• Korean Journal of Remote Sensing
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• v.21 no.2
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• pp.113-120
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• 2005

Oceanographic measurements from Ieodo Ocean Research Station and its vicinity were compared for assessment and mutually adjusted with satellite data. From the Topex/Poseidon and ERS-1/2 radar altimeter and scatterometer data, sea surface height, wind speed and direction were extracted and analyzed. Shipborne wind direction data acquired in June 1995 show good coherence with the satellite data, while sea surface height and wind speed show differences, possibly resulting from the distance between the measurement points. This can be improved by analyzing more satellite data or using other available shipborne data. The recent 3 months of Ieodo Station data between December 2004 and February 2005 were also analyzed and compared with the satellite data. The Ieodo Station data were found to have considerable gaps during the period as well as seriously biased particular when the data were averaged with some abnormal data. The Ieodo Station and satellite data were then mutually adjusted on the basis of their statistics. Ieodo Station oceanographic measurements are very efficient for ground-frothing of satellite data because they are stationary and the station is located far from the coast. On the other hand, the satellite measurements are the only data to fill up gaps and adjust biases of the Ieodo Station data.

• Korean Journal of Remote Sensing
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• v.38 no.5_1
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• pp.587-596
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• 2022

Sea levels are rising as a result of climate change, and low-lying areas along the coast are at risk of flooding. Therefore, we tried to investigate the relationship between sea level change and climate indices using satellite altimeter data (Topex/Poseidon, Jason-1/2/3) and southern oscillation index (SOI) and the Pacific decadal oscillation (PDO) data. If time domain data were converted to frequency domain, the original data can be analyzed in terms of the periodic components. Fourier transform and Wavelet transform are representative periodic analysis methods. Fourier transform can provide only the periodic signals, whereas wavelet transform can obtain both the periodic signals and their corresponding time location. The cross-wavelet transformation and the wavelet coherence are ideal for analyzing the common periods, correlation and phase difference for two time domain datasets. Our cross-wavelet transform analysis shows that two climate indices (SOI, PDO) and sea level height was a significant in 1-year period. PDO and sea level height were anti-phase. Also, our wavelet coherence analysis reveals when sea level height and climate indices were correlated in short (less than one year) and long periods, which did not appear in the cross wavelet transform. The two wavelet analyses provide the frequency domains of two different time domain datasets but also characterize the periodic components and relative phase difference. Therefore, our research results demonstrates that the wavelet analyses are useful to analyze the periodic component of climatic data and monitor the various oceanic phenomena that are difficult to find in time series analysis.

• Bulletin of the Korean Space Science Society
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• 2011.04a
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• pp.26.3-27
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• 2011

Formation of a steep plasma density gradient in the middle-latitude ionosphere during geomagnetic storms and the latitudinal migration of its location depending on the storm phase are suggested to be associated with the ionospheric signature of the plasmapause. We test this idea by using the satellite and ground observation data during the 11 April 2001 storm. The locations of the steep plasma density gradient identified by TOPEX/Poseidon (2001 LT) and DMSP (1800 and 2130 LT) satellites coincide with the ionospheric footprints of the plasmapause identified by the IMAGE satellite. This observation may support the dependence of the middle-latitude plasma density gradient location on the plasmapause motion, but does not explain why the steep density gradient whose morphology is largely different from the morphology of the middle-latitude ionization trough during quiet period is formed in association with the plasmapause. The ionospheric disturbances in the total electron content (TEC) maps shows that the steep TEC gradient is formed at the boundary of the positive ionospheric storm in low-middle latitudes and the negative ionospheric storm in middle-high latitudes. We interpret that the thermospheric neutral composition disturbance in the dayside is confined within the middle-high latitude ionospheric convection zone. The neutral composition latitudes and, therefore, the locations of the steep plasma density gradient coincide with the footprints of the plasmapause. The TEC maps show that the appearance of the steep plasma density gradient in the pre-midnight sector during the recovery phase is related to the co-rotation of the gradient that is created during the main phase.

• Proceedings of the KSRS Conference
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• 1999.11a
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• pp.140-143
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• 1999

SSH(Sea Surface Height) from TOPEX/Poseidon and SST data are analyzed to estimate characteristics of annual and inter-annual variations in the East Asian seas(110E - l80E, 20N - 50N) from November 1992 to May 1998. In EOF analysis of SSH and SST, 57% and 97% of the variance are represented by the first two modes. The first mode of SSH and SST shows strong annual variations expected for steric changes. The second mode of SSH shows a long-term variation, but that of SST shows 3 - 4month offset from annual variation. In the EOF analysis of the SSH and SST, 61% and 54% of the total variance are represented by the first three modes. The first mode represented a long-term variation, and the third mode reflected the bi-ennial variation. The first three mode were not strongly correlated with ENSO. We further apply Canonical Correlation Analysis(CCA) to find the dominant correlation patterns with ENSO.

• Proceedings of the KSRS Conference
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• v.2
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• pp.989-992
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• 2006

The new approach to the problem of oil spill detection consisting in combined use of all available quasiconcurrent satellite information (AVHRR NOAA, TOPEX/Poseidon, Jason-1, MODIS Terra/Aqua, QuikSCAT) is suggested. We present the results of the application of the proposed approach to the operational monitoring of seawater condition and pollution in the coastal zone of northeastern Black Sea conducted in 2006. This monitoring is based on daily receiving, processing and analysis of data different in nature (microwave radar images, optical and infrared data), resolution and surface coverage. These data allow us to retrieve information on seawater pollution, sea surface and air-sea boundary layer conditions, seawater temperature and suspended matter distributions, chlorophyll a concentration, mesoscale water dynamics, near-surface wind and surface wave fields. The focus is on coastal seawater circulation mechanisms and their impact on the evolution of pollutants.

• Proceedings of the KSRS Conference
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• v.1
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• pp.352-355
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• 2006

In this study, the seasonal and inter-annual variation of sea surface current in the Gulf of Thailand were revealed through the use of WOD temperature and salinity data and monthly sea surface dynamic heights (SSDH) from TOPEX/Poseidon and ERS-2 altimetry data during 1995-2001. The mean dynamic height and mean geostrohic current were derived from the climatological data while SSDH data gave monthly dynamic heights and their geopstrophic currents. The mean geostrophic current showed strong southward and westward flow of South China Sea water along the gulf entrance. Counterclockwise eddy in the inner gulf and the western side of the gulf entrance associated with upwelling in the area. Seasonal geostrophic currents show basin-wide counterclockwise circulation during the southwest monsoon season and clockwise circulation during the northeast monsoon season. Upwelling was enhanced during the southwest monsoon season. The circulation patterns varied seasonally and inter-annually probably due to the variation in wind regime. And finally we found that congregation, spawning, and migration routes of short-bodied mackerel conform well with coastal upwelling and surface circulation in the gulf.

• Proceedings of the KSRS Conference
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• v.2
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• pp.844-847
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• 2006

In this work Topex/Poseidon altimeter data 1993 - 2002 were used. There are three altimetry tracks (one ascending and two descending) that cross Tatar Strait. The data were collected in the points of sub-satellite tracks with the step 0.25 degree. 10-years average values were calculated for each month. The seasonal sea level variations were compared with tide gauges data. The well expressed annual cycle (with maximum at July-August and the minimum at February-March) prevails in the Tartar Strait. However, the seasonal variations expressed much weakly in both the altimetry track points and Kholmsk - Nevelsk tide-gauges that locate close to La Perouse Strait because of Okhotsk Sea influence. The sea level slopes between the Sakhalin Island and the continent coasts were analyzed in different seasons. We found that sea level increases near Sakhalin coast in spring and summer that corresponds to the northward flow. In autumn, otherwise, the sea level decreases near Sakhalin Island that corresponds to southward current. This result is verified by the CTD data gathered on the standard sections. Well-expressed upwelling is observed near coastline of Sakhalin Island in fall season. This phenomenon is caused by the northerly and the northwesterly wind which are typical for cold season.

• Proceedings of the KSRS Conference
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• v.2
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• pp.744-747
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• 2006

The sea level of the Java Sea is reproduced using HYbrid Coordinate Ocean Model (HYCOM) setting up in the horizontal grid from $100^{\circ}E$ to $125^{\circ}E$ and from $10^{\circ}S$ to $8^{\circ}N$. The model is initialized by ocean temperature and salinity profiles from Levitus 1998 and forced by the atmospheric field derived from NCEP reanalysis. In this research HYCOM is applied to explain the El $Ni{\tilde{n}}o$ Southern Oscillation (ENSO) impacts on the sea level of the Java Sea. The monthly tide gauge sea level data are produced based on hourly sea level data from 1993 to 1997. Altimeter sea level data are based on weekly merged products between TOPEX/Poseidon and ERS absolute dynamic topography (ADT). The simulated sea level both HYCOM and ADT agree well with the tide gauge sea level. The sea level of the Java Sea is high during the La $Ni{\tilde{n}}a$ period and low during the El $Ni{\tilde{n}}o$ period.

• Proceedings of the KSRS Conference
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• v.2
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• pp.973-976
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• 2006

The oscillations of the Caspian Sea level represent a result of mutually related hydrometeorological processes. The change in the tendency of the mean sea level variations that occurred in the middle 1970s, when the long-term level fall was replaced by its rapid and significant rise, represents an important indicator of the changes in the natural regime of the Caspian Sea. Therefore, sea level monitoring and long-term forecast of the sea level changes represent an extremely important task. The aim of this presentation is to show the experience of application of satellite altimetry methods to the investigation of seasonal and interannual variability of the sea level, wind speed and wave height, water dynamics, as well as of uplift of the Earth’s crust in different parts of the Caspian Sea and Kara-Bogaz-Gol Bay. Special attention is given to estimates of the Volga River runoff derived from satellite altimetry data. The work is based on the 1992-2005 TOPEX/Poseidon (T/P) and Jason-1 (J-1) data sets.

• Journal of Fisheries and Marine Sciences Education
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• v.24 no.2
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• pp.333-345
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• 2012

NOAA/AVHRR, Topex/Poseidon, and Jason-1 data were used to analyze sea surface temperatures and thermal fronts in the North East Asia Seas. Temporal and spatial analyses were based on data from 1993 to 2008. The amplitude and phase for the annual mode on SL and SST were investigated with harmonic analysis. The geographical distribution of amplitudes for comparison of SL and SST are slightly reverse in southwest-northeast tilted direction. The time series analysis conducted on the entire researched area presented consistent pattern. Peak of Sea Level was presented 1~2 months after the peak of the surface sea temperature was shown. This explains that Sea Level change occurs after the generation of surface sea temperature change in sea. The Sobel edge detection method delineated four fronts. Thermal fronts generally occurred over steep bathymetric slopes. Annual amplitudes and phases were bounded within these frontal areas.