Sensitivity of Simulated Tropical Precipitation to the Subgrid Scale Processes in a Cumulus Parameterization Scheme for Use in GCMs

Young-Hwa Byun(변영화),Song-You Hong(홍성유),Hua-Lu Pan 한국기상학회 2004 Asia-Pacific Journal of Atmospheric Sciences Vol.40 No.6

기상연구소 3개월 예측시스템의 예측성 평가

변영화(Young-Hwa Byun),송지혜(Jee-Hye Song),박수희(Suhee Park),임한철(Han-Chul Lim) 한국기상학회 2007 대기 Vol.17 No.1

The purpose of this study is to investigate predictability of the seasonal simulation by the METRI (Meteorological Research Institute) AGCM (Atmospheric General Circulation Model), which is a long-term prediction model for the METRI 3-month prediction system. We examine the performance skill of climate simulation and predictability by the analysis of variance of the METRI AGCM, focusing on the precipitation, 850 hPa temperature, and 500 hPa geopotential height. According to the result, the METRI AGCM shows systematic errors with seasonal march, and represents large errors over the equatorial region, compared to the observation. Also, the response of the METRI AGCM by the variation of the sea surface temperature is obvious for the wintertime and springtime. However, the METRI AGCM does not show the significant ENSO-related signal in autumn. In case of prediction over the east Asian region, errors between the prediction results and the observation are not quite large with the lead-time. However, in the predictability assessment using the analysis of variance method, longer lead-time makes the prediction better, and the predictability becomes better in the springtime.

지구온난화에 의한 가정용 전력에너지의 소비평가

임한철(Han-Cheol Lim),변영화(Young-Hwa Byun),권원태(Won-Tae Kwon),전종갑(Jong-Ghap Jhun) 한국기상학회 2008 대기 Vol.18 No.1

This study provides an impact assessment of climate change on energy consumption, based on ‘active-deal scenario'. This approach assumes that the amount of electric energy consumption depends on human spontaneous acts against local temperature change. In this study, a statistical model for estimation of the Residential Electric Energy Consumption (REEC) has been developed by using monthly mean temperature and monthly amount of electric energy consumption in the 6 major cities over the 1999-2005 period. The statistical model is utilized to estimate the past and future REEC, and to assess the economic benefits and damage in energy consumption sector. For an estimation of the future REEC, climate change scenario, which is generated by National Institute of Meteorological Research, is utilized in this study. According to the model, it is estimated that over the standard period (1999~2005), there might be economic benefits of about 31 billion Won/year in Seoul due to increasing temperature than in the 1980s. The REEC is also predicted to be gradually reduced across the Korean peninsula since the 2020s. These results suggest that Korea will gain economic benefits in the REEC sector during the 21st century as temperature increases under global warming scenarios.

METRI AGCM의 복사 모수화 개선에 따른 겨울철 기후모의의 특징적 변화

임한철(Han-Cheol Lim),변영화(Young-Hwa Byun),박수희(Suhee Park),권원태(Won-Tae Kwon) 한국기상학회 2009 대기 Vol.19 No.2

This study investigates characteristics of wintertime simulation conducted by METRI AGCM utilizing new radiation parameterization scheme. New radiation scheme is based on the method of Chou et al., and is utilized in the METRI AGCM recently. In order to analyze characteristics of seasonal simulation in boreal winter, hindcast dataset from 1979 to 2005 is produced in two experiments - control run (CTRL) and new model's run (RADI). Also, changes in performance skill and predictability due to implementation of new radiation scheme are examined. In the wintertime simulation, the RADI experiment tends to reduce warm bias in the upper troposphere probably due to intensification of longwave radiative cooling over the whole troposphere. The radiative cooling effect is related to weakening of longitudinal temperature gradient, leading to weaker tropospheric jet in the upper troposphere. In addition, changes in vertical thermodynamic structure have an influence on reduction of tropical precipitation. Moreover, the RADI case is less sensitive to variation of tropical sea surface temperature than the CTRL case, even though the RADI case simulates the mean climate pattern well. It implies that the RADI run does not have significant improvement in seasonal prediction point of view.

최근 우리나라 도시 인구 변화에 따른 도시화 효과 특성

김진욱(Kim, Jin-Uk),변영화(Byun, Young-Hwa),김진원(Kim, Jin-Won),김연희(Kim, Yeon-Hee) 한국기후변화학회 2021 한국기후변화학회지 Vol.12 No.6

HadGEM2-AO 기반의 빙상과 빙하에 의한 미래 해수면 변화 전망

김영미(Youngmi Kim),구태영(Tae-Young Goo),문혜진(Hyejin Moon),최준태(Juntae Choi),변영화(Young-Hwa Byun) 한국기상학회 2019 대기 Vol.29 No.4

Global warming causes various problems such as the increase of the sea surface temperature, the change of coastlines, ocean acidification and sea level rise. Sea level rise is an especially critical threat to coastal regions where massive population and infrastructure reside. Sea level change is affected by thermal expansion and mass increase. This study projected future sea level changes in the 21st century using the HadGEM2-AO with RCP8.5 scenario. In particular, sea level change due to water mass input from ice-sheets and glaciers melting is studied. Sea level based on surface mass balance of Greenland ice-sheet and Antarctica ice-sheet rose 0.045 m and 0.053 m over the period 1986~2005 to 2081~2100. During the same period, sea level owing to dynamical change on Greenland ice-sheet and Antarctica ice-sheet rose 0.055 m and 0.03 m, respectively. Additionally, glaciers melting results in 0.145 m sea level rise. Although most of the projected sea level changes from HadGEM2-AO are slightly smaller than those from 21 ensemble data of CMIP5, both results are significantly consistent each other within 90% uncertainty range of CMIP5.

항공기를 이용한 온실가스 CO₂와 CH₄의 연속관측: 안면도 겨울철 연직분포사례 분석

이선란(Shanlan Li),구태영(Tae-Young Goo),문혜진(Hyejin Moon),Lev Labzovskii,Samuel Takele Kenea,오영석(Young-Suk Oh),이해영(Haeyoung Lee),변영화(Young-Hwa Byun) 한국기상학회 2019 대기 Vol.29 No.5

A new Korean Meteorological Administration (KMA) airborne measurement platform has been established for regular observations for scientific purpose over South Korea since late 2017. CRDS G-2401m analyzer mounted on the King Air 350HW was used to continuous measurement of CO₂, CH₄ and CO mole fraction. The total uncertainty of measurements was estimated to be 0.07 ppm for CO₂, 0.5 ppb for CH₄, and 4.2 ppb for CO by combination of instrument precision, repeatability test simulated in-flight condition and water vapor correction uncertainty. The airborne vertical profile measurements were performed at a regional Global Atmosphere Watch (GAW) Anmyeon-do (AMY) station that belongs to the Total Carbon Column Observing Network (TCCON) and provides concurrent observations to the Greenhouse Gases Observing Satellite (GOSAT) overpasses. The vertical profile of CO₂ shows clear altitude gradient, while the CH₄ shows non-homogenous pattern in the free troposphere over Anmyeon-do. Vertically averaged CO₂ at the altitude between 1.5 and 8.0km are lower than AMY surface background value about 7 ppm but higher than that observed in free troposphere of western pacific region about 4 ppm, respectively. CH₄ shows lower level than those from ground GAW stations, comparable with flask airborne data that was taken in the western pacific region. Furthermore, this study shows that the combination of CH₄ distribution in free troposphere and trajectory analysis, taking account of convective mixing, is a useful tool in investigating CH₄ transport processes from tropical region to Korean region in winter season.

CMIP5 자료를 활용한 우리나라 미래 해수면 상승

허태경(Tae-Kyung Heo),김영미(Youngmi Kim),부경온(Kyung-On Boo),변영화(Young-Hwa Byun),조천호(Chunho Cho) 한국기상학회 2018 대기 Vol.28 No.1

This study presents future potential sea level change over the seas surrounding Korea using Climate Model Intercomparison Project Phase 5 9 model ensemble result from Representative Concentration Pathways (RCPs), downloaded from icdc.zmaw.de. At the end of 21st century, regional sea level changes are projected to rise 37.8, 48.1, 47.7, 65.0 cm under RCP2.6, RCP4.5, RCP6.0 and RCP8.5 scenario, respectively with the large uncertainty from about 40 to 60 cm. The results exhibit similar tendency with the global mean sea level rise (SLR) with small differences less than about 3 cm. For the East Sea, the Yellow Sea, and the southern sea of Korea, projected SLR in the Yellow Sea is smaller and SLR in the southern sea is larger than the other coastal seas. Differences among the seas are small within the range of 4 cm. Meanwhile, Commonwealth Scientific and Industrial Research Organization (CSIRO) data in 23 years shows that the mean rate of sea level changes around the Yellow Sea is high relative to the other coastal seas. For sea level change, contribution of ice and ocean related components are important, at local scale, Glacial Isostatic Adujstment also needs to be considered.

지역기후모델을 이용한 상세계절예측시스템 구축 및 겨울철 예측성 검증

김문현(Moon-Hyun Kim),강현석(Hyun-Suk Kang),변영화(Young-Hwa Byun),박수희(Suhee Park),권원태(Won-Tae Kwon) 한국기상학회 2011 대기 Vol.21 No.1

A dynamical downscaling system for seasonal forecast has been constructed based on a regional climate model, and its predictability was investigated for 10 years' wintertime (December-January-February; DJF) climatology in East Asia. Initial and lateral boundary conditions were obtained from the operational seasonal forecasting data, which are realtime output of the Global Data Assimilation and Prediction System (GDAPS) at Korea Meteorological Administration (KMA). Sea surface temperature was also obtained from the operational forecasts, i.e., KMA El-Nino and Global Sea Surface Temperature Forecast System. In order to determine the better configuration of the regional climate model for East Asian regions, two sensitivity experiments were carried out for one winter season (97/98 DJF): One is for the topography blending and the other is for the cumulus parameterization scheme. After determining the proper configuration, the predictability of the regional forecasting system was validated with respect to 850 h㎩ temperature and precipitation. The results showed that mean fields error and other verification statistics were generally decreased compared to GDAPS, most evident in 500 h㎩ geopotential heights. These improved simulation affected season prediction, and then HSS was better 36% and 11% about 850 h㎩ temperature and precipitation, respectively.

CMIP5 모델에 나타난 동아시아 여름몬순의 모의 성능평가와 미래변화

권상훈(Sang-Hoon Kwon ),부경온(Kyung-On Boo),심성보(Sungbo Shim),변영화(Young-Hwa Byun) 한국기상학회 2017 대기 Vol.27 No.2

This study evaluates CMIP5 model performance on rainy season evolution in the East Asian summer monsoon. Historical (1986~2005) simulation is analyzed using ensemble mean of CMIP5 19 models. Simulated rainfall amount is underestimated than the observed and onset and termination of rainy season are earlier in the simulation. Compared with evolution timing, duration of the rainy season is uncertain with large model spread. This area-averaged analysis results mix relative differences among the models. All model show similarity in the underestimated rainfall, but there are quite large difference in dynamic and thermodynamic processes. The model difference is shown in horizontal distribution analysis. BEST and WORST group is selected based on skill score. BEST shows better performance in northward movement of the rain band, summer monsoon domain. Especially, meridional gradient of equivalent potential temperature and low-level circulation for evolving frontal system is quite well captured in BEST. According to RCP8.5, CMIP5 projects earlier onset, delayed termination and longer duration of the rainy season with increasing rainfall amount at the end of 21st century. BEST and WORST shows similar projection for the rainy season evolution timing, meanwhile there are large discrepancy in thermodynamic structure. BEST and WORST in future projection are different in moisture flux, vertical structure of equivalent potential temperature and the subsequent unstable changes in the conditional instability.