• Title, Summary, Keyword: microwave scatterometer

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Antarctic Sea Ice Distribution from Integrated Microwave Sensings

  • Hwang, Jong-Sun;Yoon, Ho-Il;Min, Kyung-Duck;Kim, Jeong-Woo;Hong, Sung-Min
    • Proceedings of the KSRS Conference
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    • pp.633-633
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    • 2002
  • We investigated the distributions of sea ice using various microwave remote sensing techniques in the part of Drake passage, Antarctica, between the area 45-75$^{\circ}$W and 55-66$^{\circ}$S. We used Topex/Poseidon(T/P) radar altimeter, ERS-1 altimeter, ERS-2 scatterometer, Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR), and DMSP Special Sensor Microwave/Imager(SSM/I) data. The sea ice distributions were estimated between May and Jun., 1995 and Oct. and Nov., 1998. The two altimeter measurements (T/P and ERS-1) showed good coherence with the results from the radiometer data in the given period when the ice concentration of 20% and greater was selected. The scatterometer data also showed good correlation with altimetry-implied sea ice surface. The maximum and minimum values of sea ice distribution were appeared in Aug. and Feb., respectively. In general, the sea ice distributions estimated from radar altimeter, radioneter, and scatterometer are well correlated.

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Estimation of Soil Moisture Content in Corn Field Using Microwave Scatterometer Data

  • Kim, Yihyun;Hong, Sukyoung;Lee, Kyoungdo;Na, Sangil;Jung, Gunho
    • Korean Journal of Soil Science and Fertilizer
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    • v.47 no.4
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    • pp.235-241
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    • 2014
  • A ground-based microwave scatterometer has an advantage for monitoring soil moisture content using multi-polarization, multi-frequencies and various incidence angles. In this paper, ground-based multi-frequency (L-, C-, and X-band) polarimetric scatterometer system capable of making observations every 10 min was used to monitor the soil moisture conditions in a corn field over an entire growth cycle. Measurements of volumetric soil moisture were obtained and their relationships to the backscatter observations were examined. Time series of soil moisture content was not corresponding with backscattering coefficient pattern over the whole growth stage, although it increased until early July (Day Of Year, DOY 160). We examined the relationship between the backscattering coefficients from each band and soil moisture content of the field. Backscattering coefficients for all bands were not correlated with soil moisture content when considered over the entire stage ($r{\leq}0.48$). However, L-band Horizontal transmit and Horizontal receive polarization (HH) had a good correlation with soil moisture ($r=0.85^{**}$) when LAI was lower than 2. Prediction equations for soil moisture were developed using the L-HH data. Relation between L-HH and soil moisture shows linear pattern and related with soil moisture content ($R^2=0.77$). Results from this study show that backscattering coefficients of microwave scatterometer appear to be effective to estimate soil moisture content in the field level.

THE MECHANICAL DESIGN AND CONSTRUCTION OF A TRUCK MOUNTED SCATTEROMETER SYSTEM

  • Aziz, H.;Mahmood, N.N.;Ali, A.;Ibrahim, N.;Ahmad, Z.;Mahmood, K.A.;Jamil, H.;Brevern, P.V.;Koo, V.C.;Sing, L.K.
    • Proceedings of the KSRS Conference
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    • pp.1009-1011
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    • 2003
  • The procurement of mobile microwave scatterometer involve the consideration to ensure vehicle and equipment selection full-filled technical requirement and safety standard in Malaysia. Designing, and modification works involve engineering methodology in determining and selecting a suitable hydraulic telescopic boom that suit a selected vehicle available from the market. The vehicle is also a delivery system for microwave remote sensing equipment and other accessories to any locations in Malaysia. Total loading to be carried by the vehicle is about 4500 kg and its overall weight must be 16,000 kg as recommended by hydraulic telescopic boom manufacturers. The telescopic boom will elevate microwave scatterometer system and antenna to a maximum height of 27 m, and can also be rotated through 360$^{\circ}$. A mechanism is incorporated in the system to enable tracking or monitoring angular movement of the hydraulic telescopic boom when positioned towards required target.

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Can we obtain sea-surface flow information from satellite scatterometer winds\ulcorner

  • Park, Kyung-Ae;Cornillon, Peter;Chung, Jong-Yul;Kim, Kuh
    • Proceedings of the KSRS Conference
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    • pp.621-626
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    • 2002
  • A satellite scatterometer is a microwave radar sensor used to measure the backscattering at a sea surface. This instrument transmits radar pulses to the sea surface and measure the radar energy reflected back towards the source. Changes in wind velocity make sea surface roughness change and then affect on backscattered power. This gives us information of sea surface wind speed. Directions of wind vectors are acquired by multiple, collocated, and nearly simultaneous measurements. It should be noted that the scatterometer observes not the wind directly but the wind stress vector relative to the surface current. This suggests the possibility that the satellite scatterometer winds can include the effect of the surface current. This study shows the evidence that scatterometer measure surface wind stress, not surface winds and presents the velocity structure of oceanic warm and cold eddies.

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Estimation of rice growth parameters by X-band radar backscattering data

  • Kim, Yi-Hyun;Hong, Suk-Young;Lee, Hoon-Yol
    • Proceedings of the KSRS Conference
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    • pp.324-327
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    • 2008
  • Microwave remote sensing has great potential, especially in monsoon Asia, since optical observations are often hampered by cloudy conditions. The radar backscattering characteristics of rice crop were investigated with a ground-based automatic scatterometer system. The system was installed inside a shelter in an experimental paddy field at the National Institute of Agricultural Science and Technology (NIAST) before transplanting. The rice cultivar was a kind of Japonica type, called Chuchung. The scatterometer system consists of X-band antennas, HP8720D vector network analyzer, RF cables, and a personal computer that controls frequency, polarization and data storage. This system automatically measures fully-polarimatric backscattering coefficients of rice crop every 10 minutes, accompanied by a digital camera that takes pictures in a fixed position with the same interval. The backscattering coefficients were calculated by applying a radar equation. Plant variables, such as leaf area index (LAI), biomass, plant height and weather conditions were measured periodically throughout the rice growth season. We have performed polarimetric decomposition of paddy data such as single, double and volume scattering to extract the scattering information effectively. We investigated the relationships between backscattering coefficients and the plant variables.

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Preliminary Results On Radar Measurement Of Paddy Field Using C-Band Scatterometer System

  • Jamil, H.;Ali, A.;Yusof, S.;Ahmad, Z.;Mahmood, K.A.;Abu Bakar, S.B.;Aziz, H.;Ibrahim, N.;Koo, V.C.;Sing, L.K.
    • Proceedings of the KSRS Conference
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    • pp.1002-1004
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    • 2003
  • A ground-based, C-band full polarimetric mobile Scatterometer system has been developed in Malaysia with collaboration between Malaysian Centre for Remote Sensing (MACRES) and Multimedia University (MMU). The main purpose of this system is to measure and monitor backscattering coefficient, ${\sigma }^0$, for earth terrain such as paddy fields, forest and soil surfaces. This paper describes the preliminary results on radar backscatter measurement from paddy field using the mobile C-band Scatterometer system. The measurement campaign was conducted at Sungai Burung area in April 2003. Real time data were collected using four polarization modes (HH, HV, VV and VH), at various incidence angles ranging from 0$^0$ to 60$^0$. The measurement data show consistent results as compared to other reports, which verify the capability of this Scatterometer system as a useful tool for remote sensing.

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Examination of the Radiative Transfer Model for Computing Microwave Polarimetric Scattering Coefficients of Vegitation Canopies (풀밭에서의 마이크로파 편파별 산란 계수 계산용 Radiative Transfer 모델의 정확성검토)

  • 김재형;이진원;오이석
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.11 no.5
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    • pp.763-772
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    • 2000
  • The Radiative Transfer Model(RTM) for computation of microwave polarimetric backscattering coefficients of a various types of vegitation canopies has been examined in this paper. Leaves in the vegitation canopy are modeled by rectangular resistive sheets, which sizes and orientations are randomly distributed. Surface roughness and soil moisture of soil surface are considered in this computation. The backscattering coefficients of grasslands are computed for various values of radar parameters and canopy parameters. A polarimetric scatterometer radar system at 15 GHz has been used for measurement of the scattering coefficient from a grass canopy and a cabbage canopy. The computation results obtained by the RTM for the canopies are compared with the measurement for examination of the RTM.

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Comparison between Measurements and Scattering Model for Polarimetric Backscattering from Vegetation Canopies (식물층에서의 편파별 후방 산란 측정과 산란 모델의 비교)

  • Hong Jin-Young;Oh Yi-Sok
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.17 no.9
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    • pp.804-810
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    • 2006
  • In this paper, we describe a measurement technique for the backscattering coefficient and ground truth of a vegetation canopy in detail. A simple microwave backscattering model for vegetation canopies is verified by being compared with this measurement. An R-band$(1.7\sim2.0GHz)$ scatterometer system is used to measure the backscattering coefficient of a vegetated area in the Han-river park for various incidence angles and a wide range of the soil moisture contents. It is found that the model agrees quite well with the measurements for co-polarized radar backscatter, and needs a correction for cross polarized radar backscatter.

Analysis of Land Subsidence and Microwave Penetration on Drying Mudflat by using a Polarimetric Scatterometer Experiment (다편광 산란계 실험을 통한 개펄 건조시의 지반 침하와 마이크로파 침투 분석)

  • Lee Hoon-Yol;Chae Hee-Sam;Cho Seong-Jun
    • Proceedings of the KSRS Conference
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    • pp.145-148
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    • 2006
  • 새로 조성된 간척지 갯벌이 건조 수축하면 지반 침하와 더불어 토양 내로의 마이크로파의 침투 깊이가 증가한다 따라서 인공위성 DInSAR를 이용하여 지반 침하량을 구하고자 할 때, 건조 시 동시에 발생하는 마이크로파의 개펄 침투 현상을 규명하여 보정해 주어야 한다. 이를 위하여 다편광 산란계(Polarimetric Scatterometer)를 구성하여 건조 개펄에 대한 실내실험을 실시하였다. PolScat의 구성은 5.0-5.6GHz 대역의 dual-polarization square horn antenna를 사용하였으며 Agilent 8753ES 벡터 네트워크 분석기를 사용하였다. 길이 2m, 폭 2m, 높이 20cm의 개펄 샘플을 약 6주 동안 실내에서 건조시켜 위상을 측정한 결과 지반 침하와 함께 약 4mm의 마이크로파 투과현상이 발견되었다. 따라서 인공위성 DInSAR 지반침하량 계산에 있어서 반드시 토양 수분에 따른 마이크로파의 토양 침투 깊이를 보정해 주어야 함이 밝혀졌다.

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Measurements of Microwave Polarimetric Backscattering from a Wet Soil Surface and Comparison with a Semi-empirical Scattering Model

  • Oh, Yi-Sok
    • Proceedings of the KSRS Conference
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    • pp.154-157
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    • 1999
  • Microwave polarimetric backscattering from a wet soil surface had been measured using a Ku-band polarimetric scatterometer at the incidence angles ranging from 10$^{\circ}$ to 70$^{\circ}$ Since the accurate target parameters as well as the radar parameters are necessary for radar scattering modeling, a complete and accurate set of ground truth data were also collected, from which accurate measurements were made of the rms height, correlation length, and dielectric constant. The measured polarimetric backscattering coefficients (vv-, hh-, vh-, hv-polarizations) were compared with theoretical models and empirical models. A new semi-empirical model for microwave polarimetric radar backscattering from bare soil surfaces was developed using polarimetric radar measurements and the knowledge based on the theoretical and numerical solutions. The model was found to yield very good agreement with the backscattering measurements of this study.

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