• Ocean and Polar Research
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• v.37 no.4
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• pp.265-278
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• 2015

We analyzed the North Pacific Intermediate Water (NPIW) that was simulated in 25 coupled general circulation models (CGCMs) using historical and Representative Concentration Pathway 4.5 (RCP4.5) scenario experiments of Coupled Model Intercomparison Project Phase 5 (CMIP5), focusing on the evaluation of the performance of HadGEM2-AO. A large inter-model diversity in salinity, density, and depth of the NPIW exists even though the multi-model ensemble mean (MME) is comparable to observations. It was found that the depth of the NPIW tends to be deeper in the models in which the NPIW is relatively saltier. HadGEM2-AO simulates the lightest NPIW having the lowest salinity at shallower depth, compared with other CGCMs. Future projections of the NPIW show that the temperature of the NPIW increases, but the density decreases in all CMIP5 models. It was shown that the salinity of the NPIW decreases in most models and the decrease tends to be larger in models simulating the lighter NPIW. The HadGEM2-AO projects moderate changes in the temperature and density of the NPIW out of the CMIP5 models.

• Journal of the Korean earth science society
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• v.32 no.7
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• pp.732-749
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• 2011

In this study, 27-year (1979-2005) regional climate over the CORDEX East Asia domain was reproduced using a regional climate model, RegCM4, driven by HadGEM2-AO output, and the model's simulation skill was evaluated in terms of surface air temperature and precipitation. The RegCM4 reasonably simulated the spatial distribution and interannual variability and seasonal variability of surface air temperature, while it had systematic biases in the simulation of precipitation. In particular, simulated rainband of East Asian summer monsoon was southward shifted below $30^{\circ}N$ as compared with the observation, thereby, summer mean precipitation over South Korea was significantly underestimated. Simulated temperature from the RegCM4 driven by the HadGEM2-AO output was comparable to that driven by the reanalysis. However, the RegCM4 driven by the HadGEM2-AO had prominently poor skill in the simulation of precipitation. This can be associated with the distorted monsoon circulations in the driving data (i.e., HadGEM2-AO) such as southward shifted low-level southwesterly, which resulted in the erroneous evolution of East Asian summer monsoon simulated by RegCM4.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.343-343
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• 2012

미래 극한사상의 초과확률을 산정하기 위하여 저해상도의 전지구 기후변화 시나리오 자료를 그대로 사용하거나 이를 역학적 또는 통계적 방법으로 상세화한 고해상도 기후변화 시나리오 자료를 활용한다. 통계적 상세화는 전지구 또는 지역기후모델의 현재기후 모의 자료와 관측 자료와의 통계적 관계를 미래 예측자료에 적용하는 방법으로, 현재와 미래 기후의 시공간적 분포가 동일하다는 가정을 포함하고 있다. 반면 역학적 상세화 방법은 기후변화 강제력을 고려하는 지역기후모델을 이용하여 기후시스템의 역학 및 물리과정, 기후시스템간 의 상호작용, 기후변화의 비정상성 등을 고려할 수 있고, 변수간의 시공간적 상관성을 지구시스템의 물리 역학적 과정으로 해석할 수 있다는 장점이 있다. 이에 국립기상연구소에서는 영국 기상청의 통합모델(UM)기반의 지역기후모델(HadGEM3)을 사용하여 50 km 및 12.5 km 격자 단위로 역학적 상세화(dynamic downscaling)를 수행하였다. 본 연구에서는 역학적 상세화로 생산된 HadGEM3-RA 자료를 이용하여 현재기후(1980-2005), 가까운 미래(2020-2049)와 21세기말(2070-2099)의 20년 빈도 강수량을 비교하였다. 연구결과, 남한에 걸쳐 현재기후에 비하여 미래에는 극한강수의 크기와 빈도가 전반적으로 증가하는 경향을 확인할 수 있었다. 20년에 한번씩 발생하였던 일 극한강수는 RCP8.5를 고려한 21세기말에는 약 4년에 한번씩 발생하리라 전망되었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.32-32
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• 2017

기후변화에 따른 이상가뭄과 홍수의 영향으로 하천의 수문과 수리적 요소가 변화되고 그로인해 발생하는 지형변화와 그에 따른 수질변화 분석이 필요하다. 낙동강의 효율적인 수질관리를 위해서는 수질과 더불어 유역관리도 함께 이루어져야 한다. 기후변화로 인한 가뭄이나 홍수 등 극한 사상이 보 같은 인공구조물이 설치되어 정체성 수역이 된 낙동강 수계에 어떠한 수질변화가 일어나는지에 대한 연구가 필요하며 이를 고려한 체계적이고 통합적인 수질관리대책이 필요하다. 본 연구에서는 낙동강 유역의 합천창녕보와 창녕함안보 구간에서 HadGEM3-RA RCP 4.5와 8.5를 적용하여 미래기후시나리오를 예측하여 수문분석을 수행하였다. 수문분석 결과인 유출량을 하상변동모형의 입력자료로 적용하여 상?하류 구간의 지형변화에 미치는 영향을 분석하고자 하였다. 마지막으로 지형변화가 수질에 미치는 영향을 분석하고자 QUAL-MEV 수질모형을 적용하여 지형변화에 따른 수질분석의 상대적 비교를 통해 기후변화와 지형변화의 영향을 분석하고자 하였다. 연구결과, 기후시나리오의 경우 HadGEM3-RA RCP 4.5 보다 8.5에서 강수가 6% 증가하는 결과를 나타내고 그에 따라 유출량도 증가하고 있다. 하상변동 분석결과, 유량이 많은 풍수년에 침식과 퇴적양상이 크게 나타나고 RCP 8.5에서 변동 폭이 크게 나타났다. 하천지형변화를 고려한 수질분석결과, 유량의 증가에 따라 수질도 개선되는 결과를 나타내고 있다.

• Atmosphere
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• v.23 no.4
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• pp.367-375
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• 2013

We present here the future changes in vertical distribution of temperature and tropopause height using the HadGEM2-AO climate model forced with Representative Concentration Pathways (RCPs) scenarios. Projected changes during the 21st century are shown as differences from the baseline period (1971~2000) for global vertical distribution of temperature and tropopause height. All RCP scenarios show warming throughout the troposphere and cooling in the stratosphere with amplified warming over the lower troposphere in the Northern Hemisphere high latitudes. Upper troposphere warming reaches a maximum in the tropics at the 300 hPa level associated with lapse-rate feedback. Also, the cooling in the stratosphere and the warming in the troposphere raises the height of the tropopause.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.122-122
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• 2011

수자원 분야에서 기후변화 관련 연구는 치수 측면 보다는 이수 측면에서 주로 이뤄지고 있다. 이는 홍수분석을 위한 시간 단위를 충족시켜주는 전지구 대기순환모형(Global Circulation Model: GCM)의 자료가 드물고, 시간 단위의 GCM 자료라 하더라도 극치값(extreme value) 표현에는 한계가 있기 때문이다. 이를 극복하기 위하여 과거 관측자료의 통계적 특성으로 극치자료의 편의(bias)를 보정하고 시간 단위로 분해하기도 한다. 하지만 이런 통계적 상세화(statistical downscaling)는 미래 기후는 과거자료와 통계적 차이가 유의하지 않음을 가정하고 있어, 미래 기후는 현재와 다를 것이라는 공감대에 는 적합하지 않다. 이와 같은 이유로 타당한 극치수문변수 결과를 얻기 위해서는 시간 단위의 고분해능(high resolution) GCM이나 지역기후모델(regional climate model)과 같은 고해상도의 미래 기후변화 자료가 필요하게 된다. 이에 국립기상연구소에서는 영국 기상청의 통합모델(UM)기반의 지역기후모델(HadGEM3)을 사용하여 50 km 및 12.5 km 격자 단위로 역학적 상세화(dynamic downscaling)를 수행하였다. 본 연구에서는 개발된 HadGEM3-RA 결과의 극치수문변수 검증을 위하여 한강유역의 관측 자료와 다양한 방법으로 비교하였다. 두 자료의 극치값을 GEV (Generalized Extreme Value) 분포에 적합(fitting)시켜 비초과확률별 극치사상과, 특정 임계값(threshold value) 이상의 극치사상 발생확률을 비교하였다. 검토 결과, HadGEM3-RA는 통계적 상세화로 구한 극치값 보다는 작았으나 기존의 지역 기후모델에 비하여 현실성 있는 극치값이 계산되었음을 확인하였다.

• Journal of Korea Water Resources Association
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• v.52 no.6
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• pp.381-395
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• 2019

The purpose of this study is to predict agricultural reservoir storage rate (RSR) in a month. This algorithm was developed by multiple linear regression model (MLRM) which included the past 3 months RSRs data and the future climate change scenarios. In order to improve use of predicted RSR, this study need the severe criteria in terms of drought. So, the predicted RSR was indexed as the 3 months reservoir drought index (RDI3) and then it was disaggregated into drought duration, severity, and intensity. For the future RSR estimation by climate change scenarios, the 6 RCP 8.5 scenarios of HadGEM2-ES, CESM1-BGC, MPI-ESM-MR, INM-CM4, FGOALS-s2, and HadGEM3-RA were used in three future evaluation periods (S1: 2011~2040, S2: 2041~2070, S3: 2071~2099). The future S3 period of HadGEM2-ES scenario which has the biggest increase in precipitation and temperature showed the largest decrease to 60.2% among the 6 scenarios compared to the historical RSR (1976~2005) 77.3%. In contrast, INM-CM4 scenario which has smallest changes in precipitation and temperature in S3 period showed the smallest decrease to 72.8%. For the CESM1-BGC and MPI-ESM-MR, FGOALS-s2, and HadGEM3-RA, the S3 period RSR showed 72.6%, 72.6%, 67.4%, and 64.5% decrease respectively. The future severe drought condition of RDI3 below -0.25 showed the increase trend for the number and severity up to -2.0 during S3 period.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.1
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• pp.146-152
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• 2004

Ghrelin is an acylated peptide recently identified as the endogenous ligand for the growth hormone (GH) secretagogues receptor 1a (GHS-R1a) and is involved in a novel system for regulating GH release. To understand the long-term effects of ghrelin, here we constructed six myogenic expression vectors containing the cDNA of swine mature ghrelin (pGEM-wt-sGhln, pGEM-wt-hGhln), ghrelin mutant of $Ser^3$ with $Trp^3$ (pGEM-mt-sGhln, pGEM-mt-hGhln) and truncated ghrelin derivative (pGEM-tmtsGhln, pGEM-tmt-hGhln) encompassing the first 7 residues of ghrelin (including $Ser^3$ substituted with $Trp^3$) and adding a basic amino acid, Lys (K) in the C-terminus. The constructs, pGEM-wt-sGhln, pGEM-mt-sGhln and pGEM-tmt-sGhln were linked with the ghrelin leader sequence, while the pGEM-wt-hGhln, pGEM-mt-hGhln and pGEM-tmt-hGhln were linked with a leader sequence from the human growth hormone releasing hormone (hGHRH). Intramuscular injection of 200 ${\mu}g$ pGEM-wt-sGhln or pGEM-tmt-sGhln augmented growth over 3 weeks in normal rats and peaked at day 21 or 14 post-injection respectively, whose body weight gains were on average approximately 6% or 19% heavier over controls. However, other injectable vectors had no such enhanced growth effects. Our results suggested that the efficacy of the ghrelin leader sequence was more effective than that of hGHRH in our system. Moreover, the results indicated that skeletal muscle might have the ability to posttranslationally modify the in vivo expressed ghrelin. And the most strikingly, the short ghrelin analog seems to mimic the biological effects more efficiently when compared with the full-length ghrelin.

• Journal of the Korean earth science society
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• v.43 no.3
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• pp.367-385
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• 2022

This study evaluates the temperature and precipitation results in East Asia simulated from the Hadley Centre Global Environmental Model version 3 regional climate model (HadGEM3-RA) developed by the UK Met Office. The HadGEM3-RA is conducted in the Coordinated Regional climate Downscaling Experiment-East Asia (CORDEX-EA) Phase II domain for 15 year (2000-2014). The spatial distribution of rainbands produced from the HadGEM3-RA by the summer monsoon is in good agreement with the Asian Precipitation Highly Resolved Observational Data Integration Towards Evaluation of water resources (APRODITE) data over the East Asia. But, precipitation amount is overestimated in Southeast Asia and underestimated over the Korean Peninsula. In particular, the simulated summer rainfall and APRODITE data show the least correlation coefficient and the maximum value of root mean square error in South Korea. Prediction of temperature in Southeast Asia shows underestimation with a maximum error during winter season, while it appears the largest underestimation in South Korea during spring season. In order to evaluate local predictability, the time series of temperature and precipitation compared to the ASOS data of the Seoul Meteorological Station is similar to the spatial average verification results in which the summer precipitation and winter temperature underestimate. Especially, the underestimation of the rainfall increases when the amounts of precipitation increase in summer. The winter temperature tends to underestimate at low temperature, while it overestimates at high temperature. The results of the extreme climate index comparison show that heat wave is overestimated and heavy rainfall is underestimated. The HadGEM3-RA simulated with a horizontal resolution of 25 km shows limitations in the prediction of mesoscale convective system and topographic precipitation. This study indicates that improvement of initial data, horizontal resolution, and physical process are necessary to improve predictability of regional climate model.

• Atmosphere
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• v.23 no.4
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• pp.527-538
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• 2013

In this study, climate over Korea based on the Historical scenario induced by HadGEM2-AO is simulated by WRF. For this purpose, a system that can be used be for numerical integration over the Far East Asian area of the center of the Korean Peninsula with 12.5 km-horizontal resolution was set-up at "Haebit", the early portion of KMA Supercomputer Unit-3. Using the system, the downscaling experiments were conducted for the period 1979-2010. The simulated results of HadGEM2-AO and WRF are presented in terms of 2 m-temperature and precipitation during boreal summer and winter of Historical for the period 1981~2005, compared with observation. As for the mean 2 m-temperature, the general patterns of HadGEM2-AO and WRF are similar with observation although WRF showed lower values than observation due to the systematic bias. WRF reproduced a feature of the terrain-following characteristics reasonably well owing to the increased horizontal resolution. Both of the models simulated the observed precipitation pattern for DJF than JJA reasonably, while the rainfall over the Korean Peninsula in JJA is less than observation. HadGEM2-AO in DJF 2 m-temperature and JJA precipitation has warm and dry biases over the Korean Peninsula, respectively. WRF showed cold bias over JJA 2 m-temperature and wet bias over DJF precipitation. The larger bias in WRF was attributed to the addition of HadGEM2-AO's bias to WRF's systematic bias. Spatial correlation analysis revealed that HadGEM2-AO and WRF had above 0.8 correlation coefficients except for JJA precipitation. In the EOF analysis, both models results explained basically same phase changes and variation as observation. Despite the difference in mean and bias fields for both models, the variabilities of the two models were almost similar with observation in many respects, implying that the downscaled results can be effectively used for the study of regional climate around the Korean Peninsula.