Rainfall Rate Probability Density Evaluation and Mapping for the Estimation of Rain Attenuation in South Africa and Surrounding Islands

Owolawi, Pius A.

doi:10.2528/pier10082504

Cited by 27 publications

(21 citation statements)

References 9 publications

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“…As seen from Fig. 7, the classical PDFs contain Gauss, Rayleigh, Weibull and Logarithmic normal [32,33]. Table 1 shows that Gauss function has the minimum MSE with the distributions of feature 1 and feature 2.…”

Section: Resultsmentioning

confidence: 99%

Sparse Time-Frequency Representation Based Feature Extraction Method for Landmine Discrimination

Wang¹,

Song²,

Tian³

et al. 2013

PIER

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Abstract-Low-frequency ultra-wideband synthetic aperture radar is a promising technology for landmine detection. According to the scattering characteristics of body-of-revolution (BOR) along with azimuth angles, a discriminator based on Bayesian decision rule is proposed, which uses sequential features, i.e., double-hump distance. First, the algorithm estimates the target scatterings in all azimuth angles based on regions of interest. Second, sequential aspect features are extracted by sparse time-frequency representation. Third, the distributions of features are obtained by training samples, and then the posterior probability of landmine class is computed as an input to the classifier adopting Mahalanobis distance. The experimental results indicate that the proposed algorithm is effective in BOR target discrimination.

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Section: Resultsmentioning

confidence: 99%

Sparse Time-Frequency Representation Based Feature Extraction Method for Landmine Discrimination

Wang¹,

Song²,

Tian³

et al. 2013

PIER

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“…While Durban is subtropical, there is the immense maritime influence on its climate, hence the comparison of the Durban N (D) with distributions from tropical regions with strong maritime influence such as Singapore, Indonesia, East coast of Brazil, and Calcutta in India -sites for which a lot of work has been reported. However, we also note that South African climate is very varied, with Cape Town having a Mediterranean climate, while Pretoria has a temperate climate; hence when we look at these two cities later, their distributions will not be compared against those of tropical areas, but rather temperate and Mediterranean regions, as corroborated by Owolawi [28].…”

Section: Introductionmentioning

confidence: 88%

Raindrop Size Distribution Modeling for Radio Link Design Along the Eastern Coast of South Africa

Afullo¹

2011

PIER B

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Abstract-A study of the raindrop size distribution along the eastern coast of South Africa (Durban) is presented. The Biweight kernel estimator based on distometer measurement is used to determine the best estimate of the measured raindrop size probability distribution function (pdf). The best kernel estimator, which results in the lowest integral square error (ISE), is used to measure the closeness of the estimated lognormal and gamma pdf of raindrop size to the measured raindrop size distribution. It is established that the optimised lognormal pdf slightly outperforms the optimised gamma pdf in terms of the mean ISE and the RMSE values, with mean ISE values of 0.026 for lognormal and 0.04 for gamma distributions, respectively, and corresponding mean RMSE values of 0.073 and 0.081, respectively. The method-of-moments gamma and lognormal distributions are observed to be worse estimators of the measured pdf than the two optimized distributions. The N (D) distributions using the optimised lognormal and gamma distributions for the region are compared with those for different tropical regions, namely, India, Singapore, Nigeria, Indonesia, and Brazil. While the Indian lognormal N (D) model gives the highest peak for low raindrop sizes for all rain rates, Durban's gamma and lognormal models exhibit the widest raindrop size spread over all rain rates ranging from 1-120 mm/h. Finally, the specific attenuation due to rain using the Durban models are compared against the ITU-R models and actual measurements over a 19.5 GHz LOS link; the results indicate a need for further work involving both distrometer and radio link measurements for rain rates exceeding 30 mm/h in the eastern coast of South Africa.

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“…The conversion is unique to a particular region because it involves the geographical and climatic properties of a location. While notable methods of conversion have been developed [8,[10][11][12][13][14][15][16][17][18][19], it is interesting to note that some of these methods depend on the prevailing climatic factors. The rainfall rate conversion methods have been classified into three categories by Emiliani et al [20] namely: physical-stochastic, empirical and analytical methods.…”

Section: Integration Time Rainfall Rate Conversionmentioning

confidence: 99%

“…Many researchers [7,8] have suggested the use of integration times of 1-minute as the most suitable. Rainfall studies in Africa [4-7, 9, 10] and South African region [11][12][13] have suggested the need for adequate rainfall data at 1-minute integration time, which are scarce. However, higher integration time data (hourly, daily and even, monthly) are available from many weather stations.…”

Section: Introductionmentioning

confidence: 99%

Rain Cell Size Mapping for Microwave Link Design Systems in South Africa

Akuon¹,

Afullo²

2011

PIER B

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Abstract-Rain cell size is an input requirement for rain-induced attenuation studies. It is useful in estimating the extent of a given radio link path that will traverse the rain medium in a given rain event. The "Synthetic Storm" approach, which requires 1-minute integration time data, is used to derive the proposed rain cell sizes for various climatic zones within South Africa. The conversion of the readily available 1-hour integration time rain rate data to the desired 1-minute rain rate is carried out first for some locations and then validated by the existing measurement data and proposed global conversion factors. By the use of rain-induced attenuation prediction equation for terrestrial links that requires rain cell size as input, contour plots of specific attenuation for two high bandwidth frequencies used in terrestrial link implementations is presented. Site diversity separation distance map is proposed as well from the link budget analysis for each location to achieve an all time link availability of 99.99% of time.

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Rainfall Rate Probability Density Evaluation and Mapping for the Estimation of Rain Attenuation in South Africa and Surrounding Islands

Cited by 27 publications

References 9 publications

Sparse Time-Frequency Representation Based Feature Extraction Method for Landmine Discrimination

Sparse Time-Frequency Representation Based Feature Extraction Method for Landmine Discrimination

Raindrop Size Distribution Modeling for Radio Link Design Along the Eastern Coast of South Africa

Rain Cell Size Mapping for Microwave Link Design Systems in South Africa

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