9 research outputs found
All-Sky 1 km MODIS Land Surface Temperature Reconstruction Considering Cloud Effects Based on Machine Learning
No full textOpen AccessArticle
All-Sky 1 km MODIS Land Surface Temperature Reconstruction Considering Cloud Effects Based on Machine Learning
by Dongjin ChoORCID,Dukwon Bae,Cheolhee YooORCID,Jungho Im *ORCID,Yeonsu LeeORCID andSiwoo LeeORCID
Department of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea
*
Author to whom correspondence should be addressed.
Academic Editor: Anand Inamdar
Remote Sens. 2022, 14(8), 1815; https://doi.org/10.3390/rs14081815
Received: 9 February 2022 / Revised: 5 April 2022 / Accepted: 7 April 2022 / Published: 9 April 2022
(This article belongs to the Special Issue Land Surface Temperature Estimation Using Remote Sensing)
Download PDF Browse Figures Citation Export
Abstract
A high spatio-temporal resolution land surface temperature (LST) is necessary for various research fields because LST plays a crucial role in the energy exchange between the atmosphere and the ground surface. The moderate-resolution imaging spectroradiometer (MODIS) LST has been widely used, but it is not available under cloudy conditions. This study proposed a novel approach for reconstructing all-sky 1 km MODIS LST in South Korea during the summer seasons using various data sources, considering the cloud effects on LST. In South Korea, a Local Data Assimilation and Prediction System (LDAPS) with a relatively high spatial resolution of 1.5 km has been operated since 2013. The LDAPS model???s analysis data, binary MODIS cloud cover, and auxiliary data were used as input variables, while MODIS LST and cloudy-sky in situ LST were used together as target variables based on the light gradient boosting machine (LightGBM) approach. As a result of spatial five-fold cross-validation using MODIS LST, the proposed model had a coefficient of determination (R2) of 0.89???0.91 with a root mean square error (RMSE) of 1.11???1.39 ??C during the daytime, and an R2 of 0.96???0.97 with an RMSE of 0.59???0.60 ??C at nighttime. In addition, the reconstructed LST under the cloud was evaluated using leave-one-station-out cross-validation (LOSOCV) using 22 weather stations. From the LOSOCV results under cloudy conditions, the proposed LightGBM model had an R2 of 0.55???0.63 with an RMSE of 2.41???3.00 ??C during the daytime, and an R2 of 0.70???0.74 with an RMSE of 1.31???1.36 ??C at nighttime. These results indicated that the reconstructed LST has higher accuracy than the LDAPS model. This study also demonstrated that cloud cover information improved the cloudy-sky LST estimation accuracy by adequately reflecting the heterogeneity of the relationship between LST and input variables under clear and cloudy skies. The reconstructed all-sky LST can be used in a variety of research applications including weather monitoring and forecasting
Data Reconstruction for Remotely Sensed Chlorophyll-a Concentration in the Ross Sea Using Ensemble-Based Machine Learning
No full textPolar regions are too harsh to be continuously observed using ocean color (OC) sensors because of various limitations due to low solar elevations, ice effects, peculiar phytoplankton photosynthetic parameters, optical complexity of seawater and persistence of clouds and fog. Therefore, the OC data undergo a quality-control process, eventually accompanied by considerable data loss. We attempted to reconstruct these missing values for chlorophyll-a concentration (CHL) data using a machine-learning technique based on multiple datasets (satellite and reanalysis datasets) in the Ross Sea, Antarctica. This technique—based on an ensemble tree called random forest (RF)—was used for the reconstruction. The performance of the RF model was robust, and the reconstructed CHL data were consistent with satellite measurements. The reconstructed CHL data allowed a high intrinsic resolution of OC to be used without specific techniques (e.g., spatial average). Therefore, we believe that it is possible to study multiple characteristics of phytoplankton dynamics more quantitatively, such as bloom initiation/termination timings and peaks, as well as the variability in time scales of phytoplankton growth. In addition, because the reconstructed CHL showed relatively higher accuracy than satellite observations compared with the in situ data, our product may enable more accurate planktonic research
Satellite Remote Sensing-Based Monitoring of the Relationship Between Low-Salinity Waters and Essential Marine Variables in the East China Sea
No full text1
Downscaling MODIS nighttime land surface temperatures in urban areas using ASTER thermal data through local linear forest
No full textSpatial downscaling effectively produces high spatiotemporal resolution land surface temperature (LST) in urban areas. Although nighttime LST is an essential indicator in urban thermal research, few LST downscaling studies have focused on nighttime in fine resolution. This study proposed a novel approach using local linear forest (LLF) to downscale 1 km Moderate Resolution Imaging Spectroradiometer (MODIS) nighttime LSTs to 250 m spatial resolution in three cities: Rome, Madrid, and Seoul. First, we used Least Absolute Shrinkage and Selection Operator (LASSO) to select a set of past clear-sky ASTER LSTs (ALST) which showed a high spatial correlation with the target MODIS LST. Downscaling models were then developed using input kernels of the selected ALSTs and eight auxiliary variables: normalized difference vegetation index (NDVI), elevation, slope, built-up area percentage, road density, population density, wind speed, and distance from the built-up weighted center of the study area. Three schemes were evaluated: scheme 1 (S1) using only auxiliary variables as input kernels with a random forest (RF) model; scheme 2 (S2) using selected ALSTs and auxiliary variables as input kernels with an RF model; and scheme 3 (S3) using input kernels as in S2 but with the LLF model. Validation was performed using bias-corrected ALSTs for seven reference dates in the three cities. LLF-based S3 showed the highest accuracy with an average correlation coefficient (R) -0.94 and Root Mean Square Error (RMSE) -0.64 K while maintaining the dynamic range of the original LST at the finer resolution. The downscaled LST (DLST) based on S3 effectively depicted the nocturnal thermal spatial pattern in greater detail than the other two schemes did. The S3-based DLST also showed a relatively high spatial correlation with the in-situ nighttime air temperature within the cities. When compared to the original 1 km LST, S3-based DLST showed larger surface urban heat island intensity for the urban-type surfaces and a higher temporal correlation with nighttime air temperature
Upwelling Proxy Improvement and Validation Using Satellite Remote Sensing along Southwest of the East Sea: Case Study in 2019
No full textCoastal upwelling is a significantly imperative process for understanding the interactions between physical and ecological processes and has been investigated incessantly. In this study, we explored the upwelling index, specifically upwelling age (UA). UA enabled us to observe the initiating, sustaining, and decaying upwelling processes. Although the sensitivity of many other geophysical parameters to estimate UA has been investigated, the wind direction has not been evaluated. Thus, we assessed the appropriate wind direction for the UA and obtained efficient upwelling signals from the four coastal stations. Furthermore, we applied the UA and compared it with the satellite sea level anomaly, sea surface temperature, and chlorophyll-a changes to validate how UA depicts their spatial extents. Thus, UA can predict the timing of coastal upwelling events using predicted geophysical parameters
A hybrid machine learning approach to investigate the changing urban thermal environment by dynamic land cover transformation: A case study of Suwon, republic of Korea
No full textUrban thermal environment should be analyzed by considering the dynamic structural changes as cities grow both horizontally and vertically. Local Climate Zone (LCZ) scheme can describe built-up areas in detail, mainly based on density and height; however, the low overall accuracy of LCZ urban classes (OAurb) remains a notable limitation that requires improvement. This study proposes a hybrid analytical method considering bidirectional urban expansion and low OAurb. Temporal LCZ maps were constructed using a convolutional neural network to observe the dynamic urban growth between 2004 and 2021 in Suwon, South Korea. Unlike previous LCZ mapping studies, we utilized the additional information provided by deep learning through softmax-based probability maps. Random forest-based downscaling models were developed by combining various auxiliary variables related to the Land Surface Temperature (LST) to observe the detailed surface energy flux. A filtering method was then employed by eliminating areas where LCZs were identified with a low confidence level using extracted probability maps. Finally, thermal variability was investigated by overlaying the filtered LCZ maps and the corresponding LST. The produced LCZ maps and spatially downscaled LSTs accurately depicted dynamic urban form changes, with the LCZ maps exhibiting an average overall accuracy of approximately 90% and downscaled LSTs showing an average coefficient of determination of ∼ 0.9 and a root mean square error of 0.7 °C. Thermal variability occurring due to structural transitions varied in magnitude depending on the height and density of the buildings, while exhibiting a maximum and minimum value of 2.8 °C and − 2.2 °C, respectively. By selecting reliably classified areas, the proposed filtering method produced more rational results than the original non-filtering method, resulting in higher variability from − 0.4 °C to 0.6 °C
Reconstruction of Ocean Color Data Using Machine Learning Techniques in Polar Regions: Focusing on Off Cape Hallett, Ross Sea
No full textThe most problematic issue in the ocean color application is the presence of heavy clouds, especially in polar regions. For that reason, the demand for the ocean color application in polar regions is increased. As a way to overcome such issues, we conducted the reconstruction of the chlorophyll-a concentration (CHL) data using the machine learning-based models to raise the usability of CHL data. This analysis was first conducted on a regional scale and focused on the biologically-valued Cape Hallett, Ross Sea, Antarctica. Environmental factors and geographical information associated with phytoplankton dynamics were considered as predictors for the CHL reconstruction, which were obtained from cloud-free microwave and reanalysis data. As the machine learning models used in the present study, the ensemble-based models such as Random forest (RF) and Extremely randomized tree (ET) were selected with 10-fold cross-validation. As a result, both CHL reconstructions from the two models showed significant agreement with the standard satellite-derived CHL data. In addition, the reconstructed CHLs were close to the actual CHL value even where it was not observed by the satellites. However, there is a slight difference between the CHL reconstruction results from the RF and the ET, which is likely caused by the difference in the contribution of each predictor. In addition, we examined the variable importance for the CHL reconstruction quantitatively. As such, the sea surface and atmospheric temperature, and the photosynthetically available radiation have high contributions to the model developments. Mostly, geographic information appears to have a lower contribution relative to environmental predictors. Lastly, we estimated the partial dependences for the predictors for further study on the variable contribution and investigated the contributions to the CHL reconstruction with changes in the predictors
The Korean Organ and Organ Music in Korea
No full text본 논문은 한국의 오르간 음악의 도입 배경과 발전과정을 역사적 흐름으로서 조사하여, 한국 오르간 음악 문화의 특징을 살펴보고자 하였다. 이는 한국 오르간의 역사와 한국에서 오르간 음악교육의 환경변화 및 현실, 그리고 관련된 오르간 설치현황 등의 조사를 통하여 한국 오르간 음악의 현주소를 확인해 보고, 한국 교회 예배에서 오르간의 역할과 중요성을 살펴보고, 최근 한국에서 성장하고 있는 오르간 도입에 따른 오르간 음악의 발달을 예측하고자 하였다.
한국에 오르간이 처음 도입된 시기는 조선시대에 기독교에 대한 박해가 끝난 후 개신교 선교사들이 입국하기 시작하여 본격적인 선교활동을 시작한 1887년경으로, 1882년 한미조약이 체결되어 국교가 열리자 미국의 개신교 선교사 아펜젤러(H. G. Appenzeller, 1858-1920)와 언더우드(H.G. Underwood, 1869-1916)가 입국한 후부터 본격화 되었는데, 복음이 전파되고 교회가 세워지면서 성가대가 조직되고 한국에 ‘리드 오르간(reed organ)’이라고 볼 수 있는 풍금을 들여와 풍금에 맞추어 찬송을 하기 시작하였다. 또한, 이화학당(1886)에서 음악시간에 벙커(Bunker)부인이 풍금으로 반주했다는 기록 이외에 배재학당(1886), 경신학교(1886), 정신여학교(1887), 및 평양의 숭실학교(1887)에서 찬송을 가르칠 때 풍금을 사용하였다고 기록하고 있다. 이러한 풍금의 도입 및 사용에 관한 역사적 기록은 한국 오르간 음악의 시발점으로서 그 의의가 매우 크다.
한국에 파이프 오르간이 처음 설치된 곳은 정동교회와 명동 대성당인데, 이는 각각 개신교와 가톨릭에서 최초의 파이프 오르간이 설치되었다는 점에서 의미가 크다. 명동 대성당의 파이프의 오르간의 경우는 설치 계획 주문 설치 및 완성에 이르기까지 6년이 걸렸다고 전해지고 1924년에 완성된 것으로 보고 있다. 이외에도 원산 가톨릭 성당 및 덕원 가톨릭 수도원에 파이프 오르간이 있지만 정확한 자료가 현재는 남아 있지가 않다. 해방 이후 승동교회와 중림동 성당에 파이프 오르간이 설치되었고 1970년대 이후에 연세대학교(1977)와 세종문화회관대강당(1978)에 설치되는 등 주로 소도시보다는 대도시에 집중해서 파이프 오르간이 설치되고 있음을 알 수 있다. 1978년 한국의 문화적 상징인 세종문화회관 대강당에 설치한 파이프 오르간은 개관기념 예술제에서 오르간 연주회를 기획하여 외국의 연주자로 한스 하젤벡(Hans Haselbock), 제니퍼 베이트(Jennifer Bate)가, 국내 연주자로 곽상수, 채문경, 윤양희, 곽동순, 유회자가 오르간 연주회를 개최하였다. 이 후 한국 내에서 파이프 오르간에 대한 인식이 크게 달라졌으며 교회의 부흥과 아울러 대학에서 본격적인 교육도 이루어졌다. 이러한 부흥은 한국의 경제적인 발전과 함께 교회 및 대학 연주 홀에 파이프 오르간의 설치가 증가하기 시작하였다.
특히, 오르간 음악의 발전과 함께 오르간 곡을 작곡한 한국 작곡가들은 서양적 양식의 화성 및 대위법적 구성으로 오르간 곡을 작곡하기도 하고 이러한 서양적 양식에 한국 전통의 음계와 리듬을 결합하여 새로운 음악으로 작곡하기도 하였다. 전자의 경우 대표적인 작곡가의 작품 중의 하나로 김청묵의 <오르간을 위한 토카타>가 있으며 후자의 경우는 주영자의 <오르간을 위한 시편 23편>, 채경화의 <달아 달아 I >, 이규봉의 <령 V> 등이 있다. 특히 이영조의 <Kosmos I (코스모스 제 1번 )>은 한국 5음계로 구성된 화성과 이영조의 8음 음계로 구성된 화성을 기본으로 하여 작곡한 작품이다. 특히 이 작품은 12음 음계의 사용을 법으로 금했기 때문에 그래픽 기보를 사용했던 폴란드 작곡자들이 즐겨 쓴 그래픽 기보를 사용하여 작곡한 작품이기도 하다. 한국 오르간 작곡가들은 서양음악과 한국 특유의 가락과 정서가 담긴 한국 전통음악이 조화를 이룬 오르간 음악작품을 많이 작곡하여 독창적인 한국의 오르간 음악을 개척해나가고 있음을 알 수 있다. 본 논문에서는 이영조의 Kosmos I을 연주자의 입장에서 분석하여 봄으로써 서양의 음악양식의 화성 및 대위법적인 구성과 함께 현대 그래픽 기보로 나타낸 음악을 어떻게 연주할 수 있는 지에 대한 연주자로서의 연주기법에 대해서 논하였다.;This study was aimed to examine the characteristics of Korean organ music through the understanding of the introduction of organ music from Western countries and its development in a historical background. Through the history of organs which has been built in Korea and the changes in the educational environment of organ music the development process of organ music has been investigated.
Organs were first introduced in Korea in 1887 when Christian persecution ended and protestant missionaries started to enter the country. With the Korean-American Agreement in 1882 the state religion was freed and missionaries like H. G. Appenzeller and H. G. Underwood started coming into the country. The Christian faith started to spread the hymns which were sung under the lead of the Harmonium, a kind of Reed organ. There are many records of Harmonium used as a method to teach the hymns like Ms. Bunker at the Ewha School (1886), and also at the Baejae School (1886), Gyungshin School (1886), Jungshin Women's School (1887), and Soongsil School in Pyungyang (1887). Such historical records on the introduction and usage of the Harmonium are very meaningful as the starting point of Korean organ music.
The first pipe organ was brought in at the Jeongdong Church and Myungdong Catholic Church. These two organs are important due to the fact that the installation from the planning and designing stage all took six years finishing in 1924. There are also pipe organs in the Wonsan Catholic Church and Dukwon Catholic Monastery but no accurate records have been kept. After independence from Japan in 1945, pipe organs were installed in the Sungdong Church and the Joonglim-dong Catholic Church. After that pipe organs were installed mainly in large cities like Seoul in the Yonsei University (1977) and Sejong Arts and Culture Center (1978). As the symbol of Korean arts, the pipe organ of the Sejong Arts and Culture Center was performed for as an opening ceremony by foreign performers like Hans Haselbock, Jennifer Bate and Korean performers including Sang Soo Kwak, Moon Kyung Chae, Yang Hee Yoon, Dong Soon Kwak, and Hoe Ja Yoo. After the series of organ concerts, the recognition of the pipe organ in Korea has been greatly improved. And also the pipe organ education in the Universities has been achieved with the revival of the Korean Church. In particular, with the development in organ music Korean composers started composing organ pieces with Western style harmony and contrapuntal elements while also Korean traditional scales and rhythms were introduced.
A piece of the typical Western style can be Tocata for the Organ by Chung Muk Kim and for the combination of Western and Korean style Psalms 23 for the Organ by Young Ja Joo, Dara Dara by Kyung Hwa Chae and Ryung V by Gyu Bong Lee. In particular, 'Kosmos I' by Lee Young Jo shows the Korean 5 scale and Young Jo Lee's 8 scale as the base for the piece. Korean organ composers symphonized traditional Western music and Korean traditional tempo and emotions to make original Korean organ pieces. As a performer of Kosmos I by Lee Young Jo (performed by Author in December 15, 2003 at Kim Young Eui Concert Hall of Ewha Womans University) analysis of his piece and general interpretation of the performing skills of his piece was done.목차
Ⅰ. 서론 = 1
Ⅱ. 본론 = 4
A. 한국 오르간의 역사 = 4
1. 한국 최초의 오르간 = 5
2. 전자오르간의 도입 = 7
3. 파이프 오르간 = 11
B. 한국의 파이프 오르간 = 13
1. 초창기 한국의 파이프 오르간 = 13
2. 해방 이전 한국의 파이프 오르간 = 13
가. 정동제일교회 = 15
나. 명동성당 = 19
다. 원산가톨릭성당(함남) = 21
라. 덕원가톨릭수도원(함남) = 21
3. 해방 이후 한국의 파이프 오르간 = 21
4. 한국에 설치된 파이프 오르간의 내역(연도 순) = 34
C. 한국의 오르간 음악 교육 = 103
1. 한국의 오르간 음악 교육의 역사적 배경 = 103
2. 한국의 오르간 교육기관 = 104
3. 한국 오르가니스트 협회 = 107
D. 한국의 오르간 작곡자와 작품 = 108
1. 한국의 오르간 작곡자와 작품 = 108
2. 한국 오르간 작품의 특징 = 109
가. 자유형식으로 작곡된 작품 = 109
나. 한국적 선율을 바탕으로 사용한 작품 = 111
다. 한국 전통의 리듬을 사용한 작품 = 111
라. 한국 전통 악기의 특성을 반영한 작품 = 115
마. 오르간과 한국 전통 악기가 조화를 이룬 작품 = 116
바. 그래픽 기보를 사용한 작품 = 118
Ⅲ. 결론 = 144
참고문헌 = 147
Abstract = 149
부록 1 한국의 오르간 작곡자와 작품 = 15
