• 한국환경과학회지
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• 제26권10호
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• pp.1167-1180
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• 2017

Numerical Weather Prediction (NWP) models such as the Weather Research and Forecasting (WRF) model are essential for forecasting one-day-ahead solar irradiance. In order to evaluate the performance of the WRF in forecasting solar irradiance over the Korean Peninsula, we compared WRF prediction data from 2008 to 2010 corresponding to weather observation data (OBS) from the Korean Meteorological Administration (KMA). The WRF model showed poor performance at polluted regions such as Seoul and Suwon where the relative Root Mean Square Error (rRMSE) is over 30%. Predictions by the WRF model alone had a large amount of potential error because of the lack of actual aerosol radiative feedbacks. For the purpose of reducing this error induced by atmospheric particles, i.e., aerosols, the WRF model was coupled with the Community Multiscale Air Quality (CMAQ) model. The coupled system makes it possible to estimate the radiative feedbacks of aerosols on the solar irradiance. As a result, the solar irradiance estimated by the coupled system showed a strong dependence on both the aerosol spatial distributions and the associated optical properties. In the NF (No Feedback) case, which refers to the WRF-only stimulated system without aerosol feedbacks, the GHI was overestimated by $50-200W\;m^{-2}$ compared with OBS derived values at each site. In the YF (Yes Feedback) case, in contrast, which refers to the WRF-CMAQ two-way coupled system, the rRMSE was significantly improved by 3.1-3.7% at Suwon and Seoul where the Particulate Matter (PM) concentrations, specifically, those related to the $PM_{10}$ size fraction, were over $100{\mu}g\;m^{-3}$. Thus, the coupled system showed promise for acquiring more accurate solar irradiance forecasts.

• Journal of Korean Society for Atmospheric Environment
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• 제24권E2호
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• pp.92-101
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• 2008

The objective of this study is to evaluate and improve the capability of the Weather Research and Forecasting (WRF) model in simulating fog and visibility in local airports over Korea. The WRF model system is statistically evaluated for the 48-fog cases over Korea from 2003 to 2006. Based on the 4-yr evaluations, attempts are made to improve the simulation skill of fog and visibility over Korea by revising the statistical coefficients in the visibility algorithms of the WRF model. A comparison of four existing visibility algorithms in the WRF model shows that uncertainties in the visibility algorithms include additional degree of freedom in accuracy of numerical fog forecasts over Korea. A revised statistical algorithm using a linear-regression between the observed visibility and simulated hydrometeors and humidity near the surface exhibits overall improvement in the visibility forecasts.

• 대기
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• 제21권2호
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• pp.197-208
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• 2011

The objective of this study is to describe the short-range forecast system of the Korea Air Force (KAF) and to verificate its performace in 2009 summer. The KAF weather prediction model system, based on the Weather Research and Forecasting (WRF) model (i.e., the KAF-WRF), is configured with a parent domain overs East Asia and two nested domains with the finest horizontal grid size of 2 km. Each domain covers the Korean peninsula and South Korea, respectively. The model is integrated for 84 hour 4 times a day with the initial and boundary conditions from National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS) data. A quantitative verification system is constructed for the East Asia and Korean peninsula domains. Verification variables for the East Asia domain are 500 hPa temperature, wind and geopotential height fields, and the skill score is calculated using the difference between the analysis data from the NCEP GFS model and the forecast data of the KAF-WRF model results. Accuracy of precipitation for the Korean penisula domain is examined using the contingency table that is made of the KAF-WRF model results and the KMA (Korea Meteorological Administraion) AWS (Automatic Weather Station) data. Using the verification system, the operational model and parallel model with updated version of the WRF model and improved physics process are quantitatively evaluated for the 2009 summer. Over the East Aisa region, the parallel experimental model shows the better performance than the operation model. Errors of the experimental model in 500 hPa geopotential height near the Tibetan plateau are smaller than errors in the operational model. Over the Korean peninsula, verification of precipitation prediction skills shows that the performance of the operational model is better than that of the experimental one in simulating light precipitation. However, performance of experimental one is generally better than that of operational one, in prediction.

• 대한기계학회논문집B
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• 제39권9호
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• pp.735-742
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• 2015

본 논문에서는 국지적 기상현상의 모사가 가능하고 AWS, 기상탑, 또는 위성자료의 입력이 필요치 않은 WRF 기상수치모델을 이용하여, 풍력단지의 풍황자원 예측정확도 및 적용타당성을 비교 검증하고자 한다. 풍력단지개발 예비타당성단계에서 요구되는 풍황자원 예측을 위한 WRF 모델의 적용타당성 검증을 위해, 기상탑 풍황측정자료와 WAsP에 의한 풍황자원 예측결과와의 비교 검증을 수행하였고 제주도 북서쪽에 위치한 평대와 우도사이트를 비교 검증용 사이트로 선정하였다. 연 월평균풍속, 와이블분포, 연간발전량 및 바람장미의 예측결과가 실측자료와 비교 검증되었고 WRF 모델의 풍황해석결과는 WAsP의 결과에 비해 높은 예측 정확도를 나타내었다. 풍력단지개발 예비타당성 평가를 위한 WRF 모델의 풍황자원 예측가능성이 최종적으로 확인되었다.

• 한국군사과학기술학회지
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• 제21권3호
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• pp.403-412
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• 2018

In this study, a three-dimensional variational(3DVAR) data assimilation system was developed for the operational numerical weather prediction(NWP) system at the Republic of Korea Air Force Weather Group. The Air Force NWP system utilizes the Weather Research and Forecasting(WRF) meso-scale regional model to provide weather information for the military service. Thus, the data assimilation system was developed based on the WRF model. Experiments were conducted to identify the nested model domain to assimilate observations and the period appropriate in estimating the background error covariance(BEC) in 3DVAR. The assimilation of observations in domain 2 is beneficial to improve 24-h forecasts in domain 3. The 24-h forecast performance does not change much depending on the estimation period of the BEC in 3DVAR. The results of this study provide a basis to establish the operational data assimilation system for the Republic of Korea Air Force Weather Group.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2018년도 학술발표회
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• pp.173-173
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• 2018

본 연구는 기상-수문 분야에서 고해상도 수문기상요소를 산출하기 위해 WRF-Hydro(Weather Research and Forecasting and Model Hydrological modeling extension package) 모형을 한반도 대상으로 구축하였다. 모형은 미국 대기 연구 국립센터(NOAA)에서 개발된 커뮤니티형 고해상도 예측모델이므로 미국 등에서 활발히 활용되기 시작하였으나 아직 우리나라 적용성에 대한 연구는 많지 않다. 본 연구에서는 WRF-Hydro 모형을 한반도에 적절히 사용하기 위해 표면유출, 보수깊이, 표면거칠기와 같은 파라미터를 보정하였다. WRF-Hydro는 지역 기상모형인 WRF와 연계하여 coupled WRF/WRF-Hydro 모형을 구동하였으며, 고해상도 유출값을 얻기 위해 미국 지질조사국(USGS)에서 제공한 HydroSHEDS(Hydrological data and map based on SHuttle Elevation Derivatives at multiple Scales)를 이용하였다. 본 연구에서는 관측된 유출값을 Markov Chain Monte Carlo(MCMC) 방법을 활용하여 모형값과 비교하여 파라미터 보정을 수행하였으며, 파라미터 보정된 WRF/WRF-Hydro를 활용해 한반도 과거 홍수 및 가뭄 사상을 모의하여 결과를 분석하였다.

• 한국대기환경학회지
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• 제25권6호
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• pp.539-549
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• 2009

The purpose of this study is to estimate hourly Asian dust emission flux in springtime by using the optimized Weather Research Forecasting model (WRF) in order to accurately predict the horizontal flux of Asian dusts. Asian dust emission flux using 5 empirical formulas such as US EPA, Park and Inn, Wang, The Goddard Chemistry Aerosol Radiation and Transport (GOCART) and Dust Entrainment and Deposition (DEAD) were calculated and compared by using classified land-use types and size distribution at various locations in China and Mongolia together with the hourly meteorological elements of the WRF model. As a result, the empirical formula in US EPA among them, which was considered the various conditions such as vegetation, soil type and terrain, was better than the other 4 empirical formulas. However, these formulas were adjusted hourly and vertically in time and space because there was different order and time resolution of dust emissions from original empirical formulas.

• 한국대기환경학회지
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• 제28권3호
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• pp.261-272
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• 2012

In this study, climate variability was predicted by the Weather Research and Forecasting (WRF) model under two different scenarios (current trends scenario; SC1 and managed scenario; SC2) for future urban growth over the Seoul metropolitan area (SMA). We used the urban growth model, SLEUTH (Slope, Land-use, Excluded, Urban, Transportation, Hill-Shade) to predict the future urban growth in SMA. As a result, the difference of urban ratio between two scenarios was the maximum up to 2.2% during 50 years (2000~2050). Also, the results of SLEUTH like this were adjusted in the Weather Research and Forecasting (WRF) model to analysis the difference of the future climate for the future urbanization effect. By scenarios of urban growth, we knew that the significant differences of surface temperature with a maximum of about 4 K and PBL height with a maximum of about 200 m appeared locally in newly urbanized area. However, wind speeds are not sensitive for the future urban growth in SMA. These results show that we need to consider the future land-use changes or future urban extension in the study for the prediction of future climate changes.

• Nuclear Engineering and Technology
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• 제53권1호
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• pp.244-252
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• 2021

Wind plays an important role in cases of unexpected radioactive pollutant dispersion, deciding distribution and concentration of the leaked substance. The accurate prediction of wind has been challenging in numerical weather prediction models, especially near the surface because of the complex interaction between turbulent flow and topographic effect. In this study, we investigated the characteristics of atmospheric dispersion of radioactive material (i.e. ¹³⁷Cs) according to the simulated boundary layer around the HANARO research nuclear reactor in Korea using the Weather Research and Forecasting (WRF)-Mesoscale Model Interface (MMIF)-California Puff (CALPUFF) model system. We examined the impacts of orographic drag on wind field, stability calculation methods, and planetary boundary layer parameterizations on the dispersion of radioactive material under a radioactive leaking scenario. We found that inclusion of the orographic drag effect in the WRF model improved the wind prediction most significantly over the complex terrain area, leading the model system to estimate the radioactive concentration near the reactor more conservatively. We also emphasized the importance of the stability calculation method and employing the skillful boundary layer parameterization to ensure more accurate low atmospheric conditions, in order to simulate more feasible spatial distribution of the radioactive dispersion in leaking scenarios.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2009년도 공동학술대회
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• pp.449-451
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• 2009

지구온난화에 따른 해수면 상승과 태풍 강도의 증가는 연안역에 밀집한 주거 및 산업공간을 위협하는 요소로 최근 그 연구가 활발하게 진행되어 오고 있다. 본 연구에서는 안전한 해상교통 및 폭풍해일과 파랑예측을 위해서 반드시 필요한 해상풍에 대한 연구이다. 해상풍은 연안역에서의 자연재해를 유발하는 여러 요소 중에서 중요한 연구과제이나, 현재 가상수치모델에 의한 해상풍 및 해면기압은 시 공간적으로 불충분하다. 따라서, 중규모 기상 모형인 Weather Research and Forecasting(WRF)을 사용하여 우리나라 주변해역을 모두 포함하며, 약 9km 격자로 매일 두 번씩 72시간을 예보하는 해상풍을 산출하는 시스템을 구축하였다. 이어도 해양과학기지와 황해중부부이에서 실측한 해상풍과 검증한 결과 상당히 유의할 만한 결과를 얻었으며, 자료동화을 이용하여 향후에는 보다 정확한 해상풍을 산출할 계획이다.