• Ocean and Polar Research
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• 제34권4호
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• pp.431-444
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• 2012

We simulated and compared present and future ocean circulation in the East China Sea using an East Asia Regional Ocean model. Mean climate states for 1990~1999 and 2030~2039 were used as surface conditions for simulations of present and future ocean circulation, which were derived from the simulations of three different global climate models, ECHAM5-MPI, GFDL-CM2.0 and MIROC3.2_hires, for the 20th century and those of 21st century as projected by the IPCC SRES A1B. East Asia Regional Ocean model simulated the detailed patterns of temperature, salinity and current fields under present and future climate conditions and their changes instead of the simple structures of global climate models. To some extent, there are consistent ocean circulation changes derived from the three pairs corresponding to the global climate model in so much as the temperature increases not only in winter but summer at both the surface and bottom and that temperature and salinity changes are prominent near the Chinese coast and in the Changjiang bank. However, the simulated circulations are different among each other depending on the prescribed atmospheric conditions not only under present climate but also with regard to future climate conditions. There is not a coincident tendency in ocean circulation changes between present and future simulations derived from the three pairs. This suggests that more simulations with different pairs are needed.

• Asia-Pacific Journal of Atmospheric Sciences
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• 제54권4호
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• pp.545-561
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• 2018

Over the North East Asia, extreme anomalous precipitation were observed in 2013 and 2014. During 2013 summer the precipitation was found to be higher (two standard deviation) than the climatological mean of the region; whereas during 2014, which was a borderline El Ni?o year, precipitation was found to be lower (one standard deviation). To understand the differences of these two anomalous years the Global/Regional Integrated Model system (GRIMs) has been used. The study found that low landsurface temperature and high sea-surface temperature over ocean caused a smaller land-sea contrast of surface temperature between East Asia and North West Pacific Ocean in 2014, which could have caused an eastward shift of mean monsoon circulation in that year compared to the circulation in 2013. Due to a change in the lower level circulation and wind field over East Asia the evaporation and moisture transport patterns became very different in those two years. In 2013, this study found high latent heat flux over Eastern China, which implies an increased surface evaporation over that region, and the moisture transported to the north by the mean monsoon circulation; whereas, there was no correlated transport of moisture to the North East Asia during 2014. The precipitable water over North East Asia has a stronger correlation with the latent heat flux over southern land region than that from Ocean region in the eastern side in both the years. A new approach is proposed to estimate the sub-grid scale hydrometeors from GRIMs, overestimated in the existing model.

• 한국지구과학회지
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• 제28권5호
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• pp.613-619
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• 2007

Mesoscale low is often observed over the downstream region of the East Sea (or, northwest coast off the Japan Islands) during East-Asia winter monsoon. The low system causes a heavy snowfall at the region. A series of numerical experiments were conducted with the aid of a regional model (MM5 ver. 3.5) to examine the formation mechanism of the mesoscale low. The following results were obtained: 1) A well-developed mesoscale low was simulated by the regional model under real topography, NCEP reanalysis, and OISST; 2) The mesoscale low was simulated under a zonally averaged SST without topography. This implies that the meridional gradient of SST is the main factor in the formation of a mesoscale low; 3) A thermal contrast ($>10^{\circ}C$) of land-sea and topography-induced disturbance served as the second important factor for the formation; 4) Paektu Mountain caused the surface wind to decelerate downstream, which created a more favorable environment for thermodynamic modification than that was found in a flat topography; and 5) The types of cumulus parameterizations did not affect the development of the mesoscale low.

• 대기
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• 제17권1호
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• pp.55-68
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• 2007

Future climate changes over East Asia are projected by anthropogenic forcing of greenhouse gases and aerosols using ECHO-G/S (ECHAM4/HOPE-G). Climate simulation in the 21st century is conducted with three standard SRES scenarios (A1B, B1, and A2) and the model performance is assessed by the 20th Century (20C3M) experiment. From the present climate simulation (20C3M), the model reproduced reliable climate state in the most fields, however, cold bias in temperature and dry bias of summer in precipitation occurred. The intercomparison among models using Taylor diagram indicates that ECHO-G/S exhibits smaller mean bias and higher pattern correlation than other nine AOGCMs. Based on SRES scenarios, East Asia will experience warmer and wetter climate in the coming 21st century. Changes of geographical patterns from the present to the future are considerably similar through all the scenarios except for the magnitude difference. The temperature in winter and precipitation in summer show remarkable increase. In spite of the large uncertainty in simulating precipitation by regional scale, we found that the summer (winter) precipitation at eastern coast (north of $40^{\circ}N$) of East Asia has significantly increased. In the 21st century, the warming over the continents of East Asia showed much more increase than that over the ocean. Hence, more enhanced (weakened) land-sea thermal contrast over East Asia in summer (winter) will cause strong (weak) monsoon. In summer, the low pressure located in East Asia becomes deeper and the moisture from the south or southeast is transported more into the land. These result in increasing precipitation amount over East Asia, especially at the coastal region. In winter, the increase (decrease) of precipitation is accompanied by strengthening (weakening) of baroclinicity over the land (sea) of East Asia.

• 한국지구과학회지
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• 제32권7호
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• pp.770-783
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• 2011

본 연구에서는 ECHAM5 모델을 통하여 생산된 현재 및 A1B 미래 기후 변화 시나리오에 따른 미래기후 자료를 미 환경예측 센터의 분광모델인 RSM을 이용하여 역학적 규모축소를 수행하였다. 현재 기후 모의는 1980-2000년 기간에 대하여 수행되었으며, 미래 기후 모의는 2040-2070 기간에 대하여 CORDEX에서 제시한 동아시아 영역에서 수행되었다. RSM의 현재 기후 모의 검증을 통해 이 모델이 기후 관점에서 대기 상태를 적절히 모의함을 판단할 수 있었다. 미래 기후 모의 결과를 현재 기후 모의 결과와 비교하여 본 결과, 여름철에 열대 해양, 남아시아, 일본 부근에서 강수가 증가하였으며, 겨울철에는 서북 태평양 지역과 열대 인도양에서 강수가 증가하였고 열대 동인도양에서는 감소하였다. 동아시아 강수의 기후장에 있어서는 미래 기후가 현재와 큰 차이를 보이지 않지만 2050년 이후의 여름철 강수는 점차 증가하는 추세를 나타내고 있다. 미래 기후의 지상 온도는 현재와 비교해 볼 때 명확한 상승이 분석되었다. 대기장에 있어서는 미래 기후에서 지구 온난화에 대한 반응으로 전체적으로 온도와 지위고도장이 증가하는 변화를 나타내었으며 이에 따라 상층 기압골이 발달함을 보였다.

• 대기
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• 제29권2호
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• pp.115-129
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• 2019

Surface winds over the ocean influence not only the climate change through air-sea interactions but the coastal erosion through the changes in wave height and direction. Thus, demands on a reliable projection of future changes in surface winds have been increasing in various fields. For the future projections, climate models have been widely used and, as a priori, their simulations of surface wind are required to be evaluated. In this study, we evaluate the climatological mean surface winds over the Korean Waters simulated by five regional climate models participating in Coordinated Regional Climate Downscaling Experiment (CORDEX) for East Asia (EA), an international regional climate model inter-comparison project. Compared with the ERA-interim reanalysis data, the CORDEX-EA models, except for HadGEM3-RA, produce stronger wind both in summer and winter. The HadGEM3-RA underestimates the wind speed and inadequately simulate the spatial distribution especially in summer. This summer wind error appears to be coincident with mean sea-level pressure in the North Pacific. For wind direction, all of the CORDEX-EA models simulate the well-known seasonal reversal of surface wind similar to the ERA-interim. Our results suggest that especially in summer, large-scale atmospheric circulation, downscaled by regional models with spectral nudging, significantly affect the regional surface wind on its pattern and strength.

• Ocean and Polar Research
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• 제34권2호
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• pp.253-264
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• 2012

In the northwestern Pacific, spawning of the common squid, Todarodes pacificus, occurs at continental shelf and slope areas of 100-500 m, and the optimum temperature for the spawning and survival of paralarvae is assumed to be $18-23^{\circ}C$. To predict the spawning ground of Todarodes pacificus under future climate conditions, we simulated the present and future ocean circulations, using an East Asia regional ocean model (Modular Ocean Model, MOM version3), projected by two different global climate models (MPI_echam5, MIROC_hires), under an IPCC SRES A1B emission scenario. Mean climate states for 1990-1999 and 2030-2039 from 20th and 21th Century Climate Change model simulation (from the IPCC 4th Assessment Report) were used as surface conditions for simulations, and we examined changes in spawning ground between the 1990s and 2030s. The results revealed that the distribution of spawning ground in the 2030s in both climate models shifted northward in the East China Sea and East Sea, for both autumn and winter populations, compared to that of the 1990s. Also, the spawning area (with $1/6^{\circ}{\times}1/6^{\circ}$ grid) in the 2030s of the autumn and winter populations will decline by 11.6% (MPI_echam5) to 30.8% (MIROC_hires) and 3.0% (MPI_echam5) to 18.2% (MIROC_hires), respectively, from those of the 1990s.

• 대기
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• 제15권2호
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• pp.75-90
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• 2005

이 연구에서는 지면-대기 모수화 방안 (BATS1e)이 접합된 미국 국립기상연구센터 (NCAR)에서 개발한 지역기후모델(RegCM2)을 이용하여 지면피복의 변화가 동아시아 여름몬순에 미치는 영향에 대해서 조사하였다. 지면피복 변화의 영향을 분석하기 위하여 두 종류의 지면피복 자료를 이용하였다. 하나는 NCAR에서 제공하는 지면피복 자료 (CTL 실험)이고 다른 하나는 최근의 기상위성자료로부터 직접 분류한 고해상도 지면피복분류 자료(LCV 실험)이다. CTL 실험에서는 중국 중부지역과 몽고지역의 지면온도가 각각 약 $1-3^{\circ}C$ 높고 낮게 모의되었다. 또한 모의 영역 북부지역에서는 강수가 과다하게 모의된 반면 모의영역 남부 바다지역의 강수는 과소하게 모의되었다. 지면피복 변화에 의한 알베도, 거칠기 길이 및 최소기공저항계수와 같은 지면의 생물리적 요소들의 변화는 지면-대기 상호작용을 변경시켰다. 즉, 지면피복이 낙엽활엽수림에서 농지와 관계농지로 변경된 LCV 실험의 중국 중부지역에서는 잠열 속과 풍속이 현저하게 증가되었다. 그 결과 CTL 실험에서 나타났던 중국 중부지역에서의 온난편차가 LCV 실험에서는 대부분 완화되었다. 중국 중부지역에서의 강한 기온 하강은 태평양과 대륙사이의 기압 차를 약화시키고 있다. 남동에서 북서방향으로의 기압경도력이 약화됨에 따라 중국 남부와 남중국해로부터 북동쪽으로의 수증기 수송도 약화되었다. 이러한 수증기 수송의 변화는 모의 영역 북부지역에서의 과다한 강수 모의와 남중국해에서의 과소한 강수모의를 동시에 크게 완화시켰다. 그러나 지면피복의 변화는 특히 7월과 8월에 한반도와 일본 열도 지역에서의 강수를 크게 증기시키고 있다.

• 대기
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• 제30권4호
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• pp.361-376
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• 2020

This study evaluates multiple Regional Climate Models (RCMs) in simulating temperature and precipitation over the Far East Asia (FEA) and estimates the portions of the total uncertainty originating in the RCMs and the driving Global Climate Models (GCMs) using nine present-day (1981~2000) climate data obtained from combinations of three GCMs and three RCMs in the CORDEX-EA phase2. Downscaling using the RCMs generally improves the present temperature and precipitation simulated in the GCMs. The mean temperature climate in the RCM simulations is similar to that in the GCMs; however, RCMs yield notably better spatial variability than the GCMs. In particular, the RCMs generally yield positive added values to the variability of the summer temperature and the winter precipitation. Evaluating the uncertainties by the GCMs (VARGCM) and the RCMs (VARRCM) on the basis of two-way ANOVA shows that VARRCM is greater than VARGCM in contrast to previous studies which showed VARGCM is larger. In particular, in the winter temperature, the ocean has a very large VARRCM of up to 30%. Precipitation shows that VARRCM is greater than VARGCM in all seasons, but the difference is insignificant. In the following study, we will analyze how the uncertainty of the climate model in the present-day period affects future climate change prospects.

• 대한원격탐사학회지
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• 제24권4호
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• pp.309-324
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• 2008

Terra/Aqua MODIS의 적외관측 자료를 이용하여 동아시아 지역에서 물리적 방법과 split-window 방법으로 총가강수량을 산출하는 알고리즘을 개발하였다. 물리적 방법에서는 동아시아 지역에 대한 분석 예측 자료를 생산하는 RDAPS 자료를 알고리즘의 초기 추정치로 사용하였다. 이 과정에서 복사전달계산을 위해 빠르고 정확도가 높은 RTTOV-7 모델을 이용하였다. Split-window를 이용한 총가강수량 산출에서는 동아시아 지역의 라디오존데 관측자료를 훈련자료로 사용하여 밝기온도를 계산하였고, 이로부터 관측된 밝기온도로부터 총가강수량을 산출할 수 있는 회귀식을 도출하였다. 위의 두 알고리즘을 2004년 8월과 12월의 MODIS 적외 자료에 적용하여 산출한 결과를 해양에서는 DMSP SSM/I 결과와 육지에서는 라디오존데 관측 결과와 비교하여 검증하였고, 이를 바탕으로 총가강수량의 정확성에 영향을 미치는 요인과 산출과정에 중요한 물리과정을 분석하였다. 비교결과 RDAPS, MODIS, split-window 방법에 비해 물리적 방법을 이용한 총가강수량의 산출 정확성이 높은 것으로 나타났다. 그러나 물리적 방법은 초기 추정치에 따라 산출결과가 상이하게 나타나는 단점을 가지고 있는 것으로 파악되었다. 따라서 TIGR 자료와 같은 기후 평균값을 초기치로 적용함에 있어 주의가 요구된다. 이러한 원인으로 지표 부근의 수증기에 대한 정보 부족 등을 들 수 있다. 이러한 단점에도 불구하고 지표와 지형의 변화가 큰 한반도를 포함한 동아시아 지역에서는 물리적 방법에 의한 총가강수량 산출의 효율성이 큰 것으로 사료된다.