• 대한원격탐사학회지
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• 제17권4호
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• pp.297-305
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• 2001

Ocean satellite altimetry-implied free-air gravity anomalies have had the shortest wavelengths removed during the processing to generate the optimal solution between multiple radar altimeter missions. ERS-1 168day mission altimetry was residualized to a reference geoid surface generated by integrating Anderson & Knudsen’s free-air gravity anomalies for the Barents Sea. The altimetry tracks were reduced and filtered to extract the shortest wavelengths (between 4 and 111 km) from both ascending and descending tracks, respectively. These data were recombined using existing quadrant-swapping techniques in the wavenumber domain to generate a correlated, high frequency gravity field related to the local geologic sources. This added-value surface adjusted the reference free-air gravity anomalies to better reflect features in the gravity field at a wavelength related to the distance between altimetry ground tracks.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.683-686
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• 2005

This study addresses a photogrammetric approach to generate Mars topographic products from mapping data of Mars Global Surveyor (MGS). High-resolution stereo images and laser altimetry data collected from the MGS mission are combined and processed to produce Digital Elevation Models (DEM) and orthoimages. First, altimeter data is registered to high resolution images and considerable registration offset (around 325 m) is discovered on high resolution stereo images. Altimetry data, exterior orientation elements of the camera and conjugate points are used for bundle adjustment to solve this mis-registration and detennine the ground coordinates. The mis-registration of altimetry data are effectively eliminated after the bundle adjustment. Using the adjusted exterior orientation the ground coordinates of conjugate points are detennined. A sufficient number of corresponding points collected through image matching and their precise 3-D ground coordinates are used to generate DEM and orthoimages. A posteriori standard deviations of ground points after bundle adjustment indicate the accuracy of OEM generated in this study. This paper addresses the photogrammetric procedure: the registration of altimetry data to stereo pair images, the bundle adjustment and the evaluation, and the generation of OEM and orthoimages.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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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.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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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.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.337-340
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• 2002

Monitoring of wave height is important primarily to reduce storm risks at sea and along the coast. Wave heights in recent years have increased 50% for the last 40 years, thus requiring intensive monitoring. Satellite altimetry offers a powerful tool for regular and extensive monitoring of the wave height. We extracted significant wave height (SWH) using several altimeter missions from 1987-1995 over the Northwest Pacific and compared with ECMWF reanalysis (ERA) products. For large wave heights > 2.5 m, the ERA wave heights are smaller than the altimetric ones, while for small wave heights the ERA wave heights are larger. Comparison in SWH between altimetric derivations and ERA model products shows the discrepancy of 0.46-0.21$\times$SWH(m).

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.43-46
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• 2006

The main tsunami wave triggered by the December 2004 Sumatra tsunami was detected in the ocean south of India by satellite altimeters on Jason, Topex/Poseidon and Envisat. All three altimeters also detected shorter-wavelength (10 to 100 km), slower-propagating surface waves, spreading from the site of the earthquake. The shorter waves give additional information about the tsunami event, and can be used to better define the generating region in this, and future tsunamis. The properties of the area of shorter tsunami-generated waves may also be important in designing a future satellite-based detection system.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2015년도 학술발표회
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• pp.467-467
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• 2015

Sustainable water resource management requires the assessment of hydrological variability in response to climate fluctuations and anthropogenic activities. Determining quantitative estimates of water balance and total basin discharge are of utmost importance to understand the variations within a basin. Hard-to-reach areas with few infrastructures, coupled with lengthy administrative procedures makes in-situ data collection and water management processes very difficult and unreliable. In this study, the hydrological behavior of Lake Chad whose extent, extreme climatic and environmental conditions make it difficult to collect field observations was examined. During a 10 year period [January 2003 to December 2013], dataset from space-borne and global hydrological models observations were analyzed. Terrestial water storage (TWS) data retrieved from Gravity Recovery and Climate Experiment (GRACE), lake level variations from Satellite altimetry, water fluxes and soil moisture from Global Land Data Assimilation System (GLDAS) were used for this study. Furthermore, we combined altimetry lake volume with TWS over the lake drainage basin to estimate groundwater and soil moisture variations. This will be validated with groundwater estimates from WaterGAP Global Hydrology Model (WGHM) outputs. TWS showed similar variation patterns Lake water level as expected. The TWS in the basin area is governed by the lake's surface water. As expected, rainfall from GLDAS precedes GRACE TWS with a phase lag of about 1 month. Estimates of groundwater and soil moisture content volume changes derived by combining altimetric Lake Volume with TWS over the drainage basin are ongoing. Results obtained shall be compared with WaterGap Hydrology Model (WGHM) groundwater estimate outputs.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.672-675
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• 2006

The geostrophic current component is estimated from the sea surface velocity observed by the long-range High-Frequency Ocean Radar (HF radar) system in the upstream of the Kuroshio, by comparing with geostrophic velocity determined from along-track T/P and Jason-1 altimetry data. However, the sea surface velocity of the HF radar (HF velocity) contains not only the geostrophic current but also the ageostrophic current such as tidal current and wind-driven Ekman current. Tidal current component is first extracted by the harmonic analysis of the time series of the HF velocity. Then, the Ekman current is further estimated from daily wind data of IFREMER by applying the least-square method to the residual difference between the HF velocity and the altimetry geostrophic velocity. As a result, the Ekman current in the HF velocity is estimated as 1.32 % of the wind speed and as rotated 45$^{\circ}$ clockwise to the wind direction. These parameters are found almost common in the Kuroshio area and in the Open Ocean. After these corrections, the geostrophic velocity component in the HF velocity agrees well with the altimetry geostrophic velocity.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.969-972
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• 2006

The long-range High-Frequency (HF) ocean radar system has observed surface velocity field in the upstream of the Kuroshio north of Ishigaki Island and east of Taiwan since 2001. Applying a new method to extract geostrophic velocity component from the HF surface velocity data with the aid of satellite-born wind data, time series of daily surface geostrophic velocity field has been determined. Despite limited width of the study area of the HF radar, analysis of the sea surface height anomaly determined from the satellite altimetry data in a wider area can provide estimated dates of arrival of mesoscale eddies in the study area of the HF radar. Variations of the Kuroshio position and strength are studied in detail for these cases of interaction with mesoscale eddy, although number of occurrence of direct interaction with the Kuroshio in the study area is not statistically enough. For example, when an anticyclonic eddy approaches to the Kuroshio, the Kuroshio axis is found tend to move northward, keeping away from the approaching eddy from the east.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2009년도 학술대회 초록집
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• pp.113-118
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• 2009

어떤 넓은 지역의 솟아오름 또는 내려앉음은 중력값의 변화, 지오이드의 변화, 측정점들의 높이의 변화 등으로부터 추출할 수 있다. 지난 십 여 년 동안, 1) 대전의 한 측점에서 측정한 절대중력값이 작아졌고, 2) 인공위성에 의한 높이측정 자료로부터 추출한 황해 지역의 지오이드의 높이가 늘어났으며, 3) GNSS측정자료로부터 추출한 한반도 남부의 육지 지역의 높이가 늘어났다. 이 세 가지를 종합해 보면, 한반도 및 황해를 포함하는 넓은 지역은 2 mm/yr 정도의 속도로 솟아오르고 있다고 해석할 수 있다.