• 대기
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• 제23권2호
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• pp.143-160
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• 2013

The effect of 3DVAR (Three Dimension Variational data Assimilation) was examined by comparing observation and the simulations of CNTL (to which data assimilation was not applied) and ALL (to which data assimilation was applied using ground observation data and radar data) for the case of a heavy snowfall event (case A) of 11-12 February 2011 in the Yeongdong region. In case A, heavy snow intensively came in the Yeongdong coastal region rather than Daegwallyeong, in particular, around the Gangneung and Donghae regions with total precipitation in Bukgangneung at approximately 91 mm according to the AWS observation. It can be seen that compared to CNTL, ALL simulated larger precipitation along the Yeongdong coastline extending from Sokcho to Donghae while simulating smaller precipitation for inland areas including Daegwallyeong. On comparison of the total accumulated precipitations from simulations of CNTL and ALL, and the observed total accumulated precipitation, the positive effect of the assimilation of ground observation data and radar data could be identified in Bukgangneung and Donghae, on the other hand, the negative effect of the assimilation could be identified in the Daegwallyeong and Sokcho regions. In order to examine the average accuracy of precipitation prediction by CNTL and ALL for the entire Gangwon region including the major points mentioned earlier, the three hour accumulated precipitation from simulations of CNTL and ALL were divided into 5, 10, 15, 20, 25 and 30 mm/3hr and threat Scores were calculated by forecasting time. ALL showed relatively higher TSs than CNTL for all threshold values although there were some differences. That is, when considered generally based on the Gangwon region, the accuracy of precipitation prediction from ALL was improved somewhat compared to that from CNTL.

• 한국환경과학회지
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• 제19권8호
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• pp.983-999
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• 2010

Wind power energy is one of the favorable and fast growing renewable energies. It is most important for exact analysis of wind to evaluate and forecast the wind power energy. The purpose of this study is to improve the performance of numerical atmospheric model by data assimilation over a complex coastal area. The benefit of the profiler is its high temporal resolution and dense observation data at the lower troposphere. Three wind profiler sites used in this study are inhomogeneously situated near south-western coastal area of Korean Peninsula. The method of the data assimilation for using the profiler to the model simulation is the three-dimensional variational data assimilation (3DVAR). The experiment of two cases, with/without assimilation, were conducted for how to effect on model results with wind profiler data. It was found that the assimilated case shows the more reasonable results than the other case compared with vertical observation and surface Automatic Weather Station(AWS) data. Although the effect of sonde data was better than profiler at a higher altitude, the profiler data improves the model performance at lower atmosphere. Comparison with the results of 4 June and 5 June suggests that the efficiency with hourly assimilated profiler data is strongly influenced by synoptic conditions. The reduction rate of Normalized Mean Error(NME), mean bias normalized by averaged wind speed of observation, on 4 June was 28% which was larger than 13% of 5 June. In order to examine the difference in wind power energy, the wind power density(WPD) was calculated and compared.

• KEPCO Journal on Electric Power and Energy
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• 제7권1호
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• pp.145-152
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• 2021

Environmental change due to construction of large offshore wind farm has been a debate for a long time in Korea. There are various data acquired on hydrodynamics around this area before and during construction of offshore wind farm but no data during operation could be made due to delayed schedule. In this study, environmental change such as bathymetry change and scouring was forecasted using MIKE, numerical hydrodynamics model, and its results were validated using the observation data before and during construction.

• 한국대기환경학회지
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• 제26권2호
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• pp.177-189
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• 2010

In order to incorporate correctly the large or local scale circulation in an atmospheric model, a nudging term is introduced into the equation of motion. The MM5 model was used to assess the meteorological values differences in each case, during ozone episode days in Gwangyang bay. The main objective of this study is to investigate the effect of horizontal and vertical flow fields according to the surface and vertical observation data assimilation by upper wind conditions. Therefore, we carried out several numerical experiments with various parameterization methods for nudging coefficient considering the upper wind conditions (synoptic or asynoptic condition). Nudging considering the synoptic and asynoptic nudging coefficient does have a clear advantage over dynamic initialization, therefore appropriate limitation of these nudging coefficient values on its upper wind conditions is necessary before making an assessment. Obviously, under the weak synoptic wind, there was apparent advantage associated with nudging coefficient by the regional difference. The accuracy for the prediction of the meteorological values has been improved by applying the appropriate PBL (Planetary Boundary Layer) limitation of circulation.

• 한국환경과학회지
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• 제31권6호
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• pp.525-533
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• 2022

Baengnyeongdo, located within the Asian dust stream, is an ideal place to analyze Asian dust moving into the West Sea due to its low emission of artificial pollutants. Baengnyeongdo is being used to analyze the vertical distribution of dust from the lower atmosphere to the upper layer through remote observation. This study compared the ground concentration of dust between Baengnyeongdo and the metropolitan area, estimated the lag time of transport of Asian dust from Baengnyeongdo to the metropolitan area, and examined the homogeneity of upper winds using the rawinsonde method. The results showed that the cross correlation coefficient was higher and the lag time was shorter for each observation station when the distance from Baengnyeongdo was shorter. The upper wind at Baengnyeongdo is dominated by the west/northwest wind. It is the basis for the correlation of dust concentration between Baengnyeongdo and the metropolitan area located to the east. In the future, upper wind data and Asian dust concentration data over the West Sea and Baengnyeongdo are expected to contribute to research related to the movement and prediction of Asian dust and preparation for Asian dust in the metropolitan area.

• 대한원격탐사학회지
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• 제38권5_1호
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• pp.471-484
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• 2022

본 연구는 전산유체역학 모델을 이용하여 기상청에서 운용하는 종관기상관측소(automated synoptic observing system, ASOS) 10개 지점을 대상으로 ASOS 주변 지형과 건물이 기온과 바람(풍속, 풍향) 관측 환경에 미치는 영향을 분석하였다. ASOS에서 최근 10년간 8월의 관측 자료를 기반으로 전산유체역학(computational fluid dynamics, CFD) 모델의 초기·경계 자료를 구축하였다. 실제 토지 피복을 고려한 경우와 모든 피복을 초지로 가정한 경우에 대해, 관측 고도에서 초기 기온 대비 기온 변화율을 비교함으로써 기온 관측 환경을 분석하였다. 기온 관측 환경은 관측 지점 주위의 토지 피복에 의한 영향을 많이 받았다. ASOS 주변에 지표면 온도가 높은 건물과 도로가 밀집한 경우에 기온 변화율이 크게 나타났다. 반면, 모든 토지 피복을 초지로 가정한 경우에는 초기 기온 대비 기온 변화율이 작았다. 실제 토지 피복을 고려하여 관측 고도의 유입류 대비 풍속 변화율과 풍향 변화를 비교함으로써 풍속과 풍향 관측 환경을 분석하였다. 풍속과 풍향은 ASOS 주변에 관측 고도보다 높거나 비슷한 높이의 지형과 건물 영향을 크게 받았으며, 원거리에 위치한 장애물에 의한 영향도 나타났다. 본 연구 결과는 종관기상관측소의 이전과 신설 단계에서 관측 환경 평가에 활용될 것이다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.1343-1345
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• 2003

An internal wave observation experiment by SAR in South China Sea is described. Two scenes of Radarsat ScanSAR images were acquired. Internal solitary waves are found in all the two images. It is concluded that these internal waves are generated in Bashi channel. Relationship between internal wave generation and tide is studied based on analyzing of tidal data of Legaspi in Philippine. Using ocean environmental data of this sea area internal waves’ amplitude and wave speed are detected by SAR images.

• 한국환경과학회지
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• 제17권3호
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• pp.325-334
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• 2008

The feasibility of the automation of upper-air sounding is examined by using recent 3-year$(2002\sim2004)$ observation data from Autosonde at Haenam, Korea. The Autosonde has been successfully operated since 2002 in order to produce an intensive observation data at high-impact weather events for research purpose. It is found from the analysis of recent 3 years' operation data of the system that the system could be capable of making a stable observation when strong wind greater than 20 m/s was recorded under the influence of typhoons Rusa in 2002 and Maemi in 2003. It might be concluded that there is some possibility in automating upper-air sounding for operational purpose through the reduction of operator's payment and operating cost for upper-air sounding.

• 대한원격탐사학회지
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• 제37권6_2호
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• pp.1803-1818
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• 2021

기후변화로 인해 가뭄의 발생 빈도가 증가함에 따라 광범위하게 발생하는 가뭄의 상황을 정확하게 판단할 수 있는 모니터링 체계를 갖추는 것이 매우 중요하다. 그러나 지상 관측 기상자료만으로는 한국의 전 지역에 대한 복잡한 가뭄을 모두 파악하기에는 한계가 존재하는 반면, 인공위성 원격탐사자료는 광범위한 지역에서의 가뭄의 공간적 특성을 파악하고 가뭄을 탐지하는 데 효과적으로 이용될 수 있다. 본 연구에서는 남한의 가뭄 식별을 위한 원격탐사자료의 활용 가능성을 분석하고자 하였다. 다양한 측면의 가뭄을 모니터링하기 위해 가뭄에 영향을 미치는 주요 변수인 강수량과 잠재증발산량의 원격탐사 및 지상 관측자료를 수집하였다. 원격탐사자료의 적용성 평가는 관측자료와의 비교를 중심으로 수행하였다. 먼저 원격탐사자료의 적용성과 정확성을 평가하기 위하여 관측자료와의 상관관계를 분석하고, 기상학적 가뭄 모니터링을 위해 강수량과 잠재증발산량을 이용하여 다양한 측면의 가뭄지수들을 산정하였다. 이후 원격탐사자료의 가뭄 모니터링 능력을 평가하기 위해 가뭄지수에 대한 ROC 분석을 적용하여 과거 가뭄 재현성을 확인하였다. 마지막으로 원격탐사자료를 이용한 고해상도의 가뭄 지도를 작성하여 남한의 실제 가뭄에 대한 원격탐사자료의 모니터링 활용 가능성을 평가하였다. 원격탐사자료의 적용을 통해 향후 미 계측 유역을 포함한 남한 전 지역에서 다양하게 발생하는 가뭄 상황을 파악하고 이해할 수 있을 것으로 판단되었다.

• 대기
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• 제32권4호
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• pp.323-340
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• 2022

We analyzed the high-resolution wind data of Aircraft-Based Observation from the Mode-Selective Enhanced Surveillance (Mode-S EHS) data in Korea. For assessment of its quality, the Mode-S wind data was compared with the ECMWF ReAnalysis 5 (ERA5) reanalysis and Aircraft Meteorological Data Relay (AMDAR) data for more than 3-months from 7 May 2021 to 24 August 2021 near Incheon International Airport, Korea. Considering that the AMDAR reports are not provided by all commercial aircraft, total number of the Mode-S derived wind data with a second sampling rate was about twice larger than that of available AMDAR wind data. After the quality control procedures by removing erroneous samples, it was found that the root mean square errors (RMSEs) of the Mode-S retrieved winds are similar to that from the AMDAR winds. In particular, between 550 and 650 hPa levels, RMSE of the Mode-S (AMDAR) zonal wind against ERA5 data was about 2.3 m s^-1 (1.9 m s^-1), and those increased to 3.3 m s^-1 (2.4 m s^-1) in 200~500 hPa levels. A similar trend was found in the meridional wind, but a distinct positive mean bias of 2.16 m s^-1 was observed between 875 and 1,000 hPa levels. Winds retrieved from the Mode-S also showed a good agreement directly with AMDAR data. As the Mode-S provides a large amount of data with a reliable quality, it can be useful for both data assimilation in the numerical weather prediction model and situational awareness of wind and turbulence for aviation safety in Korea.