• Title, Summary, Keyword: weather radar

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DCT and DWT based Damaged Weather Radar Image Retrieval (DCT 및 DWT 기반의 손상된 기상레이더 영상 복원 기법)

  • Jang, Bong-Joo;Lim, Sanghun;Kim, Won;Noh, Huiseong
    • Journal of Korea Multimedia Society
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    • v.20 no.2
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    • pp.153-162
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    • 2017
  • Today, weather radar is used as a key tool for modern high-tech weather observations and forecasts, along with a wide variety of ground gauges and weather satellites. In this paper, we propose a frequency transform based weather radar image processing technique to improve the weather radar image damaged by beam blocking and clutter removal in order to minimize the uncertainty of the weather radar observation. In the proposed method, DCT based mean energy correction is performed to improve damage caused by beam shielding, and DWT based morphological image processing and high frequency cancellation are performed to improve damage caused by clutter removal. Experimental results show that the application of the proposed method to the damaged original weather radar image improves the quality of weather radar image adaptively to the weather echo feature around the damaged area. In addition, radar QPE calculated from the improved weather radar image was also qualitatively confirmed to be improved by the damage. In the future, we will develop quantitative evaluation scales through continuous research and develop an improved algorithm of the proposed method through numerical comparison.

Weather Radar Image Gener ation Method Using Inter polation based on CUDA

  • Yang, Liu;Jang, Bong-Joo;Lim, Sanghun;Kwon, Ki-Chang;Lee, Suk-Hwan;Kwon, Ki-Ryong
    • Journal of Korea Multimedia Society
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    • v.18 no.4
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    • pp.473-482
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    • 2015
  • Doppler weather radar is an important tool for meteorological research. Through several decades of development, Doppler weather radar has enormous progress in understanding, detection and warning of meso and micro scale weather system. It makes a significant contribution to weather forecast and weather disaster warning. But the large amount of data process limits the application of Doppler weather radar. This paper proposed for fast weather radar data processing based on CUDA. CDUA is a powerful platform for highly parallel programming developed by NVIDIA. Through running plenty of threads, radar data can be calculated at same time. In experiment, CUDA parallel program can significantly improve weather data processing time.

Analysis of Quality Control Technique Characteristics on Single Polarization Radar Data (단일편파 레이더자료 품질관리기술 특성 분석)

  • Park, Sora;Kim, Heon-Ae;Cha, Joo Wan;Park, Jong-Seo;Han, Hye-Young
    • Atmosphere
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    • v.24 no.1
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    • pp.77-87
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    • 2014
  • The radar reflectivity is significantly affected by ground clutter, beam blockage, anomalous propagation (AP), birds, insects, chaff, etc. The quality of radar reflectivity is very important in quantitative precipitation estimation. Therefore, Weather Radar Center (WRC) of Korea Meteorological Administration (KMA) employed two quality control algorithms: 1) Open Radar Product Generator (ORPG) and 2) fuzzy quality control algorithm to improve quality of radar reflectivity. In this study, an occurrence of AP echoes and the performance of both quality control algorithms are investigated. Consequently, AP echoes frequently occur during the spring and fall seasons. Moreover, while the ORPG QC algorithm has the merit of removing non-precipitation echoes, such as AP echoes, it also removes weak rain echoes and snow echoes. In contrast, the fuzzy QC algorithm has the advantage of preserving snow echoes and weak rain echoes, but it eliminates the partial area of the contaminated echo, including the AP echoes.

Elimination of Chaff Echoes in Reflectivity Composite from an Operational Weather Radar Network using Infrared Satellite Data (위성 적외영상 자료를 이용한 현업용 기상레이더 반사도 합성자료의 채프에코 제거)

  • Han, Hye-Young;Heo, Bok-Haeng;Jung, Sung-Hwa;Lee, GyuWon;You, Cheol-Hwan;Lee, Jong-Ho
    • Atmosphere
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    • v.21 no.3
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    • pp.285-300
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    • 2011
  • To discriminate and eliminate chaff echoes in radar measurements, a new removal algorithm in two-dimensional reflectivity composite at the height of 1.5 km has been developed by using the brightness temperature($T_B$) obtained from MTSAT-1R. This algorithm utilizes the fact that chaffs are not appeared in infrared satellite data of MTSAT-1R, but detected in radar measurements due to their significant backscattering in the given radar wavelength. The algorithm is evaluated for three different situations: chaff only, chaff mixed with convective storms, and chaff covered with clouds. The algorithm shows excellent performance for the cases of chaff only and chaff mixed with convective storms. However, the performance of the algorithm significantly depends on the presence of clouds. Thus, the statistical analysis of $T_B$ is performed in order to optimize the monthly threshold.

A Comparative Study of the Rainfall Intensity Between Ground Rain Gauge and Weather Radar (지상우량계와 기상레이더 강우강도의 비교연구)

  • Ryu, Chan-Su;Kang, In-Sook;Lim, Jae-Hwan
    • Journal of the Chosun Natural Science
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    • v.4 no.3
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    • pp.229-237
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    • 2011
  • Today they use a weather radar with spatially high resolution in predicting rainfall intensity and utilizing the information for super short-range forecast in order to make predictions of such severe meteorological phenomena as heavy rainfall and snow. For a weather radar, they use the Z-R relation between the reflectivity factor(Z) and rainfall intensity(R) by rainfall particles in the atmosphere in order to estimate intensity. Most used among the various Z-R relation is $Z=200R^{1.6}$ applied to stratiform rain. It's also used to estimate basic rainfall intensity of a weather radar run by the weather center. This study set out to compare rainfall intensity between the reflectivity of a weather radar and the ground rainfall of ASOS(Automatic Surface Observation System) by analyzing many different cases of heavy rain, analyze the errors of different weather radars and identify their problems, and investigate their applicability to nowcasting in case of severe weather.

Study about Real-time Total Monitoring Technique for Various Kinds of Multi Weather Radar Data (이기종-다중 기상레이더 자료의 실시간 통합 모니터링 기법 연구)

  • Jang, Bong-Joo;Lee, Keon-Haeng;Lim, Sanghun;Lee, Dong-Ryul;Kwon, Ki-Ryong
    • Journal of Korea Multimedia Society
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    • v.19 no.4
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    • pp.689-705
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    • 2016
  • This paper proposed an realtime total monitoring platform for various kind of multi weather radars to analyze and predict weather phenomenons and prevent meteorological disasters. Our platform is designed to process each weather radar data on each radar site to minimize overloads from conversion and transmission of large volumed radar data, and to set observers up the definitive radar data via public framework server separately. By proposed method, weather radar data having different spatial or temporal resolutions can be automatically synchronized with there own spatio-temporal domains on public GIS platform having only one spatio-temporal criterion. Simulation result shows that our method facilitates the realtime weather monitoring from weather radars having various spatio-temporal resolutions without other data synchronization or assimilation processes. Moreover, since this platform doesn't require some additional computer equipments or high-technical mechanisms it has economic efficiency for it's systemic constructions.

Improvement of a Detecting Algorithm for Geometric Center of Typhoon using Weather Radar Data (레이더 자료를 이용한 기하학적 태풍중심 탐지 기법 개선)

  • Jung, Woomi;Suk, Mi-Kyung;Choi, Youn;Kim, Kwang-Ho
    • Atmosphere
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    • v.30 no.4
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    • pp.347-360
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    • 2020
  • The automatic algorithm optimized for the Korean Peninsula was developed to detect and track the center of typhoon based on a geometrical method using high-resolution retrieved WISSDOM (WInd Syntheses System using DOppler Measurements) wind and reflectivity data. This algorithm analyzes the center of typhoon by detecting the geometric circular structure of the typhoon's eye in radar reflectivity and vorticity 2D field data. For optimizing the algorithm, the main factors of the algorithm were selected and the optimal thresholds were determined through sensitivity experiments for each factor. The center of typhoon was detected for 5 typhoon cases that approached or landed on Korean Peninsula. The performance was verified by comparing and analyzing from the best track of Korea Meteorological Administration (KMA). The detection rate for vorticity use was 15% higher on average than that for reflectivity use. The detection rate for vorticity use was up to 90% for DIANMU case in 2010. The difference between the detected locations and best tracks of KMA was 0.2° on average when using reflectivity and vorticity. After the optimization, the detection rate was improved overall, especially the detection rate more increased when using reflectivity than using vorticity. And the difference of location was reduced to 0.18° on average, increasing the accuracy.

Merging Radar Rainfalls of Single and Dual-polarization Radar to Improve the Accuracy of Quantitative Precipitation Estimation (정량적 강우강도 정확도 향상을 위한 단일편파와 이중편파레이더 강수량 합성)

  • Lee, Jae-Kyoung;Kim, Ji-Hyeon;Park, Hye-Sook;Suk, Mi-Kyung
    • Atmosphere
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    • v.24 no.3
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    • pp.365-378
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    • 2014
  • The limits of S-band dual-polarization radars in Korea are not reflected on the recent weather forecasts of Korea Meteorological Administration and furthermore, they are only utilized for rainfall estimations and hydrometeor classification researches. Therefore, this study applied four merging methods [SA (Simple Average), WA (Weighted Average), SSE (Sum of Squared Error), TV (Time-varying mergence)] to the QPE (Quantitative Precipitation Estimation) model [called RAR (Radar-AWS Rainfall) calculation system] using single-polarization radars and S-band dual-polarization radar in order to improve the accuracy of the rainfall estimation of the RAR calculation system. As a result, the merging results of the WA and SSE methods, which are assigned different weights due to the accuracy of the individual model, performed better than the popular merging method, the SA (Simple Average) method. In particular, the results of TVWA (Time-Varying WA) and TVSSE (Time-Varying SSE), which were weighted differently due to the time-varying model error and standard deviation, were superior to the WA and SSE. Among of all the merging methods, the accuracy of the TVWA merging results showed the best performance. Therefore, merging the rainfalls from the RAR calculation system and S-band dual-polarization radar using the merging method proposed by this study enables to improve the accuracy of the quantitative rainfall estimation of the RAR calculation system. Moreover, this study is worthy of the fundamental research on the active utilization of dual-polarization radar for weather forecasts.

Sensitivity Analysis of Polarimetric Observations by Two Different Pulse Lengths of Dual-Polarization Weather Radar (펄스길이에 따른 이중편파변수의 민감도 분석)

  • Lee, Jeong-Eun;Jung, Sung-Hwa;Kim, Jong-Seong;Jang, KunIl
    • Atmosphere
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    • v.29 no.2
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    • pp.197-211
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    • 2019
  • The observational sensitivity of dual-polarization weather radar was quantitatively analyzed by using two different pulse widths. For this purpose, test radar scan strategy which consisted of consecutive radar scan using long (LP: $2{\mu}s$) and short (SP: $1{\mu}s$) pulses at the same elevation angle was employed. The test scan strategy was conducted at three operational S-band dual-polarization radars (KSN, JNI, and GSN) of Korea Meteorological Administration (KMA). First, the minimum detectable reflectivity (MDR) was analyzed as a function of range using large data set of reflectivity ($Z_H$) obtained from JNI and GSN radars. The MDR of LP was as much as 7~22 dB smaller than that of SP. The LP could measure $Z_H$ greater than 0 dBZ within the maximum observational range of 240 km. Secondly, polarimetric observations and the spatial extent of radar echo between two pulses were compared. The cross-polar correlation coefficient (${\rho}_{hv}$) from LP was greater than that from SP at weak reflectivity (0~20 dBZ). The ratio of $Z_H$ (> 0 dBZ) and ${\rho}_{hv}$(> 0.95) bin to total bin calculated from LP were greater than those from SP (maximum 7.1% and 13.2%). Thirdly, the frequency of $Z_H$ (FOR) during three precipitation events was analyzed. The FOR of LP was greater than that of SP, and the difference in FOR between them increased with increasing range. We conclude that the use of LP can enhance the sensitivity of polarimetric observations and is more suitable for detecting weak echoes.

Hierarchical Compression Technique for Reflectivity Data of Weather Radar (기상레이더 반사도 자료의 계층적 압축 기법)

  • Jang, Bong-Joo;Lee, Keon-Haeng;Lim, Sanghun;Kwon, Ki-Ryong
    • Journal of Korea Multimedia Society
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    • v.18 no.7
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    • pp.793-805
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    • 2015
  • Nowadays the amount of data obtained from advanced weather radars is growing to provide higher spatio-temporal resolution. Accordingly radar data compression is important to use limited network bandwidth and storage effectively. In this paper, we proposed a hierarchical compression method for weather radar data having high spatio-temporal resolution. The method is applied to radar reflectivity and evaluated in aspects of accuracy of quantitative rainfall intensity. The technique provides three compression levels from only 1 compressed stream for three radar user groups-signal processor, quality controller, weather analyst. Experimental results show that the method has maximum 13% and minimum 33% of compression rates, and outperforms 25% higher than general compression technique such as gzip.