• 대기
• /
• 제21권1호
• /
• pp.17-33
• /
• 2011

A dynamical downscaling system for seasonal forecast has been constructed based on a regional climate model, and its predictability was investigated for 10 years' wintertime (December-January-February; DJF) climatology in East Asia. Initial and lateral boundary conditions were obtained from the operational seasonal forecasting data, which are realtime output of the Global Data Assimilation and Prediction System (GDAPS) at Korea Meteorological Administration (KMA). Sea surface temperature was also obtained from the operational forecasts, i.e., KMA El-Nino and Global Sea Surface Temperature Forecast System. In order to determine the better configuration of the regional climate model for East Asian regions, two sensitivity experiments were carried out for one winter season (97/98 DJF): One is for the topography blending and the other is for the cumulus parameterization scheme. After determining the proper configuration, the predictability of the regional forecasting system was validated with respect to 850 hPa temperature and precipitation. The results showed that mean fields error and other verification statistics were generally decreased compared to GDAPS, most evident in 500 hPa geopotential heights. These improved simulation affected season prediction, and then HSS was better 36% and 11% about 850 hPa temperature and precipitation, respectively.

• 한국지구과학회지
• /
• 제34권4호
• /
• pp.303-312
• /
• 2013

중위도 기압골과 태풍 이동속도와의 상호작용에 대한 예측에서 한국기상청 전구자료동화예측시스템(GDAPS) 모델 바이어스 경향을 알아보기 위해 태풍 산바 사례가 선정되었다. 이 연구는 태풍 분석 및 예측 시스템(TAPS) 및 기상정보시스템-3(COMIS-3)에 저장된 태풍자료로부터 2012년 9월 15일 00UTC로 초기화 된 한국 기상청 GDAPS 분석장과 예측장을 사용하였다. 먼저 해면기압장은 500 hPa 제트구역과 연관하여 중위도 하층 저기압이 발생됨을 보여주었다. 이후 태풍 산바가 중위도 지역으로 들어온 후, 태풍의 이동속도가 증가될 것이라 예측되었다. 특히, 태풍 산바가 9월 17일 00UTC와 06UTC에 전향을 할 시점에 태풍 산바는 중위도 기압골 전면에서 중위도 서풍대와 상호작용을 하였다. 반면, 기상청 GDAPS 해면기압 예측장은 하층 중위도 저기압의 강도를 분석장보다 약하게 예측하였다. 결국 태풍 산바의 이동속도에 영향을 주는 중위도 순환은 분석장보다 느리게 나타났다. 이 순환은 500 hPa에서 제트가 약화됨으로서 증명되었다. 이런 이유로, 기상청 GDAPS 예측장은 태풍 산바가 중위도 기압골과 상호작용함으로써 느린 이동속도의 바이어스를 나타내었다.

• 대기
• /
• 제17권2호
• /
• pp.207-216
• /
• 2007

The Moving-nest Typhoon Model (MTM) was installed on the Korea Meteorological Administration (KMA)'s CRAY X1E in 2006 and started its test operation in August 2006 to provide track and intensity forecasts of tropical cyclones. In this study, feasibility of the MTM forecast is compared with the Global Data Assimilation and Prediction System (GDAPS) of the KMA and the operational typhoon forecast models in the Japan Meteorological Agency (JMA), from the sixth tropical cyclone to the twentieth in 2006. Forecast skills in terms of the storm position error of the two KMA models were comparable, but MTM showed a slightly better ability. While both GDAPS and MTM produced larger errors than JMA models in track forecast, the predicted intensity was much improved by MTM, making it comparable to the JMA's typhoon forecast model. It is believed that the Geophysical Fluid Dynamics Laboratory (GFDL) bogus initialization method in MTM improves the ability to forecast typhoon intensity.

• 대기
• /
• 제28권4호
• /
• pp.403-414
• /
• 2018

Predictability of Northern Hemisphere blocking in the Korea Meteorological Administration (KMA) Global Data Assimilation and Prediction System (GDAPS) is evaluated for the period of July 2016 to May 2017. Using the operational model output, blocking is defined by a meridional gradient reversal of 500-hPa geopotential height as Tibaldi-Molteni Index. Its predictability is quantified by computing the critical success index and bias score against ERA-Interim data. It turns out that Northwest Pacific blockings, among others, are reasonably well predicted with a forecast lead time of 2~3 days. The highest prediction skill is found in spring with 3.5 lead days, whereas the lowest prediction skill is observed in autumn with 2.25 lead days. Although further analyses are needed with longer dataset, this result suggests that Northern Hemisphere blocking is not well predicted in the operational weather prediction model beyond a short-term weather prediction limit. In the spring, summer, and autumn periods, there was a tendency to overestimate the Western North Pacific blocking.

• 대기
• /
• 제30권2호
• /
• pp.115-124
• /
• 2020

The Northern Hemisphere extratropical prediction skill of the Korea Meteorological Administration (KMA) Global Data Assimilation and Prediction System (GDAPS) is examined for January 2019. The real-time prediction skill, evaluated with mean squared skill score (MSSS) of 30-90°N geopotential height field at 500 hPa (Z500), is ~8 days in the troposphere. The MSSS of Z500 considerably decreases after 3 days mainly due to the increasing eddy errors. The eddy errors are largely explained by the eddy-phased errors with minor contribution of amplitude errors. In particular, planetary-scale eddy errors are considered as a main reason of rapidly increasing errors. It turns out that such errors are associated with the blocking highs over North Pacific (NP) and Euro-Atlantic (EA) regions. The model overestimates the blocking highs over NP and EA regions in time, showing dependence of blocking predictability on blocking initializations. This result suggests that the extratropical prediction skill could be improved by better representing blocking in the model.

• 한국수자원학회논문집
• /
• 제39권3호
• /
• pp.275-288
• /
• 2006

본 연구에서는 GDAPS(T213) 중기 기상 수치예보 자료를 활용한 ESP (Ensemble Streamflow Prediction) 기법을 개발하여 미래에 발생할 수 있는 댐 유입량의 중장기적 확률예측을 위해 초과 확률구간별 댐 유입량을 예측하고 RPSS 검증기법으로 예측결과의 정확도를 분석하였다. 개발된 ESP시스템을 적용한 결과 일단위 개념의 확률예보는 높은 불확실성을 내포할 수 있고, 중장기 확률예보에 초점을 맞추어 1, 3, 7일 등의 예측시간 해상도에 대한 ESP정확도의 민감도를 분석한 결과 예측시간 해상도 간격이 증가할수록 예측결과의 불확실성이 감소하면서 그 정확도가 전반적으로 증가함을 살펴볼 수 있었다. 이러한 결과를 바탕으로 GDAPS 자료를 활용한 1주 단위의 한달(28일)예보를 수행한 ESP 결과는 각 초과 확률구간 분포의 적절한 증가 및 감소로 인하여 그 시간적 변동성이 안정적으로 예측되고 예측결과의 불확실성을 감소시킬 수 있어 그 활용가치가 높은 것으로 나타났다. 이러한 관점에서 본 연구의 ESP 시스템은 중장기적 측면에서 GDAPS 자료의 활용가치를 높일 수 있고, 기존 ESP 결과보다 향상된 정확도로 댐 유입량을 예측할 수 있으므로 실시간 댐 유입량 예측에 적용한다면 수자원 관리 차원에서 유용한 수단이 될 수 있을 것이다.

• 대기
• /
• 제15권1호
• /
• pp.35-46
• /
• 2005

Today, the outreach of National Meteorological Service such as PC cluster based Numerical Weather Prediction (NWP) technique is vigorous in the world wide. In this regard, WMO (World Meteorological Organization) asked KMA (Korea Meteorological Administration) to formulate a regional project, which cover most of RA II members, using similar technical system with KMA's. In that sense, Meteorological Research Institute (METRI) in KMA developed Mongolian NWP System (MNWPS) based on PC cluster and transferred the technology to Weather Service Center in Mongolia. The hybrid parallel algorithm and channel bonding technique were adopted to cut cost and showed 41% faster performance than single MPI (Message Passing Interface) approach. The cluster technique of Beowulf type was also adopted for convenient management and saving resources. The Linux based free operating system provide very cost effective solution for operating multi-nodes. Additionally, the GNU software provide many tools, utilities and applications for construction and management of a cluster. A flash flood event happened in Mongolia (2 September 2003) was selected for test run, and MNWPS successfully simulated the event with initial and boundary condition from Global Data Assimilation and Prediction System (GDAPS) of KMA. Now, the cluster based NWP System in Mongolia has been operated for local prediction around the region and provided various auxiliary charts.

• 대기
• /
• 제16권4호
• /
• pp.303-318
• /
• 2006

A parameterization of gravity wave drag induced by cumulus convection (GWDC) proposed by Chun and Baik is implemented in the KMA operational global NWP model (GDAPS), and effects of the GWDC on the forecast for July 2005 by GDAPS are investigated. The forecast result is compared with NCEP final analyses data (FNL) and model's own analysis data. Cloud-top gravity wave stresses are concentrated in the tropical region, and the resultant forcing by the GWDC is strong in the tropical upper troposphere and lower stratosphere. Nevertheless, the effect of the GWDC is strong in the mid- to high latitudes of Southern Hemisphere and high latitudes of Northern Hemisphere. By examining the effect of the GWDC on the amplitude of the geopotential height perturbation with zonal wavenumbers 1-3, it is found that impact of the GWDC is extended to the high latitudes through the change of planetary wave activity, which is maximum in the winter hemisphere. The GWDC reduces the amplitude of zonal wavenumber 1 but increases wavenumber 2 in the winter hemisphere. This change alleviates model biases in the zonal wind not only in the lower stratosphere where the GWDC is imposed, but also in the whole troposphere, especially in the mid- to high latitudes of Southern Hemisphere. By examining root mean square error, it is found that the GWDC parameterization improves GDAPS forecast skill in the Southern Hemisphere before 7 days and partially in the Northern Hemisphere after about 5 days.

• 대기
• /
• 제18권3호
• /
• pp.159-169
• /
• 2008

The characteristics of the typhoon's extratropical transition (ET) over the western North Pacific area were investigated using the cyclone phase space (CPS) diagram method suggested by Hart (2003). The data used in this study were the global data assimilation prediction system (GDAPS) and NCEP data set. The number of typhoons selected were 75 cases during 2002 to 2007, and the three parameters were analyzed : the motion relative thickness asymmetry of the storm (B), the upper thermal wind shear and the lower thermal wind shear. Comparing the best-track data provided by the Regional Specialized Meteorological Center /Tokyo, the time of the ET based on CPS was 2~6 hours earlier than the best-track data. And it was shown that the 400- km and 30 kt wind radius of storm for the CPS method were better agreement than the previous suggested radius 500- km.

• 대한토목학회논문집
• /
• 제30권6B호
• /
• pp.579-587
• /
• 2010

기상청에서 제공하는 강우수치예보정보를 활용하여 10일이내의 중기유량예측을 수행하였다. 기상청의 원시예보자료로는 2일예보를 위한 RDAPS와 10일예측을 위한 GDAPS예측자료를 활용하였다. 수치예보의 정확도를 제고하기 위하여 강우상세 정보를 생산할 수 있는 강수진단모형(QPM)과 QPM모의결과에 내재된 계통적 편이를 제거하기 위하여 분위사상과정 (Quantile Mapping)을 적용하였다. QPM모의결과를 유출모형의 입력정보로 활용하기 위하여 일관적인 체계를 갖춘 유역강수 정보로 변환하여, 장기연속유출모형인 SSARR모형을 이용하여 금강유역내 주요지점에서의 유량예측을 수행하여 유량예측에 대한 검증을 수행하였다. 2006년 1월 1일부터 6월 20일까지 강수예측을 수행한 결과 2일예측인 RQPM의 경우 기간 총강수량을 기준으로 실적강우대비 89.7%의 강수모의값을 보임으로서 양호한 예측성능을 확인할 수 있었다. 유량예측모의에 있어서는 2일예측의 경우 일부 강우사상에서 예측누락과 예측오류가 발생하였지만 전반적으로 유량예측이 양호한 수준이었다. 다만, 하류지점의 경우 조절유량에 의한 유출모형보정의 어려움과 수위-유량관계곡선의 신뢰도저하등의 이유로 예측성능이 떨어지는 경우도 있었다. GQPM에 대한 10일강우예측은 첨두강수와 강수총량에 있어서 다소 과소한 모의값을 보이고 있으며, 강수보정효과도 RDAPS에 비하여 저조한 수준이었다. 이 부분은 강수예측의 사후보정으로는 한계가 있는 것으로 보여지며 원시예측모형의 안정화를 통하여 개선할 수 있는 부분으로 판단된다.