeev et al , 2003]. There are theoretical studies showing that for a range of frequencies commonly observed in vigorous convection, dominant vertical wavelengths of generated gravity waves is approximately twice the depth of the heating region and it is independent of the horizontal scale of the heating and frequency of the heating [ Beres et al , 2004].…”

Simultaneous upward and downward propagating inertia‐gravity waves in the MLT observed at Andes Lidar Observatory

“…These observations suggested that IGWs in the TLS have typical horizontal wavelengths of 200-2000 km, vertical wavelengths of 2-10 km, and intrinsic frequencies of 2-5 f (where f is the inertial frequency). In the upper stratosphere and mesosphere/lower thermosphere (MLT), IGWs were reported from lidar [Collins et al, 1994;Hu et al, 2002;Rajeev et al, 2003;Xu et al, 2006;Li et al, 2007Li et al, , 2010Lu et al, 2009Lu et al, , 2015aLu et al, , 2015bLu et al, , 2017Chen et al, 2013Chen et al, , 2016Cai et al, 2014;Baumgarten et al, 2015] and radar [Muraoka et al, 1987;Yamamoto et al, 1987;Gavrilov et al, 2000;Zhou and Morton, 2006;Nicolls et al, 2010;Chen et al, 2011Chen et al, , 2014Chen et al, , 2015Suzuki et al, 2013] measurements. These observations indicate that most IGWs in the MLT evidently exhibited a quasi-monochromatic feature.…”

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

“…As a delicate method, hodograph technique is extensively utilized to extract the predominant inertia–gravity wave (IGW) from the observational profiles of radiosonde (Huang et al., 2018; Tsuda et al., 1994; Vincent & Alexander, 2000; Yamamori & Sato, 2006; S. D. Zhang & Yi, 2005; S. D. Zhang et al., 2012, 2017), radar (Gavrilov et al., 2000; Nicolls et al., 2010; Suzuki et al., 2013; M. Yamamoto et al., 1987; Zhou & Morton, 2006), and lidar (Cai et al., 2014; Chen et al., 2013, 2016; Collins et al., 1994; Hu et al., 2002; T. Li et al., 2007; Lu et al., 2015, 2017; Rajeev et al., 2003; Xu et al., 2006). Combined with Doppler shifting equation, this technique can estimate the temporal and spatial parameters of quasi‐monochromatic IGW, such as wave period, wavelength, and propagation direction.…”