https://repository.kopri.re.kr/handle/201206/9707 2026-04-01T10:14:06Z 2026-04-01T10:14:06Z Song, Byeong-Gwon Song, I-S Chun, H-Y Lee, Changsup Kam, H. Kim, Y. H. Kang, M-J Hindley, N. P. Mitchell, N. J. https://repository.kopri.re.kr/handle/201206/12985 2022-03-24T07:15:28Z 2021-05-27T00:00:00Z

Title: Activities of Small-Scale Gravity Waves in the Upper Mesosphere Observed From Meteor Radar at King Sejong Station, Antarctica (62.22°S, 58.78°W) and Their Potential Sources Authors: Song, Byeong-Gwon; Song, I-S; Chun, H-Y; Lee, Changsup; Kam, H.; Kim, Y. H.; Kang, M-J; Hindley, N. P.; Mitchell, N. J. Abstract: Gravity wave (GW) activities in the upper mesosphere (80-100 km) and their potential sources are investigated using meteor radar observations at King Sejong Station, Antarctica (KSS; 62.22°S, 58.78°W) during recent 14 years (2007-2020). GW activities are estimated by horizontal wind variances of small-scale GWs (periods <2 h, horizontal wavelength <400 km, or vertical wavelength <3-5 km). The wind variances show clear semiannual variations with maxima at solstices, and annual variations are also seen above z = 90 km. The deseasonalized wind variances at z = 96.8 km have a statistically significant periodicity of ∼11 years that can be associated with solar cycle variations. Three major potential GW sources in the lower atmosphere are examined. Orography is a potential source of GWs in winter and autumn, when the basic-state wind is westerly from the surface up to the mesosphere. The residual of the nonlinear balance equation (RNBE) at 5 hPa, a diagnostic of the GWs associated with jet stream, is the largest in winter and has a secondary maximum in spring. The correlation between the observed GWs and RNBE is significant in equinoxes, while correlation is low in winter. Deep convection in storm tracks is a potential source in autumn and winter. Secondary GWs generated in the mesosphere can also be observed in the upper mesosphere. Ray-tracing analysis for airglow images observed at KSS indicates that secondary GWs are mostly generated in winter mesosphere, which may be associated with the breaking of orographic GWs.

2021-05-27T00:00:00Z Song, Byeong-Gwon Chun, Hye-Yeong Song, In-Sun https://repository.kopri.re.kr/handle/201206/13038 2022-03-24T07:15:10Z 2020-10-01T00:00:00Z

Title: Role of Gravity Waves in a Vortex-Split Sudden Stratospheric Warming in January 2009 Authors: Song, Byeong-Gwon; Chun, Hye-Yeong; Song, In-Sun Abstract: The role of gravity waves (GWs) in a sudden stratospheric warming (SSW) event that occurred in January 2009 (SSW09) is investigated using the MERRA-2 reanalysis dataset. Nearly 2 weeks prior to the central date (Lag = 0), at which the zonal-mean zonal wind at 10 hPa and 60ºN first becomes negative, westward GW drag (GWD) is significantly enhanced in the lower mesosphere and stratosphere. At 5 days before Lag = 0, planetary waves (PWs) of zonal wavenumber (ZWN)-2 in the stratosphere are enhanced, while PWs of ZWN-1 are weakened, which are evident from the amplitudes of the PWs and their Eliassen-Palm flux divergence (EPD). To examine the relationship between PWs and GWs, a nonconservative GWD (NCGWD) source term of the linearized quasi-geostrophic potential vorticity equation is considered. A ZWN-2 pattern of the NCGWD forcing is developed around z = 55-60 km with a secondary peak around z = 40 km just before the PWs of ZWN-2 in the stratosphere began to enhance. A significant positive correlation between the NCGWD forcing in the upper stratosphere and lower mesosphere (USLM; 0.3-0.1 hPa in the present data) and the PWs of ZWN-2 in the stratosphere (5-1 hPa) exists. This result demonstrates that the amplification of the PWs of ZWN-2 in the stratosphere before the onset of SSW09 is likely related to the generation of PWs by GWD in the USLM, which is revealed by the enhanced downward-propagating PWs of ZWN-2 into the stratosphere from above.

2020-10-01T00:00:00Z Song, In-Sun Lee, Changsup Chun, Hye-Yeong Kim, Jeong-Han Jee, Geonhwa Song, Byeong-Gwon Bacmeister, Julio T. https://repository.kopri.re.kr/handle/201206/12057 2022-03-24T07:15:01Z 2020-07-01T00:00:00Z

Title: Propagation of gravity waves and its effects on pseudomomentum flux in a sudden stratospheric warming event Authors: Song, In-Sun; Lee, Changsup; Chun, Hye-Yeong; Kim, Jeong-Han; Jee, Geonhwa; Song, Byeong-Gwon; Bacmeister, Julio T. Abstract: Effects of realistic propagation of gravity waves (GWs) on distribution of GW pseudomomentum fluxes are explored using a global ray-tracing model for the 2009 sudden stratospheric warming (SSW) event. Four-dimensional (4D; x-z and t) and two-dimensional (2D; z and t) results are compared for various parameterized pseudomomentum fluxes. In ray-tracing equations, refraction due to horizontal wind shear and curvature effects are found important and comparable to one another in magnitude. In the 4D, westward pseudomomentum fluxes are enhanced in the upper troposphere and northern stratosphere due to refraction and curvature effects around fluctuating jet flows. In the northern polar upper mesosphere and lower thermosphere, eastward pseudomomentum fluxes are increased in the 4D. GWs are found to propagate more to the upper atmosphere in the 4D, since horizontal propagation and change in wave numbers due to refraction and curvature effects can make it more possible that GWs elude critical level filtering and saturation in the lower atmosphere. GW focusing effects occur around jet cores, and ray-tube effects appear where the polar stratospheric jets vary substantially in space and time. Enhancement of the structure of zonal wave number 2 in pseudomomentum fluxes in the middle stratosphere begins from the early stage of the SSW evolution. An increase in pseudomomentum fluxes in the upper atmosphere is present even after the onset in the 4D. Significantly enhanced pseudomomentum fluxes, when the polar vortex is disturbed, are related to GWs with small intrinsic group velocity (wave capture), and they would change nonlocally nearby large-scale vortex structures without substantially changing local mean flows.

2020-07-01T00:00:00Z Yoo, J.­H. Song, In-Sun Chun, H.­Y. Song, Byeong-Gwon https://repository.kopri.re.kr/handle/201206/12060 2022-03-24T07:14:56Z 2020-04-01T00:00:00Z

Title: Inertia­Gravity Waves Revealed in Radiosonde Data at Jang Bogo Station, Antarctica (74°37′S, 164°13′E): 2. Potential Sources and Their Relation to Inertia­Gravity Waves Authors: Yoo, J.­H.; Song, In-Sun; Chun, H.­Y.; Song, Byeong-Gwon Abstract: Potential sources of inertia-gravity waves (IGWs) in the lower stratosphere (z = 15-22 km) at Jang Bogo Station, Antarctica (74 degrees 37 ' S, 164 degrees 13 ' E) are investigated using 3-year (December 2014 to November 2017) radiosonde data, including the 25-month result (December 2014 to December 2016) analyzed in Yoo et al. (2018, https://doi.org/10.1029/2018JD029164, Part 1). For this investigation, three-dimensional backward ray tracing calculations are conducted using the Gravity wave Regional Or Global RAy Tracer. Among 248 IGWs, 112, 68, and 68 waves are generated in the troposphere (z < 8 km), tropopause (z = 8-15 km), and lower stratosphere (z = 15-18.5 km), respectively. These waves mainly propagate from the northwestern and southwestern regions of Jang Bogo Station dominated by the prevailing westerlies between the upper troposphere and lower stratosphere. Potential sources of IGWs are categorized into orography, fronts, convection, and the flow imbalance including the upper-tropospheric jet stream. In the troposphere, relatively large numbers of waves are associated with fronts (37) and orography (35) compared with convection (28). In the tropopause (stratosphere), 36 (42) waves, including 11 cases associated with the upper-tropospheric jet stream, are excited by the flow imbalance. Waves related to the flow imbalance are characterized by low intrinsic frequency (1-2f), short vertical wavelength (1-2 km), and longer horizontal wavelength (50-1000 km), whereas the waves induced by the tropospheric sources have wider ranges of intrinsic frequency (1-20f) and vertical wavelengths (1-15 km) with relatively shorter horizontal wavelengths (less than 500 km).

2020-04-01T00:00:00Z