Effective rain-cell diameters and rain-column heights in the tropics

Pan, Q.W.; Bryant, G. H.

doi:10.1049/el:19941201

Cited by 13 publications

(14 citation statements)

References 1 publication

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“…Similar observations has also been reported by precipitation radar measurements [18,19]. The change in the slope of the exceedance curves for rain occurs because the rainfall structure changes around the breakpoint and tend to saturate at very high rain-rates [4,5,16,17]. Thirteen-year meteorological records at Suva, also shows that the average monthly rainfall exceeds 150 mm, of which 62% occurs in the wet season (November -April) [20].…”

Section: Rain-rate Analysissupporting

confidence: 72%

“…Pan and Bryant [16] were the first to identify the presence of these breakpoints from the measurements carried out in Lae, Papua New Guinea. The rain-rate and the exceedance reported are 105 mm/h and 0.01%, respectively.…”

Section: Rain-rate Analysismentioning

confidence: 99%

“…The breakpoint in attenuation A B could be calculated using the ITU-R model equation To accommodate a margin of error in the estimate of the rain cell diameters in the tropics, a lower limit of the elevation angle of 60 8 is taken in applying the ITU-R recommendation equation to estimate the attenuation A. The power-law kR a L is the general expression for calculating of total path attenuation caused by a constant rain-rate along a path length L and has been used by many researchers [2,9,16]. k and a are frequency dependent coefficients [25].…”

Section: Procedures For Modifying the Itu-r Modelmentioning

confidence: 99%

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Modified rain attenuation model for tropical regions for Ku‐Band signals

Ramachandran¹,

Kumar²

2006

Satell Commun Network

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SUMMARYAttenuation measurement on Ku-band satellite signal in a tropical site, Fiji is presented. Rain-attenuation prediction by ITU-R and the Crane Global models showed noticeable deviation to the measured values. Unlike the monotonic decrease predicted by these models, exceedance of rain-rate and attenuation in Fiji and other tropical regions showed the presence of breakpoints. For Suva, the breakpoint in rain-rate and attenuation were at 58 mm/h and 9.4 dB with exceedances of 0.009 and 0.018%, respectively. Modifications to the ITU-R model are proposed in this paper, for adopting it in the tropics. These modifications are based on the properties that in the tropics (i) the accumulation time factor at the breakpoints is an invariant (ii) for elevation angles 5608 and at high rain rates multiple rain cells intersect the slant path. The attenuation exceedance is predicted by two expressions similar to the ITU-R model, one for rain-rates lower than the breakpoint rain-rate and the other above it. The modified prediction model show remarkable agreement with the measured Ku-band attenuation in seven tropical sites.

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Section: Rain-rate Analysissupporting

confidence: 72%

Section: Rain-rate Analysismentioning

confidence: 99%

Section: Procedures For Modifying the Itu-r Modelmentioning

confidence: 99%

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Modified rain attenuation model for tropical regions for Ku‐Band signals

Ramachandran¹,

Kumar²

2006

Satell Commun Network

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“…Noting that a saturation break, similar to one identi"ed by Moupfuma [13] in his experiments, occurred in the rain-rate exceedances at&105 mm/h shown in Figure 8 and at&13 dB [14] in the attenuation exceedances shown in Figure 9, we were able to use our measured accumulation time factors to make estimates of rain-cell diameters and heights. These have been reported elsewhere [15]. For this type of tropical rain we were able to predict a steady increase of rain height from about 5 km at 20 mm/h rain rate to about 10 km at 105 mm/h.…”

Section: Volume Saturation Of Rainsupporting

confidence: 57%

High elevation angle satellite‐to‐earth 12 GHz propagation measurements in the tropics

Pan

Bryant

McMahon

et al. 2001

Int. J. Satell. Commun.

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SUMMARYA simple, low-cost propagation terminal for measuring path attenuation and site diversity, using satellite transmissions at 12 GHz, is described. The novelty of this system is the use of a standard domestic satellite low-noise block (LNB) front-end connected directly to a spectrum analyser in place of an expensive beacon receiver. A description of the equipment, an analysis of relevant system parameters, and a discussion of the environmental conditions are presented. The method used to obtain a clear-sky baseline reference and a description of the channel signal processing are given. Analysis of the rainfall rate and attenuation exceedances statistics has led to the proposal of a new model to derive the e!ective rain-cell diameters and e!ective rain-column heights in tropical areas for attenuation predictions in satellite communication link budget calculations. Site-diversity statistics are also examined. Though the main site is only 6.5 km inland from the second coastal site, there are marked di!erences in their rain-cell characteristics. The signi"cance of volume saturation of rain cells on modelling, the operating margins of the measuring system, and the relevance of the site-diversity data to enhancing the understanding of the proposed volume saturation model are discussed.

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“…In addition to received signal levels, the rainfall rate data were also acquired at ECL and RIS. The two data sets were processed, Several authors performed rain cell size measurements using meteorological radars located in temperate regions [17]- [20], and a high-elevation slant path at a tropical site [21]. Some of the results were presented in the form of a functional relation between the average cell diameter and the rainfall rate and seem to be in reasonable agreement with the assumed values for parameters β and d o of the model represented by expression (1).…”

Section: The Misme and Fimbel Model And Its Extensionmentioning

confidence: 54%