• 대기
• /
• 제18권1호
• /
• pp.55-70
• /
• 2008

The global time slice approach is a transient experiment using high resolution atmosphere-only model with boundary condition from the low resolution globally coupled ocean-atmosphere model. The present study employs this "time slice concept" using ECHAM4 atmosphere-only model at a horizontal resolution of T106 with the lower boundary forcing obtained from a lower-resolution (T42) greenhouse gas + aerosol forcing experiment performed using the ECHO-G/S (ECHAM4/HOPE-G) coupled model. In order to assess the impact of horizontal resolution on simulated East Asian summer monsoon climate, the differences in climate response between the time slice experiments of the present and that of IPCC SRES AR4 participating 21 models including coarser (T30) coupled model are compared. The higher resolution model from time slice experiment in the present climate show successful performance in simulating the northward migration and the location of the maximum rainfall during the rainy season over East Asia, although its rainfall amount was somewhat weak compared to the observation. Based on the present climate simulation, the possible change of East Asian summer monsoon rainfall in the future climate by the IPCC SRES A1B scenario, tends to be increased especially over the eastern part of Japan during July and September. The increase of the precipitation over this region seems to be related with the weakening of northwestern part of North Pacific High and the formation of anticyclonic flow over the south of Yangtze River in the future climate.

• Ocean and Polar Research
• /
• 제43권3호
• /
• pp.179-192
• /
• 2021

In this study, an integrated wave model from global to coastal scales was developed to improve the operational wave prediction performance of the Korean Meteorological Administration (KMA). In this system, the wave model was upgraded to the WaveWatch III version 6.07 with the improved parameterization of the source term. Considering the increased resolution of the wind input field and the introduction of the high-performance KMA 5^th Supercomputer, the spatial resolution of global and regional wave models has been doubled compared to the operational model. The physical processes and coefficients of the wave model were optimized for the current KMA global atmospheric forecasting system, the Korean Integrated Model (KIM), which is being operated since April 2020. Based on the sensitivity experiment results, the wind-wave growth parameter (β_max) for the global wave model was determined to be 1.33 with the lowest root mean square errors (RMSE). The value of β_max showed the lowest error when applied to regional/coastal wave models for the period of the typhoon season when strong winds occur. Applying the new system to the case of August 2020, the RMSE for the 48-hour significant wave height prediction was reduced by 13.4 to 17.7% compared to the existing KMA operating model. The new integrated wave prediction system plans to replace the KMA operating model after long-term verification.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
• /
• pp.415-418
• /
• 2004

The Studying is on developing precision of the moisture information on a soil. We used the data of AQUA AMSR-E which were obtained by Direct Receiving System in Korea Meteorological Administration(KMA). Although we know the Soil Moisture Information(SMI) helps the numerical weather model to produce the realistic results, we couldn't do it for the problem on a spatial resolution of the data is too low to apply. So we've tried to develop in a spatial resolution by using the AMSR-E data with a Digital Elevation Model(DEM) and Normal Difference Vegetation Index(NDVI) from AQUA MODIS and compared the difference between their information in statics. The result is more precise than the simple algorithm by a polarization ratio, and we could get the better result to use in forecast practically, if it's apply to get more detail in the vegetation temperature.

• 한국제4기학회:학술대회논문집
• /
• 한국제4기학회 2004년도 하계학술대회
• /
• pp.20-23
• /
• 2004

• 대기
• /
• 제34권2호
• /
• pp.97-106
• /
• 2024

The seasonal forecast skill of tropical cyclones (TCs) in the Northern Hemisphere from the Korea Meteorological Administration (KMA) Global Seasonal Forecast System version 6 (GloSea6) hindcast has been verified for the period 1993 to 2016. The operational climate prediction system at KMA was upgraded from GloSea5 to GloSea6 in 2022, therefore further validation was warranted for the seasonal predictability and variability of this new system for TC forecasts. In this study, we examine the frequency, track density, duration, and strength of TCs in the North Indian Ocean, the western North Pacific, the eastern North Pacific, and the North Atlantic against the best track data. This methodology follows a previous study covering the period 1996 to 2009 published in 2020. GloSea6 indicates a higher frequency of TC generation compared to observations in the western North Pacific and the eastern North Pacific, suggesting the possibility of more TC generation than GloSea5. Additionally, GloSea6 exhibits better interannual variability of TC frequency, which shows relatively good correlation with observations in the North Atlantic and the western North Pacific. Regarding TC intensity, GloSea6 still underestimates the minimum surface pressures and maximum wind speeds from TCs, as is common among most climate models due to lower horizontal resolutions. However, GloSea6 is likely capable of simulating slightly stronger TCs than GloSea5, partly attributed to more frequent 6-hourly outputs compared to the previous daily outputs.

• 대기
• /
• 제30권4호
• /
• pp.319-333
• /
• 2020

Aircraft observations constitute one of the major sources of temperature observations which provide three-dimensional information. But it is well known that the aircraft temperature data have warm bias against sonde observation data, and therefore, the correction of aircraft temperature bias is important to improve the model performance. In this study, the algorithm of the bias correction modified from operational KMA (Korea Meteorological Administration) global model is adopted in the preprocessing of aircraft observations, and the effect of the bias correction of aircraft temperature is investigated by conducting the two experiments. The assimilation with the bias correction showed better consistency in the analysis-forecast cycle in terms of the differences between observations (radiosonde and GPSRO (Global Positioning System Radio Occultation)) and 6h forecast. This resulted in an improved forecasting skill level of the mid-level temperature and geopotential height in terms of the root-mean-square error. It was noted that the benefits of the correction of aircraft temperature bias was the upper-level temperature in the midlatitudes, and this affected various parameters (winds, geopotential height) via the model dynamics.

• 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.

• 대기
• /
• 제13권4호
• /
• pp.57-70
• /
• 2003

기상연구소 주요사업 "한반도 악기상 집중관측사업(KEOP)"의 일환으로 2001년 기반공사를 시작하여 2002년 초부터 오토존데, 윈드프로파일러 등 첨단관측장비의 해남기상관측소에 도입 및 설치와 2002년 11월 연구용 도플로 레이더의 (구)무안기상대에 이전 설치로 국가 악기상 집중관측센터는 안정적으로 구축되었다. 이 집중관측센터를 중심으로 기존 기상청 관측망과 연계하여 2002년에 여름철 장마, 태풍 "루사" 그리고 강설과 같은 악기상 집중관측과 국제집중관측프로그램(CAMP/CEOP)에 참여를 위한 고층 및 플럭스 관측자료의 안정적 생산 및 DB 구축 능력 평가를 위한 고층 및 플럭스 집중관측을 국내 대학들과 협력하여 성공리에 실시하였다. 이들 집중관측자료의 초기 분석결과, 국가 악기상 집중관측센터에 설치된 첨단관측장비에서 생산된 관측자료는 악기상 구조 및 발달과정 분석연구 뿐만 아니라 지표 플럭스 연구 활성화에 크게 기여할 것으로 판단되었다. 특히 태풍 "루사" 통과시 오토존데를 이용한 3시간별 고층관측을 통한 태풍 "루사" 중심 구조 분석은 매우 의미 있는 결과로 사료된다. 앞으로 2003년 1월부터 안정적으로 운영되는 윈드프로파일러 자료를 이용하여 악기상 관련 전선 및 하층바람 구조 및 발달 과정 분석을 분석하고, 아울러 연구용 X-밴드 도플러 레이더, 오토존데 관측 자료간의 비교분석으로 윈드프로파일러 관측자료의 정확도를 평가하고자 한다. 광학강우강도계, 마이크로 강수레이더, 연구용 X-밴드 도플러 레이더 그리고 기상청 진도 S-밴드 레이더를 이용하여 악기상 강수시스템의 구조 및 발달 과정 분석할 예정이다. 또한 국가 악기상 집중관측센터는 태풍과 장마, 겨울철 폭설과 한파와 같은 악기상 집중 관측외에 봄과 가을철에 많은 강수를 동반한 저기압 통과시, 황사 발생의 경우 등에 특별관측을 수행하여 특이기상 현상의 이해력을 증진시키는데 활용코자 한다.

• 대기
• /
• 제23권1호
• /
• pp.63-71
• /
• 2013

KMA is operationally monitoring El Ni$\tilde{n}$o and La Ni$\tilde{n}$a events, which have tremendous impacts on global climate. Many scientific studies have used to define onset of El Ni$\tilde{n}$o and La Ni$\tilde{n}$a events based on the moving average and persistency of SST indices, and KMA has adopted such definition. Though the definition has been widely accepted, in the operational aspect there is a critical problem to use moving average and condition for the persistence. Because the future values for the SST indices cannot be used in the operational monitoring, the onset timing in El Ni$\tilde{n}$o and La Ni$\tilde{n}$a can be significantly delayed. We suggest here an appropriate definition of El Ni$\tilde{n}$o and La Ni$\tilde{n}$a events in the operational aspect. Instead of using the moving average and the condition for the persistence, the onset is defined based on NINO3.4 SST during last 3 months. In order to compare the new definition with the current KMA definition, we applied them to recent 60-years SST data. It is clear that the new definition can declare the onset timing of El Ni$\tilde{n}$o and La Ni$\tilde{n}$a several months earlier than that of the KMA definition. It suggest that the new definition is more appropriate to the operational monitoring on El Ni$\tilde{n}$o and La Ni$\tilde{n}$a.

• 대기
• /
• 제25권2호
• /
• pp.367-374
• /
• 2015

Korean Peninsula has high potential for occurrence of aviation turbulence. A Korean aviation Turbulence Guidance (KTG) system focused on the Korean Peninsula, named Korean-Peninsula KTG (KP-KTG) system, is developed using the high resolution (horizontal grid spacing of 1.5 km) Local Data Assimilation and Prediction System (LDAPS) of the Korea Meteorological Administration (KMA). The KP-KTG system is constructed first by selection of 15 best diagnostics of aviation turbulence using the method of probability of detection (POD) with pilot reports (PIREPs) and the LDAPS analysis data. The 15 best diagnostics are combined into an ensemble KTG predictor, named KP-KTG, with their weighting scores computed by the values of area under curve (AUC) of each diagnostics. The performance of the KP-KTG, represented by AUC, is larger than 0.84 in the recent two years (June 2012~May 2014), which is very good considering relatively small number of PIREPs. The KP-KTG can provide localized turbulence forecasting in Korean Peninsula, and its skill score is as good as that of the operational-KTG conducting in East Asia.