• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 2003년도 한국해안해양공학발표논문집
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• pp.18-27
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• 2003

The goal of the UN Framework Convention on Climate Change (UNFCCC) is to stabilize atmospheric CO2 concentration for preventing global warming in future. However, there are many unknown factors regarding stabilization of CO2 concentration. What level of concentration should be appropriate to prevent global warming？ When should we stop the increase of CO2 concentration\ulcorner What kind of countermeasures of reducing CO2 emission will be available for CO2 stabilization？(omitted)

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• 제18권1호
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• pp.55-70
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• 2008

The global time slice approach is a transient experiment using high resolution atmosphere-only model with boundary condition from the low resolution globally coupled ocean-atmosphere model. The present study employs this "time slice concept" using ECHAM4 atmosphere-only model at a horizontal resolution of T106 with the lower boundary forcing obtained from a lower-resolution (T42) greenhouse gas + aerosol forcing experiment performed using the ECHO-G/S (ECHAM4/HOPE-G) coupled model. In order to assess the impact of horizontal resolution on simulated East Asian summer monsoon climate, the differences in climate response between the time slice experiments of the present and that of IPCC SRES AR4 participating 21 models including coarser (T30) coupled model are compared. The higher resolution model from time slice experiment in the present climate show successful performance in simulating the northward migration and the location of the maximum rainfall during the rainy season over East Asia, although its rainfall amount was somewhat weak compared to the observation. Based on the present climate simulation, the possible change of East Asian summer monsoon rainfall in the future climate by the IPCC SRES A1B scenario, tends to be increased especially over the eastern part of Japan during July and September. The increase of the precipitation over this region seems to be related with the weakening of northwestern part of North Pacific High and the formation of anticyclonic flow over the south of Yangtze River in the future climate.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2022년도 학술발표회
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• pp.147-147
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• 2022

In January 2021 heavy flood affected South Kalimantan with causing many casualties. The heavy rainfall is predicted to be generated due to the ENSO (El Nino-Southern Oscillation). The weak La-Nina mode appeared to generate more convective cloud above the warmed ocean and result in extreme rainfall with high anomaly compared to past historical rainfall event. Subsequently, the antecedent soil moisture distribution showed to have an important role in generating the flood response. Saturated flow and infiltration excess mainly contributed to the runoff generation due to the high moisture capacity. The hydro-meteorological processes in this event were deeply analyzed using the coupled atmospheric model of Weather Research and Forecasting (WRF) and the hydrological model extension (WRF-Hydro). The sensitivity analysis of the flood response to the SST anomaly and the soil moisture capacity also compared. Result showed that although SST and soil moisture are the main contributors, soil moisture have more significant contribution to the runoff generation despite of anomaly rainfall occurred. Model performance was validated using the Global Precipitation Measurement (GPM) and Soil Moisture Operational Products System (SMOPS) and performed reasonably well. The model was able to capture the hydro-meteorological process of atmosphere and hydrological feedbacks in the extreme weather event.

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• 제29권2호
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• pp.149-164
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• 2019

The purpose of this study is to introduce the improvement of current operational climate prediction system of KMA and to compare previous and improved that. Whereas the previous system is based on GloSea5GA3, the improved one is built on GloSea5GC2. GloSea5GC2 is a fully coupled global climate model with an atmosphere, ocean, sea-ice and land components through the coupler OASIS. This is comprised of component configurations Global Atmosphere 6.0 (GA6.0), Global Land 6.0 (GL6.0), Global Ocean 5.0 (GO5.0) and Global Sea Ice 6.0 (GSI6.0). The compositions have improved sea-ice parameters over the previous model. The model resolution is N216L85 (~60 km in mid-latitudes) in the atmosphere and ORCA0.25L75 ($0.25^{\circ}$ on a tri-polar grid) in the ocean. In this research, the predictability of each system is evaluated using by RMSE, Correlation and MSSS, and the variables are 500 hPa geopotential height (h500), 850 hPa temperature (t850) and Sea surface temperature (SST). A predictive performance shows that GloSea5GC2 is better than GloSea5GA3. For example, the RMSE of h500 of 1-month forecast is decreased from 23.89 gpm to 22.21 gpm in East Asia. For Nino3.4 area of SST, the improvements to GloSeaGC2 result in a decrease in RMSE, which become apparent over time. It can be concluded that GloSea5GC2 has a great performance for seasonal prediction.

• 한국지구과학회지
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• 제40권6호
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• pp.584-598
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• 2019

본 연구에서는 지역 기상-해양 접합모델을 이용하여 2018년 8월 28일부터 30일까지 한반도 서울-경기지역에 내린 강수에 대해 대기-해양 상호작용의 효과를 분석하였다. 지역 기상-해양 접합모델에서 기상모델은 WRF (Weather Research Forecasts)가 사용되었으며, 해양모델은 ROMS (Regional Oceanic Modeling System)가 사용되었다. 단일 기상 모델은 WRF모델만 이용되었으며, ECMWF Re-Analysis Interim 의 해수면온도자료가 바닥경계자료로 사용되었다. 관측자료와 비교하여, 대기-해양 상호작용의 효과가 고려된 접합모델은 서울-경기지역의 강수 및 황해 해수면온도에 대해 공간상관계수가 각각 0.6과 0.84로 이는 지역 기상모델보다 높게 나타났다. 또한, 평균편향오차(MBE, Mean Bias Error)은 각각 -2.32와 -0.62로 지역 기상모델 보다 낮은 오차율을 보였다. 상당온위와 해수면온도 및 역학적 수렴장으로 분석한 대기-해양 상호작용의 효과는 황해 해수면온도의 변화를 유도하였고, 그 변화는 하층대기에서 열적 불안정과 운동학적 수렴대의 차이를 발생시켰다. 열적 불안정과 수렴대는 결과적으로 서울-경기 지역에서 상승운동을 유도하였고, 결과적으로 기상-해양 접합모델에서 모의된 강수가 관측과 더 유사한 공간분포를 나타냈다. 그러나 복잡한 관계에 있는 대기-해양 상호작용의 효과를 더 명확히 파악하기 위해서는 다양한 사례연구와 장기적인 분석이 필요하지만, 본 연구는 기상-해양 상호작용이 강수 예보에 중요성에 대한 또 다른 증거를 제시한다.

• 대기
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• 제32권3호
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• pp.235-246
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• 2022

A large number of MJO skill metrics and process-oriented MJO simulation metrics have been developed by previous studies including the MJO Working Group and Task Force. To assess models' successes and shortcomings in the MJO simulation, a standardized set of diagnostics with the additional set of dynamics-oriented diagnostics are applied. The Global Coupled (GC) model developed for the operation of the climate prediction system is used with the comparison between the GC2 and GC3.1. Two GC models successfully capture three-dimensional dynamic and thermodynamic structure as well as coherent eastward propagation from the reference regions of the Indian Ocean and the western Pacific. The low-level moisture convergence (LLMC) ahead of the MJO deep convection, the low-level westerly and easterly associated with the coupled Rossby-Kelvin wave and the upper-level divergence are simulated successfully. The GC3.1 model simulates a better three-dimensional structure of MJO and thus reproduces more realistic eastward propagation. In GC2, the MJO convection following the LLMC near and east of the Maritime Continent is much weaker than observation and has an asymmetric distribution of both low and upper-level circulation anomalies. The common shortcomings of GC2 and GC3.1 are revealed in the shorter MJO periods and relatively weak LLMC as well as convective activity over the western Indian Ocean.

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• 제26권4호
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• pp.687-696
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• 2016

The western North Pacific subtropical high (WNPSH) in boreal summer has interannual and interdecadal variability, which affects East Asian summer monsoon variability. In particular, it is well known that the intensity of WNPSH is reversely related to that of summer monsoon in North East Asia in association with Pacific Japan (PJ)-like pattern. Many coupled climate models weakly simulate this large-scale teleconnection pattern and also exhibit the diverse variability of WNPSH. This study discusses the inter-model differences of WNPSH simulated by different climate models, which participate in the Coupled Model Intercomparison Project phase 5 (CMIP5). In comparing with reanalysis observation, the 29 CMIP5 models could be assorted into two difference groups in terms of interannual variability of WNPSH. This study also discusses the dynamical or thermodynamics factors for the differences of two groups of the CMIP5 climate models. As results, the regressed precipitation in well-simulating group onto the Nino3.4 index ($5^{\circ}N-5^{\circ}S$, $170^{\circ}W-120^{\circ}W$) is stronger than that in poorly-simulating group. We suggest that this difference of two groups of the CMIP5 climate models would have an effect on simulating the interannual variability of WNPSH.

• 한국환경과학회지
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• 제7권1호
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• pp.27-35
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• 1998

The present study intends to investigate the transient response of an atmosphere /ocean general circulation model to a gradual Increase of atmospheric carbon dioxide. To detect the climatic change of the for 1% $CO_2$ run with increasing $CO_2$ and the control run with fried $CO_2$ are compared. From response of the surface air temperature due to the gradual increase of atmospheric carbon dioxide is slowly increased with latitudes and is clearly larger over continents than oceans. The annual goffal mean temperature is continuously increased with 0.03552 per one year with strong SIN ratio and distinguished from the natural variability The time dependent response of the gradual increasing $CO_2$ has the strong seasonal variability with small change In summer and large change in winter, and the strong regional In the Asian and the American continents. It has been suggested that the direct and the feedback processes in the climate systems should be investigated by the detailed sensitivity runs to get the meaninguul estimate of the $CO_2$ forced variability.

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• 제27권3호
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• pp.261-276
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• 2017

The main objectives of this study are to introduce Global Seasonal forecasting system version5 (GloSea5) of KMA and to evaluate the performance of ensemble prediction of system. KMA has performed an operational seasonal forecast system which is a joint system between KMA and UK Met office since 2014. GloSea5 is a fully coupled global climate model which consists of atmosphere (UM), ocean (NEMO), land surface (JULES) and sea ice (CICE) components through the coupler OASIS. The model resolution, used in GloSea5, is N216L85 (~60 km in mid-latitudes) in the atmosphere and ORCA0.25L75 ($0.25^{\circ}$ on a tri-polar grid) in the ocean. In this research, we evaluate the performance of this system using by RMSE, Correlation and MSSS for ensemble mean values. The forecast (FCST) and hindcast (HCST) are separately verified, and the operational data of GloSea5 are used from 2014 to 2015. The performance skills are similar to the past study. For example, the RMSE of h500 is increased from 22.30 gpm of 1 week forecast to 53.82 gpm of 7 week forecast but there is a similar error about 50~53 gpm after 3 week forecast. The Nino Index of SST shows a great correlation (higher than 0.9) up to 7 week forecast in Nino 3.4 area. It can be concluded that GloSea5 has a great performance for seasonal prediction.

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• 제32권1호
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• pp.71-84
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• 2022

This paper describes verification results for the ocean analysis field produced by the Nucleus for European Modelling of the Ocean (NEMO) of the Korea Meteorological Administration (KMA) against observed Argo floats and drift buoys over the western Pacific Ocean and the equatorial Pacific during 2020~2021. This is confirmed by a comparison of the verification for the newly updated version of the HYbrid Coordinate Ocean Model/Navy Coupled Ocean Data Assimilation (HYCOM/NCODA) against same observations. NEMO shows that the vertical ocean temperature is much closer to the Argo floats than HYCOM for most seasons in terms of bias and root mean square error. On the other hand, there are overall considerable cold biases for HYCOM, which may be due to the more rapid decreasing temperature at the shallow thermocline in HYCOM. Conclusion demonstrated that the NEMO analysis for ocean temperature is more reliable than the analysis produced by the latest version of HYCOM as well as by the out-of-date HYCOM applied to the precedent study. The surface ocean current produced by NEMO also shows 14% closer to the AOML (Atlantic Oceanographic and Meteorological Laboratory) in situ drift buoys observations than HYCOM over the western Pacific Ocean. Over the equatorial Pacific, however, HYCOM shows slightly closer to AOML observation than NEMO in some seasons. Overall, this study suggests that the resulting information may be used to promote more use of NEMO analysis.