• Journal of Astronomy and Space Sciences
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• v.15 no.2
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• pp.391-400
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• 1998

KSR-II, a two-stage sounding rocket of KARI was launched successfully at the west coast of the Korean Peninsula at 1000LST, June 11, 1998. For the ozone measurement mission, 8-channel UV and visible radiometers were onboard the rocket. The rocket measured the first in situ stratospheric and mesospheric ozone density profile over Korea during its ascending phase using the radiometer. Comparisons with Dobson spectrophotometer, ozonesonde, and HALOE onboard the UARS are shown together. Our results are in reasonable agreements with others.

• Journal of Astronomy and Space Sciences
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• v.17 no.2
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• pp.277-284
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• 2000

KARI(Korea Aerospace Research Institute) has measured the ozone density profiles over the Korean Peninsular since the launch of the Korean Sounding Rocket-I (KSR-I) in 1993. The purpose of ozone measurements is to obtain the stratospheric and mesospheric vertical ozone density profiles over the Korean Peninsular with solar UV radiometers. With the visible channel of the radiometer, the attitude variation of the rocket was corrected and compensated. Developed system is based on ozone detector designs onboard the KSR-I and KSR-II. We discuss the development of ozone detector which will be onboard the KSR-III and its circuit and vibration test results for EM model.

• Korean Journal of Remote Sensing
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• v.12 no.1
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• pp.60-80
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• 1996

AVHRR(Advanced Very High Resolution Radiometer) on NOAA satellite provides data in five spectral, one in visible range, one in near infrared and three in thermal range. In this paper, application of NOAA/AVHRR data is studied for environment monitoring such as cloud top temperature, surface temperature, albedo, sea surface temperature, vegetation index, forest fire, flood, snow cover and so on. The analyses for cloud top temperature, surface temperature, albedo, sea surface temperature, vegetation index and forest fire showed reasonable agreement. But monitoring for flood and snow cover was uneasy due to the limitations such as cloud contamination, low spatial resolution. So this research had only simple purpose to identify well-defined waterbody for dynamic monitoring of flood. Based on development of these basic algorithms, we have a plan to further reseach for environment monitoring using AVHRR data.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.296-296
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• 2022

농업적 가뭄은 토양의 수분함량(토양수분)이 마르기 시작하면서 식생 활동에 영향을 주는 것으로 정의할 수 있다. 광범위한 농업적 가뭄을 판별하기 위해 인공위성 자료를 토대로 토양수분을 산정하고 이를 이용해 가뭄지수를 산정하고, 가뭄 상태를 판별한다. 기존 인공위성 기반의 토양수분의 경우, microwave sensor에서 제공되는 밝기온도(brightness temperature)를 통해 토양수분을 추정하는 방식이 일반적으로 활용되었다. 하지만, microwave sensor에서 제공되는 자료들의 공간해상도가 10 km 이상이기 때문에, 한반도나 더 작게는 유역 단위, 행정 단위별 가뭄 분석을 하기에는 적합하지 않다. 이에 본 연구에서는 공간 해상도 500m의 광학센서(visible infrared imaging radiometer suite sensor (VIIRS))에서 제공되는 지표면 온도(land surface temperature)와 지표 반사도(land surface albedo) 자료들을 조합하여 토양수분을 산정하는 방식을 제안하고, 산출된 토양수분으로 농업적 가뭄을 모니터링한 결과를 제시하고자 한다. 기존의 microwave sensor로 산출된 토양수분 결과 값과의 비교 및 검증을 통해 광학센서를 통한 토양수분 산출물의 한반도 내 적용성을 확인할 수 있다.

• Korean Journal of Remote Sensing
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• v.37 no.1
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• pp.169-176
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• 2021

The Global Space-based Inter-Calibration System (GSICS) is an international partnership sponsored by World Meteorological Organization (WMO) to continue and improve climate monitoring and to ensure consistent accuracy between observation data from meteorological satellites operating around the world. The objective for GSICS is to inter-calibration from pairs of satellites observations, which includes direct comparison of collocated Geostationary Earth Orbit (GEO)-Low Earth Orbit (LEO) observations. One of the GSICS inter-calibration methods, the Ray-matching technique, is a surrogate approach that uses matched, co-angled and co-located pixels to transfer the calibration from a well calibrated satellite sensor to another sensor. In Korea, the first GEO satellite, Communication Ocean and Meteorological Satellite (COMS), is used to participate in the GSICS program. The National Meteorological Satellite Center (NMSC), which operated COMS/MI, calculated the Radiative Transfer Model (RTM)-based GSICS coefficient coefficients. The L1P reproduced through GSICS correction coefficient showed lower RMSE and Bias than L1B without GSICS correction coefficient applied. The calculation cycles of the GSICS correction coefficients for COMS/MI visible channel are provided annual and diurnal (2, 5, 10, 14-day), but long-term evaluation according to these cycles was not performed. The purpose of this paper is to perform evaluation depending on the annual/diurnal cycles of COMS/MI GSICS correction coefficients based on the ray-matching technique using Suomi-NPP/Visible Infrared Imaging Radiometer Suite (VIIRS) data as reference data. As a result of evaluation, the diurnal cycle had a higher coincidence rate with the reference data than the annual cycle, and the 14-day diurnal cycle was the most suitable for use as the GSICS correction coefficient.

• Asian Journal of Turfgrass Science
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• v.22 no.1
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• pp.1-12
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• 2008

Remote sensing using multispectral radiometry may be a useful tool to detect drought stress in turf. The objective of this research was to investigate the correlation between drought stress and multispectral reflectance (MSR) from the turf canopy. St. Augustinegrass (Stenotaphrum secundatum[Walt.] Kuntze.) cultivars 'Floratam' and 'Palmetto', 'SeaIsle 1' seashore paspalum Paspalum vaginatum Swartz.), 'Empire' zoysiagrass (Zoysia japonica Steud.), and 'Pensacola' bahiagrass (Paspalum notatumFlugge) were established in lysimeters in the University of Florida Envirotron greenhouse facility in Gainesville. Irrigation was applied at 100%, 80%, 60%, or 40% of evapotranspiration (ET). Weekly evaluations included: a) shoot quality, leaf rolling, leaf firing b) soil moisture, chlorophyll content index; c) photosynthesis and d) multispectral reflectance. All the measurements were correlated with MSR data. Drought stress affected the infrared spectral region more than the visible spectral region. Reflectance sensitivity to water content of leaves was higher in the infrared spectral region than in the visible spectral region. Grasses irrigated at 100% and 80% of ET had no differences in normalized difference vegetation indices (NDVI), leaf area index (LAI), and stress indices. Grasses irrigated at 60% and 40% of ET had differences in NDVI, LAI, and stress indices. All measured wavelengths except 710nm were highly correlated (P < 0.0001) with turf visual quality, leaf firing, leaf rolling, soil moisture, chlorophyll content index, and photosynthesis. MSR could detect drought stress from the turf canopy.

• Korean Journal of Remote Sensing
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• v.32 no.2
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• pp.73-86
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• 2016

In this study, an algorithm to estimate Aerosol Optical Thickness (AOT) over small cities during nighttime has been developed by using the radiance from artificial light sources in small cities measured from Visible Infrared Imaging Radiometer Suite (VIIRS) sensor's Day/Night Band (DNB) aboard the Suomi-National Polar Partnership (Suomi-NPP) satellite. The algorithm is based on Beer's extinction law with the light sources from the artificial lights over small cities. AOT is retrieved for cloud-free pixels over individual cities, and cloud-screening was conducted by using the measurements from M-bands of VIIRS at infrared wavelengths. The retrieved nighttime AOT is compared with the aerosol products from MODerate resolution Imaging Spectroradiometer (MODIS) aboard Terra and Aqua satellites. As a result, the correlation coefficients over individual cities range from around 0.6 and 0.7 between the retrieved nighttime AOT and MODIS AOT with Root-Mean-Squared Difference (RMSD) ranged from 0.14 to 0.18. In addition, sensitivity tests were conducted for the factors affecting the nighttime AOT to estimate the range of uncertainty in the nighttime AOT retrievals. The results of this study indicate that it is promising to infer AOT using the DNB measaurements over small cities in Korea at night. After further development and refinement in the future, the developed retrieval algorithm is expected to produce nighttime aerosol information which is not operationally available over Korea.

• Korean Journal of Environment and Ecology
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• v.28 no.4
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• pp.484-489
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• 2014

In this paper, we examined factors that influenced light pollution in Korean national parks during peak and off-peak tourist seasons. Cloud-and moonlight-free nighttime satellite images that were collected during October 2012(for peak season) and January 2013(for off-peak season) by the Day and Night Band (DNB) of the Visible Infrared Imaging Radiometer Suite (VIIRS) sensor were used to estimate the levels of light pollution in 19 national parks (excluding the Bukhansan and Mudeungsan National Parks). Bootstrapping regression analyses were conducted to examine the effects of socioeconomic and policy factors on light pollution in the study national parks for peak and off-peak tourist seasons, separately. The characteristics of light pollution in the national parks varied by season. During the peak tourist season, light pollution in the national parks were affected more by night lights nearby the parks than those within in the parks, while in the off-peak season, light sources in the parks were more important. Scattering of light emitted from hotels and other recreational facilities outside the parks that led to the sky glow effect can be attributed to the greater impact of night lights nearby the parks during the peak season. This result suggests that regulating light pollution nearby the park areas is needed to mitigate light pollution in the national parks, especially in a peak tourist season.

• Korean Journal of Remote Sensing
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• v.35 no.2
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• pp.265-278
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• 2019

Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB) data help to enable rapid emergency responses through detection of the artificial and natural disasters occurring at night. The DNB data without correction of lunar irradiance effect distributed by Korea Ocean Science Center (KOSC) has advantage for rapid change detection because of direct receiving. In this study, radiance differences according to the phase of the moon was analyzed for urban and mountain areas in Korean Peninsula using the DNB data directly receiving to KOSC. Lunar irradiance correction algorithm was proposed for the change detection. Relative correction was performed by regression analysis between the selected pixels considering the land cover classification in the reference DNB image during the new moon and the input DNB image. As a result of daily difference image analysis, the brightness value change in urban area and mountain area was ${\pm}30$ radiance and below ${\pm}1$ radiance respectively. The object based change detection was performed after the extraction of the main object of interest based on the average image of time series data in order to reduce the matching and geometric error between DNB images. The changes in brightness occurring in mountainous areas were effectively detected after the calibration of lunar irradiance effect, and it showed that the developed technology could be used for real time change detection.

• Korean Journal of Remote Sensing
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• v.34 no.6_1
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• pp.1025-1032
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• 2018

Snow Cover is a form of precipitation that is defined by snow on the surface and is the single largest component of the cryosphere that plays an important role in maintaining the energy balance between the earth's surface and the atmosphere. It affects the regulation of the Earth's surface temperature. However, since snow cover is mainly distributed in area where human access is difficult, snow cover detection using satellites is actively performed, and snow cover detection in forest area is an important process as well as distinguishing between cloud and snow. In this study, we applied the Normalized Difference Snow Index (NDSI) and the Normalized Difference Vegetation Index (NDVI) to the geostationary satellites for the snow detection of forest area in existing polar orbit satellites. On the rest of the forest area, the snow cover detection using $R_{1.61{\mu}m}$ anomaly technique and NDSI was performed. As a result of the indirect validation using the snow cover data and the Visible Infrared Imaging Radiometer (VIIRS) snow cover data, the probability of detection (POD) was 99.95 % and the False Alarm Ratio (FAR) was 16.63 %. We also performed qualitative validation using the Himawari-8 Advanced Himawari Imager (AHI) RGB image. The result showed that the areas detected by the VIIRS Snow Cover miss pixel are mixed with the area detected by the research false pixel.