• 대기
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• 제26권4호
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• pp.673-686
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• 2016

Understanding limitation of simulation for Planetary Boundary Layer (PBL) height in mesoscale meteorological model is important for accurate meteorological variable and diffusion of air pollution. This study examined the accuracy for simulated PBL heights using two different PBL schemes (MYJ, YSU) in Weather Research and Forecasting (WRF) model during the radiosonde observation period. The simulated PBL height were verified using atmospheric sounding data obtained from radiosonde observations that were conducted during 5 months from August to December 2014 over the Gumi weir in Nakdong river. Four Dimensional Data Assimilation (FDDA) using radiosonde observation data were conducted to reduce error of PBL height in WRF model. The assessment result of PBL height showed that RMSE with YSU scheme were lower than that with MYJ scheme in the day and night time, respectively. Especially, the WRF model with YSU scheme produced lower PBL height than with the MYJ scheme during night time. The YSU scheme showed lower RMSE than the MYJ scheme on sunny, cloudy and rainy day, too. The experiment result of FDDA showed that PBL height error were reduced by FDDA and PBL height at the nudging coefficient of $3.0{\times}10^{-1}$ (YSU_FDDA_2) were similar to observation compared to the nudging coefficient of $3.0{\times}10^{-4}$ (YSU_FDDA_1).

• 한국대기환경학회지
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• 제27권6호
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• pp.791-804
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• 2011

Numerical simulations were carried out to investigate the impact of PBL (Planetary boundary layer) scheme implemented in WRF on the result of meteorological fields and CMAQ modeling. 25-day period, representing high ozone concentration, was selected for the simulations. The three WRF domains covered East Asia region, Korean Peninsula and Seoul metropolitan area. The sensitivity of WRF-CMAQ modeling to the various PBL schemes was assessed and quantified by comparing model output and against observation from the meteorological and the air quality monitoring network within the domain. The meteorological variables evaluated included temperature, wind speed and direction over surface sites and upper air sounding sites. The CMAQ variables included gaseous species $O_3$ and $NO_x$ over monitoring stations. Although difference of PBL schemes implemented in WRF, they did not appreciably affect the WRF and CMAQ performance. There are partially differences between non-local and local mixing scheme, but are not distinct differences for the results of weather and air quality. It is suggested that impact of parameterization of vertical eddy diffusivity scheme in CMAQ also need to be researched in the future study.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2008년도 춘계학술대회 논문집
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• pp.553-554
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• 2008

• 한국항공운항학회지
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• 제24권3호
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• pp.10-18
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• 2016

This paper deals with the Performance Based Logistics(PBL) application scheme pertaining to optimal maintenance program for logistics of Korean Fighter Experimental(KF-X) Project. For enhancement of the performance based logistics system application to KF-X program the selection of appropriate standards fit to maximize cost-cutting, a set of performance metrics fit for the purpose of the contract, foreign technology dependence of core equipments and parts were considered. Thus, selecting appropriate standards fit for Korean logistics environment, domestic maintenance enterprise for stable rate of operation of KF-X, a systematic reliability task that is able to measure quantitative combat capability are suggested.

• 대기
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• 제20권3호
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• pp.319-332
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• 2010

Sensitivity experiments of WRF model using different planetary boundary layer (PBL) and land surface model (LSM) parameterizations are evaluated for prediction of wind fields within the surface layer. The experiments were performed with three PBL schemes (YSU, Pleim, MYJ) in combination with three land surface models (Noah, RUC, Pleim). The WRF model was conducted on a nested grid from 27-km to 1-km horizontal resolution. The simulations validated wind speed and direction at 10 m and 80 m above ground level at a 1-km spatial resolution over the South Korea. Statistical verification results indicate that Pleim and YSU PBL schemes are in good agreement with observations at 10 m above ground level, while the MYJ scheme produced predictions similar to the observed wind speed at 80 m above ground level. LSM comparisons indicate that the RUC model performs best in predicting 10-m and 80-m wind speed. It is found that MYJ (PBL) - RUC (LSM) simulations yielded the best results for wind field in the surface layer. The choice of PBL and LSM parameterization will contribute to more accurate wind predictions for air quality studies and wind power using WRF.

• 대기
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• 제16권3호
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• pp.203-213
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• 2006

The objective of this paper is to investigate the effects of physical parameterization on the simulation of a snowfall event over Korea caused by air-mass transformation by using the PSU/NCAR MM5. A heavy snowfall event over Korea during 3-5 January 2003 is selected. In addition to the control experiments employing simple-ice microphysics scheme, MRF PBL scheme, and original surface layer process, three consequent physics sensitivity experiments are performed. Each experiment exchanges microphysics (Reisner Graupel), boundary layer (YSU PBL) schemes, and revised surface layer process with a reduced thermal roughness length for the control run. The control run reproduces an overall pattern of snowfall over Korea, but with a high bias by a factor of about 2. As revealed in the previous studies, the cloud microphysics and PBL parameterizations do not show a significant sensitivity for the case of snowfall. A more sophisticated cloud processes does not reveal a discernible effect on the simulated snowfall. Further, high bias in snowfall is exaggerated when a more realistic PBL scheme is employed. On the other hand, it is found that the revised surface layer process plays a role in improving the prediction of snowfall by reducing it. Thus, it is found that a realistic design of surface layer physics in mesoscale models is an important factor to the reduction of systematic bias of the snowfall over Korea that is caused by air-mass transformation over the Yellow sea.

• 대한원격탐사학회지
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• 제36권5_1호
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• pp.793-806
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• 2020

이 연구에서는 중규모 기상모델인 WRF의 행성경계층 모수화 방안에 따른 PBLH의 정확도를 평가하기 위해 PBL 모수화 방안 가운데 YSU(Yonsei University), MYJ(Mellor-Yamada-Janjic), ACM2(Asymmetric Convective Model), BouLac(Bougeault-Lacarrere) PBL 방안을 대상으로 사례 기간(2014년 6월 26일~30일)에 대해 수치 실험을 수행하였다. 이동형 차량탑재 라이다 시스템(LIVE)으로 생산된 후방산란 신호를 이용하여 산출한 PBLH와 WRF의 PBL 방안별 예측장에서 산출된 PBLH를 상호 비교 분석하였다. 대체적으로 비국지 방안을 사용한 실험이 국지 방안을 사용한 경우보다 라이다 관측에 대해 더 높은 상관도를 나타냈다. 낮 시간에 대한 PBLH 차이의 표준 편차는 YSU(≈0.39 km), BouLac(≈0.45 km), ACM2(≈0.47 km), MYJ(≈0.53 km) PBL 방안 순으로 작은 값을 보였다. 사례 기간에 대한 RMSE 비교에서는 YSU PBL 방안이 가장 높은 정밀도를 가지는 것으로 나타났다. 차량에 탑재된 기상라이다는 여러 기상 조건하에서 수치모델 행성경계층 분석을 위한 가이던스(guidance)를 제공할 수 있을 것으로 기대된다.

• 대기
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• 제27권1호
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• pp.17-28
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• 2017

The sensitivity of the typhoon track and intensity simulation to physics schemes of the global model are examined for the typhoon Bolaven and Tembin cases by using the Global/Regional Integrated Model System-Global Model Program (GRIMs-GMP) with the physics package version 2.0 of the Korea Institute of Atmospheric Prediction Systems. Microphysics, Cloudiness, and Planetary boundary Layer (PBL) parameterizations are changed and the impact of each scheme change to typhoon simulation is compared with the control simulation and observation. It is found that change of microphysics scheme from WRF Single-Moment 5-class (WSM5) to 1-class (WSM1) affects to the typhoon simulation significantly, showing the intensified typhoon activity and increased precipitation amount, while the effect of the prognostic cloudiness and PBL enhanced mixing scheme is not noticeable. It appears that WSM1 simulates relatively unstable and drier atmospheric structure than WSM5, which is induced by the latent heat change and the associated radiative effect due to not considering ice cloud. And WSM1 results the enhanced typhoon intensity and heavy rainfall simulation. It suggests that the microphysics is important to improve the capability for typhoon simulation of a global model and to increase the predictability of medium range forecast.

• 한국지구과학회지
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• 제36권6호
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• pp.553-566
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• 2015

수도권 지역의 고해상도 수치실험에 있어 연직 해상도와 대기경계층 모수화 방안의 효과를 조사하였다. WRF 모델을 이용하여 2013년 10월 25일 0000 UTC 부터 10월 26일 0000 UTC까지 수치 적분을 수행하였다. 수치 결과는 서울 남부에 위치한 선릉지역에서 관측된 6시간 간격의 라디오존데 자료와 서울지역의 43개 자동 기상 관측소 자료를 이용하여 검증하였다. 대기 하층의 연직해상도 비교 실험은 연직 44, 50, 60개의 층으로 구성되었으며, 특히 약 2 km고도 이하의 층을 세분화하였다. 연직 해상도가 가장 높은 60개층 실험에서 대기경계층 고도의 일 변동이 가장 뚜렷하게 나타났고, 특히 산악 지형과 같은 고지대에서는 대기경계층 고도와 10 m 바람장에서 연직해상도 실험 별 차이가 크게 나타났다. WRF 모델 내 ACM2, YSU, MYJ 대기경계층 모수화 방안에 따른 온도의 민감도 실험에서는 모든 실험수행 시간대에서 수치 모델 결과가 라디오존데 관측에 비교하여 온도를 과소 모의하였다. 지상 온도는 YSU 방안과 ACM2 방안이 MYJ 방안에 비해 상대적으로 편차가 낮게 나타났다.

• 한국환경과학회지
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• 제14권11호
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• pp.1015-1026
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• 2005

The southeastern coastal area of the Korean peninsula has a complex terrain including an irregular coastline and moderately high mountains. This implies that mesoscale circulations such as mountain-valley breeze and land-sea breeze can play an important role in wind field and ocean forcing. In this study, to improve the accuracy of complex coastal rind field(surface wind and sea surface wind), we carried out the sensitivity experiments based on PBL schemes in PSU/NCAR Mesoscale Model (MM5), which is being used in the operational system at Korea Meteorological Administration. Four widely used PBL parameterization schemes in sensitivity experiments were chosen: Medium-Range Forecast (MRF), High-resolution Blackadar, Eta, and Gayno-Seaman scheme. Thereafter, case(2004. 8. 26 - 8. 27) of weak-gradient flows was simulated, and the time series and the vertical profiles of the simulated wind speed and wind direction were compared with those of hourly surface observations (AWS, BUOY) and QuikSCAT data. In the simulated results, the strength of rind speed of all schemes was overestimated in complex coastal regions, while that of about four different schemes was underestimated in islands and over the sea. Sea surface wind using the Eta scheme showed the highest wind speed over the sea and its distribution was similar to the observational data. Horizontal distribution of the simulated wind direction was very similar to that of real observational data in case of all schemes. Simulated and observed vertical distribution of wind field was also similar under boundary layer(about 1 km), however the simulated wind speed was underestimated in upper layer.