A New Rain Attenuation Conversion Technique for Tropical Regions

Abdulrahman, A. Y.; Rahman, Tharek Abdul; Rahim, S. K. A.; Islam, Md. Rafiqul

doi:10.2528/pierb10062105

Cited by 32 publications

(28 citation statements)

References 10 publications

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“…The performance of communication links in frequencies above 5 GHz are affected by rain attenuation so the attenuation is one of the most crucial factors to be considered in the link budget estimation [1,2]. The rain attenuation is a function of raindrop, and consequently can be predicted when the DSD data are available [1,[3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Performance Evaluation of Micro Rain Radar Over Sumatra Through Comparison With Disdrometer and Wind Profiler

Marzuki¹,

Hashiguchi²,

Shimomai³

et al. 2016

PIER M

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Abstract-Micro Rain Radar (MRR) is a vertical pointing microwave profiler to measure hydrometeors and related parameters in high resolution. However, it is known that the MRR suffers from certain limitations due to several factors. This paper evaluates the performance of the MRR installed at Kototabang, west Sumatra, Indonesia (0.20 • S, 100.32 • E, 864 m above sea level). The DSD and rainfall rate from the MRR standard processing method had been evaluated by using collocated measurements of MRR, Parsivel disdrometer and Optical Rain Gauge (ORG) during 2014. Furthermore, 1.3 GHz wind profiler (BLR) observation was used to examine the vertical profiles of radar reflectivity and Doppler velocity. It was found that there were noticeable differences between the MRR and Parsivel in the small and large size ends of the DSD. At small sized drop (< 1 mm), the DSD spectra of MRR was higher than that obtained by the Parsivel otherwise it was smaller for large sized drop (> 2 mm). Underestimation of large sized drops in the MRR could be responsible for the underestimation of surface rainfall rate and daily rainfall. The source of differences in the DSD seems the measurement shortcomings such as attenuation correction and vertical wind effects, particularly during heavy rain. The shortcomings were observed from the comparison of mean Doppler velocity profiles between the MRR and the BLR. While the melting layer height of the two instruments was the same, the mean Doppler velocities of MRR shown downward increasing (DI) pattern through all rainfall intensities. On the other hand, for the BLR, the DI was only observed for heavy rain (> 10 mm/h), while downward decreasing was observed for light rain (< 5 mm/h). Similar pattern was also observed for the vertical profile of radar reflectivity. Thus, some corrections are needed for heavy rain, nevertheless, the MRR installed at Kototabang can be utilized for light rain. Comparisons indicated that the mean Doppler velocity and the DSD for the light rain as well as Z-R relation were in reasonable agreement with the reference of BLR, Parsivel and previous studies using the MRR.

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Section: Introductionmentioning

confidence: 99%

Performance Evaluation of Micro Rain Radar Over Sumatra Through Comparison With Disdrometer and Wind Profiler

Marzuki¹,

Hashiguchi²,

Shimomai³

et al. 2016

PIER M

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“…The significance of Figure 5 and Table V can be demonstrated as follows: The ITU-R specifies the availability of 99.99% (i.e, 0.01 % of the time in an average year) for commercial operators. Usually propagation impairments have a significant effect only for less than one percent of the time during a year; therefore the system gain must be enhanced through an additional fade margin to meet the desired availability and quality of service, QoS specifications [3]. For example, as shown The newly released ITU-R P.530-14 and three classical rain attenuation prediction models are validated in this article, using the data bank available from six geographically spread DIGI MINILINKs operating at 15 GHz in Peninsula Malaysia.…”

Section: B Experimental Proceduresmentioning

confidence: 99%

Statistical Evaluation of Measured Rain Attenuation in Tropical Climate and Comparison with Prediction Models

Yusuf

Falade

Olufeagba

et al. 2016

J. Microw. Optoelectron. Electromagn. Appl.

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Abstract-Substantial modifications have been made to the expressions for calculating distance factor and extrapolation techniques in the latest ITU-R P.530-14. However, its performance has not been rigorously evaluated in the tropical and equatorial climates. In this article, the new ITU-R method and three prediction models are validated using measurement data from tropical Malaysian climate. The data were collected on six geographically spread terrestrial microwave DIGI MINI-LINKs operating at 15 GHz. When tested against measurements, the Da Silva Mello model yields a significant improvement for the prediction of rain attenuation distributions. The prediction errors observed in the ITU-R model suggest the need for more data campaign in the afore-mentioned climates. I. INTRODUCTIONTraditionally frequencies above 10 GHz are commonly employed in the current microwave point-topoint networks, due to large bandwidth and freedom from traffic congestion. However, in these frequency bands, the performance of the fixed service (FS) is predominantly controlled by rain in 2012; however, its performance has not been largely evaluated using data collected from tropical climates. Therefore, the main aim of this article is to evaluate the performance of the newly released ITU-R model and the three afore-mentioned models, using measurement data from six locations in a tropical climate. The data used are the rain rate and rain attenuation data banks available from six geographically spread terrestrial microwave DIGI MINI-LINKs operating at 15 GHz as described in[13]. It should be mentioned here that the ITU-R P.530-14 was not yet in force when our previous works were reported. II. THEORETICAL BACKGROUND OF RAIN ATTENUATION PREDICTION MODELSRain attenuation can be conveniently defined as the product of specific attenuation (dB/km) corresponding to the point rain rate (typically measured at one end of the link) and the effective propagation path length (km) [1]. The path correction factor is defined as the ratio of effective path length to the physical path length of a microwave link, and its value is usually less than unity, except in rear cases [14].The concept of effective path length is thus a way of 'averaging out' the spatial inhomegeneity of rain rate and thus specific attenuation [15]. Note that the degree of spatial inhomogeneity in rain rate generally varies with rainfall intensity. Therefore the variation of path length reduction factor can be expressed as a function of rain rate or the corresponding time exceedance [16].Attenuation p A exceeded at p % of time can either be obtained from direct measurements, or predicted from the knowledge of long-term rainfall rate. Generally, the required inputs in most attenuation prediction models for terrestrial point-to-point microwave links are the rainfall rate exceeded at p % of time, the effective propagation path length and the link's operating frequency [7], [16]. Thus p

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“…However, results from some recent researches have suggested that some ITU-R models may not necessarily be best suited or most reliable for all frequencies or in all geographical areas [14][15][16][17].…”

Section: An Overview Of Selected Rain Attenuation Prediction Modelsmentioning

confidence: 99%

“…Attenuation experienced in tropical areas is caused by considerably higher rainfall rates and bigger size of raindrops compared to other parts of the world [11]. Since the Ku frequency band (14/12 GHZ) has shown serious signs of depletion, research activity have since been directed towards the full utilization of the Ka band (30/20 GHz), while the V band (50/40 GHz) is being considered for applications in the near future [14]. Utilization of higher frequency bands such as the Ku band for satellite communication provides a number of important benefits.…”

mentioning

confidence: 99%