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1.
A previous study (Suckling and Hay, 1976a) described a method for calculating hourly values of the direct and diffuse solar radiation for cloudless sky conditions. This paper presents an extension which incorporates the effects of clouds through the use of hourly values of cloud amount and type for up to four layers and hourly bright sunshine totals. The latter data provide a more accurate measure of the length of time the direct radiation of the sun is not attenuated by cloud. On an average, the cloud layer‐sunshine (CLS) model estimated daily total solar radiation at five Canadian locations to within ±15 per cent of the measured values. This was an improvement over an earlier model (Davies et al., 1975) based on cloud data alone, but the relative advantage, as well as the overall errors themselves, were diminished as the averaging period was increased to five and ten days. The CLS model has the additional advantage of calculating the separate direct and diffuse components of the total solar radiation. 相似文献
2.
I. Foyo-Moreno I. Alados F. J. Olmo J. Vida L. Alados-Arboledas 《Theoretical and Applied Climatology》2001,68(1-2):41-50
Summary Knowledge of ultraviolet radiation is necessary in different applications, in the absence of measurements, this radiometric
flux must be estimated from available parameters. To compute this flux under all sky conditions one must consider the influence
of clouds. Clouds are the largest modulators of the solar radiative flux reaching the Earth’s surface. The amount and type
of cloud cover prevailing at a given time and location largely determines the amount and type of solar radiation received
at the Earth’s surface. This cloud radiative effect is different for the different solar spectral bands. In this work, we
analyse the cloud radiative effect over ultraviolet radiation (290–385 nm). This could be done by defining a cloud modification
Factor. We have developed such cloud modification Factor considering two different types of clouds. The efficiency of the
cloud radiative effect scheme has been tested in combination with a cloudless sky empirical model using independent data sets.
The performance of the model has been tested in relation to its predictive capability of global ultraviolet radiation. For
this purpose, data recorded at two radiometric stations are used. The first one is located at the University of Almería, a
seashore location (36.83° N, 2.41° W, 20 m a.m.s.l.), while the second one is located at Granada (37.18° N, 3.58° W, 660 m
a.m.s.l.), an inland location. The database includes hourly values of the relevant variables that cover the years 1993–94
in Almería and 1994–95 in Granada. Cloud cover information provided by the Spanish Meteorological Service has been include
to compute the clouds radiative effect. After our study, it appears that the combination of an appropriate cloudless sky model
with the cloud modification Factor scheme provides estimates of ultraviolet radiation with mean bias deviation of about 5%
that is close to experimental errors. Comparisons with similar formulations of the cloud radiative effect over the whole solar
spectrum provides evidence for the spectral dependency of the cloud radiative effect.
Received November 15, 1999 Revised September 11, 2000 相似文献
3.
H. Tooming 《Theoretical and Applied Climatology》2002,72(3-4):165-172
Summary ?The dependence of global and diffuse radiation on surface albedo due to multiple reflection of radiation between the surface
and the atmosphere (base of clouds) is found on the basis of data obtained at the Tartu–T?ravere Actinometric Station over
the period 1955–2000. It is found that the monthly totals of global radiation increase by up to 1.38–1.88 times, particularly
in the winter half-year between November and March, when snow cover albedo may be high. A semi-empirical formula is derived
for calculating with sufficient accuracy the monthly totals of global radiation, considering the amount of cloudiness and
the surface albedo. In the time series of the monthly total by global radiation a downward trend occurs in winter months.
A decrease in global radiation by up to 20% in the past 46 years can be explained primarily by a relatively high negative
trend in the snow cover duration and surface albedo (up to − 0.24). As a result, days are growing darker, a new phenomenon
associated with climate change, which undoubtedly affects human mood to some extent.
Received November 8, 2001; revised January 24, 2002; accepted February 2, 2002 相似文献
4.
锡林浩特市太阳辐射变化及相关气象要素分析 总被引：1，自引：0，他引：1
利用1990—2010年锡林浩特气象站太阳总辐射、日照时数、日照百分率、降水量、气温以及总云量的观测资料,运用5a滑动平均及最小二乘原理等方法,分析了锡林浩特市1990—2010年来的总辐射变化规律,并分析了气温、降水、日照、云量等的变化以及与太阳总辐射的相关关系。研究结果表明,锡林浩特市太阳总辐射呈现波动增加的趋势,但四季太阳辐射量在近21a的年际波动略有不同。相关要素分析表明,太阳总辐射与日照时数和夏季、秋季气温有很显著的正相关关系,与降水量和春季、夏季的总云量呈负相关关系。 相似文献
5.
Summary Two UV-Biometer 501A instruments were used to estimate global erythemal irradiance at two locations in southwest Sweden;
the Earth Sciences Centre, University of G?teborg (57.69° N; 11.92° E) and the island of Nordkoster, 200 km to the north (58.83° N;
10.72° E).
A semi-empirical radiative transfer model was used to calculate the global erythemally effective irradiance under clear skies.
A ratio of the hourly measured to clear-sky modelled irradiance was then derived for zenith angles 35–70°. Subsequent comparisons
were then made with routine measurements of sunshine duration at G?teborg and sunshine duration, cloud cover, type and height
at Nordkoster.
Cloud transmission of UV-B irradiance decreases with increasing solar zenith angle, with cloud attenuation being 8% stronger
at Nordkoster Island for zenith angles >>;60°. Transmission also decreases with increasing cloud cover such that overcast
cloud conditions reduce transmissions by an average of 75%. In addition, cloud type affects the amount of ground incident
irradiant flux. Fractus cloud afforded the least UV-B transmission (0.16), while cirrus filaments afforded the most (0.95).
The spatial and temporal distribution of clouds appears tobe non-random. Under conditions of 1 to 3 octas, sky cover, clouds
appear to be concentrated in line with the sensor and Sun on more occasions than that expected given a random cloud distribution.
The same cloud cover condition also resulted in many instances of ground incident irradiance above clear-sky values. The presence
of cumuliform clouds appears to increase the likelihood of the latter phenomena.
Received January 4, 1998 相似文献
6.
Summary Thin plate smoothing splines incorporating topographic dependence were used to interpolate daily global solar radiation in
the Bavarian forest ecosystem monitoring network, with the degree of data smoothing determined by minimizing the generalized
cross validation. A simple cross validation method was used to discuss the spatial distribution of mean relative errors at
18 forest climate stations. The results show that, from this network 14%–30% mean relative errors can be expected for most
of these forest climate stations in summer, and 20%–30% mean relative errors can be found at a few of forest climate stations
in winter. Time-averaging can reduce these interpolation errors. In this network a mean relative error of 10% can be expected
for weekly and biweekly mean solar radiation at most of forest climate stations in summer. Large errors are related to low
radiation amount under heavy cloud cover. Mean relative errors increase as daily global solar radiation decreases.
Received April 20, 1999 Revised January 20, 2000 相似文献
7.
Solar Radiation Climatology of Alaska 总被引：1，自引：1，他引：0
Summary There are only six locations in Alaska for which global radiation data of more than a year in duration are available. This
is an extremely sparse coverage for a state which covers 1.5×10&6 km2 and stretches over at least three climatic zones. Cloud observations are, however, available from 18 stations. We used fractional
cloud cover and cloud type data to model the global radiation and thus obtain a more complete radiation coverage for Alaska.
This extended data set allowed an analysis of geographic and seasonal trends.
A simple 1-layer model based on Haurwitz’s semi-empirical approach, allowing for changes in cloud type and fractional coverage,
was developed. The model predicts the annual global radiation fluxes to within 2–11% of the observed values. Estimated monthly
mean values gave an average accuracy within about 6% of the measurements. The estimates agree well with the observations during
the first four months of the year but less so for the last four. Changing surface albedo might explain this deviation.
Previously, the 1993 National Solar Radiation Data Base (NSRDB) from the National Renewable Energy Laboratory (NREL) modeled
global radiation data for 16 Alaskan stations. Although more complete and complex, the NREL model requires a larger number
of input parameters, which are not available for Alaska. Hence, we believe that our model, which is based on cloud-radiation
relationship and is specifically tuned to Alaskan conditions, produces better results for this region. Annual global solar
radiation flux measurements are compared with results from global coverage models based on the International Satellite Cloud
Climatology Project (ISCCP) data. Contour plots of seasonal and mean annual spatial distribution of global radiation for Alaska
are presented and discussed in the context of their climatic and geographic settings.
Received July 16, 1997 Revised May 18,1998 相似文献
8.
K. O. Ogunjobi Y. J. Kim J. A. Adedokun S. Y. Ryu J. E. Kim 《Theoretical and Applied Climatology》2002,72(3-4):265-272
Summary ?Daily global and diffuse radiation measurements have been used to characterize the atmosphere optical conditions at Kwangju
(Lat.35.13N, Long.126.53E) and Seoul (Lat.37.57N, Long.126.98E) in South Korea and Ile-Ife (Lat.7.14N, Long.4.56E) in Nigeria.
The clearness index, (CI) which gives the percentage depletion by the sky of the incoming global radiation and the diffuse
ratio, (DR) which represents the effectiveness of the sky in scattering incoming radiation have been analyzed in this study. Results
show an average clearness index value of 0.57 for the year 1999 with maximum values occurring during the wet seasons at Ile-Ife.
The average clearness indexes for Kwangju and Seoul from 1998–2000 was 0.48 and 0.34, respectively, with both stations having
maximum clearness indexes in the winter seasons. The diffuse ratio was higher at Kwangju and Seoul than at Ile-Ife due to
heavy dust pollution from the Gobi desert in the Korea peninsula in spring, and high biomass burning at Kwangju in the fall.
Department of Physics, Obafemi Awolowo University, Ile-Ife, Nigeria
Received May 7, 2001; Revised November 24, 2001 相似文献
9.
The study presents a critical assessment of the possibility of global solar irradiation computation by using air temperature instead of sunshine duration with the classical Ångström equations. The reason for this approach comes from the fact that, although the air temperature is a worldwide measured meteorological parameter, this is rarely used in solar radiation estimation techniques. More than that, the literature is very silent concerning the testing of such models in Eastern Europe. Two new global solar irradiation models (to be called AEAT) related to solar irradiation under clear sky conditions and having the minimum and maximum daily air temperature as input parameters were tested and compared with others from the literature against data measured at five stations in Romania in the year 2000. The accuracy of AEAT is acceptable and comparable to that of the models which use sunshine duration or cloud amount as input parameters. Since temperature-based Ångström correlations are strongly sensitive to origin, the approach for AEAT as a tool for potential users is presented in detail. Additionally reported is a new method to increase the generality of AEAT concerning the extension of the geographical application area. Based on overall results it was concluded that air temperature successfully substitutes sunshine duration in the estimation of the available solar energy. 相似文献
10.
Summary The diffuse sky radiation component in the ultraviolet wavelengths is often at least 50% of the global irradiance under clear skies, and is the dominant component of ultraviolet global radiation under translucent overcast skies. The distribution of sky radiance was measured in a rural area and modeled for wavelength bands of ultraviolet-B (UVB, 280–320 nm) and ultraviolet-A (UVA, 320–400 nm). Sky radiance measurements were made during the summer of 1993 over a wide range of solar zenith angles using radiance sensors mounted on a hand-operated hemispherical rotation mount. UVB irradiance measurements were also made during each scan. Since the ratio of measured irradiance under overcast skies and that predicted for clear skies was not correlated with cloud base height, opaque cloud fraction, or solar zenith angle, it was concluded that the scattering from the clouds dominated the global irradiance, and this scattering was relatively unaffected by the scattering off opaque clouds in the translucent atmosphere.Analysis of the translucent overcast sky UVA and UVB radiance measurements using a semi-empirical distribution model showed that the spectral influences on multiple scattering, single scattering, and horizon brightening components of the distributions agreed with basic atmospheric radiation theory. The best model used solar zenith, the sky zenith, and the scattering angle with resultant coefficient of determination values of 0.62 and 0.25 for the UVA and UVB respectively. The developed equations can be applied directly to the diffuse sky irradiance on the horizontal to provide radiance distributions for the sky.With 6 Figures 相似文献
11.
A method is described for evaluating the ‘partial derivatives’ of globally averaged top-of-atmosphere (TOA) radiation changes
with respect to basic climate model physical parameters. This method is used to analyse feedbacks in the Australian Bureau
of Meteorology Research Centre general circulation model. The parameters considered are surface temperature, water vapour,
lapse rate and cloud cover. The climate forcing which produces the changes is a globally uniform sea surface temperature (SST)
perturbation. The first and second order differentials of model parameters with respect to the forcing (i.e. SST changes)
are estimated from quadratic least square fitting. Except for total cloud cover, variables are found to be strong functions
of global SST. Strongly non-linear variations of lapse rate and high cloud amount and height appear to relate to the non-linear
response in penetrative convection. Globally averaged TOA radiation differentials with respect to model parameters are also
evaluated. With the exception of total cloud contributions, a high correlation is generally found to exist, on the global
mean level, between TOA radiation and the respective parameter perturbations. The largest non-linear terms contributing to
radiative changes are those due to lapse rate and high cloud. The contributions of linear and non-linear terms to the overall
radiative response from a 4 K SST perturbation are assessed. Significant non-linear responses are found to be associated with
lapse rate, water vapour and cloud changes. Although the exact magnitude of these responses is likely to be a function of
the particular model as well as the imposed SST perturbation pattern, the present experiments flag these as processes which
cannot properly be understood from linear theory in the evaluation of climate change sensitivity.
Received: 16 January 1997/Accepted: 9 May 1997 相似文献
12.
福建省散射辐射的计算方法及其分布特征 总被引：2，自引：0，他引：2
提出了综合考虑日照百分率和总云量来计算散射辐射的公式。将散射辐射Ｄ除以日照百分率Ｓ１，称其为净散射辐射。同时求出各月及年的净散射辐射与当地天文辐射的比值和总云量的相关系数ｒ。各月与年的相关系数均为正值，且ｒ均大于ｒ０．０１。在此基础上建立计算散射辐射的经验公式：Ｄ＝Ｓ１Ｑｏｅ＾ａ＋ｂＮ，式中Ｄ为散射辐射；Ｓ１为日照百分率；Ｑｏ为天文辐射；Ｎ为总云量；ａ和ｂ为经验系数。使用该经验公式求得福建省所有市 相似文献
13.
Summary The total cloud cover is deduced from measurements of monthly mean averages of the percent of possible sunshine duration at three locations in Egypt, Cairo, Bahtim and Sedi-Barrani stations during the period 1987–1995. This sunshine-derived total cloud cover (Cs) is compared to conventional ground-based observations of total cloud covers (Cg) made by meteorological observers. A linear relationship between the two estimates is calculated, and the difference between the two estimates as a function of Cs and Cg is fitted with a least-squares linear equation. It is found that on the average the sunshine-derived values of total cloud cover are about 7% lower than the corresponding ground-based estimated of total cloud cover. Both of these parameters are mainly used in solar radiation models and the error sources are mainly depending upon the way to describe sky cover. 相似文献
14.
我国散射辐射的气候计算方法及其分布特征 总被引：1，自引：0，他引：1
使用全国６４个日射站的散射辐射资料，首先计算与建立了各地１月、４月、７月和１０月的月散射辐射值与总云量、日照百分率之间的相关系数与经验关系式，并对经验关系式进行了方差检验。该经验关系式为：Ｄ＝Ｑ０（ｓ１＋０．０１）（ａ＋ｂＮ）。应用该经验关系式和２００多个地面气象站的资料，计算了各地的１月、４月、７月和１０月的散射辐射值。最后对我国四季散射辐射的分布及其年变化作简要的分析。 相似文献
15.
This paper focuses on different ways of characterizing the solar radiative regime of a day and the stability of this regime. The days may be stratified in classes of cloud shade, observed total cloud cover amount, daily averaged clearness index, and fractal dimension of the solar global irradiance signal. A new Boolean parameter related to solar irradiance fluctuation is defined, namely the sunshine stability number. The time averaged value of the sunshine stability number is used for the characterization of the radiative regime stability during a given time interval. Ranking the days from the view-point of the stability of their radiative regime is performed by using the daily average value of the sunshine stability number and appropriately defined values of disorder and complexity, respectively. Measurements performed in the Romanian town of Timisoara (latitude 45°46?? N, longitude 21°25?? E and 85?m altitude above mean sea level) are used here. They refer to time series of global and diffuse solar irradiance recorded at 15-s time interval between sunrise and sunset during all the days in 2009. 相似文献
16.
Daily global solar irradiation (R s) is one of the main inputs in environmental modeling. Because of the lack of its measuring facilities, high-quality and long-term data are limited. In this research, R s values were estimated based on measured sunshine duration and cloud cover of our synoptic meteorological stations in central and southern Iran during 2008, 2009, and 2011. Clear sky solar irradiation was estimated from linear regression using extraterrestrial solar irradiation as the independent variable with normalized root mean square error (NRMSE) of 4.69 %. Daily R s was calibrated using measured sunshine duration and cloud cover data under different sky conditions during 2008 and 2009. The 2011 data were used for model validation. According to the results, in the presence of clouds, the R s model using sunshine duration data was more accurate when compared with the model using cloud cover data (NRMSE = 11. 69 %). In both models, with increasing sky cloudiness, the accuracy decreased. In the study region, more than 92 % of sunshine durations were clear or partly cloudy, which received close to 95 % of total solar irradiation. Hence, it was possible to estimate solar irradiation with a good accuracy in most days with the measurements of sunshine duration. 相似文献
17.
基于卫星资料同化和LAPS-WRF模式系统的云天太阳辐射数值模拟改进方法 总被引：2，自引：0，他引：2
太阳能光伏发电已成为仅次于水电和风能的第三大可再生能源,光伏发电受云量时空变化的影响较大,因此准确模拟云天太阳辐射的时空变化对电网安全运行至关重要。围绕如何减小中尺度气象模式的云初始场误差,进而改进云天的太阳辐射模拟这一关键科学问题,本文通过研究基于卫星资料同化的LAPS（Local Analysis Prediction System）多时间层三维云分析同化方法,改进三维云结构,并将LAPS模式输出结果作为WRF（Weather Research and Forecasting）模式的初始场,模拟了2008年1月及夏季（6～8月）北京地区的总云量和总辐射的时空分布,重点分析了多云和有降水天气过程总辐射的模拟改进效果及其原因。结果表明,同化前后的总云量模拟值与观测值的时间变化趋势基本一致,但大部分时次总云量的模拟值低于观测值;大部分多云及降水时段同化后总云量模拟值较接近于实测值。1月晴天、多云天以及夏季晴天同化前后总辐射模拟值与实测值的时间变化趋势较一致,但同化前后两者的相关性差异不明显;晴天条件下同化前后总辐射模拟值均低于实测值,1月多云条件下多数时段同化后总辐射模拟误差减小不明显,与总云量的改进效果不显著有关。夏季多云、有降水及6月典型降水三种天气条件下同化前后总辐射模拟值与观测值的相关性稍差,同化后两者的相关性较同化前有所改进,尤其是6月典型降水过程改进效果较明显;同化前总辐射模拟误差较大,而同化后误差显著减小,尤其是6月典型降水过程同化后均方根误差和平均相对误差较同化前分别减小了102.6 W m-2和355.9%,最大相对误差减小更显著;同化后总辐射模拟误差小于同化前的比例高达75%,即大部分时刻同化后模拟误差小于同化前。多云和有降水天气过程总辐射模拟效果的显著改进与总云量的改进密切相关,即同化后总云量模拟值增加,云的反射和散射作用增强,导致模拟总辐射减小,即更接近于实测总辐射值。研究结果对于多云和降水天气条件下太阳辐射的模拟效果改进、太阳能资源客观评估以及光伏电站的发电量预测具有一定的科学和实际应用价值。 相似文献
18.
Summary ¶The paper deals with the computation of solar energy available in a specific location. First, a new formula describing the relation between global solar irradiation and the duration of bright sunshine is established. The analysis of its use shows that global solar clear sky irradiance models are essential tools for daily computation of global irradiation. An integrated spectral atmospheric transmittance model is presented, it can be used to compute beam and diffuse clear sky irradiance for all applications where broadband solar energy input is needed. Since it is desirable to use simplified estimation methods for many applications, a parametric global solar irradiance model, derived from the spectral model, is also presented. This model needs only surface meteorological data as input. The influence of the averaging method used for the input parameters on the model accuracy is evaluated. Comparison of model results with the measurements shows an acceptable level of accuracy with the new model. Finally, an application of daily global solar energy computation is presented.Received May 17, 2002; revised October 14, 2002; accepted February 11, 2003
Published online September 10, 2003 相似文献
19.
Summary Cloud parameters and surface radiative fluxes predicted by regional atmospheric models are directly compared with observations
for a 10-day period in late summer 1995 characterized by predominantly large-scale synoptic conditions. Observations of total
cloud cover and vertical cloud structure are inferred from measurements with a ground-based network of Lidar ceilometers and
IR-radiometers and from satellite observations on a 100 kilometer scale. Ground-based observations show that at altitudes
below 3 km, implying liquid water clouds, there is a considerable portion of optically non-opaque clouds. Vertical distributions
of cloud temperatures simultaneously inferred from the ground-based infrared radiometer network and from satellite can only
be reconciled if the occurrence of optically thin cloud structures at mid- and high tropospheric levels is assumed to be frequent.
Results of three regional atmospheric models, i.e. the GKSS-REMO, SMHI-HIRLAM, and KNMI-RACMO, are quantitatively compared
with the observations. The main finding is that all models predict too much cloud amount at low altitude below 900 hPa, which
is then compensated by an underestimation of cloud amount around 800 hPa. This is likely to be related with the finding that
all models tend to underestimate the planetary boundary layer height. All models overpredict the high-level cloud amount albeit
it is difficult to quantify to what extent due to the frequent presence of optically thin clouds. Whereas reasonably alike
in cloud parameters, the models differ considerably in radiative fluxes. One model links a well matching incoming solar radiation
to a radiatively transparent atmosphere over a too cool surface, another model underpredicts incoming solar radiation at the
surface due to a too strong cloud feedback to radiation, the last model represents all surface radiative fluxes quite well
on average, but underestimates the sensitivity of atmospheric transmissivity to cloud amount.
Received August 31, 2000 Revised March 15, 2001 相似文献
20.
Solar irradiance, sunshine duration and daylight illuminance derived from METEOSAT data for some European sites 总被引：1，自引：0，他引：1
Summary
Radiometric ground truth data from seven Norwegian stations (58–64° N), and from five other European stations (38–61° N),
are compared to satellite-derived data in the present paper. Hourly global irradiance at ground level is estimated by the
Heliosat procedure from the “visible” channel of the geostationary satellite METEOSAT. With increasing latitude this satelllite
sees the earth’s surface at an increasingly unfavourable angle. Nevertheless, in this paper, global irradiance estimates reproduce
high latitude ground truth data with negligible Mean Bias Deviations (MBD) and only minor deviations regarding frequency distributions.
Moreover, the Root Mean Square Deviations (RMSD) are comparable to those typically seen between ground truth stations some
20–30 km apart.
Using a number of auxiliary models, a multiplicity of ground level solar radiation data is obtained from satellite-derived
global irradiance data, and made available at the SATEL-LIGHT www server. The accuracy of the half-hourly data thus derived
from Heliosat global irradiances, using models for diffuse fraction, luminous efficacy and slope/horizontal ratios, is successfully
verified against ground truth data.
Received August 31, 2000/Revised January 31, 2001 相似文献