• Journal of Astronomy and Space Sciences
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• v.24 no.4
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• pp.285-296
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• 2007

The Precipitable Water Vapor (PWV) from GPS with high resolution in terms of time and space might reduce the limitations of the numerical weather prediction (NWP) model for easily variable phenomena, such as precipitation and cloud. We have converted to PWV from Global Positioning System (GPS) data of Korea Astronomy and Space Science Institute (KASI) and Ministry of Maritime Affairs & Fisheries (MOMAF). First of all, we have selected the heavy rainfall case of having a predictability limitation in time and space due to small-scale motion. In order to evaluate the effect for GPS PWV, we have executed the sensitivity experiment with PWV from GPS data over Korean peninsula in the Weather Research & Forecasting 3-Dimensional Variational (WRF-3DVAR). We have also suggested the direction of further research for an improvement of the predictability of NWP model on the basis of this case.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.34 no.6
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• pp.222-232
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• 2022

In this study we investigated the characteristics of long-term tidal constituents based on 30 tidal gauge data along the coasts of Korea and its the effects on total water level (TWL) forecasts. The results show that the solar annual (Sa) and semiannual (Ssa) tides were dominant among long-term tidal constituents, and they are relatively large in western coast of Korea peninsula. To investigate the effect of long-term tidal constituents on TWL forecasts, we produced predicted tides in 2021 with and without long-term tidal constituents. The TWL forecasts with and without long-term tidal constituents are then calculated by adding surge forecasts into predicted tides. Comparing with the TWL without long-term tidal constituents, the results with long-term tidal constituents reveals small bias in summer and relatively large negative bias in winter. It is concluded that the large error found in winter generally caused by double-counting of meteorological factors in predicted tides and surge forecasts. The predicted surge for 2021 based on the harmonic analysis shows seasonality, and it reduces the large negative bias shown in winter when it subtracted from the TWL forecasts with long-term tidal constituents.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.06a
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• pp.155-156
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• 2014

선박의 안전한 입출항 지원을 위한 항만항행 환경정보로서 해양환경정보 제공기술을 개발하였다. 선박 안전 입출항을 위한 해양환경정보로는 바람, 조류, 조위, 수심 등의 정보를 고려하였으며, 각각 해역 전체의 공간분포와 항로상 변동을 제공할 수 있도록 정보를 생산하였다. 바람은 기상청의 예보자료를 활용하여 항만 공간 규모에 적합하도록 상세 공간 간격으로 최적화하여 생산하였으며, 조류와 조류는 자체적으로 개발한 조석조류 수치모델 결과에 기반한 실시간 예측 기법을 적용하여 생산하였다. 수심은 해도에 제시된 약최저저조면의 수심에 실시간 조위 변동을 적용하여 선박에서 만나게 될 실제 수심을 생산하였다. 제공 정보 중 공간 분포는 사용자가 원하신 시간에 대해 해역 전체의 정보를 제공하며, 항로상 정보는 선박이 운항하게 될 항적 계획에 따라 공간적으로 시간적으로 변동하는 정보를 제공한다. 본 연구의 결과는 항만 입출항 선박의 안전운항에 기여할 것으로 기대된다.

• Atmosphere
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• v.29 no.2
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• pp.219-226
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• 2019

Generally, the weather forecast system has been run using prescribed ocean condition. As it is widely known that coupling between atmosphere and ocean process produces consistent initial condition at all-time scales to improve forecast skill, there are many trials on the application of data assimilation of coupled model. In this study, we implemented a weakly coupled data assimilation (short for WCDA) system in global NWP model with low horizontal resolution for coupled forecast with uncoupled initialization, following WCDA system at the Met Office. The experiment is carried out for a typhoon evolution forecast in 2017. Air-sea exchange process provides SST cooling and gives a substantial impact on tendency of central pressure changes in the decaying phase of the typhoon, except the underestimated central pressure. Coupled data assimilation is a challenging new area, requiring further work, but it would offer the potential for improving air-sea feedback process on NWP timescales and finally contributing forecast accuracy.

• Journal of Wind Energy
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• v.14 no.3
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• pp.25-33
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• 2023

In order to secure the safety of increasing offshore activities such as offshore wind farm maintenance and fishing, IMPACT, a mid-term marine weather forecasting system, was established by predicting marine weather up to 7 days in advance. Forecast data from the Korea Hydrographic and Oceanographic Agency (KHOA), which provides the most reliable marine meteorological service in Korea, was used, but wind speed and wave height forecast errors increased as the leading forecast period increased, so improvement of the accuracy of the model results was needed. The Model Output Statistics (MOS) method, a post-correction method using statistical machine learning, was applied to improve the prediction accuracy of wave height, which is an important factor in forecasting the risk of marine activities. Compared with the observed data, the wave height prediction results by the model before correction for 6 to 7 days ahead showed an RMSE of 0.692 m and R of 0.591, and there was a tendency to underestimate high waves. After correction with the MOS technique, RMSE was 0.554 m and R was 0.732, confirming that accuracy was significantly improved.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.3
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• pp.262-273
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• 2003

We have analyzed the characteristics of the monthly mean sea surface winds and wind waves near the Korean marginal seas in the 2002 year on the basis of prediction results of the sea surface winds from MM5/KMA model, which is being used for the operation system at the Korea Meteorological Administration and the third generation wave model, WAVEWATCH-III. which takes the sea surface winds derived from MM5/KMA model as the initial data. Statistical comparisons have been applied with both the marine meteorological observation buoy and the TOPEX/POSEIDON satellite wave heights data to verify the model results. The correlation coefficients between the models and observation data reach up to about 60-80％, supporting that these models satisfactorily simulate the sea surface winds and wave heights even at the coastal regions except for Chilbal-Do located very close to the land. Based on these verification results, the distributions of monthly mean sea surface winds, significant wave heights, wave lengths and wave periods around the Korean marginal seas during 2002 year have been represented.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.1064-1067
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• 2011

선박경제운항이란 파도와 바람과 같은 해양 기상정보 예측을 바탕으로 선박의 운항방법에 따른 연료 소모량과 운항시간을 예상해보고, 가장 경제적인 운항을 하는 것을 말한다. 본 논문에서는 실용화할 수 있는 범용의 경제운항시스템 개발에 중점을 두었다. 기존의 시스템들을 살펴보면 임의의 정해진 경로를 대상으로 실험하는 경우가 많은데, 이를 개선하여 임의의 출발점과 도착점이 주어지면 A*알고리즘을 통해서 지리상 최단경로를 찾아내도록 하여 시스템을 자동화하였으며 적용범위를 세계 전역으로 확대 하였다. 그리고 기존의 엔진출력을 고정하거나 속력을 일정하게 운항한다는 가정에서 벗어나서 엔진출력을 탐색하여 보다 효율적인 운항 솔루션을 찾아내도록 하였다. 그리고 사용측면에서는 운항사들에게 보다 효용성 높은 시스템이 되기 위해서, 일방적인 권고보다는 연료소모량과 운항시간 별로 다양한 솔루션들을 제공하여 운항사의 판단을 존중함과 동시에 운항보조시스템으로서의 역할에 충실할 수 있도록 하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.11a
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• pp.1383-1386
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• 2021

태풍 관련 해양 사고에 대한 구체적인 예방책이나 대책이 없는 현재 태풍 사고 예방을 위한 대책이 필요하다. 이에 본 논문에서는 빅데이터를 이용해 기상 예보, 현재 항해 중인 선박, 선박사고 지역 등을 나타내는 시스템을 구현하였다. 또한 본 논문에서는 사용자의 편의를 위해 국민의 대부분이 사용한다고 할 수 있는 스마트폰에서 사용할 수 있도록 애플리케이션으로 서비스를 제공할 수 있도록 개발하였다.

• Journal of the Korean earth science society
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• v.40 no.6
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• pp.584-598
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• 2019

In this study, the effects of air-sea interactions on precipitation over the Seoul-Gyeonggi region of the Korean Peninsula from 28 to 30 August 2018, were analyzed using a Regional atmosphere-ocean Coupled Model (RCM). In the RCM, a WRF (Weather Research Forecasts) was used as the atmosphere model whereas ROMS (Regional Oceanic Modeling System) was used as the ocean model. In a Regional Single atmosphere Model (RSM), only the WRF model was used. In addition, the sea surface temperature data of ECMWF Reanalysis Interim was used as low boundary data. Compared with the observational data, the RCM considering the effect of air-sea interaction represented that the spatial correlations were 0.6 and 0.84, respectively, for the precipitation and the Yellow Sea surface temperature in the Seoul-Gyeonggi area, which was higher than the RSM. whereas the mean bias error (MBE) was -2.32 and -0.62, respectively, which was lower than the RSM. The air-sea interaction effect, analyzed by equivalent potential temperature, SST, dynamic convergence fields, induced the change of SST in the Yellow Sea. In addition, the changed SST caused the difference in thermal instability and kinematic convergence in the lower atmosphere. The thermal instability and convergence over the Seoul-Gyeonggi region induced upward motion, and consequently, the precipitation in the RCM was similar to the spatial distribution of the observed data compared to the precipitation in the RSM. Although various case studies and climatic analyses are needed to clearly understand the effects of complex air-sea interaction, this study results provide evidence for the importance of the air-sea interaction in predicting precipitation in the Seoul-Gyeonggi region.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.4
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• pp.273-283
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• 2020

Numerical simulations of the storm surge and waves induced by the Typhoon Bolaven incident on the west sea of Korea in 2012 are performed using the JMA-MSM weather field provided by the Japan Meteorological Agency, and the calculated surge heights are compared with the time history observed at harbours along the various coasts of Korea. For the waves occurring coincidentally with the storm surges the calculated significant wave heights are compared with the data measured using the wave buoys operated by the Korea Hydrographic and Oceanographic Agency and the Korea Meteorological Administration. Additional simulations are also performed based on the pressure and wind fields obtained using the best track information provided by the Joint Typhoon Warning Center, and the calculated results are compared and analyzed. The waves and storm surges calculated using JMA-MSM wether field agree well with the observations because of the better reflection of the topography and the pre-background weather field. On the other hand, the calculated results based on the weather fields produced using the JTWC best track information show some limitations of the general trend of the variations of wave and surge heights. Based on the results of this study it is found that the reliable weather fields are essential for the accurate simulation of storm surges and waves.