scholarly journals Assessment of Global Solar Radiation at Selected Points in Nigeria Using Artificial Neural Network Model (ANNM)

2019 ◽  
pp. 376-390 ◽  
Author(s):  
Ibeh Gabriel Friday ◽  
Bernadette Chidomnso Udochukwu ◽  
Tertsea Igbawua ◽  
Tyovenda Alaxander ◽  
Ofoma John Ndubuisi
Keyword(s):  
Transfer Function ◽  
Solar Radiation ◽  
Global Solar Radiation ◽  
Activation Function ◽  
Temporal Variations ◽  
Dry Season ◽  
Coefficient Of Determination ◽  
Wet Season ◽  
North West ◽  
North East

In this study, spatial distribution, temporal variations, annual distribution, estimation and prediction of solar radiation in Nigeria was carried out using ANNs. Levenberg-Marquardt backpropagation algorithms was used for the training of the network using solar radiation data along the years (1979-2014). The data records were divided into three portions (training, testing and validation). The network processed the available data by dividing it into three portions randomly: 70% for the training, 15% for validation and the remaining 15% for testing. Input parameters were chosen as latitude, longitude, day of the year, year while observed solar radiation was chosen as targeted data (from a processed file). The output parameter was the estimated solar radiation. The network designs were tested with root mean square error and then the most successful network (taken to be best network) which is network with less error was used to carry out the study. The hyperbolic tangent sigmoid transfer function was also used between the input and the hidden layers as activation function, while the linear transfer function was used from hidden layers to the output layer as the activation function. The performance of ANNs was validated by; estimating the difference between the annual measured and estimated values were determined using coefficient of determination (R2). Results revealed that the R2 result was 0.82 (82%). The result of spatial variations indicated that both wet and dry seasons have their highest concentration in North-East of Nigeria. It is pertinent to also note that the lowest concentration occurred in North-West during wet season, while the lowest occurred at the South-South and South-West of Nigeria in dry season. In addition, the lowest in dry season is about 25W/m2, while that of wet season is about 15W/m2. The agreement between the temporal and annual variation of observed and estimated solar radiation reveals that the model exhibits good performance in studying solar radiation. The model was further used to predict two years ahead of the years of study.

scholarly journals Comparative Study of Ground Measured, Satellite-Derived, and Estimated Global Solar Radiation Data in Nigeria

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Boluwaji M. Olomiyesan ◽  
Onyedi D. Oyedum
Keyword(s):  
Solar Radiation ◽  
Comparative Study ◽  
Global Radiation ◽  
Statistical Error ◽  
Global Solar Radiation ◽  
Coefficient Of Determination ◽  
Mean Bias Error ◽  
Percentage Error ◽  
Radiation Data ◽  
Proposed Model

In this study, the performance of three global solar radiation models and the accuracy of global solar radiation data derived from three sources were compared. Twenty-two years (1984–2005) of surface meteorological data consisting of monthly mean daily sunshine duration, minimum and maximum temperatures, and global solar radiation collected from the Nigerian Meteorological (NIMET) Agency, Oshodi, Lagos, and the National Aeronautics Space Agency (NASA) for three locations in North-Western region of Nigeria were used. A new model incorporating Garcia model into Angstrom-Prescott model was proposed for estimating global radiation in Nigeria. The performances of the models used were determined by using mean bias error (MBE), mean percentage error (MPE), root mean square error (RMSE), and coefficient of determination (R2). Based on the statistical error indices, the proposed model was found to have the best accuracy with the least RMSE values (0.376 for Sokoto, 0.463 for Kaduna, and 0.449 for Kano) and highest coefficient of determination, R2 values of 0.922, 0.938, and 0.961 for Sokoto, Kano, and Kaduna, respectively. Also, the comparative study result indicates that the estimated global radiation from the proposed model has a better error range and fits the ground measured data better than the satellite-derived data.

scholarly journals Seasonal flooding, instream habitat structure and fish assemblages in the Mulgrave River, north-east Queensland: towards a new conceptual framework for understanding fish-habitat dynamics in small tropical rivers

2008 ◽  
Vol 59 (2) ◽  
pp. 97 ◽  
Author(s):  
Thomas S. Rayner ◽  
Bradley J. Pusey ◽  
Richard G. Pearson
Keyword(s):  
Habitat Structure ◽  
Fish Assemblages ◽  
Fish Habitat ◽  
Dry Season ◽  
Assemblage Structure ◽  
Tropical Rivers ◽  
Wet Season ◽  
Seasonal Flooding ◽  
North East ◽  
Habitat Dynamics

Strong relationships between seasonal flooding, instream habitat structure and fish assemblages have been well documented in large tropical rivers (e.g. the flood pulse concept). However, the mechanics of these relationships are likely to differ substantially in smaller coastal rivers, such as those in Costa Rica, south-east Brazil and Australia’s Wet Tropics. These systems typically feature steep upland streams with short, deeply incised lowland channels and poorly connected floodplains. This hypothesis was investigated by documenting spatial and temporal variation in fish-habitat relationships in the Mulgrave River, north-east Queensland. Sampling was conducted at four lowland sites under a range of flow conditions, from dry-season baseflows to a one-in-ten-year flood. Longitudinal environmental gradients and fine-scale habitat patches were important in regulating fish assemblage structure during the dry season. However, high wet-season flows, constrained by the deep channel, acted as disturbances rather than gentle flood-pulses. In particular, the mobilisation of bed sediments led to scouring of aquatic vegetation and a dramatic reduction in habitat heterogeneity. Seasonal movements of fish led to significant changes in assemblage structure – from a community dominated by Neosilurus ater, Hypseleotris compressa, Awaous acritosus and Redigobius bikolanus during the dry season, to one dominated by Nematalosa erebi, Ambassis agrammus and Glossamia aprion during the wet season. Based on these observations, together with information from the literature, a conceptual model of fish-habitat dynamics is presented that is better suited to small tropical rivers than those developed in larger systems with expansive floodplains.

Analysis of Experimental Solar Radiation Data for Osogbo, Nigeria

2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Abdulhamid Yusuf ◽  
Hakeem Bolarinwa ◽  
Lukman Animasahun ◽  
Yinusa Babatunde
Keyword(s):  
Solar Radiation ◽  
Global Solar Radiation ◽  
Total Radiation ◽  
Wet Season ◽  
Annual Average ◽  
Percentage Frequency ◽  
Monthly Average ◽  
Radiation Data ◽  
Maximum Value ◽  
Daily Total

An analysis of measured global solar radiation (GR) in Osogbo (7.77oN, 4.57oE, 288m) is presented in the form of hourly average, monthly average and percentage frequency distribution. The experimental data corresponds to a year data of 2017. The results reveal that the monthly average values of daily total radiation exhibit seasonal variation with maximum value in dry season month of March (16.59MJ/m2) and minimum value in wet season month of August (8.98 MJ/m2). The annual average GR value is 14.20 MJ/m2 while the annual cumulative GR is 5122 MJ/m2. The solar radiation climate of Osogbo has also been compared to those reported for a number of locations. The percentage frequency of days possessing irradiation rate greater than 15 MJ/m2 is 14 percent whereas that possessing less than 10 MJ/m2 is 61 percent. We conclude, based upon the above analysis that Osogbo is characterized by relatively low global solar radiation.

Agronomic studies on soybean (Glycine max (L.) Merrill) in the dry season of the tropics. III. Effect of artificial photoperiod extension on phenology, growth and seed yield

1991 ◽  
Vol 42 (7) ◽  
pp. 1109 ◽  
Author(s):  
JD Mayers ◽  
RJ Lawn ◽  
DE Byth
Keyword(s):  
Seed Yield ◽  
Dry Season ◽  
Yield Potential ◽  
Wet Season ◽  
Canopy Development ◽  
North West ◽  
Precocious Flowering ◽  
Natural Photoperiod ◽  
Artificial Photoperiod ◽  
Delayed Flowering

Soybean cultivars developed for the tropical wet season performed poorly when grown in the dry season in north-west Australia. The proposition that breeding for later flowering time might enhance yields was tested by using artificial photoperiod extension (14 h day-1 for 28 days post-emergence) to delay flowering of field plots of agronomically improved genotypes. Canopy development and interception of photosynthetically active radiation (PAR), dry matter (DM) accumulation, seed yield and seed composition were examined, and compared with that from plants grown under natural photoperiods. Photoperiod extension delayed flowering an average 24 days, and maturity by an average 14.5 days, the effect being greater in the earlier-flowering genotypes. Differences among genotypes and photoperiod treatments in above-ground DM at the beginning and end of flowering were almost entirely due to the consequences of differences in phenology for cumulative PAR interception. DM at maturity was a simple linear function of crop duration (r2 = 0.95**), while seed yield exhibited an optimum-type response with DM ( R2 = 0.79**). The net consequence was that photoperiod extension increased DM production by an average 2.23 t ha-1 and seed yield by an average 0.65 t ha-1. The analyses suggested that a crop duration of c. 143-146 days would be needed to maximize seed yield under the agronomic conditions of the study, whereas the longest duration among the agronomically improved genotypes under natural photoperiod conditions was 136 days. It was concluded that breeding to constrain precocious flowering under short day conditions would be a viable strategy to improve the yield potential of soybean in the dry season.

scholarly journals Quantification of Temporal Variations in Base Flow Index Using Sporadic River Data: Application to the Bua Catchment, Malawi

Water ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 901 ◽  
Author(s):  
Laura Kelly ◽  
Robert M. Kalin ◽  
Douglas Bertram ◽  
Modesta Kanjaye ◽  
Macpherson Nkhata ◽  
...  
Keyword(s):  
Water Resources ◽  
River Flow ◽  
Temporal Variations ◽  
Dry Season ◽  
Base Flow ◽  
Flow Index ◽  
Wet Season ◽  
Data Application ◽  
Base Flow Index ◽  
Long Term Trends

This study investigated how sporadic river datasets could be used to quantify temporal variations in the base flow index (BFI). The BFI represents the baseflow component of river flow which is often used as a proxy indicator for groundwater discharge to a river. The Bua catchment in Malawi was used as a case study, whereby the smoothed minima method was applied to river flow data from six gauges (ranging from 1953 to 2009) and the Mann-Kendall (MK) statistical test was used to identify trends in BFI. The results showed that baseflow plays an important role within the catchment. Average annual BFIs > 0.74 were found for gauges in the lower reaches of the catchment, in contrast to lower BFIs < 0.54 which were found for gauges in the higher reaches. Minimal difference between annual and wet season BFI was observed, however dry season BFI was >0.94 across all gauges indicating the importance of baseflow in maintaining any dry season flows. Long term trends were identified in the annual and wet season BFI, but no evidence of a trend was found in the dry season BFI. Sustainable management of the investigated catchment should, therefore, account for the temporal variations in baseflow, with special regard to water resources allocation within the region and consideration in future scheme appraisals aimed at developing water resources. Further, this demonstration of how to work with sporadic river data to investigate baseflow serves as an important example for other catchments faced with similar challenges.

scholarly journals Estimates of daily global solar radiation based on the daily temperature extremes and precipitation sums

2004 ◽  
Vol 52 (5) ◽  
pp. 13-28
Author(s):  
Miroslav Trnka
Keyword(s):  
Solar Radiation ◽  
Sunshine Duration ◽  
Regression Line ◽  
Global Solar Radiation ◽  
Daily Temperature ◽  
Coefficient Of Determination ◽  
Mean Bias Error ◽  
Daily Maximum ◽  
Bias Error ◽  
Temperature Extremes

Two methods for estimating daily global solar radiation (RG) based on the daily temperature extremes and precipitation sum are compared in the study. All parameters necessary for application of both methods were derived either from literature or from climatic characteristics easily available at the given meteorological stations excluding need for measured RG data. The performance of both methods was assessed with a help of meteorological database including 4 stations in the Czech Republic (data were provided by the Czech Hydrometeorological Institute) and 6 in Austria (data provided by the Austrian Weather Service) containing in total 41 640 observational day. For each day in the database observed daily sum of RG, daily maximum and minimum temperatures and precipitation sum were available. Coefficient of determination, slope of regression line forced through origin, mean bias error (MBE) and root mean square error (RMSE) were used as performance indicators. The first method proposed by Winslow et al. (2001) – Eq. (1) is capable to explain 86% of daily RG variability, with systematic error represented by MBE equaling to 0.19 MJ.m–2.day-1 and random error indicated by RMSE reaching up to 3.09. The second method published by Thornton and Running (1999)-Eq. (2) was found to be in almost all parameters inferior to the Eq. (1) and thus the Eq. (1) is recommended to be used in the Central European region (up to 600 m above the sea level). This method might be recommended for stations where neither measured RG or sunshine duration hours exist. However, one should take into consideration that relative MBE and RMSE are in some months higher than 10% and 30% respectively, which may compromise results of subsequent calculations made with use of estimated solar radiation data and alter the order of the method suitability.

scholarly journals Calibration of Methods to Estimate Solar Irradiance in Northeastern Pará

2020 ◽  
Vol 35 (2) ◽  
pp. 345-355
Author(s):  
João Vitor de Nóvoa Pinto ◽  
Hildo Giuseppe Garcia Caldas Nunes ◽  
Daniely Florencia Silva de Souza ◽  
Deborah Luciany Pires Costa ◽  
Paulo Jorge de Oliveira Ponte de Souza
Keyword(s):  
Solar Radiation ◽  
Performance Index ◽  
Solar Irradiance ◽  
Sunshine Duration ◽  
Dry Season ◽  
Daily Maximum ◽  
Wet Season ◽  
Average Performance ◽  
Daily Minimum ◽  
Air Temperatures

Abstract Two models aimed to estimate solar irradiance were calibrated in six locations in Northeastern Pará (Belém, Cametá, Conceição do Araguaia, Marabá, Soure, and Tucuruí). The first one is the equation of Angström-Prescott (AP), which requires observations of sunshine duration hours. The second model is a modified version of Hargreaves' radiation formula (MH), which requires observations of daily maximum and daily minimum air temperatures. Both models were calibrated to estimate daily and monthly solar radiation. The calibration of both equations for each season (i.e., dry season and wet season) in each location was also tested. AP has an average performance about 74% higher than MH for daily estimates (excluding Soure) and 83% higher than MH for monthly estimates (excluding Soure and Tucuruí). The use of seasonally calibrated equations slightly improves the performance of AP, measured by the performance index, by 0.68% and improves the performance of MH in most locations, when estimating daily solar radiation. The performance of both models is much higher when estimating monthly solar radiation than daily solar radiation, with an increase of the performance index of 10.95% for AP.

scholarly journals Variabilidade Espacial da Radiação Solar na Região de Manaus - AM durante o Experimento GOAmazon 2014/15 (Spatial variability of solar radiation in Manaus-AM region during GOAmazon Experiment 2014/15)

2017 ◽  
Vol 10 (6) ◽  
pp. 1802
Author(s):  
Alice Dos Santos Macedo ◽  
Gilberto Fisch
Keyword(s):  
Solar Radiation ◽  
Spatial Variability ◽  
Rural Areas ◽  
Cloud Cover ◽  
Global Solar Radiation ◽  
Horizontal Gradient ◽  
Strong Impact ◽  
Wet Season ◽  
E 600 ◽  
The City

Este trabalho realizou um estudo da variabilidade espacial em 2014 da irradiância solar na região de Manaus-AM, através de dados observacionais, inserido no Projeto GOAmazon 2014/15. Também, como forma complementar, foi realizada a análise da cobertura de nuvens, chuva e aerossóis e suas interrelações com a irradiância solar. Como resultado, observa-se que os menores valores médios da irradiância solar ocorreram na área urbana,o que é justificado, em parte pela urbanização que altera os fluxos envolvidos, diminuindo a irradiância solar à superfície. Os valores típicos são entre 400 e 600 Wm-2na estação chuvosa (fevereiro/março) com um desvio padrão de 200 e 380 Wm-2e entre 650 e 800 Wm-2na estação seca (agosto-setembro) com desvio padrão de 190 e 300 Wm-2. A B S T R A C T   The solar radiation is an important climatic element in the Amazon region, as it has a strong  impact for ecological (by the preservation of the biodiversity) and technological (as a renewable energy) areas. Consequently, this study contributes for these themes, conducting an observational study of the spatial variability of the solar irradiance for Manaus-AM area, with data collected during the project GOAmazon 2014/15. The cloud cover and rainfall and their relationships with solar radiation were also analysed. The maximum values observed for the wet season (february and march) are in the range 450 and 600 Wm-2 with high standart deviation (300 - 350 Wm-2 ), while they are in the range from 650 and 800 Wm-2  during the dry period (august - september) with lower standart deviation (200 - 300 Wm-2).  These values are directly associated with cloud cover and rainfall. In general, the urban area (Manaus city) showed the low values of solar radiation at the surface compared with its neighborhood, inducing a horizontal gradient of clouds/rainfall and solar energy between the city and the semi rural areas.  Keywords: piranometer, global solar radiation, cloud cover, total sky imager

Effect of hormonal growth promotant implants in weaner and hogget ewes on subsequent growth and reproductive performance

2004 ◽  
Vol 44 (8) ◽  
pp. 755
Author(s):  
G. Bortolussi ◽  
A. R. Bird ◽  
C. L. Playford ◽  
J. Moore
Keyword(s):  
Reproductive Performance ◽  
Average Daily Gain ◽  
Later Life ◽  
Dry Season ◽  
Control Group ◽  
Wet Season ◽  
Negative Effects ◽  
North West ◽  
Daily Gain

Ninety young Merino ewes, depastured on Mitchell (Astrebla spp.) grass pastures in North West Queensland, were used in a hormonal growth promotant implantation study. The ewes were given 1 implant of Compudose, Ralgro, Revalor or Synovex-H, either at lamb marking (mid-dry season) or the start of the following summer wet season, which was ~180 days post-marking. The hormonal growth promotant implanted groups had greater (P<0.05) liveweights than the control group early in the trial (days 22 and 57) and also from the end of the period of activity of the wet season implant (day 277) until the middle of the dry season (day 412). Dry season (at lamb marking) implantation did not improve average daily gain. From the end of the wet season onwards, ewes with a wet season implant were heavier (P<0.05) than those ewes implanted at lamb marking. This liveweight advantage had diminished by the start of the autumn mating. Hormonal growth promotant implantation had a favourable (P<0.05) effect on growth rate, but adversely affected reproduction in the ewes, regardless of time of implantation. Implantation with Compudose or Synovex-H significantly (P<0.001) reduced the demonstration of oestrus, while Revalor or Synovex-H reduced pregnancy rates by up to 100%. Despite Ralgro reducing these variables by up to 25%, its effect was not significant. All ewes that were diagnosed as pregnant at 140 days later produced lambs. It was concluded from this study that hormonal growth promotant implantation at lamb marking provides no later-life advantage, while wet season implantation provides a growth or liveweight advantage to young Merino ewes and this persists for a long period after implantation. Despite the lack of an effect of Ralgro on oestrus and pregnancy results, however, implantation of young breeding ewes of any age should not be carried out, due to the long term and negative effects on reproductive performance. Wet season implantation may be best used for animals intended for slaughter.

scholarly journals Occurrence of fluorotelomer alcohols at two Alpine summits: sources, transport and temporal trends

2017 ◽  
Vol 14 (4) ◽  
pp. 215 ◽  
Author(s):  
Zhenlan Xu ◽  
Lingxiangyu Li ◽  
Bernhard Henkelmann ◽  
Karl-Werner Schramm
Keyword(s):  
Human Health ◽  
Limit Of Detection ◽  
Air Flow ◽  
Temporal Trends ◽  
Temporal Variations ◽  
Polar Regions ◽  
Air Mass ◽  
North West ◽  
North East ◽  
Fluorotelomer Alcohols

Environmental contextThe transport and fate of organic pollutants such as fluorotelomer alcohols (FTOHs) in the atmosphere affect their risks to the environment and human health. On the basis of hourly trajectory predictions, we found that, from 2007 to 2010, individual levels of 6:2, 8:2 and 10:2 FTOH were from non-detectable to 72.4pgm–3 at two Alpine summits. Air mass origin was an important factor determining the Alpine atmospheric FTOH levels. AbstractThe transport and fate of fluorotelomer alcohols (FTOHs) in the atmosphere affect their risks to the environment and human health. In this study, we aimed to investigate the sources, transport and temporal variations of FTOHs (6:2, 8:2 and 10:2 FTOH) at two Alpine summits (Sonnblick and Zugspitze). The active air sampler consisting of four XAD cartridges was applied to collect FTOHs from 2007 to 2010. Four separate cartridges were assigned for four air flow regimes (three European sectors and one mixed source origin), and switched and controlled on the basis of an hourly trajectory prediction. FTOH (6:2, 8:2 and 10:2) was measured with individual concentrations ranging from less than the limit of detection to 72.4pgm–3. Also, 8:2 FTOH was the dominant compound, accounting for 41–72% of the total FTOH (ΣFTOH) concentration. Significant differences were not observed in FTOH concentrations between Sonnblick and Zugspitze since the two sites are relatively close compared with the geographic extent of the area studied. Air-flow regime was an important factor determining the atmospheric FTOH levels. Particularly at Zugspitze, air mass from the NE (regions north-east of the Alps) showed the highest median ΣFTOH concentration (36.9pgm–3), followed by S (the Po basin in Italy), NW (regions north-west of Alps) and M (mixed source origin, polar regions or high altitudes). Furthermore, the seasonal variation in FTOH concentrations was not correlated with the site temperatures, but was dependent on the wind speed. Overall, the results indicated low FTOH concentrations at these two Alpine summits compared with European populated cities and provided important information for understanding the fate of FTOHs in the Alpine atmosphere.

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