• Title/Summary/Keyword: Cloudy

Search Result 298, Processing Time 0.03 seconds

A Reflectance Normalization Via BRDF Model for the Korean Vegetation using MODIS 250m Data (한반도 식생에 대한 MODIS 250m 자료의 BRDF 효과에 대한 반사도 정규화)

  • Yeom, Jong-Min;Han, Kyung-Soo;Kim, Young-Seup
    • Korean Journal of Remote Sensing
    • /
    • v.21 no.6
    • /
    • pp.445-456
    • /
    • 2005
  • The land surface parameters should be determined with sufficient accuracy, because these play an important role in climate change near the ground. As the surface reflectance presents strong anisotropy, off-nadir viewing results a strong dependency of observations on the Sun - target - sensor geometry. They contribute to the random noise which is produced by surface angular effects. The principal objective of the study is to provide a database of accurate surface reflectance eliminated the angular effects from MODIS 250m reflective channel data over Korea. The MODIS (Moderate Resolution Imaging Spectroradiometer) sensor has provided visible and near infrared channel reflectance at 250m resolution on a daily basis. The successive analytic processing steps were firstly performed on a per-pixel basis to remove cloudy pixels. And for the geometric distortion, the correction process were performed by the nearest neighbor resampling using 2nd-order polynomial obtained from the geolocation information of MODIS Data set. In order to correct the surface anisotropy effects, this paper attempted the semiempirical kernel-driven Bi- directional Reflectance Distribution Function(BRDF) model. The algorithm yields an inversion of the kernel-driven model to the angular components, such as viewing zenith angle, solar zenith angle, viewing azimuth angle, solar azimuth angle from reflectance observed by satellite. First we consider sets of the model observations comprised with a 31-day period to perform the BRDF model. In the next step, Nadir view reflectance normalization is carried out through the modification of the angular components, separated by BRDF model for each spectral band and each pixel. Modeled reflectance values show a good agreement with measured reflectance values and their RMSE(Root Mean Square Error) was totally about 0.01(maximum=0.03). Finally, we provide a normalized surface reflectance database consisted of 36 images for 2001 over Korea.

Detection of Forest Fire Damage from Sentinel-1 SAR Data through the Synergistic Use of Principal Component Analysis and K-means Clustering (Sentinel-1 SAR 영상을 이용한 주성분분석 및 K-means Clustering 기반 산불 탐지)

  • Lee, Jaese;Kim, Woohyeok;Im, Jungho;Kwon, Chunguen;Kim, Sungyong
    • Korean Journal of Remote Sensing
    • /
    • v.37 no.5_3
    • /
    • pp.1373-1387
    • /
    • 2021
  • Forest fire poses a significant threat to the environment and society, affecting carbon cycle and surface energy balance, and resulting in socioeconomic losses. Widely used multi-spectral satellite image-based approaches for burned area detection have a problem in that they do not work under cloudy conditions. Therefore, in this study, Sentinel-1 Synthetic Aperture Radar (SAR) data from Europe Space Agency, which can be collected in all weather conditions, were used to identify forest fire damaged area based on a series of processes including Principal Component Analysis (PCA) and K-means clustering. Four forest fire cases, which occurred in Gangneung·Donghae and Goseong·Sokcho in Gangwon-do of South Korea and two areas in North Korea on April 4, 2019, were examined. The estimated burned areas were evaluated using fire reference data provided by the National Institute of Forest Science (NIFOS) for two forest fire cases in South Korea, and differenced normalized burn ratio (dNBR) for all four cases. The average accuracy using the NIFOS reference data was 86% for the Gangneung·Donghae and Goseong·Sokcho fires. Evaluation using dNBR showed an average accuracy of 84% for all four forest fire cases. It was also confirmed that the stronger the burned intensity, the higher detection the accuracy, and vice versa. Given the advantage of SAR remote sensing, the proposed statistical processing and K-means clustering-based approach can be used to quickly identify forest fire damaged area across the Korean Peninsula, where a cloud cover rate is high and small-scale forest fires frequently occur.

On Using Near-surface Remote Sensing Observation for Evaluation Gross Primary Productivity and Net Ecosystem CO2 Partitioning (근거리 원격탐사 기법을 이용한 총일차생산량 추정 및 순생태계 CO2 교환량 배분의 정확도 평가에 관하여)

  • Park, Juhan;Kang, Minseok;Cho, Sungsik;Sohn, Seungwon;Kim, Jongho;Kim, Su-Jin;Lim, Jong-Hwan;Kang, Mingu;Shim, Kyo-Moon
    • Korean Journal of Agricultural and Forest Meteorology
    • /
    • v.23 no.4
    • /
    • pp.251-267
    • /
    • 2021
  • Remotely sensed vegetation indices (VIs) are empirically related with gross primary productivity (GPP) in various spatio-temporal scales. The uncertainties in GPP-VI relationship increase with temporal resolution. Uncertainty also exists in the eddy covariance (EC)-based estimation of GPP, arising from the partitioning of the measured net ecosystem CO2 exchange (NEE) into GPP and ecosystem respiration (RE). For two forests and two agricultural sites, we correlated the EC-derived GPP in various time scales with three different near-surface remotely sensed VIs: (1) normalized difference vegetation index (NDVI), (2) enhanced vegetation index (EVI), and (3) near infrared reflectance from vegetation (NIRv) along with NIRvP (i.e., NIRv multiplied by photosynthetically active radiation, PAR). Among the compared VIs, NIRvP showed highest correlation with half-hourly and monthly GPP at all sites. The NIRvP was used to test the reliability of GPP derived by two different NEE partitioning methods: (1) original KoFlux methods (GPPOri) and (2) machine-learning based method (GPPANN). GPPANN showed higher correlation with NIRvP at half-hourly time scale, but there was no difference at daily time scale. The NIRvP-GPP correlation was lower under clear sky conditions due to co-limitation of GPP by other environmental conditions such as air temperature, vapor pressure deficit and soil moisture. However, under cloudy conditions when photosynthesis is mainly limited by radiation, the use of NIRvP was more promising to test the credibility of NEE partitioning methods. Despite the necessity of further analyses, the results suggest that NIRvP can be used as the proxy of GPP at high temporal-scale. However, for the VIs-based GPP estimation with high temporal resolution to be meaningful, complex systems-based analysis methods (related to systems thinking and self-organization that goes beyond the empirical VIs-GPP relationship) should be developed.

Characteristics and Quality Control of Precipitable Water Vapor Measured by G-band (183 GHz) Water Vapor Radiometer (G-band (183 GHz) 수증기 라디오미터의 가강수량 특성과 품질 관리)

  • Kim, Min-Seong;Koo, Tae-Young;Kim, Ji-Hyoung;Jung, Sueng-Pil;Kim, Bu-Yo;Kwon, Byung Hyuk;Lee, Kwangjae;Kang, Myeonghun;Yang, Jiwhi;Lee, ChulKyu
    • Journal of the Korean earth science society
    • /
    • v.43 no.2
    • /
    • pp.239-252
    • /
    • 2022
  • Quality control methods for the first G-band vapor radiometer (GVR) mounted on a weather aircraft in Korea were developed using the GVR Precipitable Water Vapor (PWV). The aircraft attitude information (degree of pitch and roll) was applied to quality control to select the shortest vertical path of the GVR beam. In addition, quality control was applied to remove a GVR PWV ≥20 mm. It was found that the difference between the warm load average power and sky load average power converged to near 0 when the GVR PWV increased to 20 mm or higher. This could be due to the high brightness temperature of the substratus and mesoclouds, which was confirmed by the Communication, Ocean and Meteorological Satellite (COMS) data (cloud type, cloud top height, and cloud amount), cloud combination probe (CCP), and precipitation imaging probe (PIP). The GVR PWV before and after the application of quality control on a cloudy day was quantitatively compared with that of a local data assimilation and prediction system (LDAPS). The Root Mean Square Difference (RMSD) decreased from 2.9 to 1.8 mm and the RMSD with Korea Local Analysis and Precipitation System (KLAPS) decreased from 5.4 to 4.3 mm, showing improved accuracy. In addition, the quality control effectiveness of GVR PWV suggested in this study was verified through comparison with the COMS PWV by using the GVR PWV applied with quality control and the dropsonde PWV.

Analysis of Climate, Weather, Solar Radiation and Solar Energy in Major Cities of Tajikistan (타지키스탄 주요 도시의 기후, 날씨, 일사량 및 태양에너지 분석)

  • Taeyoo Na;Jeongdu Noh;Hyeontae Kim;Seong-Seung Kang
    • The Journal of Engineering Geology
    • /
    • v.33 no.3
    • /
    • pp.389-401
    • /
    • 2023
  • Climate, weather, insolation (solar radiation), and solar energy in major cities of Tajikistan were investigated prior to construction of infrastructure for the Dushanbe Solar Station. In Dushanbe city there was a 70% probability of sunny days from May 16 to October 23, a period of 5.2 months. August had the most sunny days of in the year, with 99% probability of a sunny, the cloudiest month was February with a 41% chance of being sunny. In major cities of the Sughd and Gorno-Badakhshan states, the average number of cloudy days per month was ~3.3, with Dzhauz having 53 day and Fedchnko Glacier 79 days. For the 18 major cities of Tajikistan, the average annual total solar radiation was 2,429 W/m2, and the average monthly solar radiation was 202 W/m2. The city with the lowest annual total and monthly average solar radiation was Shartuz in Sughd state, with values ~2.7% less than the national average. The cities with the highest annual total and monthly average solar radiation were Khorog and Jirgatol in Gorno-Badakhshan state, with values ~10% above the national average. The daily average incident shortwave solar energy in the cities Dushanbe, Karakul, and Jirgatol was ~7.8 kWh per 2.4 m2 during summer (May-August), and 2.7 kWh during winter (November-February), or ~35% that of summer.

Musical Characteristics and Locality of Naeseo-deulsori (내서들일소리의 음악적 특징과 지역성)

  • Seo, Jeong-mae
    • (The) Research of the performance art and culture
    • /
    • no.43
    • /
    • pp.325-356
    • /
    • 2021
  • This study is to analyze the current status of transmission and musical characteristics of Naeseo-deulilsori in Changwon, and the purpose of this study is to illuminate the value of deulilsori in Naeseo region, so that it can be continuously inherited. Naeseo-deulsori consists of the Mosimgi-sori, Nonmaegi-sori, and Chingchingi-sori. Mosimgi-sori, which is called when planting a seedling, is divided into 6 types according to the order and situation of work. ① rice planting sound, ② rice planting sound called in the morning, ③ rice planting sound called at lunch time, ④ rice planting sound called after lunch, ⑤ rice planting sound called when it is raining or cloudy, ⑥ rice planting sound called at sunset. Mosimgi-sori, which is called when planting a seedling, is based on Menali-tori, but partly influenced by Yugjabaegi-tori. However, it was typical Menali-tori in the slow The sound of rice planting in the nearby Haman region, but as the speed increased in the fast The sound of rice planting, the characteristics of Menali-tori faded and la↘mi perfect fourth descending frequently appeared. In the sound of rice planting in Goseong, both slow and fast sounds were strongly influenced by Yugjabaegi-tori. In the end, the sound of rice planting in the Naeseo region is less Yugjabaegi-tori than in the Goseong region and stronger than in Haman region. This combination of tori is a musical bargaining phenomenon that appears in the border region, and it can be said to be a geographical and regional characteristic of the Naeseo region. Nonmaegi-sori has the same sound as 'Sangsadeio' throughout the nearby Goseong and Haman regions. However, in Nonmaegi-sori in the Naeseo region, a strong Gyeong-tori tendency is found in the sound received. Looking at the flow of the melody of Nonmaegi-sori, it seems that the pitch has been changed by the intestines in recent years, and this modified melodic form has continued as it is. In order to guarantee locality, this part seems to need to be corrected in the future.

A Studs on Farmers Syndrome and Its Risk Factors of Vinylhouse Workers and Evaluation of Risk Factors of Vinylhouse Works (일부 농촌지역 비닐하우스 농사자들의 작업환경 및 농부증 실태와 관련요인평가)

  • Lee, Jung-Jeung
    • Journal of agricultural medicine and community health
    • /
    • v.29 no.1
    • /
    • pp.101-119
    • /
    • 2004
  • Objectives: In order to estimate risk factors affecting the health of vinylhouse workers and harmful environments in vinylhouse working. Methods: The investigator performed questionnaires and laboratory examinations on 102 vinylhouse workers and 69 farmers in 7 myoens (Korean subcounties). one eup (a Korean town), Goryeong-gun, Gyeongsangbuk-do between April 8 and 18, 2004 (for 11 days), and measured the heavy metal in the air and the soil, temperature, humidity, air current, harmful gases in vinylhouses. Results: Even in cloudy days, the temperature in vinylhouses in daylight was $33.4^{\circ}$ and the temperature difference between inside and outside vinylhouses was around $16^{\circ}$. Oxygen concentration was similar inside and outside vinylhouses, while carbon dioxide concentration was lower inside than outside vinylhouses. Carbon monoxide was not detected. In the air inside vinylhouses, cadmium was not detected. Lean concentration in the soil was lower inside vinylhouses than outside vinylhouses at surface, while cadmium concentration was similar inside and outside vinylhouses in the soil except some areas. Out of male vinylhouse workers. 16.4---- were positive farmer's syndrome and 49.2---- were suspicious, while out of females, 41.5---- were positive and 46.3---- were suspicious. Out of male farmers, 30.4---- were positive farmer's syndrome, while out of female farmers, 60.0---- were positive and 28.3---- were suspicious. There was no difference between vinylhouse workers and farmers in the distribution of hypertension and abnormal liver function, while diabetes mellitus was more common in farmers than in vinylhouse workers. Vinylhouse working, sex, and hours of farming per day were selected as significant variables affecting farmer's syndrome in this study, and the rate of positive farmer's syndrome was rather lower in vinylhouse workers than in farmers. Females were higher than males in the rate, and those who farmed at least 10 hours per day were higher in the rate than those who farmed less than 10 hours per day. Out of the vinylhouse workers, no differences were found between the distribution of farmer's syndrome and farming-related variables such as the total period of farming, the size of farm land, the mean farming hours per day, the number of family members who farm together, the frequency of scattering agricultural chemicals. In addition, there were no differences between the distribution and the wearing masks and protectors and personal sanitation among those who scattered agricultural chemicals by themselves. There were no differences found in blood lean concentration, urinary cadmium concentration, serum cholinesterase, and hemoglobin according to the distribution of farmer's syndrome. In the vinylhouse workers, females were higher than males in the rate of farmer's syndrome, and those who farmed at least 10 hours per day were higher in the rate than those who farmed less than 10 hours per day. Meanwhile, the rate was lower in those who slept at least 8 hours a day than in those who slept less than 8 hours. Conclusions: In conclusion, the physical environments inside vinylhouses were harmful, but no significant difference was found in harmfulness of the chemical environments. The chronic diseases such as farmer's syndrome. hypertension, diabetes, and dyshepatia were not common in the vinylhouse workers than in the farmers. Meanwhile, farmer's syndrome was more common in the vinylhouse workers who worked longer and slept less.

  • PDF

Studies on the Drying Mechanism of Stratified Soil-Comparison between Bare Surface and Grass plot- (성층토양의 건조기구에 관한 연구)

  • 김철기
    • Magazine of the Korean Society of Agricultural Engineers
    • /
    • v.15 no.1
    • /
    • pp.2913-2924
    • /
    • 1973
  • This study was to investigate the drying mechanism of stratified soil by investigating 'effects of the upper soil on moisture loss of the lower soil and vice versa' and at the same time by examining how the drying progressed in the stratified soils with bare surface and with vegetated surface respectively. There were six plots of the stratified soils with bare surface($A_1- A_6$ plot) and the same other six plots($B_1- B_5$ plot), with vegetated surface(white clover). These six plots were made by permutating two kinds of soils from three kinds of soils; clay loam(CL). Sandy loam(SL). Sand(s). Each layer was leveled by saturating sufficient water. Depth of each plot was 40cm by making each layer 20cm deep and its area. $90{\times}90(cm^2)$. The cell was put at the point of the central and mid-depth of the each layer in the each plot in order to measure the soil moisture by using OHMMETER. soil moisture tester, and movement of soil water from out sides was cut off by putting the vinyl on the four sides. The results obtained were as follow; 1. Drying progressed from the surface layer to the lower layer regardless of plots. There was a tendency thet drying of the upper soil was faster than that of the lower soil and drying of the plot with vegetated surface was also faster than that of the plot with bare surface. 2. Soil moisture was recovered at approximately the field capacity or moisture equivalent by infiltration in the course of drying, when there was a rainfall. 3. Effects of soil texture of the lower soil on dryness of the upper soil in the stratified soil were explained as follows; a) When the lower soil was S and the upper, CL or SL, dryness of the upper soils overlying the lower soil of S was much faster than that overlying the lower soil of SL or CL, because sandy soil, having the small field capacity value and playing a part of the layer cutting off to some extent capillary water supply. Drying of SL was remarkably faster than that of CL in the upper soil. b) When the lower soil was SL and the upper S or CL, drying of the upper soil was the slowest because of the lower SL, having a comparatively large field capacity value. Drying of CL tended to be faster than that of S in the upper soil. c) When the lower soil was CL and the upper S or SL, drying of the upper soil was relatively fast because of the lower CL, having the largest field capacity value but the slowest capillary conductivity. Drying of SL tended to be faster than that of S in the upper soil. 4. According to a change in soil moisture content of the upper soil and the lower soil during a day there was a tendency that soil moisture contents of CL and SL in the upper soil were decreased to its minimum value but that of S increased to its maximum value, during 3 hours between 12.00 and 15.00. There was another tendency that soil moisture contents of CL, SL and S in the lower soil were all slightly decreased by temperature rising and those in a cloudy day were smaller than those in a clear day. 5. The ratio of the accumulated soil moisture consumption to the accumulated guage evaporation in the plot with vegetated surface was generally larger than that in the plot with bare surface. The ratio tended to decrease in the course of time, and also there was a tendency that it mainly depended on the texture of the upper soil at the first period and the texture of the lower soil at the last period. 6. A change in the ratio of the accumulated soil moisture consumption was larger in the lower soil of SL than in the lower soil of S. when the upper soil was CL and the lower, SL and S. The ratio showed the biggest figure among any other plots, and the ratio in the lower soil plot of CL indicated sligtly bigger than that in the lower soil plot of S, when the upper soil was SL and the lower, CL and S. The ratio showed less figure than that of two cases above mentioned, when the upper soil was S and the lower CL and SL and that in the lower soil plot of CL indicated a less ratio than that in the lower soil plot of SL. As a result of this experiments, the various soil layers wero arranged in the following order with regard to the ratio of the accumulated soil moisture consumption: SL/CL>SL/S>CL/SL>CL/S$\fallingdotseq$S/SL>S/CL.

  • PDF