Short-period mesospheric gravity waves and their sources at the South Pole

Mehta, D.; Gerrard, A. J.; Ebihara, Yusuke; Weatherwax, A. T.; Lanzerotti, L. J.

doi:10.5194/acp-17-911-2017

Cited by 7 publications

(9 citation statements)

References 40 publications

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“…However, low LTAs over Antarctica have also been seen by Mehta et al. (2017), with higher phase speed measurements originating near the surface around the south pole. Preusse et al.…”

Section: Resultssupporting

confidence: 55%

Determining Gravity Wave Sources and Propagation in the Southern Hemisphere by Ray‐Tracing AIRS Measurements

Perrett

Hindley

Hoffmann

et al. 2021

Geophysical Research Letters

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Gravity waves (GWs) are key drivers of the atmospheric general circulation. They transport a significant fraction of the momentum needed to constrain the atmospheric mean flow above the troposphere. GWs are generated by a complex mix of sources primarily located at surface and lower-atmospheric levels (e.g., Fritts & Alexander, 2003, and references therein). One of the most intense regions of GW activity is the stratosphere above the Southern Ocean in austral winter (e.g., Hindley et al., 2015, and references therein). Despite the known importance of GWs to the dynamics of this region, weather and climate models are known to consistently underestimate GW momentum fluxes here. This leads to significant biases in the simulated large-scale circulation (e.g., Garcia et al., 2017; McLandress et al., 2012). Therefore, understanding the sources and propagation characteristics of GWs is vitally important to improving our understanding and simulations of the Antarctic high-latitude circulation, which in turn impacts upon weather, ozone and climate processes at both local and global scales (e.g.,

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“…However, low LTAs over Antarctica have also been seen by Mehta et al. (2017), with higher phase speed measurements originating near the surface around the south pole. Preusse et al.…”

Section: Resultssupporting

confidence: 55%

Determining Gravity Wave Sources and Propagation in the Southern Hemisphere by Ray‐Tracing AIRS Measurements

Perrett

Hindley

Hoffmann

et al. 2021

Geophysical Research Letters

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“…Gavrilov et al (1996) reported that up to 50 % of the detected waves propagate downwards in the altitude range 70 to 80 km. In the troposphere and lower stratosphere (below 20 km) Sato (1994) reported less than 10 % downwardpropagating GWs, and Mihalikova et al (2016) reported 18.4 % during wintertime and 10.7 % during summertime. From rocket observations of zonal and meridional wind components with a vertical resolution of 1 km in the altitude range 30 to 60 km, Hirota and Niki (1985) found, in middle and high latitudes, about 20 % downward-propagating GWs and 30 %-40 % in low latitudes at Northern Hemisphere stations.…”

Section: Resultsmentioning

confidence: 99%

Advanced hodograph-based analysis technique to derive gravity-wave parameters from lidar observations

2020

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Abstract. An advanced hodograph-based analysis technique to derive gravity-wave (GW) parameters from observations of temperature and winds is developed and presented as a step-by-step recipe with justification for every step in such an analysis. As the most adequate background removal technique the 2-D FFT is suggested. For an unbiased analysis of fluctuation whose amplitude grows with height exponentially, we propose applying a scaling function of the form exp (z∕(ςH)), where H is scale height, z is altitude, and the constant ς can be derived by a linear fit to the fluctuation profile and should be in the range 1–10. The most essential part of the proposed analysis technique consists of fitting cosine waves to simultaneously measured profiles of zonal and meridional winds and temperature and subsequent hodograph analysis of these fitted waves. The linear wave theory applied in this analysis is extended by introducing a wave packet envelope term exp⁡(-(z-z0)2/2σ2) that accounts for limited extent of GWs in the observational data set. The novelty of our approach is that its robustness ultimately allows for automation of the hodograph analysis and resolves many more GWs than can be inferred by the manually applied hodograph technique. This technique allows us to unambiguously identify upward- and downward-propagating GWs and their parameters. This technique is applied to unique lidar measurements of temperature and horizontal winds measured in an altitude range of 30 to 70 km.

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“…The waves that were traced all the way down to the troposphere (204 waves) have intrinsic periods greater than 6.5 min, horizontal wavelengths greater than 20 km, and propagation directions predominantly southward; show a very pronounced concentration of wave initiation to the northwest at approximately 100-300 km from the observing point; and occurred consistently throughout all seasons. One possibility for the origin of these waves is the interaction of planetary waves with the background wind fields, as discussed recently by Mehta et al (2017) for the case of short-period mesospheric GWs detected at the South Pole. A detailed investigation of this hypothesis for the waves reported here is beyond the scope of this work.…”

Section: Discussionmentioning

confidence: 98%

A Climatological Study of Short‐Period Gravity Waves and Ripples at Davis Station, Antarctica (68°S, 78°E), During the (Austral Winter February–October) Period 1999–2013

et al. 2017

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A scanning radiometer deployed at Davis Station, Antarctica (68°S, 78°E), has been recording infrared (1.10–1.65 μm) images of a small region (24 km × 24 km) of the zenith night sky once per minute each austral winter night since February 1999. These images have been processed to extract information on the passage of gravity waves (GWs) (horizontal wavelength, λh > 15 km) and ripples (λh ≤ 15 km) over the observing station. Phase speeds, periods, horizontal wavelengths, and predominant propagation directions have been deduced. Observed speeds were found to be highly correlated with horizontal wavelengths as has been reported in previous studies. Reverse ray tracing of the detected GWs only enabled us to identify four distinct groups. On average, only 15% of waves detected can be traced back to the troposphere, and a large proportion (~45%) were not successfully reverse traced substantially below the airglow layer. Two smaller groups were found to reach a termination condition for reverse ray tracing at altitudes near 50 km and 75 km. Of those that reached the termination altitude in the troposphere (10 km), most of the end points fell within a radius of 300 km of the station, with a very pronounced concentration of wave initiation to the northwest of the observing point. The predominant direction of propagation was southward, and they were observed throughout the year. Recent reports suggest the interaction of planetary waves with the background wind field as a potential source for these waves.

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Short-period mesospheric gravity waves and their sources at the South Pole

Cited by 7 publications

References 40 publications

Determining Gravity Wave Sources and Propagation in the Southern Hemisphere by Ray‐Tracing AIRS Measurements

Determining Gravity Wave Sources and Propagation in the Southern Hemisphere by Ray‐Tracing AIRS Measurements

Advanced hodograph-based analysis technique to derive gravity-wave parameters from lidar observations

A Climatological Study of Short‐Period Gravity Waves and Ripples at Davis Station, Antarctica (68°S, 78°E), During the (Austral Winter February–October) Period 1999–2013

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