Daily Sunshine Duration Research Articles

Association of environmental factors with the onset of status epilepticus

Objective The goal of the work described here was to investigate the influence of environmental factors on admissions of patients with status epilepticus (SE) to the intensive care unit (ICU). Methods This retrospective cohort study analyzed all admissions to a university hospital ICU because of SE. Poisson regression and likelihood ratio tests were employed to determine associations between environmental factors and the incidence of SE. Results Data on 184 patients (mean age: 57, range: 18–89) indicated a significant ( P < 0.0001 ) diurnal pattern, with admissions peaking between 4 and 5 PM and reaching a minimum in the early morning. No significant weekly, monthly, or seasonal pattern was observed. Admissions varied significantly across the lunar cycle ( P = 0.003 ) , peaking at Day 3 after new moon and being minimal 3 days before new moon. The incidence of SE increased on bright days ( P = 0.04 ) and with the duration of daily sunshine ( P = 0.03 ) . High relative humidity ( P < 0.01 ) , high temperature ( P < 0.05 ) , and dark days ( P = 0.02 ) were significantly protective factors. The incidence of SE on weekends was significantly lower in the subgroup of patients with known epilepsy ( P = 0.004 ) , and the risk of nonconvulsive SE was significantly higher in summer ( P = 0.04 ) . Conclusions Admissions of patients with SE to the ICU are significantly associated with several environmental protective and precipitating factors, such as diurnal, weekly, and lunar cycles and weather variables.

An unexpected pattern of distinct weekly periodicities in climatological variables in Germany

Statistical analyses of data from 12 German meteorological stations meeting WMO standards in the period 1991–2005 are presented. These stations represent different local climate conditions in terms of both meteorology and pollution situation. For the average over data of all stations, we identified significant weekly periodicities in many variables such as temperature, daily temperature range, sunshine duration, cloud amount, precipitation, and precipitation frequency. Not only data of stations situated in congested urban areas, but also data of remote stations as e.g. on Mount Zugspitze 2960 m above sea level in the Alps showed significant in‐phase weekly cycles. These weekly periodicities cannot be explained completely by local pollution effects or local heat emissions. We tend towards the hypothesis that the anthropogenic weekly emission cycle and the subsequent aerosol cycle interact with the atmospheric dynamics on a larger scale which leads to a forcing of a naturally existing 7‐day period among the spectrum of atmospheric periods.

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.

Global Solar Radiation Potential, Part 1: Model Development

Solar engineers, architects, agriculturists, and hydrologists dealing with many applications of solar energy require a reasonably accurate knowledge about the availability of solar resources at any place. For this purpose, in the past, several empirical correlations have been developed in order to predict the solar radiation around the world. The present study, consisting of two parts, analyzes global solar radiation over the Central Anatolia Region (CAR) of Turkey along with its twelve provinces. Part 1 of this study includes the solar radiation models developed, while their statistical analysis is presented in Part 2. In the analysis, the data of the monthly average daily global solar radiation and sunshine duration measured by the Turkish State Meteorological Service in the period from January 1990 to December 1996 are used. Empirical models to estimate the monthly global solar radiation on a horizontal surface for each province are developed. The results obtained have indicated that the models developed here predict solar radiation reasonably well for future projections.

Proxy-based reconstruction of erythemal UV doses over Estonia for 1955–2004

Abstract. A proxy-based reconstruction of the erythemally-weighted UV doses for 1955-2004 has been performed for the Tartu-Tõravere Meteorological Station (58°16' N, 26°28' E, 70 m a.s.l.) site. The pyrheliometer-measured daily sum of direct irradiance on partly cloudy and clear days, and the pyranometer-measured daily sum of global irradiance on overcast days were used as the cloudiness influence related proxies. The TOMS ozone data have been used for detecting the daily deviations from the climatic value (averaged annual cycle). In 1998–2004, the biases between the measured and reconstructed daily doses in 55.5% of the cases were within ±10% and in 83.5% of the cases within ±20%, on average. In the summer half-year these amounts were 62% and 88%, respectively. In most years the results for longer intervals did not differ significantly, if no correction was made for the daily deviations of total ozone from its climatic value. The annual and summer half-yearly erythemal doses (contributing, on average, 89% of the annual value) agreed within ±2%, except for the years after major volcanic eruptions and one extremely fine weather year (2002). Using the daily relative sunshine duration as a proxy without detailed correction for atmospheric turbidity results in biases of 2–4% in the summer half-yearly dose in the years after major volcanic eruptions and a few other years of high atmospheric turbidity. The year-to-year variations of the summer half-yearly erythemal dose in 1955–2004 were found to be within 92–111% relative to their average value. Exclusion of eight extreme years reduces this range for the remaining to 95–105.5%. Due to the quasi-periodic alternation of wet and dry periods, the interval of cloudy summers 1976–1993 regularly manifests summer half-yearly erythemal dose values lower than the 1955–2004 average. Since 1996/1997 midwinters have been darker than on average.

Relation between Sudden Infant Death Syndrome and Weather Factors in Japan

We examined the relation between sudden infant death syndrome (SIDS) mortality and meteorological factors, specifically ambient temperature, sunshine duration, and atmospheric pressure, in Japan. Using both the data of daily SIDS mortality and meteorological factors for the years 1972 through 1995, we calculated the Mantel-Haenszel rate ratios of SIDS, controlling for selected covariates. We found an inverse association of SIDS mortality rate with daily mean temperature and daily mean sunshine duration. In conclusion, although this was an exploratory study, further investigation of the relation between SIDS and meteorological factors appears to be warranted.

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.

Generation of a typical meteorological year using sunshine duration data

In this paper, we discuss the possibility of using the daily sunshine duration or the daily sunshine duration over day-length data instead of daily global solar radiation in order to develop a Typical Meteorological Year, TMY2, for localities with abundant data of daily sunshine duration. The analysis is done using the latest methodology proposed in the literature. The number of coinciding months is about 40% when daily sunshine duration or the daily sunshine duration over day-length data is used instead of daily global solar radiation as one of the parameters in obtaining TMY2. Such a relatively low figure is probably due to the unreliable solar radiation data recorded by Robitzch-type actinographs used in the present work.

Statistical analysis of solar measurements in Algeria using beta distributions

A method of smoothing solar data by beta probability distributions is implemented in this paper. In the first step, this method has been used to process daily sunshine duration data recorded at thirty-three meteorological stations in Algeria for eleven year periods or more. In the second step, it has been applied to hourly global solar irradiation flux measured in Algiers during the 1987/89 period. For each location and each month of the year, beta probability density functions fitting the monthly frequency distributions of the daily sunshine duration measurements are obtained. Both the parameters characterising the resulting beta distributions are then mapped, enabling us to build the frequency distributions of sunshine duration for every site in Algeria. In the case of solar radiation for Algiers, the recorded data have been processed following two different ways. The first one consists in sorting the hourly global solar irradiation data into eight typical classes of the daily clearness index. The second one is based on the repartition of these data per month. The results of the first classification show that for each class of daily clearness index, the hourly data under consideration are modelled by only one beta distribution. When using the second classification, linear combinations of two beta distributions are found to fit the monthly frequency distributions of the hourly solar radiation data.

How substantial are ultraviolet-B supplementation inaccuracies in experimental square-wave delivery systems?

Square-wave (SQW) ultraviolet-B (UV-B: 280–315 nm) radiation supplementation systems continue to be used in outdoor experimental locations due to the economically restrictive installation and maintenance costs, and technical expertise required to effectively operate more advanced modulated (MOD) delivery systems. However, continued yet contentious criticisms of SQW delivery systems risk creating prejudices as to the validity of plant responses measured in these with potentially negative repercussions on future UV-B experimentation. Consequently, we quantified the magnitude of UV-B supplementation inaccuracies in our typical outdoor step-wise SQW delivery system using 7-year records of computer-modeled and instrument-measured solar UV-B irradiances and synchronous measurements of total solar (300–3000 nm) radiation and daily sunshine duration. Both broad- and narrow-band instrument measurements confirmed that our step-wise SQW delivery system rendered larger total daily supplemental UV-B exposures (time-integrated UV-B irradiances) than a MOD delivery system on only substantially overcast days (25% or less daily sunshine duration). These larger supplemental UV-B exposures were augmented with increased magnitude of the added artificial UV-B supplement. However, their ranges did not exceed those in a MOD delivery system by more than 10% for added UV-B supplements of realistic magnitude (30% or less above background), except on virtually completely overcast days (5% or less daily sunshine duration). Also, our step-wise SQW delivery system rendered higher photon flux ratios of UV-B/total solar radiation than a MOD delivery system on only substantially overcast days, the ranges of which were also augmented with increased magnitude of the added artificial UV-B supplement. However, these features were restricted to high solar angles, since with reduced solar angle these higher photon flux ratios also included progressively less overcast days. Nevertheless, ranges of photon flux ratio increases were well below reported thresholds inhibiting to plant growth at all solar angles for the added artificial UV-B supplements of realistic magnitude, except on virtually completely overcast days. Results point to an under-estimation of clear-sky UV-B irradiance by the computer-encoded semi-empirical model commonly utilized to predict background and supplemental UV-B irradiances for SQW delivery systems. They confirm the superiority of MOD delivery systems in providing more realistic conditions of UV-B increases but likewise demonstrate little justification on balance for branding results derived from all field-based SQW delivery systems as exaggerated where sensible irradiation protocols and realistic UV-B supplements are applied.

Characteristics of the spatial distribution and yearly variation of aerosol optical depth over China in last 30 years

The yearly and monthly mean aerosol optical depth (AOD) at 0.75 μm were retrieved using a new method improved from Qiu's algorithm from the data of daily direct solar radiation, sunshine duration, surface pressure, and vapor pressure at 46 A class solar radiation stations over China from 1961 to 1990, as well as the Total Ozone Mapping Spectrometer (TOMS) derived ozone data from 1979 to 1990. Then the analysis on the distribution of yearly mean AOD and its variation over China in the last 30 years were made from the derived AOD data. It was found that the yearly mean AOD has pattern related to the geographical features with the maximums over basins. One of the maximum centers at Sichuan Basin, southwest of China, and the other is in the south Xinjiang Basin, northwest of China. In most areas of China the maximum of AOD occurs in spring, but the season of reaching the minimum varies with regions. The monthly mean AOD distributions are similar to the annual mean pattern, having strong ”basin“ effect, but the month‐to‐month differences are still obvious. In addition, AOD increased dramatically over China mainland from 1961 to 1990, particularly in the middle and lower reaches area of the Yangzi River and the east part of southwest China. In north China, Shandong peninsula, the east part of Qinghai Province, and coastal areas of Guangdong Province, a significant increasing trend of AOD is shown, while in most parts of northwest China and northeast China, the increase trend is less significant. However, in the western part of Xinjiang autonomous region and part of Yunnan Province, only a decreasing tendency is shown. Of the total 46 stations, the yearly averaged AOD variation curve can be briefly divided into two periods. One period is from 1961 to 1975, when AOD is smaller than the 30 year mean value; the other period is from 1976 to 1990, when AOD is higher than the mean value. Except for the peak in 1982 and 1983, which may be attributed to the eruptions of El Chichon, the curve shows a significant increasing trend from 1961 to 1990. The monthly averaged AODs of the total 46 stations also obviously increased.

Reconstruction of daily global radiation for past years for use in agricultural models

A method of estimation of daily global radiation based on standard meteorological observations is presented. Global radiation may be calculated with one-dimensional regression equations, either with or without conditions (constraints). Daily duration of sunshine, mean cloudiness or temperature range can be used as predictors in either case. In general to select the proper equations with conditions, humidity was chosen as a master variable. Formulation and validation of the regression equations is done on the basis of data from 42 German radiation stations. The annual root mean square error (RMSE) between values calculated for individual days with the estimation method developed, and measured data, was about 1.6 MJ m−2 day−1 using sunshine duration as the predictor and 3.0 MJ m−2 day−1 using both temperature range and relative humidity as predictors.This estimation method has been used for reconstruction of daily global radiation for about 400 German meteorological stations for years, and for stations without observations of global radiation. Reconstructed data will be used in agricultural and hydrological models.

Analysis of solar radiation over Egypt

The database utilized in this analysis consisted of daily sunshine duration and hourly global and diffuse radiation on a horizontal surface (for Matruh Cairo, and Aswan), and normal incidence beam radiation (for Cairo and Aswan only). Monthly-average hourly and daily values are reported for each of these three types of measured radiation, together with the calculated monthly-average daily values for the components of global radiation, horizontal beam and diffuse radiation. The monthly-average hourly and daily clearsky index values have also been calculated and analyzed. Monthly-average daily frequency distributions of the clearsky index values are reported for each month. The annual-average daily global irradiation values are 19.4, 18.67, and 21.78 MJ/m2 and for diffuse irradiation they are 6.34, 6.65 and 6.23 MJ/m2 for Matruh, Cairo and Aswan, respectively. For the normal incidence beam irradiation the annual-average daily values are 16.94 and 24.46 MJ/m2 for Cairo and Aswan, respectively. The annual-average daily fractions of the direct component of horizontal global radiation are 0.70, 0.61 and 0.72 for the three stations, respectively. The annual-average daily values for the clearsky index are 0.585, 0.566, and 0.648, and the average frequency of clear days annually are 67.3, 42.3 and 77.6% respectively. The annual variations and trend analysis were analyzed for daily global, direct, and diffuse radiation on a horizontal surface, daily sunshine duration, and for the daily ratios G/G0, and D/G for the stations Matruh, Cairo and Aswan. The distribution of these components of radiation and their ratios over the study stations in Egypt is also discussed. The results show that Egypt is characterized by relatively high average-daily radiation rates, both global and direct, and a relatively high frequency of clear days. Cairo, due to its urbanization and high pollution, has relatively low average-daily radiation rates, particularly in direct radiation, and the frequency of clear days.

Application of genetic algorithm for determination of Angström equation coefficients

Genetic algorithm analysis of the monthly average daily irradiation and sunshine duration data of four Turkish locations has been performed for determining the Angström equation coefficients. This analysis provides the parameter estimations as new data are recorded and consequently yields the time variability of the parameters. Application of the genetic algorithm procedure is presented in this paper for determining the coefficients and their statistical distributions as well as the relationships between them. Good correlation is obtained ( r≥0.93) in all the cases, showing the validity of the Angström equation for Turkish locations. Besides, the analysis presents a new way of estimating the Angström equation parameters.

Characteristics of atmospheric aerosol optical depth variation over China in recent 30 years

This note retrieves the annual and monthly mean 0.75 μm aerosol optical depth (AOD) by using the daily direct solar radiation and sunshine duration data of 47 solar stations from 1961 to 1990. The characteristic of AOD variation over China in recent 30 years was analyzed. The results indicate that AOD increased obviously over China from 1961 to 1990. AOD increased most rapidly over the east part of Southwest China, the middle-and-lower reaches of the Yangtze River and the Tibetan Plateau. The increasing trend of AOD is also relatively distinct in North China, the Shandong Peninsula, east part of Qinghai Province, and coastal areas of Guangdong Province. However, in most parts of Northwest China and Northeast China, the increase of AOD is less significant, while in the west part of the Xinjiang Uygur Autonomous Region and some parts of Yunnan Province, AOD shows decreasing tendency. Generally, AOD reaches its maximum in spring and the minimum appears in summer. As to the linear trend, the maximum occurs in spring but the minimum in winter. Among the 47 stations selected in this note, the largest three stations of AOD are Chengdu, Chongqing and Nanchong, respectively, which all lie in the Sichuan Basin, and the smallest value of AOD occurs in Jinghong located in Yunnan Province.

Uses of sunshine duration to estimate the global solar radiation over eight meteorological stations in Egypt

The climatological Ångstrom regression coefficients have been determined by three methods and used to predict the global solar radiation over eight meteorological stations. Each of the three methods depends on the correlation between two ratios. The first ratio is between the long period of monthly average sunshine duration s̄ and the corresponding maximum of daily sunshine duration (day length) N, and the second ratio is between the measured monthly average daily global solar radiation H̄ and the corresponding monthly mean daily extraterrestrial solar radiation on the horizontal surface H̄0. A comparison between the measured data and the estimated values has been done. The t-statistics is used as a statistical indicator to choose the coefficients of the best method that gives a percentage of error less than 10%.

Ozone indices based on simple meteorological parameters: potentials and limitations of regression and neural network models

This study tested the usefulness of extremely simple meteorological models for the prediction of ozone indices. The models were developed with the input parameters of daily maximum temperature and sunshine duration and are based on a data collection period of three years. For a rural environment in eastern Austria, the meteorological and ozone data of three summer periods have been used to develop functions to describe three ozone exposure indices (daily maximum, 7 h mean 9.00–16.00 h, accumulated ozone dose AOT40). Data sets for other years or stations not included in the development of the models were used as test data to validate the performance of the models. Generally, optimized regression models performed better than simplest linear models, especially in the case of AOT40. For the description of the summer period from May to September, the mean absolute daily differences between observed and calculated indices were 8±6 ppb for the maximum half hour mean value, 6±5 ppb for the 7 h mean and 41±40 ppb h for the AOT40. When the parameters were further optimized to describe individual months separately, the mean absolute residuals decreased by ⩽10%. Neural network models did not always perform better than the regression models. This is attributed to the low number of inputs in this comparison and to the simple architecture of these models (2-2-1). Further factorial analyses of those days when the residuals were higher than the mean plus one standard deviation should reveal possible reasons why the models did not perform well on certain days. It was observed that overestimations by the models mainly occurred on days with partly overcast, hazy or very windy conditions. Underestimations more frequently occurred on weekdays than on weekends. It is suggested that the application of this kind of meteorological model will be more successful in topographically homogeneous regions and in rural environments with relatively constant rates of emission and long-range transport of ozone precursors. Under conditions too demanding for advanced physico/chemical models, the presented models may offer useful alternatives to derive ecologically relevant ozone indices directly from meteorological parameters.

A comparison of methods to estimate daily global solar irradiation from other climatic variables on the Canadian prairies

Historic estimates of daily global solar irradiation are often required for climatic impact studies. Regression equations with daily global solar irradiation, H, as the dependent variable and other climatic variables as the independent variables provide a practical way to estimate H at locations where it is not measured. They may also have potential to estimate H before 1953, the year of the first routine H measurements in Canada. This study compares several regression equations for calculating H on the Canadian prairies. Simple linear regression with daily bright sunshine duration as the dependent variable accounted for 90% of the variation of H in summer and 75% of the variation of H in winter. Linear regression with the daily air temperature range as the dependent variable accounted for 45% of the variation of H in summer and only 6% of the variation of H in winter. Linear regression with precipitation status (wet or dry) as the dependent variable accounted for only 35% of the summer-time variation in H, but stratifying other regression analyses into wet and dry days reduced their root-mean-squared errors. For periods with sufficiently dense bright sunshine observations (i.e. after 1960), however, H was more accurately estimated from spatially interpolated bright sunshine duration than from locally observed air temperature range or precipitation status. The daily air temperature range and precipitation status may have utility for estimating H for periods before 1953, when they are the only widely available climatic data on the Canadian prairies. Between 1953 and 1989, a period of large climatic variation, the regression coefficients did not vary significantly between contrasting years with cool-wet, intermediate and warm-dry summers. They should apply equally well earlier in the century.

Topography and Radiation Exchange of a Mountainous Watershed

Abstract This report deals with the radiation exchange of a complex terrain. A relatively simple network for computing topographic parameters global radiation, and net radiation of a mountainous terrain was developed and applied to a forested Appalachian watershed encompassing 39.2 ha (Watershed 4, U.S. Forest Service at Parsons, West Virginia, 39°20′N, 79°40′W). Monthly sums of global radiation and net radiation of the watershed were computed for the period of 40 years (1951–90). Topographic map of the watershed in scale 1:2500 and data on global radiation at a horizontal surface in the study area (1955–77), monthly average air temperature, moisture and cloudiness were used in the analysis. The topographic analysis showed that for the 432 terrain segments, covering the whole area of the watershed, the average daily possible sunshine duration varied from 9.3 to 11.9 h, with an average of 11.0 h, which is about 92% of the possible sunshine duration at a horizontal surface at the study area. The sky view fa...