太阳能板自动寻光转动控制系统

为了提高光伏太阳能板的太阳能转换效率,设计了一种太阳能板自动寻光转动控制器,此装置通过寻光电路检测太阳光源方向,当产生偏差信号时,经A/D转换电路输入单片机,单片机处理输出相应电信号驱动电机转动,准确地跟踪太阳光线移动.该装置结构简单、成本低廉、跟踪精度高,可用于太阳能发电系统中,能够提高太阳能的利用效率.     

和静县太阳总辐射计算及太阳能资源评估

基于焉耆国家基准气候站1993-2012年逐月太阳总辐射和日照观测资料以及和静、巴音布鲁克1961-2012年月日照百分率资料,建立回归分析方程,推算和静县山区及平原地区逐月的太阳总辐射,对比分析了和静县山区及平原地区太阳总辐射变化特征,从太阳能资源丰富度、资源稳定性及可利用价值等方面对和静县太阳能资源状况进行评估。结果表明：1961-2012年和静县平原及山区太阳总辐射均呈减少的趋势,平原地区7月太阳总辐射最多,山区5月最多,最少值均出现在1月;平原地区属太阳能资源很丰富区,山区为丰富区;平原地区及山区太阳能资源均较稳定;平原地区年平均可利用太阳辐射的天数为286 d,山区为267 d;平原和山区一天中上午和中午是最有利的利用时段。     

吉林省太阳辐射变化规律及太阳能资源利用研究

为揭示吉林省的太阳能资源变化规律,利用线性回归分析、线性相关分析及M-K检验法对吉林省长春、延吉两个气象站点1960年以来的太阳总辐射资料进行研究。结果表明：吉林省的年平均太阳总辐射为4787.4 MJ/㎡•a,夏季太阳总辐射最大,春季次之,冬季最小。吉林省年平均太阳总辐射在波动中下降,且下降趋势不显著,20世纪60年代太阳总辐射较高,80年代达到最低值,90年代以后小幅度回升。春、秋、冬三季的太阳总辐射呈不同程度的下降趋势,冬季的下降趋势显著,夏季呈显著增加。吉林省年日照时数在空间分布上呈现出由西向东逐渐减少的地域分布差异;而在时间上也呈现出由春季到冬季依次减少的分布特征。吉林省的太阳能资源总量丰富,变化趋势不显著,这对于吉林省利用太阳能资源是十分有利的。     

Classification of daily solar irradiation by fractional analysis of 10-min-means of solar irradiance

Summary This paper deals with fractal analysis of daily solar irradiances measured with a time step of 10 minutes at Golden and Boulder located in Colorado. The aim is to estimate the fractal dimensions in order to perform classification of daily solar irradiances. The estimated fractal dimension and the clearness index KT are used as classification criteria. The results show that these criteria lead to three classes: clear sky, partially covered sky and overcast sky. The results also show that the evaluation of the fractal dimension of the irradiance signal based on a data set with 10 minutes time step is possible.     

太阳辐射各因子的变化对太阳紫外辐射的影响

利用北京地区１９９０年太阳分光辐射的观测资料，计算了影响太阳紫外辐射的各因子的变化所引起的太阳紫外辐射的变化。当臭氧、水汽、气溶胶分别减少５％时，到达地面的太阳紫外辐射将分别增加０．８４％、０．２７％和１．９０％。在分析太阳紫外辐射的变化趋势时，应当全面考虑各个因子的影响。     

Transient processes of solar radiation

In the present study, transients—rises and falls of the value of solar irradiance in the conditions of alternating Cumulus humilis and Cumulus fractus clouds—are studied to find their main characteristics, that is, the scope of their duration, magnitude, frequency, and shape. Of course, all these variables have a stochastic character and have been calculated using statistical analysis of ten automatic recordings. The results of the study characterize these clouds and show the degree of problems in generating PV electricity.     

EMD analysis of solar insolation

Summary A new time series analysis technique, Empirical Mode Decomposition (EMD), which has been successfully applied to nonlinear and nonstationary data, is used to examine paleoclimate cycles in the Pleistocene (1 Ma bp–20 Ka bp). The purpose of this study is to improve knowledge of the climatic significance of solar insolation. The results show that the eccentricity band signal is much larger than previously estimated, having an amplitude of about 1% of solar irradiance which is comparable to the amplitude of the precession and obliquity band signals. This finding implies the need to reconsider the role of solar radiation on the formation and maintenance of quaternary ice sheet cycles.     

Estimating global solar radiation

A model is presented to calculate daily totals of global solar radiation. First, cloudless sky radiation is evaluated from transmission due to absorption and scattering. Cloud effects are added using cloud layer transmission. A simple expression to account for additional radiation due to reflection between the ground surface and cloud bases is also included. Atmospheric transmissions are obtained from previous studies. Precipitable water and observations of cloud type and amount for different layers in the atmosphere are the only meteorological variables required. The model is evaluated and tested with data collected at stations in and around Lake Ontario: a lake station near Grimsby in 1969 and land stations at Burlington, Scarborough, Peterborough, Trenton and Kingston, Ontario in 1972 and 1973 during the International Field Year for the Great Lakes. Good agreement between calculated and measured radiation was obtained at all stations, particularly for 5- and 10-day means. Model performance was largely independent of both cloud amount and season.     

日射仪器的温度特性

本文主要叙述广泛使用于气象、农业、能源、科研等部门测量太阳辐射的DFY-1型直接辐射表和DFY-2型天空辐射表的温度特性。     

Dynamic behaviour of diffuse solar radiation

In the present experimental study, the dynamic properties of diffuse solar radiation have been assessed for both overcast and discrete clouds. It is shown that the Baseline Surface Radiation Network methodology can be accepted completely for studying diffuse radiation.     

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     

Evaluation and estimation of daily global solar radiation from the estimated direct and diffuse solar radiation

Active layer plays a key role in regulating the dynamics of hydrothermal processes and ecosystems that are sensitive to the changing climate in permafrost regions. However, little is known about the hydrothermal dynamics during freeze-thaw processes in permafrost regions with different vegetation types on the Qinghai-Tibetan Plateau (QTP). In the present study, the freezing and thawing processes at four sites (QT01, 03, 04, and 05) with different vegetation types on the QTP was analyzed. The results indicated that the impact on the soil water and heat during the summer thawing process was markedly greater than that during the autumn freezing process. Furthermore, the thermal-orbit regression slopes for all sites exhibited a homologous variation as the depth increased, with the slowest attenuation for the meadow sites (QT01 and QT03) and a slightly faster attenuation for the desert steppe site (QT05). The air and ground surface temperatures were similar in winter, but the ground surface temperature was significantly higher than the air temperature in summer in the radiation-rich environment at all sites on the QTP. The results also indicated that the n-factors were between 0.36 and 0.55 during the thawing season, and the annual mean temperature near the permafrost table was between − 1.26 and − 1.84 °C. In the alpine desert steppe region, the thermal conditions exhibited to show a warming trend, with a current permafrost table temperature of − 0.22 °C. The annual changing amplitude of the ground temperature at the permafrost table was different for different vegetation types.     

The medieval solar activity maximum

Paleoclimatic studies of the Medieval Solar Maximum (c. A.D. 1100–1250, corresponding with the span of the Medieval Warm Epoch) may prove useful because it provides a better analog to the present solar forcing than the intervening era. The Medieval Solar Activity Maximum caused the cosmogenic isotope production minimum during the 12th and 13th Centuries A.D. reflected by ¹⁴C and¹⁰Be records stored in natural archives. These records suggest solar activity has returned to Medieval Solar Maximum highs after a prolonged period of reduced solar activity. Climate forcing by increased solar activity may explain some of this century's temperature rise without assuming unacceptably high climate sensitivity. By analogy with the Medieval Solar Activity Maximum, the contemporary solar activity maximum may be projected to last for 150 years. The maximum temperature increase forced by increased solar activity stays well below the predicted doubled atmospheric CO₂ greenhouse forcing.     

Past millennial solar forcing magnitude

A set of global climate model simulations for the last thousand years developed by the Max Planck Institute is compared with paleoclimate proxy data and instrumental data, focusing on surface temperatures for land areas between 30° and 75°N. The proxy data are obtained from six previously published Northern Hemispheric-scale temperature reconstructions, here re-calibrated for consistency, which are compared with the simulations utilizing a newly developed statistical framework for ranking several competing simulations by means of their statistical distance against past climate variations. The climate model simulations are driven by either “low” or “high” solar forcing amplitudes (0.1 and 0.25 % smaller total solar irradiance in the Maunder Minimum period compared to the present) in addition to several other known climate forcings of importance. Our results indicate that the high solar forcing amplitude results in a poorer match with the hemispheric-scale temperature reconstructions and lends stronger statistical support for the low-amplitude solar forcing. However, results are likely conditional upon the sensitivity of the climate model used and strongly dependent on the choice of temperature reconstruction, hence a greater consensus is needed regarding the reconstruction of past temperatures as this currently provides a great source of uncertainty.     

几种水平面太阳总辐射量计算模型的对比分析

利用中国区域1961-1999年39 a间98个常规气象观测数据,建立6个模型分别以天文辐射、干洁大气总辐射和湿洁大气总辐射为起始数据,进行太阳辐射日总量的模拟,对比分析了6个水平面太阳总辐射量计算模型的性能.结果表明:在三种起始数据中,干洁大气总辐射和湿洁大气总辐射均能较好地体现宏观地势对太阳辐射空间分布的影响,以湿洁大气总辐射为起始数据的计算模型拟合精度相对较高.对6个水平面太阳总辐射量计算模型的对比分析发现:2个以日照百分率为主导因子,气温日较差为修正项的综合模型拟合误差最小,精度最高;经典的日照百分率模型次之,但其模型系数最稳定可靠;3个气温日较差模型拟合效果最差.最终选用经验系数稳定、拟合精度较高的日照百分率模型,制作了2001年中国水平面太阳辐射日总量空间分布图.     

Spectral distribution of solar radiation in Athens

Summary A 25-year (1966–1990) record of measurements of the broadband direct solar irradiances performed in Athens, has been utilized to determine the radiant energy distribution in several spectral bands. Using these data the year-to-year trend of the time sequences of the mean values of the irradiation ratios in the various spectral intervals, viz. blue, green/orange, red, and photosynthetically active radiation (PAR) and the total direct irradiance for the whole spectrum, are evaluated.From this trend the following can be concluded: the blue spectral band (0.380–0.525 m) decreased from the beginning of the examined period until the mid-seventies and then increased gradually; the red band (0.630–0.710 m) shows similar trend but opposite in sense. The PAR band (0.380–0.710 m) decreased slightly until 1985 and then increases. In the green/orange band (0.525–0.630 m) the trend can be considered as nearly constant throughout the examined period. This trend of the irradiation ratios is related to the aerosol and gaseous pollutant content of the atmosphere, which probably reflects the urbanization, industrialization and heavy traffic conditions of the Athens area, during the last three decades.With 2 Figures     

Long-term variations of solar radiation in Europe

Presented are the results of the analysis of the series of seasonal and annual means of short-wave solar radiation measured at 180 actinometric stations of Europe in 1964–2010. It is demonstrated that there are two strongly pronounced periods, namely, the decrease from the early 1960s to the late 1980s and the increase in the subsequent 20 years. Total solar radiation decreased by 1.8% per 10 years on average during the first period and increased by 2.9% per 10 years during the second period. The increase in solar radiation during the second period is observed at the majority of stations due to the increase in the direct solar radiation (by 8.3% per 10 years on average). The diffuse radiation decreased by 3.1% on average for that period. The highest values of the ratio of the diffuse radiation to the direct one were registered in the 1980s–early 1990s.     

The solar cycle and Indian rainfall

Summary The objective of this study is to examine critically the relationship between solar cycles and Indian monsoon rainfall, for the period 1871–1984, and to search for significant periodicities, by utilizing the maximum entropy spectral technique (MEST). The results of this study using MEST show clearly a significant 11-year cycle in solar activity and rainfall. Also present is a significant 7.33-year cycle in rainfall. The double (Hale) sunspot cycle is not discernible here either in sunspot number or in rainfall. The cross-spectral analysis between the sunspot number and rainfall confirms the existence of a reasonable correlation over an 11-year cycle with a relative phase lag of 0.16 year (sun lead).

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Zusammenfassung Zweck dieser Studie ist die kritische Überprüfung des Zusammenhangs zwischen Sonnenzyklus und dem indischen Monsunregen im Zeitraum 1871–1984 und die Festlegung spezifischer Periodizitäten mittels der Maximal-Entropie-Analyse (MEST). Die Resultate zeigen einen signifikanten 7,33-jährigen Niederschlagszyklus. Der doppelte (Hale) Sonnenfleckenzyklus ist hierbei nicht ausnehmbar, weder bei der Anzahl der Sonnenflecken, noch beim Niederschlag. Die Kreuz-Spektralanalyse zwischen Sonnenfleckenzyklus und Niederschlag bestätigt die Existenz einer Korrelation über einen 11jährigen Zyklus mit einer relativen Phasenverzögerung von 0,16 Jahren.

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On leave from the Indian Institute of Tropical Meteorology, Pune, India.

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With 3 Figures