https://repository.kopri.re.kr/handle/201206/9715 2026-04-06T06:41:42Z https://repository.kopri.re.kr/handle/201206/10941 Title: In Search of Winter Blocking in the Western North Pacific Ocean Authors: Kim, Seon-Hwa; Kim, Baek-Min Abstract: We investigate winter blocking activity over the western North Pacific (WNP) through an inter-comparison of four detection methods, which are categorized into two types (anomaly and reversal). Most of the blocking events in the anomaly-based methods are initiated from the eastern North Pacific. Reversal-based methods capture the blocking occurrence associated with Rossby wave breaking, especially cyclonic breaking. As the two types capture different aspects of WNP blocking, the resultant regional impact is also largely different. At the onset, anomaly-based methods show a strong cold anomaly downstream of the blocking in conjunction with a Pacific/North America (PNA)-like pattern. Reversal-based methods indicate a weak cold anomaly in company with a western Pacific (WP)-like pattern, which appears downstream and upstream of the blocking in the local reversal and large-scale reversal methods, respectively. At the end of WNP blocking, all methods show strong cold anomalies both upstream and downstream of the blocking. 2019-08-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/10997 Title: Reexamination of the Madden？Julian Oscillation Effect on Wintertime Sea Ice Concentrations in the North Pacific Authors: Hong, Ja-Young; Kim, Joo-Hong; Park, Doo-Sun R. Abstract: In the Pacific sector of the Arctic, a noticeable dipole pattern of the sea ice concentration (SIC) between the Sea of Okhotsk and the Bering Sea has been reported on timescales of weeks to months. The dipole pattern owes its existence to the large-scale circulation variability across the North Pacific. Meanwhile, it is well known that eastward propagating tropical convection on an intra-seasonal timescale, the Madden？Julian Oscillation (MJO), forms large-scale circulation anomalies in the North Pacific through the poleward-propagating Rossby waves that are stimulated by MJO-related tropical convection, which is often manifested as a Pacific？North American teleconnection pattern. Few studies, however, have focused on the lagged MJO influence on the SIC change in the high-latitude North Pacific by poleward-propagating waves. Thus, herein we investigate the intra-seasonal SIC variations associated with the MJO phases by considering the lagged circulation response. The dipole pattern in the composite daily SIC change map between the two seas becomes apparent after approximately one week of MJO phases 3 and 7. In the Bering Sea (the Sea of Okhotsk), the SIC increases after MJO phase 3 (phase 7), while it decreases in phase 7 (phase 3). The lagged anomalous circulation pattern in the North Pacific associated with the MJO leads to SIC changes primarily through the dynamic response in 10 m winds and the resultant sea ice motion. 2019-01-01T00:00:00Z