Surveillance of waste disposal activity at sea using satellite ocean color imagers: GOCI and MODIS     

Gi Hoon Hong  Dong Beom Yang  Hyun-Mi Lee  Sung Ryull Yang  Hee Woon Chung  Chang Joon Kim  Young-Il Kim  Chang Soo Chung  Yu-Hwan Ahn  Young-Je Park  Jeong-Eon Moon 《Ocean Science Journal》2012,47(3):387-394

Korean Geostationary Ocean Color Imager (GOCI) and Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua observations of the variation in ocean color at the sea surface were utilized to monitor the impact of nutrient-rich sewage sludge disposal in the oligotrophic area of the Yellow Sea. MODIS revealed that algal blooms persisted in the spring annually at the dump site in the Yellow Sea since year 2000 to the present. A number of implications of using products of the satellite ocean color imagers were exploited here based on the measurements in the Yellow Sea. GOCI observes almost every hour during the daylight period, every day since June 2011. Therefore, GOCI provides a powerful tool to monitor waste disposal at sea in real time. Tracking of disposal activity from a large tanker was possible hour by hour from the GOCI timeseries images compared to MODIS. Smaller changes in the color of the ocean surface can be easily observed, as GOCI resolves images at smaller scales in space and time in comparison to polar orbiting satellites, e.g., MODIS. GOCI may be widely used to monitor various marine activities in the sea, including waste disposal activity from ships.  相似文献   

Initial validation of GOCI water products against in situ data collected around Korean peninsula for 2010–2011     

Jeong-Eon Moon  Young-Je Park  Joo-Hyung Ryu  Jong-Kuk Choi  Jae-Hyun Ahn  Jee-Eun Min  Young-Baek Son  Sun-Ju Lee  Hee-Jeong Han  Yu-Hwan Ahn 《Ocean Science Journal》2012,47(3):261-277

This paper provides initial validation results for GOCI-derived water products using match-ups between the satellite and ship-borne in situ data for the period of 2010?C2011, with a focus on remote-sensing reflectance (R _rs ). Match-up data were constructed through systematic quality control of both in situ and GOCI data, and a manual inspection of associated GOCI images to identify pixels contaminated by cloud, land and inter-slot radiometric discrepancy. Efforts were made to process and quality check the in situ R _rs data. This selection process yielded 32 optimal match-ups for the R _rs spectra, chlorophyll a concentration (Chl_a) and colored dissolved organic matter (CDOM), and with 20 match-ups for suspended particulate matter concentration (SPM). Most of the match-ups are located close to shore and thus the validation should be interpreted limiting to near-shore coastal waters. The R _rs match-ups showed the mean relative errors of 18?C33% for the visible bands with the lowest 18?C19% for the 490 nm and 555 nm bands and 33% for the 412 nm band. Correlation for the R _rs match-ups was high in the 490?C865 nm bands (R²=0.72?C0.84) and lower in the 412 nm band (R²=0.43) and 443 nm band (R²=0.66). The match-ups for Chl_a showed a low correlation (<0.41) although the mean absolute percentage error was 35% for the GOCI standard Chl_a. The CDOM match-ups showed an even worse comparison with R²<0.2. These match-up comparison for Chl_a and CDOM would imply the difficulty to estimate Chl_a and CDOM in near-shore waters where the variability in SPM would dominate the variability in R _rs . Clearly, the match-up statistics for SPM was better with R²=0.73 and 0.87 for two evaluated algorithms, although GOCI-derived SPM overestimated low concentration and underestimated high concentration. Based on this initial match-up analysis, we made several recommendations -1) to collect more offshore under-water measurements of the R _rs data, 2) to include quality flags in level-2 products, 3) to introduce an ISRD correction in the GOCI processing chain, 4) to investigate other types of in-water algorithms such as semianalytical ones, and 5) to investigate vicarious calibration for GOCI data and to maintain accurate and consistent calibration of field radiometric instruments.  相似文献   

Development of atmospheric correction algorithm for Geostationary Ocean Color Imager (GOCI)   总被引：2，自引：0，他引：2  

Jae-Hyun Ahn  Young-Je Park  Joo-Hyung Ryu  Boram Lee  Im Sang Oh 《Ocean Science Journal》2012,47(3):247-259

This paper describes an atmospheric correction algorithm for Geostationary Ocean Color Imager (GOCI) and its early phase evaluation. This algorithm was implemented in GOCI Data Processing System (GDPS) version 1.1. The algorithm is based on the standard SeaWiFS method, which accounts for multiple scattering effects and partially updated in terms of turbid case-2 water correction, optimized aerosol models, and solar angle correction per slot. For turbid water correction, we used a regional empirical relationship between water reflectance at the red (660 nm) and near infrared bands (745 nm and 865 nm). The relationship was derived from turbid pixels in satellite images after atmospheric correction, and processed using aerosol properties derived for neighboring non-turbid waters. For validation of the GOCI atmospheric correction, we compared our results with in situ measurements of normalized water leaving radiance (nL _w ) spectra that were obtained during several cruises in 2011 around Korean peninsula. The match up showed an acceptable result with mean ratio of the GOCI to in situ nL _w (??), 1.17, 1.24, 1.26, 1.15, 0.86 and 0.99 at 412 nm, 443 nm, 490 nm, 555 nm, 660 nm and 680 nm, respectively. It is speculated that part of the deviation arose from a lack of vicarious calibration and uncertainties in the above water nLw measurements.  相似文献   

Assessment of the APCC coupled MME suite in predicting the distinctive climate impacts of two flavors of ENSO during boreal winter     

Hye-In Jeong  Doo Young Lee  Karumuri Ashok  Joong-Bae Ahn  June-Yi Lee  Jing-Jia Luo  Jae-Kyung E. Schemm  Harry H. Hendon  Karl Braganza  Yoo-Geun Ham 《Climate Dynamics》2012,39(1-2):475-493

Forecast skill of the APEC Climate Center (APCC) Multi-Model Ensemble (MME) seasonal forecast system in predicting two main types of El Niño-Southern Oscillation (ENSO), namely canonical (or cold tongue) and Modoki ENSO, and their regional climate impacts is assessed for boreal winter. The APCC MME is constructed by simple composite of ensemble forecasts from five independent coupled ocean-atmosphere climate models. Based on a hindcast set targeting boreal winter prediction for the period 1982–2004, we show that the MME can predict and discern the important differences in the patterns of tropical Pacific sea surface temperature anomaly between the canonical and Modoki ENSO one and four month ahead. Importantly, the four month lead MME beats the persistent forecast. The MME reasonably predicts the distinct impacts of the canonical ENSO, including the strong winter monsoon rainfall over East Asia, the below normal rainfall and above normal temperature over Australia, the anomalously wet conditions across the south and cold conditions over the whole area of USA, and the anomalously dry conditions over South America. However, there are some limitations in capturing its regional impacts, especially, over Australasia and tropical South America at a lead time of one and four months. Nonetheless, forecast skills for rainfall and temperature over East Asia and North America during ENSO Modoki are comparable to or slightly higher than those during canonical ENSO events.  相似文献   

Line-by-line radiative transfer model for infrared spectrum of AERI     

Kwang-Mog Lee  Joong-Hyun Park  Myoung-Hwan Ahn  Mi-Lim Ou  Yoonjae Kim 《Asia-Pacific Journal of Atmospheric Sciences》2012,48(2):135-143

Infrared radiance spectra measured in space or on the ground have been used for many applications, such as the retrieval of atmospheric temperature and humidity profiles. The Korean Meteorological Administration (KMA) recently installed an Atmospheric Emitted Radiance Interferometer (AERI) system at the Korea Global Atmosphere Watch Center (36°32??N, 125°19??E) in Anmyondo to measure the downward radiance spectra on the ground. For further utilization of such interferometeric radiance measurements, an accurate line-by-line radiative transfer model is required. This study introduces a line-by-line radiative transfer model developed at Kyungpook National University (KNU_LBL) and presents comparisons of spectra simulated using the KNU_LBL model and measured by the AERI system, that is installed inside a secure container. When compared with the Atmospheric and Environmental Research (AER) radiative transfer codes, the KNU_LBL model provides nearly identical spectra for various model atmospheres. The simulated spectra are also in good agreement with the AERI spectra for clear sky conditions, and a further improvement is made when taking into account of the emissions and absorption by CO₂ and H₂O for the light path inside the container, even though the path is short.  相似文献   

Analytic hierarchy models for regional groundwater monitoring well allocation in Southeast Asian countries and South Korea     

Gyoo-Bum Kim  Joo-Sung Ahn  Atsunao Marui 《Environmental Earth Sciences》2009,59(2):325-338

Groundwater has played an important role in economic development in Southeast Asian countries, but some problems caused by nature or human actions such as contamination, over pumping, and land subsidence bring the necessity of more systematic groundwater monitoring wells. The analytical hierarchy process with pairwise comparison was used to allocate and organize the regional groundwater monitoring wells in five regions, Thailand, Cambodia, East/West Malaysia, and South Korea. Five different multi criteria decision models, which were composed of three primary criteria and eight secondary criteria, were developed based on the answers of the questionnaire from 76 groundwater experts in Thailand, 100 in Cambodia, 101 in East Malaysia, 87 in West Malaysia, and 93 in South Korea. It was revealed that the weights of model criteria for each country, which also represent relative importance on groundwater monitoring, were different according to the diverse groundwater situation. The most important factor to determine the number of monitoring well was ‘number of households using only groundwater as a water source’ for Thailand and South Korea, ‘number of contamination sources’ for Cambodia, ‘amount of groundwater use for drinking-water supply’ for East Malaysia, and ‘number of wells with contaminated water’ for West Malaysia.  相似文献   

Pore pressure model based on accumulated stress   总被引：2，自引：2，他引：0  

Taehyo Park  Duhee Park  Jae-Kwang Ahn 《Bulletin of Earthquake Engineering》2015,13(7):1913-1926

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Conceptualizing a multi-layered shingle aquifer model based on volcanic stratigraphy and water inflow to lava caves in Jeju Island,Korea     

Ung San Ahn  Dong-Chan Koh  Joonghyeok Heo  Byong-Wook Cho  Taehee Kim  Byoung-Woo Yum 《水文研究》2021,35(8):e14316

Volcanic aquifers supply a substantial portion of water resources in many parts of the world, including islands, and their productivity depends strongly on volcanic stratigraphy, which exhibits considerable heterogeneity. We investigated water inflow to lava tube caves formed from numerous basaltic lava flows in the northeastern coastal area of Jeju Island after storm events and monitored relative inflow rates monthly over 1 year to characterize groundwater flow processes in the upper parts of volcanic aquifers, and to evaluate the applicability of the previous hydrogeological models proposed for the island. Considerable water inflow arose shortly after storms from exposed palaeosol layers on the walls of the caves. The monthly monitoring results showed that wall inflow associated with these palaeosol layers is substantial. In both cases, discharge from ceiling drips was much less and more temporally variable compared to wall inflow discharge. Water flowing into the caves was rapidly drained through the floor at all monitoring sites. The lateral extent of the palaeosol layers was identified using drill core logs near the cave and outcrops in the coastal area. Based on these results, we inferred that multiple perched aquifers are formed by low-permeability palaeosol layers between lava flows, which are connected by vertical flows at discontinuities in the palaeosol layer, eventually reaching the basal aquifer. This study revealed the water inflow processes observed in lava tube caves constrained by palaeosol layers, and established a hydrogeological conceptual model incorporating multiple perched aquifers in both coastal and mountainous areas associated with extensive palaeosol layers formed during volcanic hiatuses. This finding would help elucidate recharge, groundwater flow, and contaminant transport processes in many volcanic aquifers that are not adequately represented by the previous models, and contribute to better management of groundwater in those areas.  相似文献   

Dynamic characteristics of monthly rainfall in the Korean Peninsula under climate change   总被引：3，自引：1，他引：2  

Min Soo Kyoung  Hung Soo Kim  Bellie Sivakumar  Vijay P. Singh  Kyung Soo Ahn 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(4):613-625

Global climate change is one of the most serious issues we are facing today. While its exact impacts on our water resources are hard to predict, there is a general consensus among scientists that it will result in more frequent and more severe hydrologic extremes (e.g. floods, droughts). Since rainfall is the primary input for hydrologic and water resource studies, assessment of the effects of climate change on rainfall is essential for devising proper short-term emergency measures as well as long-term management strategies. This is particularly the case for a region like the Korean Peninsula, which is susceptible to both floods (because of its mountainous terrain and frequent intense rainfalls during the short rainy season) and droughts (because of its smaller area, long non-rainy season, and lack of storage facilities). In view of this, an attempt is made in the present study to investigate the potential impacts of climate change on rainfall in the Korean Peninsula. More specifically, the dynamics of ‘present rainfall’ and ‘future rainfall’ at the Seoul meteorological station in the Han River basin are examined and compared; monthly scale is considered in both cases. As for ‘present rainfall,’ two different data sets are used: (1) observed rainfall for the period 1971–1999; and (2) rainfall for the period 1951–1999 obtained through downscaling of coarse-scale climate outputs produced by the Bjerknes Center for Climate Research-Bergen Climate Model Version 2 (BCCR-BCM2.0) climate model with the Intergovernmental Panel on Climate Change Special Report on Emission Scenarios (IPCC SRES) 20th Century Climate in Coupled Models (20C3M) scenario. The ‘future rainfall’ (2000–2099) is obtained through downscaling of climate outputs projected by the BCCR-BCM2.0 with the A2 emission scenario. For downscaling of coarse-scale climate outputs to basin-scale rainfall, a K-nearest neighbor (K-NN) technique is used. Examination of the nature of rainfall dynamics is made through application of four methods: autocorrelation function, phase space reconstruction, correlation dimension, and close returns plot. The results are somewhat mixed, depending upon the method, as to whether the rainfall dynamics are chaotic or stochastic; however, the dynamics of the future rainfall seem more on the chaotic side than on the stochastic side, and more so when compared to that of the present rainfall.  相似文献   

Formation mechanisms of illite,chlorite and mixed-layer illite-chlorite in Triassic volcanogenic sediments from the Southland Syncline,New Zealand     

Jung Ho Ahn  Donald R. Peacor  Douglas S. Coombs 《Contributions to Mineralogy and Petrology》1988,99(1):82-89

Clay minerals from the three principal kinds of zeolitic sediments from the type area for zeolite facies alteration, the Triassic Murihiku Supergroup, Southland, New Zealand, have been studied by TEM. Bentonitic tuff consists largely of smectite and heulandite with minor illite; they occur as replacements of glass shards and are inferred to be direct alteration products of tuff alteration. Both analcime- and laumontite-rich tuffs contain chlorite, illite and mixed-layer illite-chlorite, including 11 mixed-layer sequences. Subhedral to euhedral phyllosilicate crystal shapes and other textural features imply that phyllosilicates crystallized from solution derived in part by dissolution of precursor smectite. Intralayer transitions involving illite and chlorite are inferred to be products of crystallization rather than direct alteration and replacement. Petrographically similar bentonitic and analcimized tuffs overlap each other in the stratigraphic section, supporting earlier observations that there is no systematic change in smectite relative to the illite plus chlorite derived from smectite in sections up to 8.5 km thick. The data imply that smectite may be metastable relative to illite plus chlorite. Permeability and fluid chemistry are inferred to be as significant as temperature in promoting reactions in clay minerals as well as zeolites during burial metamorphism.Contribution No. 436, from The Mineralogical Laboratory, Department of Geological Sciences, The University of Michigan, Ann Arbor, Michigan 48109  相似文献