长江三角洲地面太阳辐射变化和相关因素分析

通过对长江三角洲地区(南京,杭州,上海,合肥)1961-2000年辐射资料的比较,根据中国气象局编写的<气象辐射观测方法>对该地区年地面太阳辐射平均值进行计算,分析长江三角洲地区地面太阳辐射的长期变化及季节差异,并讨论长江三角洲地区两个重要城市杭州和南京的部分与地面太阳辐射息息相关的因子,分析长江三角洲地区直接辐射,散射辐射与总辐射的关系.结果表明:在40 a中长江三角洲地区4个代表城市总辐射长期变化分为两个阶段,1980s为谷值,谷值前有明显的下降趋势,后期总辐射变化趋势发生逆转,就所研究城市而言,1960s到1980s地面太阳总辐射的下降主要是由于直接辐射下降引起的.     

Analysis of solar radiation over Egypt

Summary  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. Received February 26, 1998 Revised February 4, 1999     

太湖无锡地区太阳总辐射的气候学计算及特征分析

为了便于研究水气界面辐射传输、水下光辐照度以及湖泊储热量，探讨太湖地区总辐射概况及其变化。文章在概述当前太阳总辐射气候学计算的主要方法及公式基础上，采用最小二乘法，利用上海、南京、杭州3站1961~2000年共40年的历史资料，确定各站的经验系数，然后内插求出太湖无锡地区的经验系数。由此推导出太湖无锡地区太阳总辐射的气候学计算公式，并利用无锡站日照百分率资料求算出近40年到达地面的太阳实际总辐射。然后利用太湖站1998年的太阳总辐射实测资料检验其公式精度，确定公式的可信度。最后对计算值进行分析，阐述了近40年来太湖无锡地区太阳总辐射的变化特征及其原因。研究结果表明:无锡地区太阳总辐射呈下降趋势，而这种下降主要是由于大气中悬浮物增加所致；总辐射年内变化趋势基本上与天文辐射相吻合，但又存在差异，这主要与梅雨的存在有关。     

Analysis of sky conditions using 40 year records of solar radiation data in China

Summary Forty years of daily global and diffuse radiation data have been used to characterize the atmospheric optical conditions at 14 premium radiation stations in China. The clearness index (K _T ), diffuse ratio (K _D ), and diffuse coefficient (K _C ) have been analyzed for long-term and seasonal variations, correlations of relative sunshine (R _S ) versus clearness index and diffuse coefficient, respectively. Two polynomial models have been developed to simulate clearness index and diffuse ratio by using relative sunshine data and have been shown to be reasonable at most of the 14 stations. The results show that there are significant declining trends in clearness index and increasing trends in diffuse ratio at most of the 14 premium radiation stations, but there are no significant trends for diffuse coefficient. The seasonal variations of clearness index are determined by the regional climate and changes with relative sunshine.     

Influence of the total atmospheric optical depth and cloud cover on solar irradiance components

Broadband solar irradiance data obtained in the spectral range 400–940 nm at Kwangju, South Korea from 1999–2000 have been analyzed to investigate the effects of cloud cover and atmospheric optical depth on solar radiation components. Results from measurements indicate that the percentage of direct and diffuse horizontal components of solar irradiance depend largely on total optical depth (TOD) and cloud cover. During summer and spring, the percentages of diffuse solar irradiance relative to the global irradiance were 5.0% and 4.9% as compared to 2.2% and 3.0% during winter and autumn. The diffuse solar irradiance is higher than the direct in spring and summer by 24.2%, and 40.6%, respectively, which may largely be attributed to the attenuation (scattering) of radiation by heavy dust pollution and large cloud amount. In cloud-free conditions with cloud cover ≤2/10, the fraction of the direct and diffuse components were 66.0% and 34.0%, respectively, with a mean daily global irradiance value of 7.92±2.91 MJ m⁻² day⁻¹. However, under cloudy conditions (with cloud cover ≥8/10), the diffuse and direct fractions were 97.9% and 2.2% of the global component, respectively. The annual mean TOD under cloudless conditions (cloud cover≤2/10) yields 0.74±0.33 and increased to as much as 3.15±0.67 under cloudy conditions with cloud amount ≥8/10. An empirical formula is derived for estimating the diffuse and direct components of horizontal solar irradiance by considering the total atmospheric optical depth (TOD). Results from statistical models are shown for the estimation of solar irradiance components as a function of TOD with sufficient accuracy as indicated by low standard error for each solar zenith angle (SZA).     

北京城市紫外辐射变化特征及经验估算方程

利用2004年4月—2005年6月在中国科学院大气物理研究所铁塔分部的紫外辐射观测数据,分析了北京城市紫外辐射的变化特征,结果表明,紫外辐射的变化规律与太阳总辐射一致,紫外辐射与总辐射的比值变化范围在0.02~0.04之间,晴天恒定在0.03,阴天在0.04左右,在沙尘暴过程中比值最小,为0.02。通过分析紫外辐射与大气质量数和平均晴空指数之间的关系,建立了适合于北京的全天候紫外辐射的估算方程。利用建立的估算方程及观测的总辐射值进行了紫外辐射的估算,紫外辐射的计算相对误差在10%以内。     

Derivation of Cloud Index from Geostationary Satellites and Application to the Production of Solar Irradiance and Daylight Illuminance Data

Summary  We investigate in the present paper the relationship between satellite count, global irradiance and other solar and illumination resource components, bringing a particular attention to low solar elevation situations (below 20 °) which are very important in northern latitudes. Our investigation is based on data from two geostationary satellites, METEOSAT and GOES, backed by ground measurements in Switzerland and the northeastern USA. The study of different clear sky normalizations lead to the conclusion that a linear correlation between the global clearness index and the irradiance (like the heliosat method) would be inaccurate for low solar elevations, and therefore for high latitude regions. We developed a model that directly relates an elevation dependent clearness index to the could index. This methodology presents a definite advantage because it can be generalized to address the clearness index of other solar radiation components, besides global irradiance, such as direct irradiance, diffuse illuminance, etc. The correlations described in this paper were developed on the data from Geneva (in the frame of the EC program “Satellight”) and evaluated on two other independent data sets (Albany, USA and Lausanne, Switzerland). Their precisions, on a hourly basis, are respectively 30%, 40% and 60% for the global, diffuse and beam components) (90,55 and 95 W/m²). The use of independent data for thederivation and the validation of the models shows thatthose can be used in a wide range of locations, even if the applicability has to be assessed for very different climates. Received June 27, 1998 Revised February 26, 1999     

华南地面太阳辐射状况及其转折特征分析

利用华南地区1961—2003年的太阳总辐射、直接辐射和散射辐射资料分析了该地区地面太阳辐射状况,包括年际变化和季节变化,重点分析了该地区太阳总辐射在1980—1990年代期间的转折过程,并与全国平均状况进行对比。结果表明：1961—2003年,华南地区的总辐射和直接辐射整体呈下降趋势,散射辐射的变化不显著,与全国平均辐射状况的变化趋势一致。1983年之前,华南总辐射处于迅速下降阶段,之后发生转折开始回升,至2001年前后已经恢复到平均水平。华南地区总辐射和散射辐射的季节变化非常明显,夏季最高,春秋两季次之,冬季最低,一年中散射辐射的最高和最低值相比总辐射提前一个月出现。另外,结合云量和能见度资料初步分析了广州市地面太阳辐射的变化和转折过程,表明广州地面太阳总辐射的下降及转折过程主要与该地区的大气清洁程度相关。     

Estimating solar radiation on tilted surfaces with various orientations: a study case in Karaj (Iran)

Summary The aim of this study is the evaluation of models that estimate daily global solar radiation on tilted surfaces from that measured on horizontal surfaces. Global solar radiation incident on a tilted plane consists of three components: beam radiation, diffuse radiation and reflected radiation from the ground. The Klein (1977) method, modified by Andersen (1980), was used for estimating direct solar radiation incident on tilted surfaces and an isotropic model was used for estimating reflected solar radiation incident on a tilted plane. In contrast models for the diffuse radiation component show major differences, which justifies a validation study which has been done. Eight models for derivation of daily slope diffuse irradiance from daily horizontal diffuse irradiance were tested against recorded slope irradiances at Karaj (35°55′ N; 50°56′ E), Iran. The following models were included: Badescu (2002), Tian et al. (2001), Reindl et al. (1990), Skartveit and Olseth (1986), Koronakis (1986), Steven and Unsworth (1980), Hay (1979) and Liu and Jordan (1962). All the models use the same method for calculating beam radiation as well as ground reflected radiation. However, only diffuse component of radiation was compared. Statistical indices showed that Reindl’s model gives the most accurate prediction for the south-facing surface and Koronakis’s model performs best for the west-facing surface. The Relative Root Mean Square Errors (%RMSE), except for Steven and Unsworth’s model that has unacceptable results, for whole data range from 1.02 to 10.42%. In general, Reindl’s model produces the best agreement with the measured tilted data.     

Long-Term Trends in Photosynthetically Active Radiation in Beijing

A long-term dataset of photosynthetically active radiation (Qp) is reconstructed from a broadband global solar radiation (Rs) dataset through an all-weather reconstruction model. This method is based on four years' worth of data collected in Beijing. Observation data of Rs and Qp from 2005--2008 are used to investigate the temporal variability of Qp and its dependence on the clearness index and solar zenith angle. A simple and efficient all-weather empirically derived reconstruction model is proposed to reconstruct Qp from Rs. This reconstruction method is found to estimate instantaneous Qp with high accuracy. The annual mean of the daily values of Qp during the period 1958--2005 period is 25.06 mol m-2 d-1. The magnitude of the long-term trend for the annual averaged Qp is presented (-0.19 mol m-2 yr-1 from 1958--1997 and -0.12 mol m-2 yr-1 from 1958--2005). The trend in Qp exhibits sharp decreases in the spring and summer and more gentle decreases in the autumn and winter.     

Variations and trends in global solar radiation for Turkey

Summary Since measured solar radiation data in Turkey have rather high random errors, sunshine duration data covering the period from 1960 through 1994 from 34 stations in Turkey were taken to derive estimates of monthly mean global solar radiation by a quadratic correlation. The least square linear regression method was applied for trend analysis. Significant negative trends of the annual means were observed with 71 percent of the stations A 3.44 percent decrease in global solar radiation was observed over the last 35 years in Turkey. The decrease in solar radiation is an indication of increased air pollution, as statistical parameters show that Turkey is rapidly expanding economically, and thus air quality has deteriorated correspondingly.With 3 Figures     

拉萨紫外辐射特征分析及估算公式的建立

本文利用2005~2010年的辐射观测资料对拉萨地区紫外辐射的时间变化特征及紫外辐射与总辐射比值的变化特征进行了分析,结果表明,紫外辐射与太阳总辐射的变化规律基本一致,日变化表现为正午大、早晚小;季变化特征是夏季6月最大,冬季1月最小.紫外辐射日累积值6年平均为0.87 MJ·m-2·d-1;紫外辐射有逐年递减的趋势.紫外辐射与总辐射比值也存在着明显日变化,表现为正午大、早晚小的规律;其季节变化也是夏季最大,冬季最小.紫外辐射与总辐射比值6年平均为0.0418;紫外辐射与总辐射比值也呈现逐年递减的趋势.利用2010年大气质量数和晴空指数,建立了适合于拉萨紫外辐射估量的公式,估算值的瞬时值与观测值的平均相对误差最大为8.66%,紫外辐射日累积重构值与观测值平均相对误差仅为5.5%.     

起伏地形下浙江省散射辐射时空分异规律模拟

结合影响起伏地形下太阳散射辐射的天空因素与地面因素,通过基于数字高程模型（DEM）数据的起伏地形下天文辐射模型和地形开阔度模型,综合考虑地面因素对散射辐射的影响;基于常规地面气象站观测资料建立的水平面散射辐射模型,考虑天空因素对散射辐射的影响;建立了起伏地形下浙江省散射辐射分布式估算模型;逐月计算了浙江省散射辐射（100m×100m）的空间分布。结果表明：散射分量分布与地理地形因子、季风影响、大气透明程度有关,由高纬向低纬逐渐增加;季节分布特点为,夏季〉春季〉秋季〉冬季;坡度、坡向对散射辐射的分布影响小,但辐射值与开阔度呈正相关,各季辐射最大值分布在开阔度大处,最小值在开阔度最小处,不同季节有所伸缩。计算结果可以为气候变化和环境资源研究提供基础数据。     

山东禹城紫外辐射变化特征及其估测方程的建立

本文对2005～2011年山东禹城地区观测得到的紫外辐射的时间变化特征及紫外辐射与总辐射比值的变化特征进行了分析, 并结合气温、降水和露点温度资料建立了禹城地区的紫外辐射估测方程。结果表明:紫外辐射日累计值的变化范围为0.10～1.20 MJ m-2 d-1, 年平均值为0.468 MJ m-2 d-1;紫外辐射日、季节变化规律与总辐射一致, 季节变化都表现为冬季小夏季大, 最小值出现在1月, 最大值出现在6月, 日变化则呈现早晚小中午大的特征;紫外辐射与总辐射的比值范围为0.023～0.046, 其季节变化特征也是冬季小夏季大, 该比值随晴空指数的增大而减小, 而在晴空指数大于0.5时比较稳定。利用温度日较差(日最高气温与最低气温的差值)建立了紫外辐射估测方程, 决定系数R2达0.80, 平均相对误差为0.19, 估测紫外线等级与实测紫外线等级相差不大于1的数据占95%, 该方法可以较好地进行紫外辐射等级的估测。     

Influences of the clearness index on UV solar radiation for two locations in the Tibetan Plateau-Lhasa and Haibei

Ultraviolet （UV） solar radiation has a significant influence on human health, the environment and climate. A series of measurements, including UV radiation （290 400 nm） and global solar radiation （Rs）, were continuously recorded from August 2004 at the Lhasa and Haibei sites on the Tibetan Plateau. Both observation sites＇ altitudes are above 3000 m and have similar meteorological conditions. The data from 2005 2006 was used to identify the varying characteristics of UV radiation. It＇s relation to the clearness index Ks, the relative optical mass mr, and Rs were established. The annual mean values of total daily UV radiation are 0.92 and 0.67 MJ m^-2 at Lhasa and Haibei, respectively. The UV radiation in Lhasa represented 4.6% of the global solar radiation while in Haibei this percentage was 4.2%. In the case of clear days （Ks 〉 0.8）, these percentages ranged between 4.0% and 4.5% in Lhasa and between 5.1% and 5.5% in Haibei. In the case of cloudy days （Ks 〈 0.4）, these percentages ranged from 4.4% to 6.8% in Lhasa and from 5.1% to 5.5% in Haibei. The maximum values of UV radiation for each relative optical mass diminished exponentially with mr. Thus, for Lhasa and Haibei, UV=46.25mr-129, and UV=51.76mr-142, respectively. The results of this study can be used to obtain more UV radiation data for the study of UV climate characteristics, the effects of UV on ecological processes and the feedback of the thinning of the stratospheric ozone, from more routine measurements Rs data.     

宝坻太阳辐射资料可用性研究

应用典型的辐射资料质量检验方法、辐射数据变化特征分析、人工与器测日照对比分析及太阳总辐射与相关辐射要素间的统计分析对天津市宝坻国家级基本气象站站内的太阳辐射观测系统试运行期间的辐射观测数据进行了质量分析,结果表明,试运行期间数据到报情况理想,总、散射辐射观测数据的BSRN的质量检验合格率为100%,直接辐射合格率为85%,净辐射通过了仪器阀值质量检验;太阳辐射值及变化特征符合理论实际;人工与器测日照时数具有很好的线性相关性(R2=0.96),总辐射与日照时数及散射辐射之间的线性变化与历史经验结论吻合。总体来看,宝坻太阳辐射系统观测数据可用性较高,能够满足日常业务需求。     

天津生态城太阳辐射特征分析及算法评估

利用2014年8月14日—2015年8月12日天津市生态城太阳能观测站和同期气象观测资料，统计分析生态城太阳辐射特征，并对各向同性和各向异性两种倾斜面太阳辐射计算模型的精度和误差来源进行评估，结果表明：生态城水平面和倾斜面曝辐量在月均值、季节和年总量上存在较大差异，利用水平面太阳辐射进行光伏发电预估会存在误差；太阳辐射日变化特征受不同天气条件的影响，电站需根据天气情况调整发电策略，尤其应注意多云或阴天造成的发电功率的间歇性和不稳定；两种计算模型精度相当，整体计算效果较好，引入直射比分段计算函数的不确定性是造成计算误差的主要原因。     

The Diffuse Fraction of Global Solar Irradianceat a Tropical Location

Summary The annual and monthly mean diurnal variations of the diffuse fraction of global solar irradiance arriving on the ground at a tropical station in Sub-Sahel Africa is here been reported. The monthly mean hourly values of the diffuse fraction (K _d ) for such clear-sky months as February, March and November at this location, which approach a minimum at about local noon, are observed to lie generally below 0.50 during the period from 11:00 to 15:00 hrs (LST). Consequently, solar concentrators utilising parabolic mirrors are expected to have high performance during these months in this region. Like the mainly-cloudy and wet months (June to August) in which monthly mean hourly values of K _d higher than 0.62 have been recorded, the corresponding diffuse fraction for dust-haze months (mostly December and January) with high turbidity coefficients were generally above 0.50. Monthly mean hourly values of K _d for less cloudy months (April, May, September and October) ranged between 0.48 and 0.77 during the period from 11:00 to 15:00 hrs (LST). The effects of atmospheric dust-haze, clouds and albedo on the monthly mean diurnal variation of the diffuse fraction has been discussed. Also reported are the characteristic values of K _d for sets of months with relatively similar atmospheric and sky conditions at this location. The annual variations of the monthly mean daily values of K _d which exhibit strong seasonal dependence showed a peak in August for both years. Except for the months of February and March, the monthly mean daily totals of K _d exhibited similar annual marches during both years. The major discrepancy in the values of the monthly mean daily totals of K _d in both years were recorded in the months of February, November and December, with the corresponding K _d values for these months in both years agreeing only to within 32.9% in February, 15.4% in November and 16.2% in December. Apart from the aforementioned months, the corresponding monthly mean daily totals of K _d for the remaining nine months in both years agreed mostly to within less than 8.4%. The least monthly mean daily ratios of K _d were obtained in the relatively clear month of November for both years being 0.43 in 1993 and 0.49 in 1994. On an annual average, the diffuse component was found to constitute 59.6% of the global solar irradiance arriving on the ground at this region in 1993 and 60.9% in 1994. The results been reported here have been compared with a few others emanating from other tropical stations. Received February 5, 1998 Revised May 12, 1998     

内蒙古自治区太阳总辐射的气候学计算及其时空分布特征

通过对比分析国内外太阳总辐射的气候学计算方法,最终给出内蒙古太阳辐射最佳计算公式。根据内蒙古及周边地区24个太阳辐射观测站历年各月的总辐射和日照百分率,采用最小二乘法拟合出公式中的经验系数,并在分区基础上通过内插将a、b系数推广到内蒙古108个气象站点上,从而建立了内蒙古太阳总辐射计算模型。结果表明：内蒙古太阳总辐射年际变化总体呈下降趋势,但不显著,而且不同区域在减小速率上差异明显。年变化则表现为单峰型变化趋势,以5月辐射量最大,6、7月次之,12月最小。全年和各月总辐射的空间分布形态一致,总的分布趋势由东北向西南逐渐递增。全区年总辐射在4633～6616 MJ·m^-2之间,太阳能资源丰富程度均在丰富级别以上,而且大部分地区属于资源最丰富区和很丰富区,太阳能开发利用潜力巨大。