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권희내(Hui-nae Kwon),강전호(Jeon-ho Kang),권인혁(In-Hyuk Kwon) 한국기상학회 2018 대기 Vol.28 No.4
In this study, the temperature bias of aircraft observation was estimated through comparison with sonde observation prior to developing the temperature bias correction method at the Korea Institute of Atmospheric Prediction Systems (KIAPS). First, we tried to compare aircraft temperature with collocated sonde observations at 0000 UTC on June 22, 2012. However, it was difficult to estimate the temperature bias due to the lack of samples and the uncertainty of the sonde position at high altitudes. Second, we attempted a background innovation comparison for sonde and aircraft using KIAPS Package for Observation Processing (KPOP). The one month averaged background innovation shows the aircraft temperature have a warm bias against sonde for all levels. In particular, there is a globally distinct warm bias about 0.4 K between 200 hPa and 300 hPa corresponding to flight level. Spatially, most of the areas showed the warm bias except for below 300 hPa in some part of China at 0000 and 1200 UTC and below 850 hPa in Australia at 0000 UTC. In general, the temperature bias was larger at 1200 UTC than 0000 UTC. Based on the estimated temperature bias, we have applied the static bias correction method to the aircraft temperature observation. As a result, the warm bias of the aircraft temperature has decreased at most levels, but a slight cold bias has occurred in some areas.
KIM 예보시스템에서의 Aeolus/ALADIN 수평시선 바람 자료동화
이시혜(Sihye Lee),권인혁(In-Hyuk Kwon),강전호(Jeon-Ho Kang),전형욱(Hyoung-Wook Chun),설경희(Kyung-Hee Seol),정한별(Han-Byeol Jeong),김원호(Won-Ho Kim) 한국기상학회 2022 대기 Vol.32 No.1
The Korean Integrated Model (KIM) forecast system was extended to assimilate Horizontal Line-Of-Sight (HLOS) wind observations from the Atmospheric Laser Doppler Instrument (ALADIN) on board the Atmospheric Dynamic Mission (ADM)-Aeolus satellite. Quality control procedures were developed to assess the HLOS wind data quality, and observation operators added to the KIM three-dimensional variational data assimilation system to support the new observed variables. In a global cycling experiment, assimilation of ALADIN observations led to reductions in average root-mean-square error of 2.1% and 1.3% for the zonal and meridional wind analyses when compared against European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecast System (IFS) analyses. Even though the observable variable is wind, the assimilation of ALADIN observation had an overall positive impact on the analyses of other variables, such as temperature and specific humidity. As a result, the KIM 72-hour wind forecast fields were improved in the Southern Hemisphere poleward of 30 degrees.
앙상블 자료동화 시스템에서 ASCAT 해상풍 자료동화가 분석장에 미치는 효과 분석
조영순(Youngsoon Jo),임수정(Sujeong Lim),권인혁(In-Hyuk Kwon),한현준(Hyun-Jun Han) 한국기상학회 2018 대기 Vol.28 No.3
The high-resolution ocean surface wind vector produced by scatterometer was assimilated within the Local Ensemble Transform Kalman Filter (LETKF) in Korea Institute of Atmospheric Prediction Systems (KIAPS). The Advanced Scatterometer (ASCAT) on Metop-A/B wind data was processed in the KIAPS Package for Observation Processing (KPOP), and a module capable of processing surface wind observation was implemented in the LETKF system. The LETKF data assimilation cycle for evaluating the performance improvement due to ASCAT observation was carried out for approximately 20 days from June through July 2017 when Typhoon Nepartak was present. As a result, we have found that the performance of ASCAT wind vector has a clear and beneficial effect on the data assimilation cycle. It has reduced analysis errors of wind, temperature, and humidity, as well as analysis errors of lower troposphere wind. Furthermore, by the assimilation of the ASCAT wind observation, the initial condition of the model described the typhoon structure more accurately and improved the typhoon track prediction skill. Therefore, we can expect the analysis field of LETKF will be improved if the Scatterometer wind observation is added.
비축대칭 3차원 모조 소용돌이를 이용한 열대저기압의 진로 및 강도예측
이재덕(Jae-Deok Lee),정형빈(Hyeong-Bin Cheong),강현규(Hyun-Gyu Kang),권인혁(In-Hyuk Kwon) 한국기상학회 2014 대기 Vol.24 No.2
The bogussing method was further developed by incorporating the asymmetric component into the symmetric bogus tropical cyclone of the Structure Adjustable Balanced Vortex (SABV). The asymmetric component is separated from the disturbance field associated with the tropical cyclone by establishing local polar coordinates whose center is the location of the tropical cyclone. The relative importance of wave components in azimuthal direction was evaluated, and only two or three wave components with large amplitude are added to the symmetric components. Using the Weather Research and Forecast model (WRF), initialized with the asymmetric bogus vortex, the track and central pressure of tropical cyclones were predicted. Nine tropical cyclones, which passed over Korean peninsula during 2010~2012 were selected to assess the effect of asymmetric components. Compared to the symmetric bogus tropical cyclone, the track forecast error was reduced by about 18.9% and 17.4% for 48 hours and 72 hours forecast, while the central pressure error was not improved significantly. The results suggest that the inclusion of asymmetric component is necessary to improve the track forecast of tropical cyclones.
Self-supervised Graph Learning을 통한 멀티모달 기상관측 융합
전현주 ( Hyeon-ju Jeon ),강전호 ( Jeon-ho Kang ),권인혁 ( In-hyuk Kwon ) 한국정보처리학회 2023 한국정보처리학회 학술대회논문집 Vol.30 No.2
현재 수치예보 시스템은 항공기, 위성 등 다양한 센서에서 얻은 다종 관측 데이터를 동화하여 대기 상태를 추정하고 있지만, 관측변수 또는 물리량이 서로 다른 관측들을 처리하기 위한 계산 복잡도가 매우 높다. 본 연구에서 기존 시스템의 계산 효율성을 개선하여 관측을 평가하거나 전처리하는 데에 효율적으로 활용하기 위해, 각 관측의 특성을 고려한 자기 지도학습 방법을 통해 멀티모달 기상관측으로부터 실제 대기 상태를 추정하는 방법론을 제안하고자 한다. 비균질적으로 수집되는 멀티모달 기상관측 데이터를 융합하기 위해, (i) 기상관측의 heterogeneous network를 구축하여 개별 관측의 위상정보를 표현하고, (ii) pretext task 기반의 self-supervised learning을 바탕으로 개별 관측의 특성을 표현한다. (iii) Graph neural network 기반의 예측 모델을 통해 실제에 가까운 대기 상태를 추정한다. 제안하는 모델은 대규모 수치 시뮬레이션 시스템으로 수행되는 기존 기술의 한계점을 개선함으로써, 이상 관측 탐지, 관측의 편차 보정, 관측영향 평가 등 관측 전처리 기술로 활용할 수 있다.
16세기 화폐유통 실상과 그 성격 : 악포의 유통과 금단책 운영
권인혁 제주대학교 1993 논문집 Vol.37 No.1
It is the most important matter to grasp the true nature of Akpo, the most popular currency in those days, in order to understand the real aspects of currency in the 16th Century. The Akpo, which means all kinds of Powhas except 5 Seungpo, consisted of both 3 Seungpo, 4 Seungpo and 2 Seungpo, Danpo. The former two Powhas, having utility and commodity vlaue, were the most popular exchange device, while the latter two Powhas were only used as a device of circulation without having such a utility and commedity value. In view of the established conception of currency being accounted much of the utility and commodity value in thoes days, the latter two Powhas were surely hetrogenous things. And the fact that such Powhas were used as a popular currency at that time can be a true evidence that the social circumstances were mature enough to accept that kind of currency.