• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.4
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• pp.405-411
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• 2011

In this study we tried to compare and analyze KOMPSAT-2 NOVI and vegetation coverage(VC) which is investigated by fieldwork. To standardize KOMPSAT-2 NOVI, we adjusted NOVI using reference data which is atmospheric corrected MODIS NDVI. Each vegetation coverage point data was surveyed in field using portable GPS and compared with NDVI of satellite imagery. As a results, there was high level of correlation in vegetation coverage and NOVI.

• Journal of the Korean Association of Geographic Information Studies
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• v.20 no.2
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• pp.1-16
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• 2017

This study was conducted to analyze the urban heat island(UHI) intensity of South Korea by using Moderate Resolution Imaging Spectroradiometer(MODIS) satellite imagery. For this purpose, the metropolitan area was spatially divided according to land cover classification into urban and non-urban land. From the analysis of land surface temperature(LST) in South Korea in the summer of 2009 which was calculated from MODIS satellite imagery it was determined that the highest temperature recorded nationwide was $36.0^{\circ}C$, lowest $16.2^{\circ}C$, and that the mean was $24.3^{\circ}C$, with a standard deviation of $2.4^{\circ}C$. In order to analyze UHI by cities and counties, UHI intensity was defined as the difference in average temperature between urban and non-urban land, and was calculated through RST1 and RST2. The RST1 calculation showed scattered distribution in areas of high UHI intensity, whereas the RST2 calculation showed that areas of high UHI intensity were concentrated around major cities. In order to find an effective method for analyzing UHI by cities and counties, analysis was conducted of the correlation between the urbanization ratio, number of tropical heat nights, and number of heat-wave days. Although UHI intensity derived through RST1 showed barely any correlation, that derived through RST2 showed significant correlation. The RST2 method is deemed as a more suitable analytical method for measuring the UHI of urban land in cities and counties across the country. In cities and counties with an urbanization ratio of < 20%, the rate of increase for UHI intensity in proportion to increases in urbanization ratio, was very high; whereas this rate gradually declined when the urbanization ratio was > 20%. With an increase of $1^{\circ}C$ in RST2 UHI intensity, the number of tropical heat nights and heat wave days was predicted to increase by approximately five and 0.5, respectively. These results can be used for reference when predicting the effects of increased urbanization on UHI intensity.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.317-319
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• 2008

Traditionally, it is measured by using basin or empirical formula with meteorology data, while it does not represent the evaportransporation over a regional area. With the advent of improved remote sensing technology, it becomes feasible to assess the ET over a regional scale. Firstly, the IMAGINE ATCOR atmospheric module is used to preprocess for the MODIS imagery. Then MODIS satellite images which have been corrected by radiation and geometry in conjunction with the in-situ surface meteorological measurement are used to estimate the surface heat fluxes such as soil heat flux, sensible heat flux, and latent heat flux. In addition, the correlation coefficient between the derived latent heat and the in-situ measurement is found to be over 0.76. In the future, we will continue to monitor the surface heat fluxes of paddy rice field in Chiayi area.

• Journal of the Korean Association of Geographic Information Studies
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• v.9 no.2
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• pp.102-114
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• 2006

This study aims to develop a method to analyze droughts in Nakdong river area. Satellite imagery can be applied to droughts monitoring because it can afford periodic data for large area for long time. In this study, supposing that evapotranspiration and NDVI are closely related to each other, we presented a method to estimate evapotranspiration in large area with NDVI from MODIS data and temperature. For the final analysis of droughts, water deficit is calculated by climatological water balance using the distribution of evapotranspiration and precipitation. As the results of this study, we improved the usability of satellite imagery, especially in drought analysis.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.106-106
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• 2011

지표면으로 입사하는 태양 복사 에너지를 정확하게 산출하는 것은 에너지 수지 방법을 이용한 유역 분석의 신뢰도를 높이는데 기여할 수 있다. 태양 복사 에너지는 지형 인자와 대기 인자를 이용하여 산정할 수 있으나 기상관측장비 특성상 지점값 위주의 연구가 이루어지고 있다. 본 연구에서는 이러한 공간적 제약을 완화하기 위해 원격탐사 기법을 이용하여 지표면에 들어오는 태양 복사 에너지를 산출하고자 하였다. 시간, 공간적으로 중규모 해상도를 가지고 있는 Moderate Resolution Imaging Spectroradiometer(MODIS) 위성 관측 이미지를 이용하여 태양 복사 에너지의 시공간 분포를 산정하고 그 결과를 연구 지역인 광릉/해남 KoFlux site의 지상 관측값을 이용하여 검증함으로써 산정 모형의 국내 적용성을 확인하였다. 비교적 적은 수의 인자를 필요로 하는 Allen et al.(2007) 태양 복사 에너지 산정 모형과 36가지의 서로 다른 파장 이미지를 이용하여 산출된 MODIS 대기 자료를 이용하여 결과를 산정함으로써 모형의 간편성 및 효율성을 확인할 수 있었다. 특히 광릉/해남 KoFlux site 관측치와 모형 산정값과의 상관계수가 각각 0.95, 0.96으로 매우 높은 값을 가짐으로써 모형의 높은 신뢰성을 검토하였다. 향후 연구의 결과로써 얻어진 태양 복사 에너지의 시공간 분포특성 분석을 통해 에너지 수지 방법의 정확성을 향상시키고자 한다.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.4
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• pp.437-450
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• 2004

Extensive forest fire activities occurred across the border in Russia, particularly east of Lake Baikal between the Amur and Lena rivers in May 2003. These forest fires released large amounts of particulates and gases into the atmosphere, resulting in adverse effects on regional air quality and the global radiation budget. Smoke pollution from the Russian fires near Lake Baikal was transported to Korea through Mongolia and eastern China. On 20 May 2003, a number of large fires were burning in eastern Russian, producing a thick, widespread pall of smoke over much of Northeast Asia. In this study, separation technique was used for aerosol retrieval application with imagery from MODIS aboard TERRA satellites. MODIS true-color image shows the location of fires and the grayish color of the smoke plumes over Northeast Asia. Aerosol optical thckness (AOT) retrieved from the MODIS data were compared with fire hot spots, ground-based radiation data and TOMS -based aerosol index data. Large AOT, 2.0-5.0 was observed on 20 May 2003 over Korea due to the influence of the long range transport of smoke aerosol plume from the Russian fires, while surface observed fine mode of aerosol size distribution increased.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.35-39
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• 2011

토양과 식물의 잎에서 일어나는 증발산은 주로 증발접시, 침루계 등을 이용하여 실측하거나 에디 공분산, Bowen 비 등을 이용하여 경험적으로 측정할 수 있으나, 이러한 지점별 실측 자료는 공간적인 변동성이 큰 수문기상인자 특성상 지역적인 대표값으로 적용하는 데 어려움이 따른다. 본 연구에서는 이러한 기존 증발산 관측 방법의 단점을 보완하고자 인공위성 영상자료를 기반으로 한 원격탐사 기법을 이용하여 Penman-Monteith (PM)와 Priestley-Taylor (PT) 공간 증발산 산정 모형을 적용, 우리나라 증발산의 시공간적인 분포를 산정하였다. Terra 인공위성에 탑재된 Moderate Resolution Imaging Spectroradiometer (MODIS)로부터 제공되는 위성 영상 자료를 이용하여 기존에 연구된 증발산 모형을 이용하여 증발산을 산정하고 이를 상호 비교함으로써 우리나라에 대한 적용성을 검토하였다. 본 연구의 결과는 토양 및 식생이 소비하는 물의 양을 보다 정확하게 시공간적으로 파악하여 정부 차원의 수자원 관리 계획 수립에 유용하게 이용될 것이다.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.3
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• pp.51-61
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• 2020

Drought events are not clear when those start and end compared with other natural disasters. Because drought events have different timing and severity of damage depending on the region, various studies are being conducted using satellite images to identify regional drought occurrence differences. In this study, we investigated the applicability of drought assessment using the Evaporative Stress Index (ESI) based on Moderate Resolution Imaging Spectroradiometer (MODIS) satellite images. The ESI is an indicator of agricultural drought that describes anomalies in actual and reference evapotranspiration (ET) ratios that are retrieved using remotely sensed inputs of Land Surface Temperature (LST) and Leaf Area Index (LAI). However, these approaches have a limited spatial resolution when mapping detailed vegetation stress caused by drought, and drought hazard in the actual crop cultivation areas due to the small crop cultivation in South Korea. For these reasons, the development of a drought index that provides detailed higher resolution ESI, a 500 m resolution image is essential to improve the country's drought monitoring capabilities. The newly calculated ESI was verified through the existing 5 km resolution ESI and historical records for drought impacts. This study evaluates the performance of the recently developed 500 m resolution ESI for severe and extreme drought events that occurred in South Korea in 2001, 2009, 2014, and 2017. As a result, the two ES Is showed high correlation and tendency using Receiver Operating Characteristics (ROC) analysis. In addition, it will provide the necessary information on the spatial resolution to evaluate regional drought hazard assessment and and the small-scale cultivation area across South Korea.

• Journal of the Korean Association of Geographic Information Studies
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• v.21 no.1
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• pp.46-56
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• 2018

This paper aimed to identify main factors of community characters, which have an effect on the land surface temperature(LST) change and estimate the impacting coefficient(ratio) of factors in a significant level of statistics. Chungcheongbuk-do province was selected and then partitioned into city and county areas for the sake of convenience of modeling. LST time series data and the community character data were developed based on Terra Satellite MODIS data and collected from the National Statistical Office, respectively. By the cause and effect relationship between community characters and LST, regression coefficients were estimated using a penal model. In a panel modeling, LST and community characters were used as a dependent variable and explanatory variables, respectively. Panel modeling analysis was carried out using statistical package STATA14 and one-way fixed effect model was selected as the most suitable model to evaluate the regression coefficients in the study area. The impacting ratio of LST change by any explanatory variable derived from the regression coefficients of the panel model fixed. Impacting ratios for industrial areas, elevation ${\times}$ building, energy usage, average window speed, non-urban management area, agricultural, nature and environmental conservation, average precipitation were 3.746, 2.856, 2.742, 0.553, 0.102, 0.071 and 0.003, respectively.

• Korean Journal of Remote Sensing
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• v.35 no.4
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• pp.573-587
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• 2019

A multi-temporal approach using remotely sensed time series data obtained over multiple years is a very useful method for monitoring land covers and land-cover changes. While spectral-based methods at any particular time limits the application utility due to instability of the quality of data obtained at that time, the approach based on the temporal profile can produce more accurate results since data is analyzed from a long-term perspective rather than on one point in time. In this study, a multi-temporal approach applying a multi-periodic harmonic model is proposed for classification of remotely sensed data. A harmonic model characterizes the seasonal variation of a time series by four parameters: average level, frequency, phase, and amplitude. The availability of high-quality data is very important for multi-temporal analysis.An satellite image usually have many unobserved data and bad-quality data due to the influence of observation environment and sensing system, which impede the analysis and might possibly produce inaccurate results. Harmonic analysis is also very useful for real-time data reconstruction. Multi-periodic harmonic model is applied to the reconstructed data to classify land covers and monitor land-cover change by tracking the temporal profiles. The proposed method is tested with the MODIS and GOCI NDVI time series over the Korean Peninsula for 5 years from 2012 to 2016. The results show that the multi-periodic harmonic model has a great potential for classification of land-cover types and monitoring of land-cover changes through characterizing annual temporal dynamics.