• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.378-381
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• 2007

Analyses of Tropical Rainfall Measuring Mission (TRMM) microwave radiometer (TMI) and precipitation radar (PR) data show that the rainfall inhomogeneity, represented by the coefficient of variation, decreases as rain rate increases at the low resolution (the footprint size of TMI 10 GHz channel). The rainfall inhomogeneity, however, is relatively constant for all rain rates at the high resolution (the footprint size of TMI 37 GHz channel). Consequently, radiometric signatures at lower spatial resolutions are characterized by larger dynamic range and smaller variability than those at higher spatial resolution. Based on the observed characteristics, this study develops a low-resolution (${\sim}40{\times}40$ km) rainfall retrieval algorithm utilizing realistic rainfall distributions in the a-priori databases. The purpose of the low-resolution rainfall algorithm is to make more reliable climatological rainfalls from various microwave sensors, including low-resolution radiometers.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2008년도 한국우주과학회보 제17권2호
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• pp.31.4-32
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• 2008

The microwave instruments are used many areas of the space remote sensing and space science applications. The imaging radar of synthetic aperture radar (SAR) is well known microwave radar sensor for earth surface and ocean research. Unlike radar, microwave radiometer is passive instrument and it measures the emission energy of target, i.e. brightness temperature BT, from earth surface and atmosphere. From measured BT, the geophysical data like cloud liquid water, water vapor, sea surface temperature, surface permittivity can be retrieved. In this paper, the radiometer characteristics, system configuration and principle of BT measurement are described. Also the radiometer instruments TRMM, GPM, SMOS for earth climate, and ocean salinity research are introduce. As first korean microwave payload on STSAT-2, the DREAM (Dual-channels Radiometer for Earth and Atmosphere Monitoring) is described the mission, system configuration and operation plan for life time of two years. The main issues of DREAM unlike other spaceborne radiometers, will be addressed. The calibration is the one of main issues of DREAM mission and how it contribute on the space borne radiometer. In conclusion, the radiometer instrument to space science application will be considered.

• 대한원격탐사학회지
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• 제19권1호
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• pp.53-59
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• 2003

The passive microwave remote sensing has progressed considerably in recent years Important earth surface parameters are detected and monitored by airborne and space born radiometers. However the spatial resolution of real aperture measurements is constrained by the antenna aperture size available on orbiting platforms and on the ground. The inverse problem technique is researched in order to improve the spatial resolution of microwave scanning radiometer. We solve a two-dimensional (surface) temperature-imaging problem with a major intention to develop high-resolution methods. In this paper, the scenario for estimation of both radiometer point spread function (PSF) and target configuration is explained. The PSF of the radiometer is assumed to be unknown and estimated from the observations. The configuration and brightness temperature of targets are also estimated. To do this, we deal with the parametric modeling of observation scenario. The performance of developed algorithms is illustrated on two-dimensional experimental data obtained by the water vapor radiometer.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.604-609
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• 2002

The passive microwave remote sensing has progressed considerably in recent years. Important earth surface parameters are detected and monitored by airborne and space born radiometers. However the spatial resolution of real aperture measurements is constrained by the antenna aperture size available on orbiting platforms and on the ground. The inverse problem technique is researched in order to improve the spatial resolution of microwave scanning radiometer. We solve a two-dimensional (surface) temperature-imaging problem with a major intention to develop high-resolution methods. In this paper, the scenario for estimation of both radiometer point spread function (PSF) and target configuration is explained. The PSF of the radiometer is assumed to be unknown and estimated from the observations. The configuration and brightness temperature of targets are also estimated. To do this, we deal with the parametric modeling of observation scenario. The performance of developed algorithms is illustrated on two-dimensional experimental data obtained by the water vapor radiometer.

• 한국지구과학회지
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• 제39권4호
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• pp.305-316
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• 2018

Satellite-derived sea surface winds (SSWs) and atmospheric motion vectors (AMVs) over the global ocean, particularly including the areas in and around tropical cyclones (TCs), have been provided in a real-time and continuous manner. More and better information is now derived from technologically improved multiple satellite missions and wind retrieving techniques. The status and prospects of key SSW products retrieved from scatterometers, passive microwave radiometers, synthetic aperture radar, and altimeters as well as AMVs derived by tracking features from multiple geostationary satellites are reviewed here. The quality and error characteristics, limitations, and challenges of satellite wind observations described in the literature, which need to be carefully considered to apply the observations for both operational and scientific uses, i.e., assimilation in numerical weather forecasting, are also described. Additionally, on-going efforts toward merging them, particularly for monitoring three-dimensional TC wind fields in a real-time and continuous manner and for providing global profiles of high-quality wind observations with the new mission are introduced. Future research is recommended to develop plans for providing more and better SSW and AMV products in a real-time and continuous manner from existing and new missions.

• 대한원격탐사학회지
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• 제34권6_2호
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• pp.1273-1282
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• 2018

최근 북극항로와 온난화 등의 영향으로 인해 북극해에 대한 활발한 연구가 진행되고 있다. 기존에 수동 마이크로파 복사계를 이용하여 북극해 해빙의 정량적 면적을 산출하는 연구는 진행되어 왔으나, 보다 고해상도로 해빙의 가장자리에서 발생하는 융해 및 표면 거칠기 변화에 대한 연구는 잘 이루어지지 않았다. 또한, 최근 Sentinel1-A/B자료가 무료로 배포되고, 특히 북극해 영역에 대한 수많은 자료들이 짧은 기간 동안 생산 및 제공되고 있기에, 이러한 대용량 자료들을 모자익(mosaic)하여 북극해 전체에 대한 고해상도 해빙정보 이용이 가능하게 되었다. 그러나 Sentienl-1A/B의 광역관측(Extended Wide, EW)모드 자료를 효과적으로 사용하기 위해서는 보다 정확한 방사보정이 수행되어야 한다. 이를 위해 이중편파 Sentinel-1A/B 자료에 나타나는 thermal noise와 scalloping 효과를 자동적으로 보정할 수 있는 방사보정 기법을 개발하였으며, 나아가 방사보정 된 이중편파 SAR자료를 이용할 경우 해빙과 open-water를 보다 더 잘 구분할 수 있음을 확인하였다.

• 한국지구과학회지
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• 제39권2호
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• pp.139-153
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• 2018

해상풍은 장기간동안 인공위성 산란계와 마이크로파 복사계를 주로 활용하여 관측되어왔다. 반면 위성 고도계 산출 풍속 자료의 중요성은 산란계의 탁월한 해상풍 관측 성능으로 인해 거의 부각되지 않았다. 인공위성 고도계 풍속자료는 해수면고도를 산출하기 위한 해상상태편차(sea state bias) 보정항의 입력 자료로서 활용됨에 따라 높은 정확도가 요구된다. 본 연구에서는 인공위성 고도계(GFO, Jason-1, Envisat, Jason-2, Cryosat-2, SARAL) 풍속을 검증하고 오차 특성을 분석하기 위하여 이어도 해양과학기지와 마라도, 외연도 해양기상부이의 풍속 자료를 활용하여 2007년 12월부터 2016년 5월까지 총 1504개의 일치점 자료를 생성하였다. 해양실측 풍속에 대한 고도계 풍속은 $1.59m\;s^{-1}$의 평균 제곱근오차와 $-0.35m\;s^{-1}$의 음의 편차를 보였다. 해양실측 풍속에 대한 고도계 해상풍 오차를 분석한 결과 고도계 해상풍은 풍속이 약할 때 과대추정되며 풍속이 강할 때 과소추정되는 특징을 보였다. 위성-실측 자료 간의 거리에 따른 고도계 풍속 오차를 분석한 결과 구간별 오차의 최댓값과 최솟값의 차는 거리에 따라 점차 증가하였다. 고도계 풍속의 정확도 향상을 위하여 분석된 오차 특성을 기반으로 보정식을 유도한 후 고도계 풍속을 보정하였다. 보정 전후의 풍속자료를 활용하여 해상상태편차를 산출하였으며 Jason-1의 해상상태편차에 대한 해상풍 오차 보정의 영향을 확인하였다.