• 한국환경과학회지
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• 제19권2호
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• pp.137-148
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• 2010

This paper investigates the characteristics of turbulence schemes. Turbulence closures are fundamental for modeling the atmospheric diffusion, transport and dispersion in the boundary layer. In particular, in non-homogeneous conditions, a proper description of turbulent transport in planetary boundary layer is fundamental aspect. This study is based on the Regional Atmospheric Modeling System (RAMS) and combines four different turbulence schemes to assess if the different schemes have a impact on simulation results of vertical profiles. Two of these schemes are Isotropc Deformation scheme (I.Def) and Anisotropic deformation scheme (A.Def) that are simple local scheme based on Smagorinsky scheme. The other two are Mellor-Yamada scheme (MY2.5) and Deardorff TKE scheme (D.TKE) that are more complex non-local schemes that include a prognostic equation for turbulence kinetic energy. The simulated potential temperature, wind speed and mixing ratio are compared against radiosonde observations from the study region. MY2.5 shows consistently reasonable vertical profile and closet to observation. D.TKE shows good results under relatively strong synoptic condition especially, mixing ratio simulation. Validation results show that all schemes consistently underestimated wind speed and mixing ratio but, potential temperature was somewhat overestimated.

• 대기
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• 제18권4호
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• pp.387-395
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• 2008

The impact of horizontal resolution on a regional climate model was investigated by simulating precipitation over the Korean Peninsula. As a regional climate model, the SNURCM(Seoul National University Regional Climate Model) has 21 sigma layers and includes the NCAR CLM(National Center for Atmospheric Research Community Land Model) for land-surface model, the Grell scheme for cumulus convection, the Simple Ice scheme for explicit moisture, and the MRF(Medium-Range Forecast) scheme for PBL(Planetary Boundary Layer) processing. The SNURCM was performed with 20 km resolution for Korea and 60 km resolution for East Asia during a 20-year period (1980-1999). Although the SNURCM systematically underestimated precipitation over the Korean Peninsula, the increase of model resolution simulated more precipitation in the southern region of the Korean Peninsula, and a more accurate distribution of precipitation by reflecting the effect of topography. The increase of precipitation was produced by more detailed terrain data which has a 10 minute terrain in the 20 km resolution model compared to the 30 minute terrain in the 60 km resolution model. The increase in model resolution and more detailed terrain data played an important role in generating more precipitation over the Korean Peninsula. While the high resolution model with the same terrain data resulted in increasing of precipitation over the Korean Peninsula including the adjoining sea, the difference of the terrain data resolution only influenced the precipitation distribution of the mountainous area by increasing the amount of non-convective rain. In conclusion, the regional climate model (SNURCM) with higher resolution simulated more precipitation over the Korean Peninsula by reducing the systematic underestimation of precipitation over the Korean Peninsula.

• 한국지구과학회지
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• 제35권5호
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• pp.342-353
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• 2014

Data for model analysis derived from the finite volume (fv) GCM (Goddard Earth Observing System Ver. 4, GEOS-4) and the Land Data Assimilation System (LDAS) have been utilized in a mesoscale model. These data are tested to provide initial conditions and lateral boundary forcings to the Purdue Mesoscale Model (PMM) for a case study of the Midwestern flood that took place from 21-23 May 1998. The simulated results with fvGCM and LDAS soil moisture and temperature data are compared with that of ECMWF reanalysis. The initial conditions of the land surface provided by fvGCM/LDAS show significant differences in both soil moisture and ground temperature when compared to ECMWF control run, which results in a much different atmospheric state in the Planetary Boundary Layer (PBL). The simulation result shows that significant changes to the forecasted weather system occur due to the surface initial conditions, especially for the precipitation and temperature over the land. In comparing precipitation, moisture budgets, and surface energy, not only do the intensity and the location of precipitation over the Midwestern U.S. coincide better when running fvGCM/LDAS, but also the temperature forecast agrees better when compared to ECMWF reanalysis data. However, the precipitation over the Rocky Mountains is too large due to the cumulus parameterization scheme used in the PMM. The RMS errors and biases of fvGCM/LDAS are smaller than the control run and show statistical significance supporting the conclusion that the use of LDAS improves the precipitation and temperature forecast in the case of the Midwestern flood. The same method can be applied to Korea and simulations will be carried out as more LDAS data becomes available.

• 한국지구과학회지
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• 제36권1호
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• pp.90-108
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• 2015

2010년 11월 11-13일 한반도에 영향을 미쳤던 황사에 대해 WRF-Chem 모델을 이용하여 시뮬레이션 하였다. WRF-Chem 모델에서 미세먼지의 인위적 배출량은 RETRO 전구 배출량을 사용하였고, RADM2 화학 메커니즘과 MADE/SORGAM 에어로졸 스킴 및 GOCART 광물성 먼지 옵션을, 그리고 Fast-J 광해리 스킴을 선택하여 $PM_{10}$ 농도를 시뮬레이션 하였는데 연구 결과를 요약하면 다음과 같다. WRF-Chem 모델 결과에 따른 $PM_{10}$ 농도의 공간적 분포와 연직 프로파일 분석결과 2010년 11월 11-13일에 우리나라에 영향을 미쳤던 황사는 강한 가을황사로 저기압의 발달로 인해 형성된 콤마구름 때문에 황사가 한랭전선 후면에서 갇혀 상공 2.5 km 이내에서 이동 및 유입됨을 알 수 있었다. 황사 발생 기간 동안 백령도와 서울의 기상청 관측 자료와 모델의 $PM_{10}$ 농도를 시계열로 분석한 결과 상관계수와 평균제곱근오차(RMSE)는 백령도의 경우 0.763과 $192.73{\mu}g/m^3$, 서울의 경우 0.725와 $149.68{\mu}g/m^3$로 나타났다. 미세먼지인 $PM_{10}$과 $PM_{2.5}$ 농도의 공간적 분포는 유사하였고 $PM_{2.5}$가 $PM_{10}$의 약 50% 정도로 나타났으며 이는 기상청 UM-ADAM 모델 결과와도 유사하였다. $PM_{10}$ 농도와 경계층 높이, 동서 성분 바람장의 공간적 분포는 유사성을 지니고 있어 두 개의 변수를 이용하여 $PM_{10}$의 농도를 예측하는 회귀 방정식을 구하고자 우리나라에 영향을 미쳤던 강한 가을 황사(2010년 11월 11-13일)와 봄 황사(2011년 3월 19-20일) 사례를 선정하였고, 통계 모델을 이용한 회귀식을 도출하였다.