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Sang Ho Lee and Kuh Kim

Abstract

The scattering solution around a small cylindrical island in a shelf sea of uniform depth is derived for Sverdrup, right-bounded Poincare, and Kelvin waves, which includes linear bottom friction, and the solution is extended to the subinertial frequency range. Effects of scattering on the amplitude and phase vary, depending on the type of incident waves. A Sverdrup wave scattering near the inertial frequency produces large amplitude and phase differences around the island due to singularity effect. However, the singularity effect does not happen for Poincare and Kelvin waves, even though the amplitude and phase variation depends on bottom friction and wave frequency. For an observer looking down the direction of wave propagation around the island, the maximum amplitude due to Sverdrup wave scattering occurs on the left-hand side, and the phase difference increases more than twice that by incident wave propagation. Scattering of Poincare waves at a superinertial frequency for an island located at a fixed distance from the straight coast produces its maximum amplitude on the right-hand side and at a subinertial frequency on the leeward coast. In the case of Kelvin wave scattering, the amplitude attenuates by frictional damping along the direction of wave propagation around the island and phase difference increases as much as twice that by incident wave propagation. Application of these theoretical results to tides around Cheju Island, off the south coast of Korea, suggests that the amplitude and phase variations of the M 2 and O 1 tides are due to the scattering of those tides comprised of Sverdrup and Kelvin waves having superinertial and subinertial frequencies.

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Steven Cocke, Hee-Sang Lee, Gyu-Ho Lim, and Chun-Woo Lee

Abstract

The NCAR Community Climate Model (CCM, version 3.6) is evaluated as a numerical weather prediction model. The model was run in real-time mode at relatively high resolution (T126 or approximately 1°) to produce 10-day forecasts over a 1-yr period ending 1 March 2004. The evaluation of the performance of the CCM could be useful for both the climate modeling community as well as the operational forecast centers. For climate modelers, the higher-resolution, short-range forecasts can be used to diagnose deficiencies in the physical parameterizations in the model. While climate models may produce good mean climatologies, they may fail to simulate important higher-frequency phenomena that may be important to climate. For operational centers, the examination of an open, well-developed, and studied model could provide insights that could lead to improvement in their own models. Furthermore, the CCM could be considered a candidate as a member for a suite of models for use in an operational context. And, finally, as operational centers gradually extend their forecast range, and climate scientists are paying more attention to the subseasonal time scales, the study of a climate model in the short range becomes more appropriate.

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Chun-Sil Jin, Chang-Hoi Ho, Joo-Hong Kim, Dong-Kyou Lee, Dong-Hyun Cha, and Sang-Wook Yeh

Abstract

Observational records reveal that the number of tropical cyclones (TCs) approaching East Asia in July–October is positively correlated with sea surface temperatures (SSTs) in the equatorial and northern off-equatorial central Pacific (CP) oceans, indicating the significant impact of CP El Niño (CP-EN). Through experiments using a Weather Research and Forecast (WRF) model–based regional climate model, this study demonstrates that it is northern off-equatorial CP warming, rather than equatorial CP warming, that effectively induces local anomalous steering flows pertinent to the observed increase in TC activity over East Asia during CP-EN. Sensitivity experiments, in which the prescribed CP-EN-related SST anomaly is confined near the equator, do not capture the observed TC increase over East Asia, whereas those including the off-equatorial region successfully reproduce observed atmospheric and TC variabilities. The off-equatorial CP SST anomaly acts to expand the anomalous cyclonic response in the Philippine Sea farther northward. This produces a tunnel effect in the East China Sea, by which more TCs move to East Asian coastal regions (e.g., east China, Taiwan, Korea, and Japan).

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Soo-Jin Sohn, WonMoo Kim, Jin Ho Yoo, Yun-Young Lee, Sang Myeong Oh, Bo Ra Kim, Hyunrok Lee, Sangcheol Kim, Sunny Seuseu, and Netatua Pelesikoti

Abstract

Seasonal prediction provides critical information for the tropical Pacific region, where the economy and livelihood is highly dependent on climate variability. While the highest skills of dynamical prediction systems are usually found in the tropical Pacific, National Hydrological and Meteorological Services (NHMS) in the Pacific Islands Countries (PICs) do not take full advantage of such scientific achievements. The Republic of Korea-Pacific Islands Climate Prediction Services (ROK-PI CliPS) project aims to help PICs produce regionally tailored climate prediction information using a dynamical seasonal prediction system. The project is being jointly implemented by the APEC Climate Center (APCC) and the Secretariat of the Pacific Regional Environment Programme (SPREP), in close collaboration with NHMSs in PICs. The regionally tailored, dynamical-statistical hybrid climate prediction system uses predictors that were identified through communications with NHMSs. The predictors were selected based on the empirical physical relationship of the local climate fluctuations, indicated by multi-institutional and multimodel ensembles. This hybrid system makes full use of dynamical seasonal predictions, which have not been commonly utilized in current operation in PICs. In accordance with system development, additional efforts have been made for PIC NHMSs to build capacity by increasing their knowledge and skill needed to develop such methodologies and systems. Nonetheless, the successive and strategic efforts to sustain and further improve climate predictions in the Pacific Islands region are required.

Open access
Jhoon Kim, Ukkyo Jeong, Myoung-Hwan Ahn, Jae H. Kim, Rokjin J. Park, Hanlim Lee, Chul Han Song, Yong-Sang Choi, Kwon-Ho Lee, Jung-Moon Yoo, Myeong-Jae Jeong, Seon Ki Park, Kwang-Mog Lee, Chang-Keun Song, Sang-Woo Kim, Young Joon Kim, Si-Wan Kim, Mijin Kim, Sujung Go, Xiong Liu, Kelly Chance, Christopher Chan Miller, Jay Al-Saadi, Ben Veihelmann, Pawan K. Bhartia, Omar Torres, Gonzalo González Abad, David P. Haffner, Dai Ho Ko, Seung Hoon Lee, Jung-Hun Woo, Heesung Chong, Sang Seo Park, Dennis Nicks, Won Jun Choi, Kyung-Jung Moon, Ara Cho, Jongmin Yoon, Sang-kyun Kim, Hyunkee Hong, Kyunghwa Lee, Hana Lee, Seoyoung Lee, Myungje Choi, Pepijn Veefkind, Pieternel F. Levelt, David P. Edwards, Mina Kang, Mijin Eo, Juseon Bak, Kanghyun Baek, Hyeong-Ahn Kwon, Jiwon Yang, Junsung Park, Kyung Man Han, Bo-Ram Kim, Hee-Woo Shin, Haklim Choi, Ebony Lee, Jihyo Chong, Yesol Cha, Ja-Ho Koo, Hitoshi Irie, Sachiko Hayashida, Yasko Kasai, Yugo Kanaya, Cheng Liu, Jintai Lin, James H. Crawford, Gregory R. Carmichael, Michael J. Newchurch, Barry L. Lefer, Jay R. Herman, Robert J. Swap, Alexis K. H. Lau, Thomas P. Kurosu, Glen Jaross, Berit Ahlers, Marcel Dobber, C. Thomas McElroy, and Yunsoo Choi

Abstract

The Geostationary Environment Monitoring Spectrometer (GEMS) is scheduled for launch in February 2020 to monitor air quality (AQ) at an unprecedented spatial and temporal resolution from a geostationary Earth orbit (GEO) for the first time. With the development of UV–visible spectrometers at sub-nm spectral resolution and sophisticated retrieval algorithms, estimates of the column amounts of atmospheric pollutants (O3, NO2, SO2, HCHO, CHOCHO, and aerosols) can be obtained. To date, all the UV–visible satellite missions monitoring air quality have been in low Earth orbit (LEO), allowing one to two observations per day. With UV–visible instruments on GEO platforms, the diurnal variations of these pollutants can now be determined. Details of the GEMS mission are presented, including instrumentation, scientific algorithms, predicted performance, and applications for air quality forecasts through data assimilation. GEMS will be on board the Geostationary Korea Multi-Purpose Satellite 2 (GEO-KOMPSAT-2) satellite series, which also hosts the Advanced Meteorological Imager (AMI) and Geostationary Ocean Color Imager 2 (GOCI-2). These three instruments will provide synergistic science products to better understand air quality, meteorology, the long-range transport of air pollutants, emission source distributions, and chemical processes. Faster sampling rates at higher spatial resolution will increase the probability of finding cloud-free pixels, leading to more observations of aerosols and trace gases than is possible from LEO. GEMS will be joined by NASA’s Tropospheric Emissions: Monitoring of Pollution (TEMPO) and ESA’s Sentinel-4 to form a GEO AQ satellite constellation in early 2020s, coordinated by the Committee on Earth Observation Satellites (CEOS).

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