Statistical Assessment of Average Global and Diffuse Solar Radiation on Horizontal Surfaces in Tropical Climate (original) (raw)
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GLOBAL SOLAR RADIATION STUDIES DUE TO SUNSHINE HOURS AND OTHER METEOROLOGICAL PARAMETERS
American Journal of Engineering and Applied Sciences, 2013
Multiple linear regression models were developed to estimate the monthly daily Sunshine Hours using four parameters during a period of eleven years (1997-2007) for locations in South Eastern Nigeria. These locations include Uyo (Latitude 5°18’53.7’’N), Calabar (Latitude 5°16’07.6’’N), Port Harcourt (Latitude 4°56’26.2’’N), Warri (Latitude 5°34’21.0’’N), Enugu (Latitude 6°27’42.42’’N), Owerri (Latitude 5°38’05.1’’N). The parameters include Relative Humidity, Maximum and Minimum temperatures, Rainfall and Wind Speed. The result of the correlations show that four variable correlations with the highest value of R for each of the six locations give the best result when considering the error term (RMSE). The models are Uyo (S = -16.876-2.065RF+0.237W+1.278T+0.129RH), Calabar (S = -11.049-6.540RF- 0.534W+0.142RH+1.127T), Portharcourt (S = -27.306+0.270RH+1.806T-0.281RH-1.114W), erri (S = 0.677+9.776RF-0.689W-0.057RH+0.900T), Enugu (S = 10.279+5.519RF-0.586W-0.079RH+0.217T), Warri (S = -22.424+0.272RH+1.388T-9.791RF-0.623W). But when considering average values for the six locations, the correlation gives (S = 15.395+0.159RH-0.131T+0.714RF+0.187W). Where RH is Relative humidity, T is the Difference in maximum and minimum temperature, RF is RainFall and W is wind speed. The developed models can be used in estimating Global solar radiation for the six locations under study. It can also be used to estimate Global solar radiation for other places in South Eastern Nigeria where only sunshine records are available.
The Study of Terrestrial Solar Radiation in Awka Using Measured Meteorological Data
This work investigated the terrestrial solar radiation over Awka, South Eastern Nigeria using meteorological parameters of terrestrial temperature and relative humidity collected during 2013-2014 respectively, using Davis weather station vantage pros2 (with Integrated Sensor Suite, ISS) positioned close to the ground surface. The data were logged at 30 minutes interval continuously for each day during the period. Hourly, daily and monthly averages of terrestrial radiation during dry and wet seasons were calculated from the data obtained. The result indicated that the terrestrial radiation during dry season is generally higher than during the wet season. The month of March has the highest value of terrestrial solar radiation of 410 Wm-2 , while the least terrestrial radiation of about 381 Wm-2 occurred in August. The result also showed that terrestrial solar radiation correlates positively with water vapour and more positively with temperature at 0.57 and 0.81 coefficients respectively. The results obtained from this work provide useful knowledge that is necessary to enhance the deployment of solar energy conversion systems.
Characteristics of total solar radiation in an urban tropical environment
International Journal of the Physical Sciences, 2012
The maximum total solar radiation in Ibadan (7.38° N, 3.93° E), Nigeria occurred around 13 and 14 h local time (LT) and it varied from an average value of 584.3±10.9 Wm-2 in the wet season (April to October) to 642.5±10.8 Wm-2 in the dry season (November to March) throughout the period of 1997 to 2001. Maximum total solar radiation had two peaks, one in March/April/May with value 750.3±41 Wm-2 and the other in October/November with value 633.1±63.5 Wm-2. The minimum was in July/August with the value 404.8±54 Wm-2. Diurnal total solar radiation had a similar variation with mean day total solar radiation; the latter had its maxima and minimum values to be 564.7±19, 488±36 and 308.4±40 respectively. The annual trend of solar radiation was positive throughout the period considered, which revealed global brightening. The values of total solar radiation observed in Ibadan compared well with those obtained at Ife (7.55° N, 4.56° E) a nearby tropical station. A time lag of about 3 h between the peak of the diurnal temperature and solar radiation was observed. During the month of July or August as the case may be, there was little or no time lag between the time of maximum total solar radiation and maximum diurnal temperature. Significant intra-annual solar radiation cycles (at 0.05 significant level) of 360 to 370 days (1 per year); 180 to 200 days (2 per year), 90 to 121 days (3 per year), 45 to 70days (5 per year); 20 to 35 days (10 per year), 4 to 16 days (20 per year) were obtained for all the years (1997 to 2001).
Estimation of Global Solar Radiation on Horizontal Surface from Sunshine Hours and Other Meteorologi
2013
Multiple linear regression models were developed to estimate the monthly daily Sunshine Hours using four parameters during a period of eleven years (1997 – 2007) for Calabar, Nigeria (Latitude 5o16’07.6’’N); The parameters include Relative Humidity, Maximum and Minimum temperatures, Rainfall and Wind Speed. The result of the correlations shows that the four variable correlations with the highest value of R gives the best result when considering the error term Root Mean Square Error (RMSE). The model is given as S = -11.049-6.540RF-0.534W+0.142RH+1.127T. Where RH is Relative humidity, T is the Difference in maximum and minimum temperature, RF is Rainfall, and W is wind speed. The developed model can be used in estimating Global solar radiation for Calabar and other locations with similar climatic conditions.
Modeling Global Solar Radiation for a Tropical
2015
Monthly average daily values of clearness index and relative sunshine over a period of sixteen years, using quadratic form of the Angstrom-Prescott model have been developed to estimate global solar radiation at Onne (Lat. 4 460 N, Long. 7 100 E), a tropical location. The predictive eciencies of the models are also compared with those developed for the Nigerian environment, and those which are believed to be applicable globally. The applicability of the developed equations was tested in terms of mean percentage error (MPE), mean bias error (MBE) and root mean square error (RMSE).
Assessing the distribution of monthly mean hourly solar irradiation at an African Equatorial site
Energy Conversion and Management, 2007
Existing literature lacks information on the distribution of total solar radiation and its components for locations within the Equatorial region. Locations in this region have substantial amounts of the solar energy resource. Distributions of solar radiation can provide a convenient format for reading solar radiation data. This data is required by modelers of solar energy applications. The objective of this study is to draw and assess the distributions of the monthly means of hourly total, diffuse and direct solar irradiation at a selected site in the Equatorial region. A location at latitude 02°17 0 N, longitude 32°56 0 E and altitude 1189 m, was selected for this study. The results have shown the distribution of global solar irradiation to have the highest peak of 4.0 MJ/m 2 in December and peaks of 3.0 MJ/m 2 throughout the year. A four peaked diffuse solar irradiation distribution was evident where the highest diffuse peak of 1.8 MJ/m 2 was observed in September. The distribution of the direct solar irradiation exhibited peaks of 2.0 MJ/m 2 during the first and last quarters of the year.
Analysis of the total, annual, and inter-annual hourly mean direct solar normal irradiation
Arabian Journal of Geosciences, 2022
The elaboration of a time series demands long periods of measurements. In this paper, a methodology is described and used to systematically organize time/space series of climatic data. The methodology allows a statistical and climatic analysis more interesting. The methodology allows to categorize the series in different time partitions and in subdivisions. The methodology is described using a database of H b and fractions transmitted on the terrestrial surface (Kt b) obtained from Botucatu, SP, Brazil. Values of irradiations and fractions are presented in a systematized diurnal series through tables, which shows values of annual (H a b), inter-annual (H in b), and total (H T b) hourly mean irradiations and fractions. A seasonal study was carried out from the systematized series. An analysis of the effect of cloud cover was performed. Temporal equations were generated validated by statistical indices. Effects of clouds, water vapor, and aerosols were analyzed and discussed in seasonal variations of irradiations and fractions in the series. As a result, the Kt b values follow the same tendency of H b values. Time equations were generated and validated showing high correlations. Atmospheric phenomena repeating periodically were responsible for influencing the variations observed in H b and Kt b values through modifications on the dynamics of the atmosphere. In addition to optimizing the climate series, the methodology made possible a more efficient systematization and allowed a better reading of the associated phenomena. The methodology was efficient in what was designed and can be extended to organize and systematize other climatic variables successfully. Keywords Solar irradiance • Climate analysis • Fractions transmitted • Climate series • Clouds • Water vapor and aerosols Nomenclature H b Direct solar irradiation at normal incidence (MJm −2) H G Global solar irradiation (MJm −2) * Cícero Manoel dos Santos
Models for daily global solar radiation for the Caribbean island of Trinidad
Journal of Renewable and Sustainable Energy, 2015
In this study, calibration and validation data sets from 2001-2005 and 2006-2010 respectively were used to develop various Angström-Prescott models: a five-year model and five-year dry and wet seasonal models to calculate monthly average daily global solar radiation on a horizontal surface and twelve monthly models to estimate average daily global solar radiation on a horizontal surface. Also, ten yearly models were developed for each year in the period 2001-2010. The regression coefficients, (a, b) for the five-year, dry season and wet season models were found to be (0.21, 0.38), (0.21, 0.38) and (0.27, 0.28) respectively. For the twelve monthly models, a and b varied over the ranges 0.19 - 0.37 and 0.14 - 0.42 respectively. For the ten yearly models, a and b varied over the ranges 0.15-0.31 and 0.22-0.48 respectively. The regression coefficients of the twelve monthly models yielded a linear relationship between b and a over a one-year time scale. Similarly, the ten yearly models also yielded a linear relationship between b and a over a ten-year time scale. For all the models, measured and calculated daily global solar radiation were compared by calculating the mean bias error, mean percentage error, root mean square error, correlation coefficient, Nash-Sutcliffe efficiency and p-values based on t-statistics. Good agreement was found between the measured and calculated values and hence these models can be used in Trinidad. The single five-year model was found to be adequate in modelling the dry and wet seasons. Using the full data set, 2001-2010, the average daily global solar radiation, average total global solar radiation, average daily number of sunshine hours and average total number of sunshine hours were determined to be: 16.93± 0.73 MJm-2day-1, 2.56± 0.11 GJm-2, 8.49± 0.44 hrs day-1 and 1282± 67 hrs respectively for the dry season; 15.52± 0.81 MJm-2day-1, 3.32± 0.17 GJm-2 , 7.03± 0.38 hrs day-1 and 1504± 81 hrs respectively for the wet season; and 16.08± 0.71 MJm-2day-1, 5.87± 0.26 GJm-2, 7.65± 0.24 hrs day-1 and 2792± 83 hrs respectively for the whole year.
Procedia Engineering, 2012
Diffuse irradiance under clear sky condition is of importance for many solar energy applications. In this work, a semi-empirical model for the estimation of clear sky diffuse irradiance in a tropical environment was developed. In formulating the model, clear sky diffuse irradiance data from 3 sites in Thailand, namely Chiang Mai (18.78° N 98.98° E), Nakhon Pathom (13.82°N, 100.04° E) and Songkhla (7.2° N, 100.6° E) were collected. Aerosol optical depth from AERONET of NASA and total column ozone from OMI/AURA satellite at the positions of these sites were also collected. The model expresses diffuse irradiance as an semi-empirical function of precipitable water, total column ozone, aerosol optical depth and solar zenith angle. The empirical constants of the model were obtained by using a non-linear multi-variable regression technique. To evaluate its performance, the model was used to calculate clear sky diffuse irradiance using an independent data set. It was found that diffuse irradiance calculated from this model reasonably agreed with that obtained from measurements.
Use of rainfall data to calculate incident solar radiation in Tropical countries
2010
Determining the incident solar radiation for a given location is an important aspect of any solar related application. Though solar radiation data are available at weather stations, localized nature of solar radiation due to topographic and climatic parameters demands measured or calculated solar radiation values for a given location for accurate results. Many correlations have been developed over the past few decades yielding solar radiation values from various weather parameters such as daily sunshine duration, ambient temperature difference, relative humidity, cloud cover etc. However, most of the weather data are practically difficult and costly to record hence requiring a simplistic approach to the issue. For any geographical location the cloud cover plays a major role in controlling the incident solar radiation. In tropical countries, where the climate is highly humid, cloud cover is closely related to rainfall. Therefore, day time rainfall data can be taken as representative ...