• Journal of the Korean Geographical Society
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• v.49 no.6
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• pp.833-848
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• 2014

The assessment of the current and future climate change-induced potential wind energy is an important issue in the planning and operations of wind farm. Here, the authors analyze spatiotemporal characteristics and variabilities of wind energy over Korean Peninsula in the near future (2006-2040) using Representative Concentration Pathway(RCP) scenarios data. In this study, National Institute of Meteorological Research (NIMR) regional climate model HadGEM3-RA based RCP 2.6 and 8.5 scenarios are analyzed. The comparison between ERA-interim and HadGEM3-RA during the period of 1981-2005 indicates that the historical simulation of HadGEM3-RA slightly overestimates (underestimates) the wind energy over the land (ocean). It also shows that interannual and intraseasonal variability of hindcast data is generally larger than those of reanalysis data. The investigation of RCP scenarios based future wind energy presents that future wind energy density will increase over the land and decrease over the ocean. The increase in the wind energy and its variability is particularly significant over the mountains and coastal areas, such as Jeju island in future global warming. More detailed analysis presents that the changes in synoptic conditions over East Asia in future decades can influence on the predicted wind energy abovementioned. It is also suggested that the uncertainty of the predicted future wind energy may increase because of the increase of interannual and intra-annual variability. In conclusion, our results can be used as a background data for devising a plan to develop and operate wind farm over the Korean Peninsula.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.3
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• pp.94-98
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• 2014

$LiCoO_2$ thin film has received diverse attention as cathodes material of thin-film micro-batteries. In this study, $LiCoO_2$ thin films were synthesized on Au substrates by sol-gel spin coating method and an annealing process. Their structures were studied using X-ray diffraction and Raman Spectroscopy. The particle morphologies of these thin films were observed by Scaning electron microscope. From the results of X-ray diffractometry and Raman Spectroscopy analyses, it was found that as-grown films had the structure of spinel (LT-$LiCoO_2$) and layered-Rock-salt (HT-$LiCoO_2$) at $550^{\circ}C$ and $750^{\circ}C$ respectively. The annealed films at $650^{\circ}C$ were presumed to be the mixed state of these two types. Throlugh the scanning electron microscope, It was estimated that the particle size in as-grown films at $750^{\circ}C$, were larger crystilline particle than in those at the other lower temperature and well distributed in the film.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.337-337
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• 2019

지구 온난화에 따른 기후변화로 인하여 태풍, 폭염, 홍수 및 가뭄 등과 같은 다양한 자연재해는 해마다 증가하고 있으며, 이에 따른 사회적 우려의 목소리가 커지고 있다. 특히 극한 강우와 홍수는 막대한 재산피해와 인명사고 등과 같은 재난에 직결된다. 자연재해에 대한 피해를 사전에 방지하기 위해서는 수자원 시스템을 이해하고, 미래 기후변화를 고려하는 것이 중요하다. 이미 많은 국가들은 기후변화에 대한 영향을 분석하고, 이에 적응하기 위한 노력을 하고 있다. 일반적으로 기후 모델로부터 생산된 모의자료를 이용하여 현재기간에 대비한 미래기간의 변화를 분석하게 되며, 이미 수문통계학 분야에서는 미래 강수량 변화를 살펴보기위해 다양한 연구가 수행되었다. 본 연구는 HadGEM3-RA 기후 모델의 강수 자료에서 연최대 자료를 추출하였고, 이를 이용하여 비정상성 지역빈도해석을 수행하였다. 지역빈도해석 방법은 홍수지수법(index flood method)을 이용하였고, 대상유역으로 한강유역을 선정하여 적용하였다. 또한 RCP(Representative Concentration Pathways) 시나리오는 RCP 4.5와 RCP 8.5를 적용하였으며, 각 시나리오에 따른 강수량 변화율은 전망 기간(S0:1979-2005, S1:2011-2040, S2: 2041-2070, S3:2071-2100)에 따라 비교 분석하였다.

• Journal of Climate Change Research
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• v.7 no.4
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• pp.433-442
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• 2016

In this study, we examine future changes in surface radiation associated with cloud amount and aerosol emission over East Asia. Data in this study is HadGEM2-CC (Hadley Centre Global Environmental Model version 2, Carbon Cycle) simulations of the Representative Concentration Pathways (RCPs) 2.6/4.5/8.5. Results show that temperature and precipitation increase with rising of the atmosphere $CO_2$. At the end of $21^{st}$ century (2070~2099) relative to the end of $20^{st}$ century (1981~2005), changes in temperature and precipitation rate are expected to increase by $+1.85^{\circ}C/+6.6%$ for RCP2.6, $+3.09^{\circ}C/+8.5%$ for RCP4.5, $+5.49^{\circ}C/10%$ for RCP8.5. The warming results from increasing Net Down Surface Long Wave Radiation Flux (LW) and Net Down Surface Short Wave Radiation Flux (SW) as well. SW change increases mainly from reduced total Aerosol Optical Depth (AOD) and low-level cloud amount. LW change is associated with increasing of atmospheric $CO_2$ and total cloud amount, since increasing cloud amounts are related to absorb LW radiation and remit the energy toward the surface. The enhancement of precipitation is attributed by increasing of high-level cloud amount. Such climate conditions are favorable for vegetation growth and extension. Expansion of C3 grass and shrub is distinct over East Asia, inducing large latent heat flux increment.

• Journal of Korea Water Resources Association
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• v.51 no.10
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• pp.905-916
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• 2018

The purpose of this study is to evaluate the climate change impact on watershed hydrology and flow duration in Geum River basin ($9,645.5km^2$) especially by extreme scenarios. The rainfall related extreme index, STARDEX (STAtistical and Regional dynamical Downscaling of EXtremes) was adopted to select the future extreme scenario from the 10 GCMs with RCP 8.5 scenarios by four projection periods (Historical: 1975~2005, 2020s: 2011~2040, 2050s: 2041~2070, 2080s: 2071~2100). As a result, the 5 scenarios of wet (CESM1-BGC and HadGEM2-ES), normal (MPI-ESM-MR), and dry (INM-CM4 and FGOALS-s2) were selected and applied to SWAT (Soil and Water Assessment Tool) hydrological model. The wet scenarios showed big differences comparing with the normal scenario in 2080s period. The 2080s evapotranspiration (ET) of wet scenarios varied from -3.2 to +3.1 mm, the 2080s total runoff (TR) varied from +5.5 to +128.4 mm. The dry scenarios showed big differences comparing with the normal scenario in 2020s period. The 2020s ET for dry scenarios varied from -16.8 to -13.3 mm and the TR varied from -264.0 to -132.3 mm respectively. For the flow duration change, the CFR (coefficient of flow regime, Q10/Q355) was altered from +4.2 to +10.5 for 2080s wet scenarios and from +1.7 to +2.6 for 2020s dry scenarios. As a result of the flow duration analysis according to the change of the hydrological factors of the Geum River basin applying the extreme climate change scenario, INM-CM4 showed suitable scenario to show extreme dry condition and FGOALS-s2 showed suitable scenario for the analysis of the drought condition with large flow duration variability. HadGEM2-ES was evaluated as a scenario that can be used for maximum flow analysis because the flow duration variability was small and CESM1-BGC was evaluated as a scenario that can be applied to the case of extreme flood analysis with large flow duration variability.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.5
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• pp.267-275
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• 2013

This study projected the future ocean wave climate changes based on global climate change scenario using the coupled climate model HadGEM2-AO according to the emission scenarios and using regional wave model. Annual mean significant wave height (SWH) is linked closely to annual mean wind speed during the forthcoming 21st Century. Because annual mean speed decreased in the western North Pacific, annual mean SWH is projected to decrease in the future. The annual mean SWH decreases for the last 30 years of the 21st century relative to the period 1971-2000 are 2~7% for RCP4.5 and 4~11% for RCP8.5, respectively. Also, extreme SWH and wind speed are projected to decrease in the future. In terms of seasonal mean, winter extreme SWH shows similar trend with annual extreme SWH; however, that of summer shows large increasing tendency compared with current climate in the western North Pacific. Therefore, typhoon intensity in the future might be more severe in the future climate.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.3
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• pp.19-29
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• 2014

This study was to evaluate the potential climate change impact on watershed hydrological components of evapotranspiration, surface runoff, lateral flow, return flow, and streamflow using Soil and Water Assessment Tool (SWAT). For Yongdam dam watershed (930 $km^2$), the SWAT model was calibrated for five years (2002-2006) and validated for three years (2004-2006) using daily streamflow data at three locations and daily soil moisture data at five locations. The Nash-Sutcliffe model efficiency (NSE) and coefficient of determination ($R^2$) were 0.43-0.67 and 0.48-0.70 for streamflow, and 0.16-0.65 and 0.27-0.76 for soil moisture, respectively. For future evaluation, the HadGEM3-RA climate data by Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios were adopted. The biased future data were corrected using 30 years (1982-2011, baseline period) of ground weather data. The HadGEM3-RA 2080s (2060-2099) temperature and precipitation showed increase of $+4.7^{\circ}C$ and +22.5 %, respectively based on the baseline data. The impacts of future climate change on the evapotranspiration, surface runoff, baseflow, and streamflow showed changes of +11.8 %, +36.8 %, +20.5 %, and +29.2 %, respectively. Overall, the future hydrologic results by RCP emission scenarios showed increase patterns due to the overall increase of future temperature and precipitation.

• Atmosphere
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• v.29 no.2
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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.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.195-195
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• 2018

기상청에서는 영국 전지구기후모델인 HadGEM2-AO 기반의 영국 지역기후모델 HadGEM3-RA로부터 생산된 기후변화 시나리오를 기후변화예측을 위한 국가표준시나리오 자료로 제공하고 있다. 하지만, 기후모델의 특성상, 관측자료와 모의자료 간에는 통계적인 차이가 존재하며, 이러한 차이를 무시하고 원자료를 그대로 분석에 사용하는 것은 무의미 하다. 따라서 이러한 보정하기 위해서 주로 Quantile Mapping, Quantile Delta Mapping, Detrended Quantile Mapping 방법이 주로 사용된다. 하지만 어떠한 편의보정 방법이든 극값이 다수 존재하는 미래기간 모의자료를 보정할 때에는 외삽법(extrapolation)의 적용이 필요하다. 외삽법의 경우 constant correction 방법이 주로 적용된다. 본 연구에서는 기상청의 국가표준시나리오를 대상으로 이러한 편의보정 방법의 적용에 따른 미래 극한강우량의 차이를 분석하고자 하였다. 우선, 모의자료에서 우리나라 주요 기상관측지점에 해당하는 격자로부터 강우량자료를 추출하고 연최대강우시계열을 산정하였다. 그 후, 위의 세 가지 편의보정 방법을 이용하여 강우자료의 편의보정을 수행하였으며, constant correction 방법을 적용하여 이상치를 보정하였다. 그 후, 보정된 미래기간 모의자료의 추세를 분석하고, 이를 미래 확률강우량 산정방법인 scale-invariance 기법에 적용하여 미래 확률강우량을 산정하였다. 그 결과, 외삽법의 적용에 따라 편의보정 방법에 따라 미래 자료의 추세 또는 확률강우량의 변화패턴은 큰 차이를 나타내지 않았지만, 그 값 자체는 다소 차이가 있는 것으로 나타났다. 이러한 차이는 사용된 GCM과 RCM 조합으로 인한 오차와 더해져, 미래 예측결과의 불확실성으로 나타나기에 미래 극한강우량 예측을 위해서는 다수의 GCM, RCM 조합뿐만 아니라 다수의 편의보정 방법에 따른 결과도 함께 고려(ensemble)하여 결과를 나타내는 것이 필요할 것으로 판단된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.175-175
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• 2018

우리나라에서 발생하는 대규모 자연재해의 상당부분은 강우에 의한 홍수피해이다. 최근 이러한 홍수피해는 기후변화와 더불어 극한강우 현상의 빈발에 의한 새로운 재해양상으로 전개되고 있으며, 이에 따라 정부에서도 재해발생시 원상복구의 개념이 아닌 항구복구의 개념으로 복구사업을 수행하고 있다. 그러나 설계에 기후변화에 대한 영향을 반영하고 있지 못하기 때문에 기후변화에 의하여 미래에 발생할 극한강우로 반복적인 피해가 예상되고 있으므로 기존의 방재성능목표 강우량의 설정 방법에 대한 개선이 필요하다. 전 세계적으로 이러한 기후변화에 의한 현상을 모의하기 위한 연구로 전지구기후모델(Global Climate Model, 이하 GCM)과 지역기후모델(Reginal Climate Model, 이하 RCM)을 사용하고 있다.우리나라 기상청에서도 CMIP5 국제사업의 표준 실험체계를 통해 전지구 기후변화 시나리오 산출을 위해서 영국 기상청 해들리센터의 GCM인 HadGEM2-AO를 도입하였다. 또한 한반도 기후변화 시나리오를 산출하기 위해 HadGEM3-RA 모형을 이용하여 전지구 기후변화 시나리오를 역학적으로 상세화하고 이를 한반도에 대해 12.5km 공간 해상도로 일 자료를 제공하고 있다. 하지만 유역규모 혹은 지점규모에서 사용하기 위해서는 이러한 일자료의 시 공간적인 상세화기법이 요구된다. 본 연구에서는 기후변화를 고려한 방재성능목표 강우량 개선 방향을 제안하기 위해 다양한 연구단에서 도출된 상세화 결과를 수집하고 비교분석을 통해 기후변화를 고려하고자 하였다. 다양한 연구기관에서 생산된 미래 확률 전망을 살펴본 결과, 동일한 GCM자료를 사용하더라도 상세화 방법론에 따라 서로 다른 결과가 도출되는 것을 확인하였다. 미래 예측의 불확실성을 고려하면 특정한 방법론이 우수하다고 평가하기는 어려움에 따라 앙상블 평균을 활용한 개선방향을 제안한다. 본 연구의 결과는 전국 지자체의 강우특성만을 고려한 것으로, 연안지역의 경우 해수면 상승을 고려하여 추가적인 대책이 필요할 것으로 판단된다.