지역기후 접합모델링을 이용한 우리나라 해면수온 미래변화 시범전망

장찬주(Chan Joo Jang),신호정(Ho Jeong Shin),정희석(Hee seok Jung),김철호(Cheol Ho Kim) 한국연안방재학회 2017 한국연안방재학회지 Vol.4 No.1

In spite of an increasing demand on the detailed information on climate change, future climate projections for Korean waters have been conducted very limitedly. Even for the regional climate projections, most of the previous studies used a regional ocean-only model forced by a global model projection result for the atmosphere and thus could not properly simulate the air-sea interactions on a high resolution. The goal of this study is to develop a regional climate coupled model (RCCM) for the Northwest Pacific and present a future climate projection in Korean waters with including high-resolution air-sea interaction effects. In this paper, we present preliminary results focusing on sea surface temperature (SST) changes projected for Korean waters using the RCCM developed for the Northwest Pacific. The RCCM consists of an ocean model, Regional Ocean Modeling System (ROMS) and an atmospheric model, Weather Research Forecast (WRF). The projection results show some prominent features such as a considerable surface warming in the East Sea relative to the Yellow and East China Sea and a stronger warming in summer than in winter. Compared to the ocean-only model result, the RCCM result shows a significant difference in the projected SST, especially in the Yellow Sea, implying that the regional climate modeling allowing air-sea interaction can have a considerable influence on a future climate change projection.

한국해 해양열파

장찬주(Chan Joo Jang),최원근(Wonkeun Choi) 한국에너지기후변화학회 2021 한국에너지기후변화학회 학술대회 Vol.2021 No.5

가을철 대한해협 표면혼합층의 단기변화

장찬주,김구,심태보,Jang, Chan-Joo,Kim, Kuh,Shim, Tae-Bo 한국해양학회 1995 韓國海洋學會誌 Vol.30 No.5

To investigate a short-term (from 2 hours to 24 hours) variability of a mixed layer, oceanographical data (water temperature, salinity, current) and meteorological data (wind, air temperature, solar radiation) were collected at a site in the Korea Strait at the interval of one hour for 48 hours from October 12 to 14, 1993. The average rates of temporal variations of the mixed layer depth (MLD) and temperature of the mixed layer (MLT), which are very weakly correlated with the wind stress and buoyancy flux at the sea surface, are about 5.2 m/hour and 0.2$^{\circ}C$/hour, respectively. The mixed layer is relatively shallow when both MLT and MLS (salinity of the mixed layer) are low, while MLD is relatively deep when they are high. MLT shows a sudden decrease or increase. Analysis of satellite infrared images and XBT data shows that sudden increase of MLT is caused by advection of warm water. These results suggest that the short-term variation of the mixed layer in the Korea Strait in autumn, in which surface current is relatively strong and different water masses exist, is mainly determined by advection rather than air0sea interaction such as wind stress or buoyancy flux.

연직혼합모수화가 동해 상층 모사에 미치는 영향

장찬주,임세한,Jang, Chan-Joo,Lim, Se-Han 한국군사과학기술학회 2010 한국군사과학기술학회지 Vol.13 No.6

This study investigates effects of three different parameterizations of vertical mixing scheme on upper ocean simulation of the East Sea, focusing on the seasonal variations of the sea surface temperature(SST) and the mixed layer depth(MLD) using an ocean general circulation model(GFDL MOM1.1). The considered vertical mixing schemes are the Laplacian scheme(L scheme) that use a constant eddy coefficient, the Mellor-Yamada scheme(MY scheme), and a new scheme(Noh scheme). The Noh scheme, a second-order turbulence closure, was developed considering recent observational evidences such as the enhancement of turbulent kinetic energy near the sea surface. During summer L scheme underestimates the SST, while MY scheme overestimates the SST, compared to climatological SST. Noh scheme produces the SST in better agreement with climatological one. During winter all schemes overestimate the SST up to $4^{\circ}C$ compared to climatological SST. Vertical profiles of the basin-mean temperature show that L scheme produces higher temperature below the thermocline than those of other schemes. The winter MLD simulated from L scheme is rather large compared to that from other schemes, but the differences in MLD during summer are not significant.

지구온난화의 지역적 특성: 전례 없는 기후 시기에 대한 선형 전망

신호정,장찬주,SHIN, HO-JEONG,JANG, CHAN JOO 한국해양학회 2016 바다 Vol.21 No.2

기후변화를 일으키는 외부강제력이 전지구적으로 동일하게 주어지더라도 그에 따른 기후변화와 되먹임 효과는 지역마다 다르게 나타난다. 따라서 기후변화에 나타난 내부변동성 및 다른 잡음 효과로부터 지구온난화 신호를 구별하기 위한 기후변화 탐지는 전구평균뿐만 아니라 지역규모에서도 이뤄져 왔다. 본 논문은 지구온난화로 인해 미래에 전례 없는 기후가 나타나는 시기를 추정하고 그 지역적 차이를 분석함이 목적이며 이를 위해, 기후모형 자료를 이용한 기존 연구와는 달리, 관측 자료를 이용하여 내부변동성을 추정하고 미래 온도변화를 전망하였다. 전례 없는 기후 시기는 미래에 예측된 지표 온도가 과거 관측 기록에 나타난 온도 범위를 벗어나 전례 없이 따뜻한 기후가 이후로도 지속되는 시점으로 정의하였다. 1880년부터 2014년까지 관측된 지표온도 아노말리의 연평균 시계열을 이용하여 온난화 선형추세를 계산하였고, 이 추세로부터 벗어난 최대 변이 값을 내부변동성의 크기로 간주하였다. 관측 자료로 구한 온난화 선형추세와 내부변동성의 크기가 미래에도 유지된다고 전제하고 계산한 결과에 따르면, 육지에서 전례없는 기후는, 아프리카는 서쪽에서, 유라시아는 인도와 아라비아 반도 남부 등 저위도에서, 북아메리카는 캐나다 중서부와 그린란드 등 고위도에서, 남아메리카는 아마존을 포함하는 저위도에서, 남극대륙은 로스해 주변지역에서 향후 200년 이내에 비교적 빨리 나타나며, 우리나라를 포함한 동아시아 일부 지역에서도 200년 이내로 빨리 나타난다. 반면에 북유럽을 포함하는 고위도 유라시아 지역과 미국과 멕시코를 포함하는 북아메리카 중남부에서는 400년 이후에 나타난다. 해양에서는 전례 없는 기후가 인도양, 중위도 북대서양과 남대서양, 남극해 일부 해역과 남극 로스해, 북극해 일부 해역에서 200년 이내로 비교적 빨리 나타나는 반면, 내부변동성이 큰 동적도태평양, 중위도 북태평양 등의 일부 해역에서는 수천 년이 지나야 오는 곳도 있다. 즉, 전례 없는 기후시기는 육지에서는 대륙마다 서로 다른 양상을 보이고 해양에서는 온난화 추세가 큰 고위도 해역을 제외하면 내부변동성의 영향을 많이 받는다. 결론적으로 지구온난화로 인한 전례 없는 기후는 특정 시기에 공통적으로 나타나는 것이 아니라 지역에 따라 시기적으로 상당한 차이가 있다. 따라서 기후변화 대응책을 마련할 때 온난화 추세뿐만 아니라 내부변동성의 크기도 함께 고려할 필요가 있다. Even if an external forcing that will drive a climate change is given uniformly over the globe, the corresponding climate change and the feedbacks by the climate system differ by region. Thus the detection of global warming signal has been made on a regional scale as well as on a global average against the internal variabilities and other noises involved in the climate change. The purpose of this study is to estimate a timing of unprecedented climate due to global warming and to analyze the regional differences in the estimated results. For this purpose, unlike previous studies that used climate simulation data, we used an observational dataset to estimate a magnitude of internal variability and a future temperature change. We calculated a linear trend in surface temperature using a historical temperature record from 1880 to 2014 and a magnitude of internal variability as the largest temperature displacement from the linear trend. A timing of unprecedented climate was defined as the first year when a predicted minimum temperature exceeds the maximum temperature record in a historical data and remains as such since then. Presumed that the linear trend and the maximum displacement will be maintained in the future, an unprecedented climate over the land would come within 200 years from now in the western area of Africa, the low latitudes including India and the southern part of Arabian Peninsula in Eurasia, the high latitudes including Greenland and the mid-western part of Canada in North America, the low latitudes including Amazon in South America, the areas surrounding the Ross Sea in Antarctica, and parts of East Asia including Korean Peninsula. On the other hand, an unprecedented climate would come later after 400 years in the high latitudes of Eurasia including the northern Europe, the middle and southern parts of North America including the U.S.A. and Mexico. For the ocean, an unprecedented climate would come within 200 years over the Indian Ocean, the middle latitudes of the North Atlantic and the South Atlantic, parts of the Southern Ocean, the Antarctic Ross Sea, and parts of the Arctic Sea. In the meantime, an unprecedented climate would come even after thousands of years over some other regions of ocean including the eastern tropical Pacific and the North Pacific middle latitudes where an internal variability is large. In summary, spatial pattern in timing of unprecedented climate are different for each continent. For the ocean, it is highly affected by large internal variability except for the high-latitude regions with a significant warming trend. As such, a timing of an unprecedented climate would not be uniform over the globe but considerably different by region. Our results suggest that it is necessary to consider an internal variability as well as a regional warming rate when planning a climate change mitigation and adaption policy.

선체 고정형 소나의 음영 구역 최소화

임세한,한윤후,장찬주,Lim, Se-Han,Han, Yun-Hoo,Jang, Chan-Joo 한국군사과학기술학회 2010 한국군사과학기술학회지 Vol.13 No.2

This paper introduces the Hull Mounted Sonar Vertical Scanning(HMS Verscan) technique to overcome the limitation of target detection in short range shadow zone. Numerical experiments were done with the HMS Verscan taking advantage of the vertical beamforming technique for two-dimension hydrospace(range-depth). For numerical experiments, ray model and high-frequency monostatic reverberation model were used. HMS Verscan increased a sound pressure level at the short range shadow zone through reflections at the sea surface and seafloor. Inclusion of the boundary scattering improved target detection due to the sound reflected into the shadow zone.

한국 주변해 중기 해양환경 예측모형 구축: 시범 예측

정희석(Heeseok Jung),장찬주(Chan Joo Jang),김용선(Yong Sun Kim),강수경(Sukyung Kang) 한국연안방재학회 2018 한국연안방재학회지 Vol.5 No.1

Despite its socio-economic implications for the effective management of fisheries resources, a prediction of marine environment has been rarely performed on the medium range timescale of several months to a year. In this study, we have developed an ocean mid-range prediction system (OMIDAS) based on the Regional Ocean Model System (ROMS) for the Northwest Pacific Ocean focusing on the seas around Korea. To assess the skill of mid-range prediction by the OMIDAS system, a three-month reforecast was performed for the case of March 2016 by using dynamic downscaling of Climate Forecast System version 2 operational analysis data. Although the reforcasted SST shows enhanced amplitudes relative to the Optimum Interpolation SST version 2 (OISSTv2) reanalysis data, the spatial pattern is generally similar to the OISSTv2, suggesting a relatively good performance of the OMIDAS. A reforecast experiment with two different initial conditions suggests that a higher resolution of data used for model initial condition contributes to the performance of the mid-range reforecast in the seas around Korea. Based on the preliminary analysis for the reforecast experiment, we can conclude that the OMIDAS system has measurable skill on the mid-range timescale for the seas around Korea.

고해상도 파랑후측에서 나타난 동해 파랑기후의 40년 선형추세

김기호(Kiho Kim),장찬주(Chan Joo Jang) 한국연안방재학회 2020 한국연안방재학회지 Vol.7 No.2

Changes in ocean wave climate play a crucial role in the coastal environments such as coastline change and coastal erosion. In this study, we investigate 99th percentile significant wave heights (SWH) (a measure for extreme SWHs), peak wave period (PWP), and peak wave direction (PWD) in the East Sea, using a 40-year (1979~2018) wave hindcast data simulated from a high-resolution wave model (SWAN) forced with the ERA-Interim wind fields. In association with the substantial seasonality in wind fields by the East Asian monsoon, the long-term means of wave properties (SWH, PWP, PWD) and trend of 99th percentile SWHs appear to significantly differ on the seasonal timescale. In addition, PWP shows an increasing trend in most of the East Sea, except for the northern East Sea during August to October showing a decreasing trend. Our findings suggest that while the PWP tends to increase in most of the East Sea except the northern area from August to October, the long-term trends of the 99th percentile SWH in the East Sea could considerably different depending on regions and seasons.

북서태평양 중기해양 예측모형 개발

정희석(Jung, Heeseok),장찬주(Jang, Chan Joo),김용선(Kim, Yong Sun) 한국연안방재학회 2019 한국연안방재학회 학술발표대회 논문집 Vol.2019 No.1

한반도 주변해를 포함한 북서태평양의 해양환경 중기예측을 위하여 지역해양순환모형(ROMS)를 이용해 중기해양 예측모형(Ocean Mid-rAnge prediction System, OMIDAS)을 구축하였다. 수립한 모형의 계절별 3개월 재예측 실험을 수행하였고 그 결과를 이용하여 해면수온 예측 성능을 평가하였다.

하계 동중국해 북부 해역에서 저층 냉수괴의 거동

장성태,이재학,김철호,장찬주,장영석,Jang, Sung-Tae,Lee, Jae-Hak,Kim, Cheol-Ho,Jang, Chan-Joo,Jang, Young-Suk 한국해양학회 2011 바다 Vol.16 No.1

황해저층냉수는 지난 동계의 차고 건조한 바람에 의해 생성되어, 하계에 황해 중앙골을 따라 남하하는 것으로 알려져 있다. 동중국해 북부해역에서 황해저층냉수의 특성과 거동을 파악하기 위해 2003년부터 2009년까지 하계에 관측한 자료를 분석하였다. 수괴분석을 통해 본 연구해역에 영향을 미치는 황해저층냉수를 새롭게 정의하여 북서저층냉수라고 명명하였고, 수온 $13.2^{\circ}C$ 이하, 염분 32.6~33.7 psu와 밀도 $24.7{\sim}25.5\;{\sigma}_t$로 특성지었다. 지형류 계산에 의해 연구해역에서 북서저층냉수는 약 2 cm/s 이하의 속도로 남하하는 것으로 추정하였다. 정의한 북서저층냉수는 수온의 범위와 자지하고 있는 영역에서 연간 변동을 보이며, 이러한 변동은 이전 해 동계 황동중국해의 표층수온의 변화와 밀접한 관련이 있었고, 동계 표층수온의 변화는 동계 기온에 의한 영향이 지배적임을 확인하였다. 동계 동중국해 표층수온은 북극진동 지수와 높은 상관성을 보이며, 동계의 북극진동이 음일 때 동중국해 표층수온이 하강하였고, 이러한 영향으로 북서저층냉수 세력이 동중국해 북부 해역까지 저수온을 보이면서 확장하였다. 동 연구는 동계의 북극진동지수, 황동중국해 겨울철 표층수온, 동중국해 북부의 북서저층냉수가 역학적으로 관련이 있음을 보였고, 이를 바탕으로 하계 동중국해 북부해역에서 저층냉수의 거동을 유추할 수 있을 것으로 사료된다. The Yellow Sea Cold Water (YSCW) is formed by cold and dry wind in the previous winter, and is known to spread southward along the central trough of the Yellow Sea in summer. Water characteristics of the YSCW and its movement in the northern East China Sea (ECS) are investigated by analyzing CTD (conductivity-Temperature-Depth) data collected from summertime hydrographic surveys between 2003 and 2009. By water mass analysis, we newly define the North Western Cold Water (NWCW) as a cold water mass observed in the study area. It is characterized by temperature below $13.2^{\circ}C$, salinity of 32.6~33.7 psu, and density (${\sigma}_t$) of 24.7~25.5. The NWCW appears to flow southward at about a speed less than 2 cm/s according to the geostrophic calculation. The newly defined NWCW shows an interannual variation in the range of temperature and occupied area, which is in close relation with the sea surface temperature (SST) over the Yellow Sea and the East China Sea in the previous winter season. The winter SST is determined by winter air temperature, which shows a high correlation with the winter-mean Arctic Oscillation (AO) index. The negative winter-mean AO causes the low winter SST over the Yellow Sea and the East China Sea, resulting in the summertime expansion and lower temperature of the NWCW in the study area. This study shows a dynamic relation among the winter-mean AO index, SST, and NWCW, which helps to predict the movement of NWCW in the northern ECS in summer.