Analysis of Cumulative Distribution Function of 2-year Rainfall Measurements in Ogbomoso, Nigeria

Abstract: The conversion of most available hourly rainfall data to 1-minute integration time rain rate statistic is imperative for accurate estimation of attenuation due to rain employed in the design of both terrestrial and earth-to-space microwave systems. 2-year rainfall data collected at Ogbomoso, South-west region of Nigeria, between the periods of 2009 and 2010 was used in the analysis. Result shows that a power law relationship exists between the equiprobable rain rates of two different integration times. The regression coefficients a and b obtained are slightly different from the ITU-R recommendation. The conversion factor obtained at Ogbomoso is lower compared to Ile-Ife, in the South-west region of the country. The disagreement is attributed to the effect of global warming hitting the whole universe most especially the tropical regions. This study also reveals that different conversion factors are required for different locations even within the same climatic region

Rain attenuation models at ka band for selected stations in the southwestern region of Nigeria

Rain is the major factor in radio propagation analyses that is responsible for outage on terrestrial point-to-point and point-to-multipoint radio communication systems at millimeter wave bands. This hampers radio wave signal transmission in the tropics. This paper investigates the performance of ITU-R P.530-16, Silver Mello, Moupfouma and Abdulrahman rain attenuation prediction models using locally-sourced data. The aim is to determine their suitability or otherwise in tropical Nigeria. Two years daily rainfall data were sourced from the Nigerian Meteorological Services (NIMET) for six different stations in southwestern Nigeria. Southern Nigeria is predominantly influenced by the southwest monsoon wind from the Atlantic Ocean due to its proximity to the coastal belt. The data were analyzed using these prediction models by comparing with measured data. The ITU-R P.530-16 rain attenuation prediction model closely matched the measurement value for p≥0.1% of the time but over-estimated it at p<0.1% while Abdulrahman and Silver Mello proposed prediction models generally over-estimated for p<0.01 of time exceeded. Overall, Abdulrahman proposed prediction model presented the best performances; it was closely followed by Silver Mello, ITU-R and Moupfouma prediction models respectively. These results further accentuate the need for urgent review of the ITU-R P.530-16 prediction model or alternatively, the development of a separate rain attenuation prediction model specifically for the stations in the tropical region

Review of Rain Attenuation Measurements On Earth - Space Links in Nigeria

Due to the prevailing impact of rain on microwave and millimetre wave propagation in tropical climates, fade margins derived from experimental campaigns would provide more practical estimates for planning. In this paper, the extent of work done on the experimental assessment of the attenuation induced by rain on practical earth-space links in Nigeria is presented. The cumulative rain rate distributions derived from the instantaneous precipitation indices for propagation modelling and the estimation of fade margin is presented for Ile-Ife, Akure, Ilorin, Ota, Osogbo and Ogbomoso. Results reveals the spatial variability of the point rainfall rate across these stations. Although the stations engaged with measurement on rain attenuation are limited in number, preliminary results from new stations are presented, while addition data from ongoing campaigns will provide a robust indices for modelling the digital DTH links and for evaluating the performance of pre-existing models over Nigeria

Statistics of rainfall rate at 60 minutes integration time in Malaysia

Background: This paper presents the statistics of rainfall at 60- minute integration time in Malaysia for the period of 12 months from January to December 2009. Objective: To analyze the statistics and characteristics of rainfall intensity measurement at KLIA, Malaysia. To study the behavior of measured rainfall intensity and represent the annual distribution of the measured rainfall through cumulative distribution functions together with different types of rainfall that occurred in 2009. Results: The results obtained show the cumulative distribution functions and amount of the rainfall rate for that particular year. The results also show the different cumulative distribution functions for four different rainfall types that occur in 2009. Conclusion: The study of the 12-month tipping bucket data has given the characteristics of the collected rainfall. From the results obtained, it shows that Malaysia is within equatorial region with the characteristics of two distinguishable rainfall rates that occurs during the whole year

Mapas de contorno de tasa de precipitación y atenuación por lluvias para planificación preliminar de enlaces del satélite "Simón Bolívar" en Venezuela

YNA DOI: https://doi.org/10.15446/dyna.v86n209.73774 DYNA, Volumen 86, Número 209, p. 30-39, 2019. ISSN electrónico 2346-2183. ISSN impreso 0012-7353. Rainfall rate and rain attenuation contour maps for preliminary “Simon Bolivar” satellite links planning in Venezuela Mapas de contorno de tasa de precipitación y atenuación por lluvias para planificación preliminar de enlaces del satélite "Simón Bolívar" en Venezuela Angel Dario Pinto Mangones, Nelson Alexander Pérez García, Juan Manuel Torres Tovio, Eduardo José Ramírez, Samir Oswaldo Castaño Rivera, Jaime Velez Zapata, John Dwiht Ferreira Rodríguez, Leidy Marian Rujano Molina Texto completo: PDF (English) Bookmark and Share Resumen (en_US) Predicting precipitation rate and rainfall attenuation are key aspects in planning and dimensioning of wireless communications systems operating at frequencies above 10 GHz, such as satellite communication systems at Ku and Ka bands. In this paper, contour maps of rainfall rate and rain attenuation are developed for the first time in Venezuela, based on 1-min rain rate statistics obtained from measurements carried out in Venezuela over at least 30 years period with a higher integration time and using Rice-Holmberg model, refined Moupfouma-Martin model and Recommendation ITU-R P.837-7, for rain rate estimation and Recommendation ITU-R P.618-13, Ramachandran-Kumar model, Yeo-Lee-Ong model and Rakshit-Adhikari-Maitra model, for rain attenuation prediction in “Simon Bolivar” satellite links in Venezuela. The overall results of both types of maps represent a useful tool for preliminary planning of those links in the country, specifically, in Ku and Ka bands.La tasa de precipitación y la atenuación por lluvias son aspectos claves en la planificación y dimensionamiento de sistemas inalámbricos de comunicaciones que operan en frecuencias superiores a 10 GHz, tales como los sistemas de comunicación vía satélite en las bandas Ku y Ka. En este artículo, se desarrollan por primera vez en Venezuela mapas de contorno de tasa de precipitación y atenuación por lluvias, en base a estadísticas de lluvia de 1-minuto obtenidas a partir de mediciones realizadas en Venezuela en un periodo de al menos 30 años con alto tiempo de integración y usando los modelos Rice-Holmberg, Moupfouma-Martin refinado y Recomendación ITU-R P.837-7, para la estimación de la precipitación y los modelos Recomendación ITU-R P.618-13, Ramachandran-Kumar, Yeo-Lee-Ong y Rakshit-Adhikari-Maitra, para la predicción de la atenuación por lluvias para enlaces del satélite “Simón Bolívar” en Venezuela. Los resultados generales de ambos tipos de mapas representan una herramienta útil para la planificación preliminar de dichos enlaces en el país, específicamente, en las bandas Ku y Ka

On requirements for a satellite mission to measure tropical rainfall

Tropical rainfall data are crucial in determining the role of tropical latent heating in driving the circulation of the global atmosphere. Also, the data are particularly important for testing the realism of climate models, and their ability to simulate and predict climate accurately on the seasonal time scale. Other scientific issues such as the effects of El Nino on climate could be addressed with a reliable, extended time series of tropical rainfall observations. A passive microwave sensor is planned to provide information on the integrated column precipitation content, its areal distribution, and its intensity. An active microwave sensor (radar) will define the layer depth of the precipitation and provide information about the intensity of rain reaching the surface, the key to determining the latent heat input to the atmosphere. A visible/infrared sensor will provide very high resolution information on cloud coverage, type, and top temperatures and also serve as the link between these data and the long and virtually continuous coverage by the geosynchronous meteorological satellites. The unique combination of sensor wavelengths, coverages, and resolving capabilities together with the low-altitude, non-Sun synchronous orbit provide a sampling capability that should yield monthly precipitation amounts to a reasonable accuracy over a 500- by 500-km grid

Investigation into Rain Attenuation Prediction Models at Locations in Lagos Using Remote Sensing

This paper investigated the performances of some rain attenuation prediction models at some GSM network locations in Lagos, Nigeria, using remote sensing at Ku band. Remote sensing is a collection and interpretation of information about an object without physical contact with the object being measured. Three popular terrestrial prediction models were considered in this work. These are ITU-R P.530-17, Lin and Silva Mello Models. Ten years (2010-2019) annual rainfall data with hourly integration time were sourced from the Nigerian Meteorological Agency (NIMET) and link budgets for three microwave links (Tarzan Yard, Kofo Abayomi and GLO Shop) in Victoria Island at 18 GHz were obtained from Global Communications Limited (GLO), Nigeria. Data analysis and comparison of the microwave links rainfall estimates were carried out to identify the most suitable of the three models at the selected locations of interest. Measurement data obtained from both NIMET and GLO were used to validate the predicted attenuation data from the three selected models. The ITU-R P.530-17 prediction model overestimated the measurement at Tarzan Yard; closely followed by Silva Mello, while Lin underestimated the measured data. Again, at Kofo Abayomi station, the ITU-R model overestimated the measurement, while both Silva Mello and Lin models underestimated the measurement. At the GLO Shop, the Silva Mello overestimated the measured value, while ITU-R and Lin underestimated the measurement. At 0.01% of time exceeded, NIMET measurement was higher (at 48.2 dB) than that of Tarzan Yard, Kofo Abayomi and GLO shop (43.1, 46.3 and 37.0 dB respectively). These results will provide useful information in mitigating signal outages due to rain for mobile communication systems

Usporedba modela intenziteta oborine za područja s ekvatorijalnom klimom u jugoistočnoj Aziji

Statistics of 1 minute rain rate has a major impact in the design of satellite communication systems at frequencies above 10 GHz. The effect of rain causes serious degradation of radio signals at frequencies above about 10 GHz; therefore, models for the prediction of statistics of excess path attenuation needed for the design of communication propagation paths requires a statistical description of rain-rate occurrences. In this paper, the tasks are tackled by processing 3 years rain rate data for selected sites in the equatorial region. A comparison between rain rate data set with a sampling period of 1 minute and existing rain rate prediction models is presented.Statistika minutnih intenziteta oborine ima veliki utjecaj na modeliranje satelitskih komunikacijskih sustava koji rade na frekvencijama višim od 10 GHz. Utjecaj kiše uzrokuje jaku degradaciju radio signala na frekvencijama 10 GHz i višim; stoga modeli za predviđanje prekoračenja dozvoljenog propagacijskog gušenja, koje je potrebno za izbor komunikacijskih pravaca, zahtijevaju statistički opis intenziteta oborine na tim pravcima. U ovom su radu obrađeni trogodišnji nizovi podataka s intenzitetima oborine za odabrane postaje u ekvatorijalnom području. Uspoređeni su rezultati dobiveni s nizovima podataka intenziteta oborine koji su uzorkovani s periodom jedne minute s onima dobivenima prognostičkim modelima intenziteta oborine

Development Of Rain And Scintillation Models At Ku-Sand In Southeast Asia Tropical Countries

A two year rainfall rate, attenuation and scintillation measurement was conducted in Southeast Asia Tropical countries (USM, KMITL,USP, AdMU and ITB). The data obtained are useful to investigate the impairment due to rainfall in satellite links operating in tropical and equatorial climates. The cumulative distributions of rainfall rate, attenuation and scintillation derived from the measured data are presented and compared with those obtained with existing prediction models. Existing model for prediction of slant-path have not shown good agreement with available experimental data, confirming the need of suitable models for tropical region. Results were analysed in order to understand the potentials and the limits of each prediction model. Based on the limitations of the existing models, 1-minute rainfall rate and attenuation prediction model was developed from the knowledge of the ground point rainfall rate and attenuation cumulative distribution representative of the area where the earth station is located. Comparison between predicted and experimental results has shown significant improvements in terms of reduced prediction error over existing models. The proposed models were also used for prediction against the measured data from different location such as Brazil, Singapore and Papua New Guinea. The proposed model gave a good representation of cumulative distribution with an overall low rms for measurement sites and the three different locations mentioned above. The agreement with the measured data was found to be mainly dependent on the proper parameterization of the proposed models to the radiometeorological variables along the satellite link. Therefore, it can be concluded that the proposed models has high prediction accuracy for the whole cumulative distribution of rainfall and scintillation data