• Journal of Korean Society for Atmospheric Environment
• /
• v.31 no.1
• /
• pp.1-14
• /
• 2015

This study investigates the impact of enhanced regional meteorological fields on improvement of wind energy forecasting accuracy in the southwestern coast of the Korean Peninsula. To clarify the effect of detailed surface boundary data and application of analysis nudging technique on simulated meteorological fields, several WRF simulations were carried out. Case_LT, which is a simulation with high resolution terrain height and land use data, shows the most remarkable accuracy improvement along the shoreline mainly due to modified surface characteristics such as albedo, roughness length and thermal inertia. Case_RS with high resolution SST data shows accurate SST distributions compared to observation data, and they led to change in land and sea breeze circulation. Case_GN, grid nudging applied simulation, also shows changed temperature and wind fields. Especially, the application of grid nudging dominantly influences on the change of horizontal wind components in comparison with vertical wind component.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2003.11a
• /
• pp.305-312
• /
• 2003

Remote sensing can provide invisible information in addition to acquire wide-view image data from space. Synthetic Aperture Radar (SAR) transmits microwave to the earth from a satellite and collects the reflected echo from the surface. Interferometric processing of SAR data can detect the subtle land deformation. The information of the surface movement by SAR is useful to monitor the volcanic activity, extended subsidence of urbanized area and the prediction of the earthquake caused by crustal deformation, and it complements the conventional levelling and GPS technique. PSInSAR (Permanent Scatterers Interferometric SAR) is one of interferometric techniques to be applied to practical projects in Japan. In this paper, the projects of land deformation monitoring are shown after the explanations of the PSInSAR principle. Tokai earthquake risk assessment is the first example. PSInSAR detects the subduction of crustal deformation of the adjacent area of new assumed epicenter region of the Tokai Earthquake. The extended subsidence of the urbanized area was implemented by using Japanese satellite data i.e. JERS that has so much data the surrounding of Japan as the archive. We examine the relationship between the geological structure and settlement at Nohbi basin including Nagoya city.

• Asia-Pacific Journal of Atmospheric Sciences
• /
• v.54 no.4
• /
• pp.527-544
• /
• 2018

This paper presents a nighttime sea fog detection algorithm incorporating unsupervised learning technique. The algorithm is based on data sets that combine brightness temperatures from the $3.7{\mu}m$ and $10.8{\mu}m$ channels of the meteorological imager (MI) onboard the Communication, Ocean and Meteorological Satellite (COMS), with sea surface temperature from the Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA). Previous algorithms generally employed threshold values including the brightness temperature difference between the near infrared and infrared. The threshold values were previously determined from climatological analysis or model simulation. Although this method using predetermined thresholds is very simple and effective in detecting low cloud, it has difficulty in distinguishing fog from stratus because they share similar characteristics of particle size and altitude. In order to improve this, the unsupervised learning approach, which allows a more effective interpretation from the insufficient information, has been utilized. The unsupervised learning method employed in this paper is the expectation-maximization (EM) algorithm that is widely used in incomplete data problems. It identifies distinguishing features of the data by organizing and optimizing the data. This allows for the application of optimal threshold values for fog detection by considering the characteristics of a specific domain. The algorithm has been evaluated using the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) vertical profile products, which showed promising results within a local domain with probability of detection (POD) of 0.753 and critical success index (CSI) of 0.477, respectively.

• Korean Journal of Remote Sensing
• /
• v.37 no.1
• /
• pp.161-167
• /
• 2021

This paper presents the method to quantitatively evaluate the uncertainty of the semi-empirical Bidirectional Reflectance Distribution Function (BRDF) model for Himawari-8/AHI. The uncertainty of BRDF modeling was affected by various issues such as assumption of model and number of observations, thus, it is difficult that evaluating the performance of BRDF modeling using simple uncertainty equations. Therefore, in this paper, Monte-Carlo method, which is most dependable method to analyze dynamic complex systems through iterative simulation, was used. The 1,000 input datasets for analyzing the uncertainty of BRDF modeling were generated using the Second Simulation of a Satellite Signal in the Solar Spectrum (6S) Radiative Transfer Model (RTM) simulation with MODerate Resolution Imaging Spectroradiometer (MODIS) BRDF product. Then, we randomly selected data according to the number of observations from 4 to 35 in the input dataset and performed BRDF modeling using them. Finally, the uncertainty was calculated by comparing reproduced surface reflectance through the BRDF model and simulated surface reflectance using 6S RTM and expressed as bias and root-mean-square-error (RMSE). The bias was negative for all observations and channels, but was very small within 0.01. RMSE showed a tendency to decrease as the number of observations increased, and showed a stable value within 0.05 in all channels. In addition, our results show that when the viewing zenith angle is 40° or more, the RMSE tends to increase slightly. This information can be utilized in the uncertainty analysis of subsequently retrieved geophysical variables.

• Proceedings of the KSRS Conference
• /
• 2005.10a
• /
• pp.101-103
• /
• 2005

Vicarious calibration method using MODIS-derived surface reflectivity data as inputs to a radiative transfer model have been developed for the planned COMS solar channel. Pilot test was conduced over the Simpson Desert targets in Australia. Results suggested that calibration can be achieved within $5\%$ error range.

• Journal of Korean Society for Atmospheric Environment
• /
• v.25 no.3
• /
• pp.196-210
• /
• 2009

The land surface precesses is very important to predict urban meteorological conditions. Thus, the latest land use data set to reflect the rapid progress in urbanization was applied to simulate urban thermal environment in Daegu. Because use of the U.S geological Survey (USGS) 25-category data, currently in the fifth-generation Pennsylvania State University-National Center for Atmospheric Research Mesoscale Model (MM5), does not accurately described the heterogeneity of urban surface, we replaced the land use data in USGS with the latest land-use data of the Korea Ministry of Environment over Daegu. The single urban category in existing 24-category U.S. Geological survey land cover classification used in MM5 was divided into 5 classes to account for heterogeneity of urban land cover. The new land cover classification (MC-LULC) improved the capability of MM5 to simulate the daytime part of the diurnal temperature cycle in the urban area. The 'MC-LULC' simulation produced the observed temperature field reasonably well, including spatial characteristics. The warm cores in western Daegu is characterized by an industrial area.

• Atmosphere
• /
• v.12 no.4
• /
• pp.56-68
• /
• 2002

In this study, an overview of the Earth Observing System (EOS) program is provided with discussions on its spacecrafts and instruments, and on the scientific issues. The EOS satellites aim at monitoring the Earth environmental system by observing parameters of subsystems such as atmosphere, ocean, land, and biosphere. The first EOS flagship, Terra, was launched on December 1999. Five instruments onboard Terra can measure cloud and aerosol properties, radiation, terrestrial surface, and ocean color. The second EOS flagship, Aqua, which was launched on May 2002, loads six instruments that measure clouds, radiation, precipitation, terrestrial surface, ocean color and sea surface temperature. The observational data available from the EOS satellites may complement data from the Communication-Oceanography-Meteorology satellite, which will be launched in 2008, for meteorological and environmental forecasts.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.21 no.2
• /
• pp.67-77
• /
• 2016

This study developed synthetic regression diagram for analyzing the linear trend of sea surface height, temperature, and salinity around the Korean marginal seas. In situ observed data had been quality controlled and they were verified by EOF comparison with objective analyzed data. From the synthetic regression diagram, we confirmed similar linear regression values with those of previous studies, but additionally provided detailed regression rate of each 5 to 30 year for the total periods of 1983-2013. We expect that quantitative results presented by this study will be useful as standard reference numbers for relevant studies analyzing oceanic long-term trend.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2005.05a
• /
• pp.355-358
• /
• 2005

The electrical characteristics for applying the foundation of the house to the substitutional earth electrode was reviewed fundamentally. In order to measure the earth resistance in the foundation of the house, it was performed to investigate the effect of the electrode arrangements and configurations concerning to grounding methods, and tried to the adequate simulation for comparing those experimental data. The number of steel rods and the ground resistivity were affected to change the earth resistance, but the latter caused the large variation in its resistance compared to the former in this experiment. Since the large surface area in the foundation of the house have contacted the ground usually, it is possible to use the earth electrode substitutionally.

• Proceedings of the KSRS Conference
• /
• 2003.11a
• /
• pp.1070-1072
• /
• 2003

This study focuses on examing the feasibility of differential SAR interferometry (DInSAR) in the Northeastern Kyungsang Basin, Korea. Major faults in the Kyungsang Basin such as Yangsan fault, Dongrae fault, and Ulsan fault had developed during Cretaceous, and the activeness of these faults is still controversial in Korean geology community. We attempt to measure displacements in the study area by applying DInSAR techniques to JERS-1 SAR data sets. Some surface displacements are recognized by DInSAR method at Young-il Bay in which the POSCO Company locates, although the displacements may not be directly associated with geologic structures. We also discuss atmospheric effects for the techniques used.