https://repository.kopri.re.kr/handle/201206/5123 2026-04-10T22:44:21Z 2026-04-10T22:44:21Z Cheinway Hwang Lee, Bang Yong Kwang Bae Kim Jeong Woo Kim Yu-Shen Hsiao https://repository.kopri.re.kr/handle/201206/5996 2022-03-24T07:11:19Z 2011-01-01T00:00:00Z

Title: Bathymetry Estimation Using the Gravity-Geologic Method: An Investigation of Density Contrast Predicted by the Downward Continuation Method Authors: Cheinway Hwang; Lee, Bang Yong; Kwang Bae Kim; Jeong Woo Kim; Yu-Shen Hsiao Abstract: The downward continuation (DWC) method was used to determine the density contrast between the seawater and the ocean bottom topographic mass to estimate accurate bathymetry using the gravity-geologic method (GGM) in two study areas, which are located south of Greenland (Test Area #1: 40 - 50°W and 50 - 60°N) and south of Alaska (Test Area #2: 140 - 150°W and 45 - 55°N). The data used in this study include altimetry- derived gravity anomalies, shipborne depths and gravity anomalies. Density contrasts of 1.47 and 1.30 g cm-3 were estimated by DWC for the two test areas. The considerations of predicted density contrasts can enhance the accuracy of 3 ~ 4 m for GGM.ch are located south of Greenland (Test Area #1: 40 - 50°W and 50 - 60°N) and south of Alaska (Test Area #2: 140 - 150°W and 45 - 55°N). The data used in this study include altimetry- derived gravity anomalies, shipborne depths and gravity anomalies. Density contrasts of 1.47 and 1.30 g cm-3 were estimated by DWC for the two test areas. The considerations of predicted density contrasts can enhance the accuracy of 3 ~ 4 m for GGM.

2011-01-01T00:00:00Z Dao-Yi Gong Tianjun Zhou Dong Guo Kim, Seong-Joong Miao Hu Yongqi Gao Jing Yang https://repository.kopri.re.kr/handle/201206/6079 2022-03-24T07:11:30Z 2011-01-01T00:00:00Z

Title: Spring Arctic Oscillation-East Asian summer monsoon connection through circulation changes over the western North Pacific Authors: Dao-Yi Gong; Tianjun Zhou; Dong Guo; Kim, Seong-Joong; Miao Hu; Yongqi Gao; Jing Yang Abstract: In the present study the links between spring Arctic Oscillation (AO) and East Asian summer monsoon (EASM) was investigated with focus on the importance of the North Pacific atmospheric circulation and sea surface temperature (SST). To reduce the statistical uncertainty, we analyzed high-pass filtered data with the inter-annual time scales, and excluded the El Ni？no/Southern Oscillation signals in the climate fields using a linear fitting method. The significant relationship between spring AO and EASM are supported by the changes of multi-monsoon components, including monsoon indices, precipitation, and three-dimensional atmospheric circulations. Following a stronger positive spring AO, an anomalous cyclonic circulation at 850 hPa appears in southeastern Asia and the western North Pacific in summer, with the easterly anomalies spanning from the Pacific to Asian continent along 25°N？0°N and the westerly anomalies south of 15°N. At the same time, the summer western North Pacific subtropical high becomes weaker. Consistently, the positive precipitation anomalies are developed over a broad region south of 30°N stretching from southern China to the western Pacific and the negative precipitation anomalies appear in the lower valley of the Yangtze River and southern Japan. The anomalous cyclone in the western North Pacific persisting from spring to summer plays a key role in mreduce the statistical uncertainty, we analyzed high-pass filtered data with the inter-annual time scales, and excluded the El Ni？no/Southern Oscillation signals in the climate fields using a linear fitting method. The significant relationship between spring AO and EASM are supported by the changes of multi-monsoon components, including monsoon indices, precipitation, and three-dimensional atmospheric circulations. Following a stronger positive spring AO, an anomalous cyclonic circulation at 850 hPa appears in southeastern Asia and the

2011-01-01T00:00:00Z Kwang Bae Kim Jeong Woo Kim Kim, Chang Hwan Lee, Bang Yong Yi Kyun Kwon Yu-Shen Hsiao https://repository.kopri.re.kr/handle/201206/6170 2022-03-24T07:11:29Z 2011-01-01T00:00:00Z

Title: Bathymetry enhancement by altimetry-derived gravity anomalies in the East Sea (Sea of Japan) Authors: Kwang Bae Kim; Jeong Woo Kim; Kim, Chang Hwan; Lee, Bang Yong; Yi Kyun Kwon; Yu-Shen Hsiao Abstract: The gravity-geologic method (GGM) was used to enhance the bathymetry of the East Sea (Sea of Japan) with satellite altimetry-derived free-air gravity anomalies and shipborne depth measurements. By comparison with the bathymetry model of Smith and Sandwell's (SAS) approach (1994), GGM was found to have an advantage with short wavelength (B12 km) components, while SAS better predicts longer wavelength (C25 km) components, despite its dependency on density contrast. To mitigate this limitation, a tuning density contrast of 10.25 g/cm3 between seawater and the seafloor was primarily estimated by the downward continuation method and then validated by the check points method with GGM. Similarly, SAS is limited by the ''A'' value in low-pass part of the Wiener filter, which defines the effective range of the wavelength components on bathymetry. As a final result, we present an enhanced GGM bathymetry model by integrating all available data.

2011-01-01T00:00:00Z Jee, Geonhwa https://repository.kopri.re.kr/handle/201206/8526 2022-03-24T07:13:25Z 2010-01-01T00:00:00Z

Title: Characteristics of the global ionospheric electron density during the extreme solar minimum condition Authors: Jee, Geonhwa Abstract: The last solar minimum period between the cycles 23 and 24 was anomalously low and lasted long compared with previous solar minimums. The resulting solar irradiance received in the Earth's upper atmosphere was extremely low and therefore it can readily be expected that the upper atmosphere should be greatly affected by this low solar activity. There were several studies on this effect but many of them was on the thermosphere (Solomon et al., 2010; Emmert et al., 2010). According to these studies, the thermospheric temperature was cooler and the density was lower than the previous solar minimum periods. The low solar irradiance during the last solar minimum should also affect the ionosphere, not only via the lower ion-electron production due to the lower EUV radiation but also through the interactions with the thermosphere that was already influenced by the low solar irradiance. In this study, we utilized the measurements of total electron content (TEC) from the TOPEX and JASON satellites during the periods of 1992 to 2010, which includes the last two solar minimums, in order to investigate the differences between the ionospheric behaviors during the two minimum conditions. Initially the levels of the global ionization will be examined during these minimum periods and then further discussions will be continued on the details of the ionospheric behavior such as the seasonal and storm-time variations.

2010-01-01T00:00:00Z