Seasonal variations of gravity wave activity in the lower stratosphere over an Antarctic Peninsula station

Moffat‐Griffin, Tracy; Hibbins, R. E.; Jarvis, M. J.; Colwell, Steve

doi:10.1029/2010jd015349

Cited by 36 publications

(98 citation statements)

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“…The major axis direction of the elliptical shape of the hodographs gives the horizontal IGW propagation direction, albeit with 180° ambiguity [ Andrews et al , ]. This property has been employed in a number of observational studies based on radars [e.g., Vincent and Fritts , ; Vincent and Eckermann , ; Sato , ; Chen et al , ] and radiosondes [e.g., Eckermann , ; Wang et al , ; Chun et al , ; Moffat‐Griffin et al , , ; Murphy et al , ] to understand IGW propagation characteristics. Quick examination of Figure reveals that the major axes of the hodographs roughly lie in the N‐S or NW‐SE direction in January, February, and December and in the NE‐SW or ENE‐WSW direction in May, June, July, and August.…”

Section: Resultsmentioning

confidence: 99%

Meteor radar observations of vertically propagating low‐frequency inertia‐gravity waves near the southern polar mesopause region

et al. 2017

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Vertically propagating low‐frequency inertia‐gravity waves (IGWs) are retrieved from meteor radar winds observed at King Sejong Station (KSS: 62.22°S, 58.78°W), Antarctica. IGW horizontal winds extracted from temporal band‐pass filtering in regular time‐height bins show the frequent occurrence of IGWs with the downward phase progression and the counterclockwise rotation of their horizontal wind vectors with time (i.e., upward energy propagation) near the mesopause region throughout the whole year of 2014. The vertical wavelengths of the observed IGWs roughly range from 14 km to more than 20 km, which is consistent with previous observational studies on the mesospheric IGWs over Antarctica. Stokes parameters and rotary spectra computed from the hodographs of the IGW horizontal wind components reveal that the intrinsic frequencies of the upward propagating IGWs are |f|−3|f| with seasonal variations of the relative predominance between |f|−2|f| and 2|f|−3|f|, where f is the Coriolis parameter at KSS. The hodograph analysis also indicates that the N‐S propagation is dominant in austral summer, while the NE‐SW propagation is pronounced in austral winter. The propagation direction is discussed in relation to the generation of IGWs due to dynamical imbalances occurring in the tropospheric and stratospheric jet flow systems. Ray tracing results indicate that the N‐S propagation in summer may be due to the jet flow systems roughly north of KSS and the NE‐SW propagation in winter may be either the SW propagation from the jet flow systems northeast of KSS or the NE propagation (around the South Pole) from the south of Australia and Southern Indian and Pacific Oceans.

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Section: Resultsmentioning

confidence: 99%

Meteor radar observations of vertically propagating low‐frequency inertia‐gravity waves near the southern polar mesopause region

et al. 2017

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“…Many studies have investigated the excitation of gravity waves in the lower atmosphere (Sato and Yoshiki, 2008;Gerrard et al, 2011;Moffat-Griffin et al, 2011), directly in the MLT region from auroral heating (Oyama and Watkins, 2012), and on the characteristics and seasonal variation of gravity waves in the polar MLT region (Nielsen et al, 2012;Suzuki et al, 2011). While the excitation and propagation of gravity waves during disturbed conditions, such as during sudden stratospheric warmings and stratospheric temperature enhancements , have been investigated by Wang and Alexander (2009), Yamashita et al (2010), and Gerrard et al (2011), there is a significant gap in understanding of wave generation during quiet conditions or from a climatological or quasi-climatological perspective.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2017

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Abstract. The sourcing locations and mechanisms for shortperiod, upward-propagating gravity waves at high polar latitudes remain largely unknown. Using all-sky imager data from the Amundsen-Scott South Pole Station, we determine the spatial and temporal characteristics of 94 observed smallscale waves in 3 austral winter months in 2003 and 2004. These data, together with background atmospheres from synoptic and/or climatological empirical models, are used to model gravity wave propagation from the polar mesosphere to each wave's source using a ray-tracing model. Our results provide a compelling case that a significant proportion of the observed waves are launched in several discrete layers in the tropopause and/or stratosphere. Analyses of synoptic geopotentials and temperatures indicate that wave formation is a result of baroclinic instability processes in the stratosphere and the interaction of planetary waves with the background wind fields in the tropopause. These results are significant for defining the influences of the polar vortex on the production of these small-scale, upward-propagating gravity waves at the highest polar latitudes.

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“…These numbers are consistent with other studies made for the southern polar latitudes (eg. Yoshiki and Sato, 2000;Moffat-Griffin et al, 2011;Murphy et al, 2014) and show a higher ratio of downward propagating waves existing in high latitudes as opposed to up to maximum 10 % in mid-latitudes (Sato, 1994). The dominant horizontal propagation direction exhibited random variability during the year and, depending on the month and on the average it does not show much difference between the winter and summer season.…”

Section: Resultsmentioning

confidence: 97%

“…Important is the higher observed rate of downward propagating waves in the winter season (18.4 %) which is much higher than the rates found in the midlatitudes (Sato, 1994) and in accordance with radiosonde-based studies in the Antarctic (e.g. Yoshiki and Sato, 2000;Moffat-Griffin et al, 2011;Murphy et al, 2014). The validity of obtained wave parameters was checked by using continuity equation, and a good match was obtained for both seasons.…”

Section: Discussionmentioning

confidence: 94%

“…The Antarctic peninsula and the southern Andes are long recognised as strong sources of gravity waves and wave properties were examined using a variety of instruments (see e.g., McLandress et al, 2000;Wu, 2002Wu, , 2004Jiang, 2002;Hertzog et al, 2008). Recently, a study was made based on radiosondes by Moffat-Griffin et al (2011) using the observations from Rothera (67.6 • S, 68.1 • W) which found a peak of lower stratospheric wave energy densities at equinoxes and enhanced level of downward propagation in the wintertime. A similar study performed at the Falkland Islands found different energy density variations but similar percentages of downward propagating waves (Moffat-Griffin et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

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Properties of inertia-gravity waves in the lowermost stratosphere as observed by the PANSY radar over Syowa Station in the Antarctic

et al. 2016

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Abstract. Inertia-gravity waves (IGWs) are an important component for the dynamics of the middle atmosphere. However, observational studies needed to constrain their forcing are still insufficient especially in the remote areas of the Antarctic region. One year of observational data (January to December 2013) by the PANSY radar of the wind components (vertical resolution of 150 m and temporal resolution of 30 min) are used to derive statistical analysis of the properties of IGWs with short vertical wavelengths ( ≤ 4 km) and ground-based periods longer than 4 h in the lowermost stratosphere (height range 10 to 12 km) with the help of the hodograph method. The annual change of the IGWs parameters are inspected but no pronounced year cycle is found. The year is divided into two seasons (summer and winter) based on the most prominent difference in the ratio of Coriolis parameter (f ) to intrinsic frequency (ω) distribution. Average of f/ω for the winter season is 0.40 and for the summer season 0.45 and the average horizontal wavelengths are 140 and 160 km respectively. Vertical wavelengths have an average of 1.85 km through the year. For both seasons the properties of IGWs with upward and downward propagation of the energy are also derived and compared. The percentage of downward propagating waves is 10.7 and 18.4 % in the summer and winter season respectively. This seasonal change is more than the one previously reported in the studies from mid-latitudes and model-based studies. It is in agreement with the findings of past radiosonde data-based studies from the Antarctic region. In addition, using the so-called dualbeam technique, vertical momentum flux and the variance of the horizontal perturbation velocities of IGWs are examined. Tropospheric disturbances of synoptic-scale are suggested as a source of episodes of IGWs with large variance of horizontal perturbation velocities, and this is shown in a number of cases.

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Seasonal variations of gravity wave activity in the lower stratosphere over an Antarctic Peninsula station

Cited by 36 publications

References 50 publications

Meteor radar observations of vertically propagating low‐frequency inertia‐gravity waves near the southern polar mesopause region

Meteor radar observations of vertically propagating low‐frequency inertia‐gravity waves near the southern polar mesopause region

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

Properties of inertia-gravity waves in the lowermost stratosphere as observed by the PANSY radar over Syowa Station in the Antarctic

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