https://repository.kopri.re.kr/handle/201206/5450 2026-04-05T19:16:28Z https://repository.kopri.re.kr/handle/201206/10956 Title: Gravity Waves Associated with Jet/Front Systems. Part I: Diagnostics and their Correlations with GWs Revealed in High-Resolution Global Analysis Data Authors: Chun, Hye-Yeong; Song, Byeong-Gwon; Shin, Seok-Woo; Kim, Young-Ha Abstract: Jet/front systems are the important sources of the atmospheric gravity waves (GWs). Based on mesoscale simulation results, dominant GWs associated with the jet/front systems have horizontal wavelengths of approximately 150 km, which need for parameterization in global models. Nevertheless, there is no comprehensive parameterization scheme of the jet/front GWs with a formulation of the GW momentum flux (GWMF) at launch level, due primarily to uncertainties in their generation mechanisms. In this study, we evaluate two diagnostics of the jet/front GWs, frontogenesis function (FF) and residual of the nonlinear balance equation (RNBE), by examining their spatiotemporal variations using two global reanalysis data sets over 32 years (1980？2011) and by examining correlations between the diagnostics and the GWMF resolved from high-resolution global analysis data in January and July of 2007. The FF and RNBE are maximal in the mid-to-high latitudes of the winter hemisphere, with local maxima in Greenland, East Asia, western North America, Antarctic Peninsula, and the Andes Mountains. The GWMF is dominant in two regions in the upper troposphere: (i) poleward of 30° in both hemispheres, with a larger value in the winter hemisphere, and (ii) tropical and subtropical regions in both hemispheres. The FF and RNBE are well correlated with theGWs in the mid-to-high latitudes following their seasonal variations, which successfully separate GWs in the tropics and subtropics generated by convective sources. In Part II, a parameterization based on the RNBE is developed and implemented in a climate model, and its impacts on the large-scale flow will be investigated. 2019-11-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/10826 Title: Daytime Evolution of Equatorial Plasma Bubbles Observed by the First Republic of China Satellite Authors: Kil, Hyosub; Paxton, Larry J.; Lee, Woo Kyoung; Jee, Geonhwa Abstract: Plasma bubbles in the equatorial F region are thought of as nighttime phenomena because they develop at night and are assumed to vanish after sunrise. However, bubbles occasionally persist throughout the night and into the day. This study investigates the origin of daytime irregularities and their evolution using data from the first Republic of China satellite. Our results show that daytime irregularities occur in the longitudes where bubbles have developed on previous nights. A newly reported feature is the observation of the temporal variation of the locations of daytime irregularities; daytime irregularities are concentrated near the magnetic equator early in the morning, but the location gradually shifts to higher latitudes with time. This phenomenon is explained in terms of the latitudinal redistribution of fossil bubbles by the ionospheric fountain effect. 2019-05-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/10924 Title: Plasma Blobs Associated With Medium­Scale Traveling Ionospheric Disturbances Authors: Kil, Hyosub; Paxton, Larry J.; Jee, Geonhwa; Nikoukar, Romina Abstract: Plasma blobs represent plasma density enhancements with respect to ambient plasma. The formation of blobs in low and middle latitudes is understood in association with either equatorial plasma bubbles or medium­scale traveling ionospheric disturbances (MSTIDs). This study reports four blob events identified from the Swarm satellite observations in 2014. Those blobs show the conjugate property and the alignment in the northwest­southeast direction in the Northern Hemisphere and southwest­northeast direction in the Southern Hemisphere. These are the typical characteristics of nighttime MSTIDs. The observation of MSTIDs in the total electron content maps and the absence of bubbles in the equatorial region at the times of the blob detection further support the association of those blobs with MSTIDs. 2019-04-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/10862 Title: Inertia-gravity waves revealed in radiosonde data at Jang Bogo Station, Antarctica (74o37'S, 164o13'E). Part I: Characteristics, energy, and momentum flux Authors: Yoo, J. -H.; Choi, Taejin; Chun, H. -Y.; Kim, Y. -H.; Song, In-Sun; Song, B. -G. Abstract: Characteristics of inertia-gravity waves (IGWs) at high-latitude in Antarctica are investigated using radiosondes launched daily at Jang Bogo Station (74o37'S, 164o13'E), a new Antarctic station that has been operating since 2014, in the troposphere (z = 2？7 km) and lower stratosphere (z = 15？22 km) for 25 months (December 2014？December 2016). The vertical propagation of IGWs exhibits strong seasonal variations in the stratosphere, with an enhancement (reduction) in downward (upward)-propagating IGWs from May to mid-October. In the troposphere, both upward and downward-propagating IGWs have similar occurrence rates without seasonal variations. The intrinsic phase velocity of IGWs mostly direct to the west (isotropic), while the ground-relative phase and group velocities are dominant in the east and southeast (northeast), respectively, in the stratosphere (troposphere). The intrinsic frequency, vertical wavelength, and horizontal wavelength of IGWs averaged in the troposphere (stratosphere) are 3.57 f (1.93 f) (where f is the Coriolis parameter), 1.48 (1.48) km, and 63.06 (221.81) km, respectively. The wave energy in the stratosphere has clear seasonal variations with large values in autumn and spring, while that in the troposphere is smaller without obvious seasonal variations. Zonal and meridional momentum flux (MF) averaged in the stratosphere (troposphere) are -0.008 (-0.0018) m2 s-2 and -0.0005 (0.001) m2 s-2, respectively. The MFs of downward-propagating IGWs in the stratosphere is mostly positive in both zonal and meridional directions, whereas the directional preference is not obvious in the troposphere. In Part II, sources of the observed IGWs in the troposphere and stratosphere will be examined. 2018-12-01T00:00:00Z