Mean Daily Sunshine Research Articles

Comparative Study of Solar Radiation Models for the Estimation of Solar Radiation Using Short-Term Meteorological Data in Lawra, Ghana

Monthly average daily global solar radiation data are essential for the design and study of solar energy systems. The performance and accuracy of eleven models for the estimation of monthly average global solar radiation were compared in this study. Nineteen months (Nov 2020 – May 2022) ground measurement data consisting of monthly mean daily sunshine duration, relative humidity, minimum and maximum temperatures, and global solar radiation collected from the Lawra Solar Plant were used. The models were compared using statistical indices. According to the indices, most of the models were in reasonably good agreement with the measured data. Two model equations, however, were found to have the highest accuracy and can thus be used to estimate monthly average global solar radiation in Lawra and other places with similar climatic conditions where radiation data is unavailable.

Influence of precipitations and sunshine hours on yield of paddy field grown wheat (Triticum aestivum L.) in Northern Kyushu, Japan

ABSTRACTRelationships between wheat (Triticum æstivum L.) yield components and growing season weather conditions (e.g. temperature, precipitation, and sunshine duration) were investigated for a rice-wheat rotation paddy system situated in Northern Kyushu, Japan over a 17-year period (2000–2016). A 1.0 mm increase in precipitation from 21 to 32 days after sowing decreased wheat yield by about 27 kg ha−1 at early seedling stage with one to two leaves (Zadoks (Z) growth stage Z1.1–1.2). Number of tillers and spikes showed significant negative correlations to the amount of precipitation during the period. An hour increase in mean daily sunshine hours from 94 to 111 days after sowing resulted in an 328 kg ha−1 rise in grain yield at stem elongation stage with the first and second node detection (Z3.1–3.2). The grain number per square meter also showed strong positive correlations to sunshine hours during the same period. However, this positive effect of sunshine was negated when precipitation exceeded about 30 mm during the early seedling stage. Consequently, precipitations at early seedling stage and sunshine hours at stem elongation stage mostly determined wheat yield in Northern Kyushu paddy field. Increasing precipitations during the early seedling stage highlights the pressing need for effective paddy field drainage management from wheat sowing through harvest.Abbreviations: CP: Chikushi Plains; FARC: Fukuoka prefectural Agriculture and Forestry Research Center; SARC: Saga prefectural Agricultural Research Center; DAS: days after sowing

Seasonal variation of BMI at admission in German adolescents with anorexia nervosa.

ObjectiveRecent preliminary studies indicated a seasonal association of BMI at admission to inpatient treatment for anorexia nervosa (AN), indicating lower BMI in the cold season for restrictive AN. An impaired thermoregulation was proposed as the causal factor, based on findings in animal models of AN. However, findings regarding seasonality of BMI and physical activity levels in the general population indicate lower BMI and higher physical activity in summer than in winter. Therefore, we aimed to thoroughly replicate the findings regarding seasonality of BMI at admission in patients with AN in this study.MethodAN subtype, age- and gender-standardized BMI scores (BMI-SDS) at admission, mean daily sunshine duration and ambient temperature at the residency of 304 adolescent inpatients with AN of the multi-center German AN registry were analyzed.ResultsA main effect of DSM-5 AN subtype was found (F(2,298) = 6.630, p = .002), indicating differences in BMI-SDS at admission between restrictive, binge/purge and subclinical AN. No main effect of season on BMI-SDS at admission was found (F(1,298) = 4.723, p = .025), but an interaction effect of DSM-5 subtype and season was obtained (F(2,298) = 6.625, p = .001). Post-hoc group analyses revealed a lower BMI-SDS in the warm season for restrictive AN with a non-significant small effect size (t(203.16) = 2.140, p = .033; Hedges′g = 0.28). Small correlations of mean ambient temperature (r = −.16) and daily sunshine duration (r = −.22) with BMI-SDS in restrictive AN were found. However, the data were widely scattered.ConclusionsOur findings are contrary to previous studies and question the thermoregulatory hypothesis, indicating that seasonality in AN is more complex and might be subject to other biological or psychological factors, for example physical activity or body dissatisfaction. Our results indicate only a small clinical relevance of seasonal associations of BMI-SDS merely at admission. Longitudinal studies investigating within-subject seasonal changes might be more promising to assess seasonality in AN and of higher clinical relevance.

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

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,R2values 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.

Estimation of Global Solar Radiation Using Artificial Neural Networks in Abu Dhabi City, United Arab Emirates

The geographical location (Latitude: 24 deg 28′ N and Longitude: 54 deg 22′ E) of Abu Dhabi city in the United Arab Emirates (UAE) favors the development and utilization of solar energy. This paper presents an artificial neural network (ANN) approach for the estimation of monthly mean global solar radiation (GSR) on a horizontal surface in Abu Dhabi. The ANN models are presented and implemented on a 16-yr measured meteorological data set for Abu Dhabi comprising the maximum daily temperature, mean daily wind speed, mean daily sunshine hours, and mean daily relative humidity between 1993 and 2008. The meteorological data between 1993 and 2003 are used for training the ANN and data between 2004 and 2008 are used for testing the estimated values. Multilayer perceptron (MLP) and radial basis function (RBF) are used as ANN learning algorithms. The results attest to the capability of ANN techniques and their ability to produce accurate estimation models.

Spatial estimation of monthly mean daily sunshine hours and solar radiation across mainland China

Spatial databases of climate data in digital format are required for many agricultural and eco-environmental systems. This study compared 7 approaches for interpolating monthly mean daily sunshine hours and solar radiation over mainland China. The approaches included simple geostatistical approaches to incorporation of Universal Transverse Mercator (UTM) coordinates and elevation. Performance indicators (root mean square error, mean absolute percentage error, and modeling efficiency) showed thin plate smoothing spline with UTM coordinates and elevation (TPS) outperformed other models. Besides, multiple linear regression equations for estimating solar radiation using geographical parameters (UTM coordinates and elevation) and sunshine hours predicted by TPS performed well for the study site. Spatial datasets of annual and monthly mean daily sunshine hours and solar radiation with 1 km resolution were then obtained by the best performance models. Spatial and temporal variability was clearly observed in sunshine hours and solar radiation. For both annual and seasonal scenarios, higher values of sunshine hours and solar radiation existed in north and Tibetan Plateau and lower values were observed in the middle and southern China. Lower values of annual solar radiation were also found in northeastern China. Sunshine hours and solar radiation varied with time, especially from spring to summer and from summer to autumn. The accurate gridded datasets are expected to provide significant information on more efficient use of natural resources.

A model for the estimation of the daily global sunshine duration from meteorological geostationary satellite data

In this research a simple model was proposed for the estimation of daily global sunshine duration and constructing spatially continous sunshine duration map from meteorological geostationary satellite sensor data. First cloud cover index and then daily mean cloud cover index value for each pixel were computed using a time‐series of Meteosat C3D visible type images. The statistical relationship between daily mean cloud cover index and measured bright sunshine duration values was tested and found to be linear. Using regression parameters daily sunshine duration of each pixel was calculated and then daily sunshine duration and monthly mean daily sunshine duration maps were constructed. It was shown that, by using the suggested model it is possible to calculate daily sunshine duration values over a large area where the sunshine duration data are not available and construct spatially continious long‐term sunshine duration maps.

The Effects of Seasonal Changes on Temporomandibular Disorders

The aim of our study was the evaluation of seasonal influences on development and evolution of temporomandibular disorders (TMD). In a retrospective study based on data from 1997 and 1998, we analyzed the monthly number of patients at the Department of Prosthodontics. The total number of first time examinations during these two years was 11,747. Nine hundred and sixty-one (961) patients showed symptoms frequently found in TMD. These patients were submitted to a special TMD diagnosis based on the criteria of a validated craniomandibular index questionnaire. In 568 patients (group A1), a TMD was confirmed, in the other 393 patients (group A2), the disorder could not be confirmed. Dividing up the numbers of patients into summer and winter half years, we found statistically significant relationships between patient numbers and season in TMD patients (A1) as well as in all patients (group B). The distribution of the monthly numbers of TMD patients with its maximum in winter, however, was characteristically different from that of all patients with the maximum in summer. The number of TMD patients per month was significantly correlated to the mean daily sunshine duration per month. Parallels could be drawn to seasonal variations of symptoms in Seasonal Affective Disorders (SAD). As the mechanisms which influence the emergence of psychologically impacted disease in TMD patients might be comparable to SAD, we propose that a similar therapy may be applied.

Generation of hourly solar radiation for inclined surfaces using monthly mean sunshine duration in Algeria

Hourly global solar radiation flux incident on an inclined surface is evaluated in any site of Algeria using monthly mean daily sunshine duration measurements. The methodology used consists of successive transformations of solar data, respectively, based on the exponential probability distribution of daily sunshine duration, Ångström equation, beta probability distribution of hourly global solar radiation flux, polynomial correlations of hourly direct and diffuse radiation with global solar radiation and the Klücher model. Monthly mean values of daily sunshine duration data recorded in 54 meteorological stations of Algeria and hourly solar radiation data collected in Algiers, Bechar and Tamanrasset are available for this study. Knowing the monthly mean daily sunshine duration measurements, the hourly global solar radiation data are then obtained on a tilted surface for the locations of Algiers, Tamanrasset and Bechar. The monthly mean hourly global solar radiation data estimated for Algiers are in reasonably good agreement with the experimental ones. Associated with the principal component analysis, the above method has been extended to all the other meteorological stations, and monthly mean values of hourly global solar radiation flux incident on an inclined surface have been simulated for every site of Algeria. This yields an important database useful for solar energy applications.

Flowering, fruiting and seedling of Halophila beccarii Aschers. (Hydrocharitaceae) from Malaysia

Observation on flowering and fruiting of Halophila beccarii Aschers. were made at Kemaman, Terengganu, Peninsular Malaysia from February 1996 through February 1997. The number of male and female flowers, fruits, seeds and seedlings was counted at monthly interval. Flowering and fruiting were detected almost continuously throughout the year except June when the first appearance of seedlings were observed. Flowering peaks occurred in February, September and January which coincided with dry season. Male flowers abundance in the respective months were 60.0 ± 15.3 m −2, 40.0 ± 13.1 m −2 and 50.0 ± 14.1 m −2 while female flowers abundance were 25.5 ± 8.7 m −2, 28.0 ± 8.6 m −2 and 52.0 ± 15.2 m −2. Fruiting was detected in synchrony with flowering but was not significantly related to the number of flowers. Fruit abundance were low in most months with higher density in February 1996 (21.8 ± 7.2 m −2), March 1996 (22.0 ± 8.2 m −2), April 1996 (10.0 ± 6.6 m −2), December 1996 (16.0 ± 6.0 m −2), January 1997 (12.0 ± 5.5 m −2) and February 1997 (18.8 ± 7.1 m −2). The calculated mean fruit density per square meter (from February 1996 to February 1997) was 11.0 ± 1.5 m −2. There are 1–4 seeds, with a mean of 1.7 seeds per fruit. H. beccarii from Kemaman is a monoecious perennial angiosperm which produces an estimated seed reserve of 156 m −2 year −1. Low abundance of seeds and seedlings were observed in the sampling plot. Seeds appear to be carried by tides from the sampling plot to the upper inter-tidal area among the mangrove, where they germinated into seedlings. The morphology and initial development of seedlings are similar as in Halophila spinulosa (R. Br.) Aschers., H. engelmannii Aschers., H. decipiens Ostenfeld, H. ovalis (R. Br.) Hook. f. and H. tricostata Greenway. Flowering and fruiting was not correlated with total monthly rainfall, mean daily sunshine hours, mean daily global radiation, pH, salinity and water temperature but negatively correlated with mean air temperature, suggesting that fluctuations in male and female flowers and fruit densities was influenced by changes in temperature.

Estimates of irradiance over Zimbabwe

There has developed one alternative to the actual measurement of the irradiance incident on a horizonal surface in a given location. This is its estimation from commonly-observed and/or easily obtained meteorological and geographical parameters. This technique is of particular interest to less developed countries where there is a dearth of solar radiation measuring instruments but with a number of stations with long records of surface and upper surface climatological data. Some of the parameters that have been used in this approach are sunshine hours duration, declination angle of the sun and latitude of the location, sunshine hours duration and relative humidity, sunshine hours duration, rain days and a latitude/location factor, sunshine hours, maximum air temperature, relative humidity and a latitude/location factor, and cloud cover and sunshine hours. This note is a report of the results of a regression analysis of measured values of monthly mean daily irradiance, Q, with monthly mean daily sunshine hours duration, n and monthly mean daily relative humidity, R. Further, the Angstrom-like relation between the monthly mean daily irradiance at the top of the atmosphere, Q /SUB a/ , the monthly mean day-length, N, and Q and n is also determined. The data used in these analyses are for Harare, Zimbabwe (lat. 17/sup 0/ 50'S; alt. 1471 m).