격자기반 Common Land Model을 이용한 고해상도 지표 모의

이종석(Lee Jong Seok),손인욱(Son In Ook),최현일(Choi Hyun Il) 한국방재학회 2017 한국방재학회논문집 Vol.17 No.2

기후변화는 수자원을 비롯한 자연자원에 큰 영향을 미치고 있으므로, 기후모형과 연계되는 지표모형의 격자기반 적용이 기후변화 영향평가에 요구된다. 따라서 본 논문에서는 최신 지표모형 중에 하나인 CoLM을 이용하여, 낙동강 수계의 한 소유역에 대하여 일 지면온도를 모의하였다. 격자기반 CoLM을 이용한 고해상도 지표 모의를 위하여, 지표경계조건 및 기상입력 자료를 1km 격자망에 대하여 구축하였다. 2009년에 대하여 모의된 유역평균 지면온도의 일변화는 MODIS 지면온도 관측값을 잘 반영하는 것으로 나타났다. 본 논문에서 적용한 고해상도 지표모형은 지면온도를 평가에 사용되어, 지역 및 대륙 규모의 수문학적 연구에서 기후변화로 인한 물-에너지 순환에 미치는 영향에 대한 기초적인 정보를 제공할 것으로 기대한다. Since climate change already has significant influence on water and other natural resources, a grid-based configuration of Land Surface Models (LSMs) coupled with a climate model is necessary for climate change impact assessments. This study has therefore implemented the Common Land Model (CoLM), one of state-of-the-art LSMs for daily land surface temperature simulations for a small study basin in the Nakdong River watershed. Both surface boundary conditions and meteorological forcing data were constructed at 1-km spatial grid spacing for high resolution land surface modeling by the grid-based CoLM. The time series of basin-wide daily land surface temperature results simulated in 2009 from the CoLM can successfully capture observations from MODIS LST (Land Surface Temperature) observations. It is concluded that the high resolution LSM simulations can be used to evaluate the land surface temperature, which can provide a basic information on climate change impact on surface water and energy fluxes for regional and continental hydrologic studies.

대규모 육지수문모형에서 사용 가능한 지표면 및 지표하 연계 물흐름 모형의 개발: I. 모형설명

최현일,Choi,Hyun-Il 한국방재학회 2008 한국방재학회논문집 Vol.8 No.2

지표수 흐름은 육지 물수지 계산에 중요한 요소중에 하나이다. 그러나, 기상변화의 예측과 그로 인한 방재대책수립을 위한 대규모의 기상모형과 연계되는 육지수문모형(Land Surface Model, LSM)들은 지표수 흐름을 토양수분수지로부터 간단하게 산정하고 있다. 침투계산에서 지표수 흐름깊이를 무시하는 것은 지표면 및 지표하 물흐름 모두에 계산상 오류를 초래할 수 있다. 그러므로, 육지수문모형에서 종합적인 물과 에너지 순환 예측을 하기 위해, 지표수 흐름을 위한 1차원 확산모형과 지표하 물흐름을 위한 계산망 체적평균 토양수분이송(Volume Averaged Soil-moisture Transport Model, VAST)모형을 연계하는 대규모 지표면 및 지표하 연계 물흐름 모형이 개발되었다. 이 논문에서는, 최첨단 육지수문모형중 하나인 CLM(Common Land Model)내의 지표수리수문 모의를 위한 주요부분을 비롯하여, 지형특성에 따른 지표수 흐름과 공간적 토양수분 분포의 예측개선을 위한 새로운 지표면 및 지표하 연계 물흐름 모형에 대해 기술하였다. The surface runoff is one of the important components for the surface water balance. However, most Land Surface Models(LSMs), coupled to climate models at a large scale for the prediction and prevention of disasters caused by climate changes, simplistically estimate surface runoff from the soil water budget. Ignoring the role of surface flow depth on the infiltration rate causes errors in both surface and subsurface flow calculations. Therefore, for the comprehensive terrestrial water and energy cycle predictions in LSMs, a conjunctive surface-subsurface flow model at a large scale is developed by coupling a 1-D diffusion wave model for surface flow with the 3-D Volume Averaged Soil-moisture Transport(VAST) model for subsurface flow. This paper describes the new conjunctive surface-subsurface flow formulation developed for improvement of the prediction of surface runoff and spatial distribution of soil water by topography, along with basic schemes related to the terrestrial hydrologic system in Common Land Model(CLM), one of the state-of-the-art LSMs.

Impacts of spectral nudging on the simulated surface air temperature in summer compared with the selection of shortwave radiation and land surface model physics parameterization in a high-resolution regional atmospheric model

Park, Jun,Hwang, Seung-On Pergamon 2017 Journal of Atmospheric and Solar-Terrestrial Physi Vol.164 No.-

<P><B>Abstract</B></P> <P>The impact of a spectral nudging technique for the dynamical downscaling of the summer surface air temperature in a high-resolution regional atmospheric model is assessed. The performance of this technique is measured by comparing 16 analysis-driven simulation sets of physical parameterization combinations of two shortwave radiation and four land surface model schemes of the model, which are known to be crucial for the simulation of the surface air temperature. It is found that the application of spectral nudging to the outermost domain has a greater impact on the regional climate than any combination of shortwave radiation and land surface model physics schemes. The optimal choice of two model physics parameterizations is helpful for obtaining more realistic spatiotemporal distributions of land surface variables such as the surface air temperature, precipitation, and surface fluxes. However, employing spectral nudging adds more value to the results; the improvement is greater than using sophisticated shortwave radiation and land surface model physical parameterizations. This result indicates that spectral nudging applied to the outermost domain provides a more accurate lateral boundary condition to the innermost domain when forced by analysis data by securing the consistency with large-scale forcing over a regional domain. This consequently indirectly helps two physical parameterizations to produce small-scale features closer to the observed values, leading to a better representation of the surface air temperature in a high-resolution downscaled climate.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The impact of spectral nudging is assessed with a regional numerical model. </LI> <LI> The simulated summer surface air temperature is quite reasonable. </LI> <LI> Spectral nudging improves the analysis-driven simulation results significantly. </LI> <LI> The impact of physic parameterizations is not as influential as spectral nudging. </LI> <LI> Large-scale forcing is still crucial for dynamical downscaling. </LI> </UL> </P>

Parameterizations of Snow Cover, Snow Albedo and Snow Density in Land Surface Models: A Comparative Review

이원영,Gim Hyeon-Ju,박선기 한국기상학회 2024 Asia-Pacific Journal of Atmospheric Sciences Vol.60 No.2

Snow plays a vital role in the interaction between land and atmosphere in the state-of-the-art land surface models (LSMs) and the real world. While snow plays a crucial role as a boundary condition in meteorological applications and serves as a vital water resource in certain regions, the acquisition of its observational data poses significant challenges. An effective alternative lies in utilizing simulation data generated by Land Surface Models (LSMs), which accurately calculate the snow-related physical processes. The LSMs show significant differences in the complexities of the snow parameterizations in terms of variables and processes considered. In this regard, the synthetic intercomparisons of the snow physics in the LSMs can give insight for further improvement of each LSM. This study revealed and discussed the differences in the parameterizations among LSMs related to snow cover fraction, albedo, and snow density. We selected the most popular and well-documented LSMs embedded in the earth system models or operational forecasting systems. We examined single-layer schemes, including the Unified Noah Land Surface Model (Noah LSM), the Hydrology Tiled ECMWF Scheme of Surface Exchanges over Land (HTESSEL), the Biosphere-Atmosphere Transfer Scheme (BATS), the Canadian Land Surface Scheme (CLASS), the University of Torino land surface Process Interaction model in Atmosphere (UTOPIA), and multilayer schemes of intermediate complexity including the Community Noah Land Surface Model with Multi-Parameterization Options (Noah-MP), the Community Land Model version 5 (CLM5), the Joint UK Land Environment Simulator (JULES), and the Interaction Soil-Biosphere-Atmosphere (ISBA). Through the comparison analysis, we emphasized that inclusion of geomorphic and vegetation-related variables such as elevation, slope, time-varying roughness length, and vegetation indexes as well as optimized parameters for specific regions, in the snow-related physical processes, are crucial for further improvement of the LSMs.

다양한 지표모형을 활용한 토양수분 예측 성능 평가 연구

장예근 ( Jang Ye-geun ),신승훈 ( Sin Seoung-hun ),이태화 ( Lee Tae-hwa ),장원석 ( Jang Won-seok ),신용철 ( Shin Yong-chul ),장근창 ( Jang Keun-chang ),천정화 ( Chun Jung-hwa ),김종건 ( Kim Jong-gun ) 한국농공학회 2022 한국농공학회논문집 Vol.64 No.1

Soil moisture is significantly related to crop growth and plays an important role in irrigation management. To predict soil moisture, various process-based model has been developed and used in the world. Various models (Land surface model) may have different performance depending on the model parameters and structures that causes the different model output for the same modeling condition. In this study, the three land surface models (Noah Land Surface Model, Soil Water Atmosphere Plant, Community Land Model) were used to compare the model performance (soil moisture prediction) and develop the multi-model simulation. At first, the genetic algorithm was used to estimate the optimal soil parameters for each model, and the parameters were used to predict soil moisture in the study area. Then, we used the multi-model approach based on Bayesian model averaging (BMA). The results derived from this approach showed a better match to the measurements than the results from the original single land surface model. In addition, identifying the strengths and weaknesses of the single model and utilizing multi-model methods can help to increase the accuracy of soil moisture prediction.

대규모 육지수문모형에서 사용 가능한 지표면 및 지표하 연계 물흐름 모형의 개발: II. 모형적용

최현일,Choi. Hyun-Il 한국방재학회 2008 한국방재학회논문집 Vol.8 No.3

대규모 육지수문모형(Land Surface Model, LSM)에서 종합적인 육지 물흐름 및 에너지흐름의 예측을 위해 새로운 지표면-지표하 연계 물흐름 모형이 지표하 물흐름 모의를 위한 3차원 체적평균 토양수분 이송방정식(Volume Averaged Soil-moisture Transpor, VAST)을 지표수 흐름모의를 위한 1차원 확산방정식과 연계하여 개발되었다. 각 흐름특성에 맞는 복합적인 수치해석법이 적용되어, 시간분할 방법에 의해 3차원 VAST 방정식의 종방향 흐름이 완전음해법에 의해 해석된 후, 횡방향 흐름이 양해법으로 구해지며, 그 후에 1차원 확산방정식은 MacCormack 유한차분법으로 계산한다. 이 새로운 흐름연계모형은 최신의 육지수문모형인 CLM(Common Land Model)내의 기존 1차원 수리수문계산부분을 대체하게 된다. CLM과 결합된 새로운 연계흐름모형은 오하이오 계곡부근의 시험유역에 적용되었으며, 모의결과는 지표면-지표하 물흐름 상호작용의 모의와 지표수 흐름추적방법을 사용한 새로운 모형의 유출예측이 실측치에 더 근접함을 보여준다. 이 개선된 육지수문모형은 지역적, 대륙적, 그리고 지구전체를 다루는 수문기상연구와 기후변화로 인한 재해예방을 위하여 기상모형인 CWRF(Climate extension of the next-generation Weather Research and Forecasting)와 연계될 예정이다. The new conjunctive surface-subsurface flow model at a large scale was developed by using a 1-D Diffusion Wave (DW) model for surface flow interacting with the 3-D Volume Averaged Soil-moisture Transport (VAST) model for subsurface flow for the comprehensive terrestrial water and energy predictions in Land Surface Models (LSMs). A selection of numerical implementation schemes is employed for each flow component. The 3-D VAST model is implemented using a time splitting scheme applying an explicit method for lateral flow after a fully implicit method for vertical flow. The 1-D DW model is then solved by MacCormack finite difference scheme. This new conjunctive flow model is substituted for the existing 1-D hydrologic scheme in Common Land Model (CLM), one of the state-of-the-art LSMs. The new conjunctive flow model coupled to CLM is tested for a study domain around the Ohio Valley. The simulation results show that the interaction between surface flow and subsurface flow associated with the flow routing scheme matches the runoff prediction with the observations more closely in the new coupled CLM simulations. This improved terrestrial hydrologic module will be coupled to the Climate extension of the next-generation Weather Research and Forecasting (CWRF) model for advanced regional, continental, and global hydroclimatological studies and the prevention of disasters caused by climate changes.

Common Land Model의 국내 적용성 평가를 위한 유량 및 지면온도 모의

이건행 ( Keon Haeng Lee ),최현일 ( Hyun Il Choi ),권현한 ( Hyun Han Kwon ),김상단 ( Sang Dan Kim ),정유진 ( Eu Gene Chung ),김경현 ( Kyung Hyun Kim ) 한국물환경학회 2013 한국물환경학회지 Vol.29 No.2

A grid based configuration of Land Surface Models (LSMs) coupled with a climate model can be advantageous in impact assessment of climate change for a large scale area. We assessed the applicability of Common Land Model(CoLM) to runoff and land surface temperature (LST) simulations at the domain that encompasses the Nakdong river basin. To establish a high resolution model configuration of a 1km * 1km grid size, both surface boundary condition and atmospheric inputs from the ob served weather data in 2009 were adjusted to the same resolution. The Leaf Area Index (LAI) was collected from MODerate resolution Imaging Spectroradiometer (MODIS) and the downward short wave flux was produced by a nonstationary multi site weather state model. Compared with the observed runoffs at the stations on Nakdong river, simulated runoffs properly responded to rainfall. The spatial features and the seasonal variations of the domain fairly well were captured in the simulated LSTs as well. The monthly and seasonal trend of LST were described well compared to the observations, however, the monthly averaged simulated LST exceeded the observed up 2 at the 24 stations. From the results of our study, it is shown that high resolution LSMs can be used to evaluate not only quantity but also quality of water resources as it can capture the geographical fcatures of the area of interest and its rainfall runoff response.

토지 피복별 차등 가열이 도시 지역의 흐름과 기온에 미치는 영향

박수진 ( Soo-jin Park ),최소희 ( So-hee Choi ),강정은 ( Jung-eun Kang ),김동주 ( Dong-ju Kim ),문다솜 ( Da-som Moon ),최원식 ( Wonsik Choi ),김재진 ( Jae-jin Kim ),이영곤 ( Young-gon Lee ) 대한원격탐사학회 2016 大韓遠隔探査學會誌 Vol.32 No.6

본 연구에서는 기상청 현업 국지기상모델(Local Data Assimilation and Prediction System, LDAPS)과 전산유체역학(Computational Fluid Dynamics, CFD) 모델을 접합하여, 서울 종로구 송월동에 위치한 지동기상관측소(서울 ASOS) 주변 지역의 기상 환경을 분석하였다. 토지 피복별 차등 가열이 도시 지역의 대기 흐름과 기온에 미치는 영향을 분석하기 위하여, 시간 변화에 따른 토지 피복별 지표면 온도와 그림자 영역에 대한 지표면 온도 감소 효과를 고려하였다. LDAPS 모델은 상세한 건물, 지형, 지표면 가열 효과를 고려하지 못하기 때문에, 풍속을 과대모의 하고 기온을 과소 모의하였다. 건물과 지형의 마찰 효과와 태양 복사에 의한 지표면 가열을 고려할 수 있는 LDAPS-CFD 접합 모델은 서울 ASOS 지점의 관측 풍속과 유사한 풍속을 모의하였고, 관측 기온을 잘 재현하였다. 주로 동풍이 부는 오전 시간대에는 LDAPS-CFD 접합 모델 또한 기온을 과소모의 하였는데, 이는 서울 ASOS 지점의 풍상측(동쪽)에 위치한 경희궁 주변 지역에 주로 수목이 분포하고 있고, 표면 온도가 상대적으로 낮기 때문인 것으로 판단된다. 그러나, 주로 남동풍 계열의 바람이 부는 오후 시간대에는 풍상측에 위치한 건물의 표면 가열의 효과로 인해 서울 ASOS 지점의 관측 기온을 상대적으로 잘 모의하였다. In this study, the effects of differential heating by land-use types on flow and air temperature at an Seoul Automated Synoptic Observing Systems (ASOS) located at Songwol-dong, Jongno-gu, Seoul was analyzed. For this, a computation fluid dynamics (CFD) model was coupled to the local data assimilation and prediction system (LDAPS) for reflecting the local meteorological characteristics at the boundaries of the CFD model domain. Time variation of temperatures on solid surfaces was calculated using observation data at El-Oued, Algeria of which latitude is similar to that of the target area. Considering land-use type and shadow, surface temperatures were prescribed in the LDAPS-CFD coupled model. The LDAPS overestimated wind speeds and underestimated air temperature compared to the observations. However, a coupled LDAPS-CFD model relatively well reproduced the observed wind speeds and air temperature, considering complicated flows and surface temperatures in the urban area. In the morning when the easterly was dominant around the target area, both the LDAPS and coupled LDAPS-CFD model underestimated the observed temperatures at the Seoul ASOS. This is because the Kyunghee Palace located at the upwind region was composed of green area and its surface temperature was relatively low. However, in the afternoon when the southeasterly was dominant, the LDAPS still underestimated, on the while, the coupled LDAPS-CFD model well reproduced the observed temperatures at the Seoul ASOS by considering the building-surface heating.

Noah Multi Physics 모델과 CERES-Rice 모델의 작물 생육 및 증발산 모의 비교

김광수 ( Kwang Soo Kim ),강민석 ( Min Seok Kang ),정하늘 ( Ha Neul Jeong ),김준 ( Joon Kim ) 한국농림기상학회 2013 한국농림기상학회지 Vol.15 No.4

대기와 지표면을 구성하고 있는 토양 및 식생은 생물리학적/생지화학적인 과정을 통해 서로 상호작용을 한다. 이러한 과정을 모의하기 위해 지표모델과 작물 생육모델이 사용되고 있다. 지표모델인 Noah MP 모델과 작물생육모델인 CERES-Rice 모델을 비교하기 위해 해남 플럭스 관측소 인근 지역에서 작물의 생육과 증발산량을 모의하였다. 플럭스 관측자료가 수집된 2003년부터 2012년까지 해남 플럭스 관측소의 주요 식생인 벼를 대상으로 생육과 증발산량을 모의되었다. Noah MP 모델은 단순한 식생 모의 과정으로 인해 개화기를 전후로 하는 벼의 LAI 변화양상을 정확하게 반영하지 못하였다. 벼의 생체중 예측에 있어서도 실제 관측될 수 있는 생체중보다 대략 10분의 1 수준에 해당하는 생체중이 모의되었다. 증발산량 모의의 경우에도, CERES-Rice 모델의 모의값보다 약 21%에 해당하는 증발산량을 모의하였다. 반면, CERES-Rice모델의 경우 LAI의 변화와 생체중 모의 값은 실제의벼 생육 양상과 유사할 것으로 추정되었다. 또한, 증발산량의 경우에도 해남 플럭스 관측소에서 측정된 값과 비교하였을 때 Noah-MP모델의 모의값이 CERESRice모델의 모의값에 비해 RMSE 값이 1.8배 높았다. Noah MP 모델이 보이는 높은 오차값들은 NoahMP모델이 논의 지표상태를 적절히 반영하지 못하였기때문으로 사료되었고, 특히 과소추정된 생체중을 보정하여 증발산량을 예측할 경우 오차를 30%까지 줄일수 있을 것으로 보인다. 따라서, Noah MP 모델에논에서의 지표 특성을 반영할 수 있다면 보다 정확한 물질순환과 에너지 교환을 예측할 수 있을 것으로 사료된다. Biophysical and biochemical processes through which crops interact with the atmosphere have been simulated using land surface models and crop growth models. The Noah Multi Physics (MP) model and the CERES-Rice model, which are a land surface model, and a crop growth model, respectively, were used to simulate and compare rice growth and evapotranspiration (ET) in the areas near Haenam flux tower in Korea. Simulations using these models were performed from 2003 to 2012 during which flux measurements were obtained at the Haenam site. The Noah MP model failed to simulate the pattern of temporal change in leaf area index (LAI) after heading. The simulated aboveground biomass with the Noah MP model was underestimated by about 10% of the actual biomass. The ET simulated with the Noah MP model was as low as 21% of those with the CERESRice model. In comparison with actual ET measured at Haenam flux site, the root mean square error (RMSE) of the Noah MP model was 1.8 times larger than that of the CERES-Rice model. The Noah MP model seems to show less reliable simulation of crop growth and ET due to simplified phenology processes and assimilates partitioning compared with the CERES-Rice model. When ET was adjusted by the ratio between leaf biomass simulated using CERES-Rice model and Noah MP model, however, the RMSE of ET was reduced by 30%. This suggests that an improvement of the Noah MP model in representing rice growth in paddy fields would allow more reliable simulation of matter and energy fluxes.

Analysis on the long-term variance of surface urban heat island (SUHI) using Landsat thermal infrared

Yoon, Dong Hyeon(윤동현),Lee, Tae Gyeom(이태겸),Rho, Se Ho(노세호),Koh, June Hwan(고준환) 한국지적정보학회 2019 한국지적정보학회지 Vol.21 No.1

도시는 수분에 대한 불투수성 표면과 열 흡수 과정에서의 특이성 때문에 주변 지역과 분리되는 열 환경이 형성된다. 도시에서 주변 지역보다 기온이 높게 나타나는 현상인 도시열섬현상도 그중 하나로, 도시와 이를 둘러싸고 있는 교외 지역의 온도 차이를 발생시킨다. 도시열섬현상은 두 지역을 구성하고 있는 토지이용과 지면피복 양상에 따라 달라진다. 도시열섬현상을 평가하기 위해 지표면의 온도를 측정하여 지표로 사용하는데, 오랜 기간 과거로부터 축적된 지표면 온도 정보는 도시열섬현상의 진행 과정과 현재에 대해 이해하는 중요한 정량적 자료라고 할 수 있다. 본 연구에서는 연구 대상지의 SUHI(Surface Urban Heat Island) 장기 변동과 그 경향을 확인하기 위해 1994년부터 2015년까지 원격탐사 위성의 적외선 센서를 이용하였다. 각 위성 이미지들은 지표온도를 측정함과 동시에 지면피복과 토지이용지도를 생성하는 데 사용되었다. 하지만 광학식 위성 원격탐사를 통한 지표관측에서 발생하는 대기의 상호반응은 정보의 오염으로 인한 부정확한 분석결과를 일으킨다. 이 연구에서는 SUHI를 산출하는 과정에서 유효한 정보 수준의 확보를 위해 적외선 센서에서 Single Channel Algorithm 그리고 가시광선과 근적외선에서 COST model을 적용하였다. 본 연구 결과, 서울에서 SUHI는 20년간 점진적으로 증가하고 있음을 확인하였다. 특히 SUHI는 매년 5월~8월 사이 황도 경도(Celestial Longitude) 45°~120° 범위에서 섭씨 2.51°에서 섭씨 3.98°로 증가하였음을 확인하였다. Unique heat sources different from peripheral rural areas are formed in urban areas due to impermeable surfaces and thermal peculiarities of absorbance processes. Urban heat island is a symptom that displays higher temperature in urban areas, compared to rural areas. Rural areas surrounding urban areas generate temperature differences. Land surface temperature consisting of two areas is leaded by the pattern of land use and land cover. A Land surface temperature is estimated, and are used as an index to evaluate urban heat island. Accumulated land surface temperature information from long-term studies could be important quantitative data to understand the progress and current situation in urban heat island. In this study, the Landsat thermal infrared sensors of the remote sensing satellite that cover from 1994 to 2015 are utilized to identify long-term changes of the surface urban heat island and its trends in the study area of Seoul, Korea. Each satellite image is used to measure surface temperature, and produce land cover/land use map simultaneously. However, atmospheric mutual responses produced in surface observation with optical satellite remote sensing cause inaccurate results affected by information contamination. In this study, the cosine approximation model atmospheric correction in visible and near infrared bands and single channel algorithm in thermal infrared band are conducted to secure valid information level in the process of surface urban heat island calculation. surface urban heat island in Seoul for 20 years was gradually increased from the results of this study. In case of especially celestial longitude classified from 45 to 120 in the period from May 5 to August 23 every year, surface urban heat island was increased from 2.51 to 3.98. It was identified that its incremental progress has high statistical correlations.