Estimation of Global Solar Radiation for Four Selected Sites in Nepal Using Sunshine Hours, Temperature and Relative Humidity

Rational and accurate solar energy databases, essential for designing, sizing and performing the solar energy systems in any part of the world, are not easily accessible in different localities of Nepal. In this study, daily global solar radiation, sunshine hours and meteorological data for Biratnagar, Kathmandu, Pokhara and Jumla have been used to derive the regression constants. The linear regression technique has been used to develop a model for Biratnagar, Kathmandu, Pokhara and Jumla. The model has calculated the global solar radiation for these locations. The values of global solar radiation estimated by the model are found to be in close agreement with measured values of respective sites. The estimated values were compared with Angstrom-Prescott model and examined using the root mean square error (RMSE), mean bias error (MBE), mean percentage error (MPE), coefficient of regression (R), coefficient of determinant (R2) and correlation coefficient (CC) statistical techniques. Thus, the resultant correlations and linear regression relations may be then used for the locations of similar meteorological/geographical characteristics and also can be used to estimate the missing data of solar radiation for the respective site.

The Disagreement between Anisotropic-Isotropic Diffuse Solar Radiation Models as a Function of Solar Declination: Computing the Optimum Tilt Angle of Solar Panels in the Area of Southern-Italy

In this paper a simulation to maximize the global solar radiation on a sloped collecting surface was applied to typical latitudes in the area of southern Italy, to calculate the optimum tilt angle of solar panels on building structures or large photovoltaic power plants located in that geographical area. Indeed, the area of southern Italy and in particular Sicily and Calabria are the top of European locations for acquiring solar energy. Some models of diffuse solar irradiance were taken into account to determine panels inclinations that maximized the impinging solar radiation by means of global horizontal solar radiation data provided from the Italian Institute of ENEA (Italy). An algorithm was used for the simulation providing a set of tilt angles for each latitude. The optimum tilt angle values obtained from the simulation resulted to be strictly related to the model of diffuse solar radiation that was used. Indeed, the disagreement between the values obtained using anisotropic models of diffuse solar radiation and those obtained from the isotropic model resulted to decrease significantly with increasing solar declination, showing that the isotropic model can be reliable only in summer months.

Estimation of monthly global solar radiation over twelve major cities of Libya

This study aims to estimate monthly averaged daily horizontal global solar radiation.Measured climatological data collected at twelve major cities located across Libya’s map were used to establish 7 different empirical models.The empirical coefficients of the models were calculated using the least square method.The accuracy of the models was evaluated using different statistical criteria such as Taylor diagram,mean absolute percentage error,MAPE,and root mean square error,RMSE.The results indicated that the sunshine duration-based models are more accurate than air temperature-based models,and the best performance was obtained by the quadratic regression model for all twelve Libyan cities.Moreover,this regression model can be used for the prediction of monthly mean horizontal global solar radiation at a specific site across Libya’s regions with minimum error.Furthermore,the results of the global solar irradiance produced by this method can be used for designing solar systems applications.

On the Solar Climate of the Moon and the Resulting Surface Temperature Distribution

The solar climate of our Moon is analyzed using the results of numerical simulations and the recently released data of the Diviner Lunar Radiometer Experiment (DLRE) to assess (a) the resulting distribution of the surface temperature, (b) the related global mean surface temperature Ts>, and (c) the effective radiation temperature Te often considered as a proxy for Ts> of rocky planets and/or their natural satellites, where Te is based on the global radiation budget of the well-known “thought model” of the Earth in the absence of its atmosphere. Because the Moon consists of similar rocky material like the Earth, it comes close to this thought model. However, the Moon’s astronomical features (e.g., obliquity, angular velocity of rotation, position relative to the disc of the solar system) differ from that of the Earth. Being tidally locked to the Earth, the Moon’s orbit around the Sun shows additional variation as compared to the Earth’s orbit. Since the astronomical parameters affect the solar climate, we predicted the Moon’s orbit coordinates both relative to the Sun and the Earth for a period of 20 lunations starting May 24, 2009, 00:00 UT1 with the planetary and lunar ephemeris DE430 of the Jet Propulsion Laboratory of the California Institute of Technology. The results revealed a mean heliocentric distance for the Moon and Earth of 1.00124279 AU and 1.00166376 AU, respectively. The mean geocentric distance of the Moon was 384792 km. The synodic and draconic months deviated from their respective means in a range of -5.7 h to 6.9 h and ±3.4 h, respectively. The deviations of the anomalistic months from their mean range between -2.83 d and 0.97 d with the largest negative deviations occurring around the points of inflection in the curve that represents the departure of the synodic month from its mean. Based on the two successive passages of the Sun through the ascending node of the lunar equator plane, the time interval between them corresponds to 347.29 days, i.e., it is slightly longer than the mean draconic year of 346.62 days. We computed the local solar insolation as input to the multilayer-force restore method of Kramm et al. (2017) that is based on the local energy budget equation. Due to the need to spin up the distribution of the regolith temperature to equilibrium, analysis of the model results covers only the last 12 lunations starting January 15, 2010, 07:11 UT1. The predicted slab temperatures, Tslab, considered as the realistic surface temperatures, follow the bolometric temperatures, Tbol, acceptably. According to all 24 DLRE datasets related to the subsolar longitude øss, the global averages of the bolometric temperature amounts to Tbol=201.1k± 0.6K. Based on the globally averaged emitted infrared radiation of FIR>=290.5W·m-2± 3.0W·m-2 derived from the 24 DLRE datasets, the effective radiative temperature of the Moon is Te, M>=Tbol>1/4=271.0k± 0.7K so that Tbol>≅0.742Te, M. The DLRE observations suggest that in the case of rocky planets and their natural satellites, the globally averaged surface temperature is notably lower than the effective radiation temperature. They differ by a factor that depends on the astronomical parameters especially on the angular velocity of rotation.

Evaluating effects of atmospheric CO_2 on stability of global climate:a cell-to-cell mapping approach

Atmospheric carbon dioxide concentration [CO2],incoming solar radiation and sea ice coverage are among the most important factors that control the global climate.By applying the simple cell-to-cell mapping technique to a simplified atmosphere-ocean-sea ice feedback climate model,effects of these factors on the stability of the climatic system are studied.The current climatic system is found to be stable but highly nonlinear.The resiliency of stability increases with [CO2] to a summit when [CO2] reaches 290 μL/L which is comparable to the pre-industrial level,suggesting carbon dioxide is essential to the stability of the global climate.With [CO2] rising further,the global climate stability decreases,the mean ocean temperature goes up and the sea ice coverage shrinks in the polar region.When the incoming solar radiation is intensified,the ice coverage gradually diminishes,but the mean ocean temperature remains relatively constant.Overall,our analysis suggests that at the current levels of three external factors the stability of global climate is highly resilient.However,there exists a possibility of extreme states of climate,such as a snow-ball earth and an ice-free earth.

Influence of complex topography on global solar radiation in the Yangtze River Basin

Global solar radiation（GSR） is the most direct source and form of global energy, and calculation of its quantity is highly complex due to influences of local topography and terrain inter-shielding. Digital elevation model（DEM） data as a representation of the complex terrain and multiplicity condition produces a series of topographic factors（e.g. slope, aspect, etc.）. Based on 1 km resolution DEM data, meteorological observations and NOAA-AVHRR remote sensing data, a distributed model for the calculation of GSR over rugged terrain within the Yangtze River Basin has been developed. The overarching model permits calculation of astronomical solar radiation for rugged topography and comprises a distributed direct solar radiation model, a distributed diffuse radiation model and a distributed terrain reflectance radiation model. Using the developed model, a quantitative simulation of the GSR space distribution and visualization has been undertaken, with results subsequently analyzed with respect to locality and terrain. Analyses suggest that GSR magnitude is seasonally affected, while the degree of influence was found to increase in concurrence with increasing altitude. Moreover, GSR magnitude exhibited clear spatial variation with respect to the dominant local aspect; GSR values associated with the sunny southern slopes were significantly greater than those associated with shaded slopes. Error analysis indicates a mean absolute error of 12.983 MJm-2 and a mean relative error of 3.608%, while the results based on a site authentication procedure display an absolute error of 22.621 MJm-2 and a relative error of 4.626%.

Hypersphere World-Universe Model

Dirac’s themes were the unity and beauty of Nature. He identified three revolutions in modern physics: Relativity, Quantum Mechanics and Cosmology. In his opinion: “The new cosmology will probably turn out to be philosophically even more revolutionary than relativity or the quantum theory, perhaps looking forward to the current bonanza in cosmology, where precise observations on some of the most distant objects in the universe are shedding light on the nature of reality, on the nature of matter and on the most advanced quantum theories” [Farmelo, G. (2009) The Strangest Man. The Hidden Life of Paul Dirac, Mystic of the Atom. Basic Books, Britain, 661 p]. In 1937, Paul Dirac proposed the Large Number Hypothesis and the Hypothesis of the variable gravitational “constant”;and later added the notion of continuous creation of Matter in the World. The developed Hypersphere World-Universe Model (WUM) follows these ideas, albeit introducing a different mechanism of matter creation. In this paper, we show that WUM is a natural continuation of Classical Physics and it can already serve as a basis for a New Cosmology proposed by Paul Dirac.

Hypersphere World-Universe Model: Evolution of the World

The main objective of this paper is to discuss the Evolution of a 3D Finite World (that is a Hypersphere of a 4D Nucleus of the World) from the Beginning up to the present Epoch in frames of World-Universe Model (WUM). WUM is the only cosmological model in existence that is consistent with the Law of Conservation of Angular Momentum. To be consistent with this Fundamental Law, WUM introduces Dark Epoch (spanning from the Beginning of the World for 0.45 billion years) when only Dark Matter (DM) Macroobjects (MOs) existed, and Luminous Epoch (ever since for 13.77 billion years) when Luminous MOs emerged due to Rotational Fission of Overspinning DM Superclusters’ Cores and self-annihilation of Dark Matter Particles (DMPs). WUM envisions that DM is created by the Universe in the 4D Nucleus of the World. Dark Matter Particles (DMPs) carry new DM into the 3D Hypersphere World. Luminous Matter is a byproduct of DMPs self-annihilation. By analogy with 3D ball, which has two-dimensional sphere surface (that has surface energy), we can imagine that the 3D Hypersphere World has a “Surface Energy” of the 4D Nucleus. WUM solves a number of physical problems in contemporary Cosmology and Astrophysics through DMPs and their interactions: Angular Momentum problem in birth and subsequent evolution of Galaxies and Extrasolar systems—how do they obtain it;Fermi Bubbles—two large structures in gamma-rays and X-rays above and below Galactic center;Missing Baryon problem related to the fact that the observed amount of baryonic matter did not match theoretical predictions. WUM reveals Inter-Connectivity of Primary Cosmological Parameters and calculates their values, which are in good agreement with the latest results of their measurements. In 2013, WUM predicted the values of the following Cosmological parameters: gravitational, concentration of intergalactic plasma, and the minimum energy of photons, which were experimentally confirmed in 2015-2018. “The Discovery of a Supermassive Compact Object at the Centre of Our Galaxy” (Nobel Prize in Physics 2020) made by Prof. R. Genzel and A. Ghez is a confirmation of one of the most important predictions of WUM in 2013: “Macroobjects of the World have cores made up of the discussed DM particles. Other particles, including DM and baryonic matter, form shells surrounding the cores”.

基于气象要素修正的逐时总辐射模型研究——以西安地区为例

该文引入逐时气象要素对分解模型进行修正,针对C.P.R模型,提出一种基于日照时数、温度以及相对湿度的多气象要素修正模型。基于西安2015年10月1日—2017年7月31日观测数据,分析3种天气类型下模型修正前、后的计算误差,结果显示多气象要素修正模型的各项误差指标均低于未修正模型,且对于多云天气的修正效果最明显,平均可达2%。基于多气象要素的C.P.R修正模型考虑了气象及辐射观测数据现状,可为其他地区计算水平面逐时总辐射提供方法借鉴。

中国北方太阳总辐射模型优化及适用性评价

太阳总辐射(Rs)模型是估算地表能源最简单的方法,对区域ET_(0)管理、水资源及太阳能利用具有重要意义。选取中国北方47个代表性气象站点(1994-2016年)逐日数据,采用鱼群算法优化温度模型(T1、T2和T3)、日照时数模型(N1、N2和N3)和混合模型(M1),在日和月尺度评价太阳总辐射模拟精度。结果表明:在日尺度上,基于日照时数的模型(N1-N3)精度最高,其次为基于温度的模型(T1-T3),混合模型相对较差(M1),R^(2)分别为0.90~0.93、0.64~0.78和0.80~0.90,MAE分别为1.47~1.95、2.51~4.33和4.88~6.28 MJ/(m^(2)·d);在月尺度上,基于日照时数的模型(N1-N3)精度最高,其次为混合模型(M1)和基于温度的模型(T1-T3),R2分别为0.94~0.97、0.92~0.95和0.86~0.95,MAE分别为25.45~44.29、36.21~102.73和101.25~144.56 MJ/(m^(2)·d)。因此,推荐基于日照时数模型模拟太阳总辐射。

Correlations for estimating solar radiation using sunshine hours and temperature measurement in Osogbo, Osun State, Nigeria

In this study, the global solar radiation on horizontal surface in Osogbo, Osun state, Nigeria was analyzed using ll-year data （1997-2007）. Correlations using linear and quadratic expressions were developed to relate the global solar radiation on horizontal surface based on relative sunshine hours and temperature measurements for evaluating the monthly average daily global solar radiation. The calculated monthly clearness index values indicate that the prevailing weather condition in Osogbo is heavily overcast. All the developed quadratic correlations gave better correlation coefficients （0.834, 0.872 and 0.823 respectively） than the linear models. However, the Hargreaves and Samani related based quadratic model gave the best among the three developed quadratic expressions and is therefore suggested for estimating the monthly global radiation in this site and its surroundings.

Smart model for accurate estimation of solar radiation

Prediction of solar radiation has drawn increasing attention in the recent years.This is because of the lack of solar radiation measurement stations.In the present work,14 solar radiation models have been used to assess monthly global solar radiation on a horizontal surface as function of three parameters:extraterrestrial solar irradiance(),duration sunshine()and daylight hours().Since it has been observed that each model is adequate for some months of the year,one model cannot be used for the prediction of the whole year.Therefore,a smart hybrid system is proposed which selects,based on the intelligent rules,the most suitable prediction model of the 14 models listed in this study.For the test and evaluation of the proposed models,Tamanrasset city,which is located in the south of Algeria,is selected for this study.The meteorological data sets of five years(2000–2004)have been collected from the Algerian National Office of Meteorology(NOM),and two spatial databases.The results indicate that the new hybrid model is capable of predicting the monthly global solar radiation,which offers an excellent measuring accuracy of values ranging from 93%to 97%in this location.

中国陆地生态信息空间化技术研究(Ⅱ)——太阳辐射要素

论文以MTCLIM模型为基础,根据中国的实际情况,对模型的参数进行了优化与调整,建立了适合我国的基于温度、降水和相对湿度等因子的太阳总辐射计算模式。提出了太阳总辐射空间化的模式,即先参数化,然后采用合适的空间插值方法(论文中采用地统计学方法)实现空间化。同时鉴于逐日太阳总辐射空间化工作量庞大,提出了在计算月均日结果的基础之上,采用线性插值技术快速得到逐日太阳辐射值。从而得到了中国太阳总辐射的空间分布结果。

北京地区的太阳辐射分析

根据北京市1958年-2000年的太阳辐射和日照时间的日值数据资料,对北京市的年太阳辐射历年平均 值进行了计算,分析了北京市太阳辐射量的长期变化;研究了太阳总辐射和日照时间之间的关系以及散射辐射 与总辐射之间的关系,分别得到了估算太阳总辐射和散射辐射的经验公式,研究中对所得到的经验公式进行了 误差统计,结果表明能满足工程应用的要求。

日太阳总辐射推算模型

为了推算广大无辐射观测地区的日太阳总辐射,需要根据有辐射观测地区的资料建立日太阳总辐射的推算模型。本文在深入了解国内太阳辐射观测与国内外太阳总辐射推算方法的基础上,设计了利用日照百分率、降水量与大气可降水量、温度日较差等因子推算日太阳总辐射的模型,选取武汉、宜昌、郑州2005年全年无加盖的、真实可信的太阳总辐射资料为样本序列,根据最小二乘法分别求出有日照和无日照两种情况下的模型参数,并对2005年进行了回代检验和2006年1-8月时段的独立样本检验。结果表明:模型推算序列与实际值序列的相关性均达到极显著程度,对2005-2006年8月推算的平均绝对误差和相对误差分别为1.31M J.m-2.d-1和9.5%,精度高,可以用于无辐射观测地区的日太阳总辐射的推算。

复杂地形下长江流域太阳总辐射的分布式模拟

利用长江流域气象站1960-2005年的观测资料(包括常规气象站点资料和辐射站点资料)、NOAA-AVHRR遥感数据(反演地表反照率),以1km×1km的数字高程模型(DEM)反映地形状况的主要数据,通过基于DEM数据的起伏地形下天文辐射模型和地形开阔度模型,分别建立了长江流域太阳直接辐射、散射辐射和地形反射辐射分布式模型,实现了长江流域太阳总辐射模拟,并对总辐射模拟结果进行了时空分布规律分析和对其受季节、纬度、地形因子(高度、坡度和坡向等)影响的局部规律分析,以及模拟结果的误差分析和站点验证分析。结果显示:太阳总辐射在季节上受影响的程度依次是春季>冬季>夏季>秋季;随着高度、坡度、纬度的增加,太阳总辐射受坡向影响的程度呈增强趋势,从坡向上看,向阳山坡(偏南坡)对太阳总辐射量明显高于背阴坡(偏北坡)。模拟的平均绝对误差为13.04177MJm-2,相对误差平均值3.655%,用站点验证方法显示:模拟绝对误差为22.667MJm-2,相对误差为4.867%。

太阳辐射直散分离模型比较研究——以北京地区为例

在建筑能耗模拟与太阳能建筑系统设计中,逐时的太阳直射和散射气象数据是最重要的基本参数。由于中国辐射观测数据的缺失,逐时直射和散射数据很难获得。很多学者对此进行了研究,提出了数十种直散分离模型。采用北京地区2009年—2011年3年太阳总辐射和散射实测数据,选取Erbs模型、Orglill模型、清华大学随机气象模型、宇田川光弘模型、张晴原模型5个代表性的直散分离模型进行计算验证,分析比较了实测数据和计算数据之间的相关系数R、均方根误差RMSE和相对误差RE,得出晴空指数Kt可以作为最主要的影响因子,Erbs模型预测散射的准确率最高,其次为张晴原模型和Orglill and Hollands模型。

中国太阳总辐射的日照类估算模型

对Angstr m-Prescott型日总太阳辐射月均值估算公式进行了修正,根据国内69个气象台站的太阳辐射和日照资料对修正公式中的系数进行了拟合,给出了适合国内不同地区使用的统一公式,经过误差分析,所得到的统一估算公式可满足实际工程应用的要求;并利用得到的公式对国内太阳能辐射资源的分布进行了分析.本文的研究结果为不同地区合理利用太阳能提供理论依据.

贵州高原复杂地形下太阳总辐射精细空间分布

海拔、坡度、坡向以及周围地形遮蔽作用,造成山区各部位接受到的太阳辐射能有很大差异。在前人研究的基础上,对以前的模型进行了一些改进,考虑了坡度、坡向和地形相互遮蔽作用对复杂地形下天文辐射的影响,基于数字高程模型(DEM)数据,研制了以复杂地形下天文辐射为起始数据的复杂地形下太阳总辐射的分布式模型,在模型中还考虑了散射辐射的各向异性及坡地反射辐射对复杂地形下太阳总辐射的影响。应用100m×100m分辨率的DEM数据及气象站常规观测气象资料,计算了贵州高原复杂地形下100m×100m分辨率的复杂地形下太阳总辐射。结果表明:(1)局地地形因子如坡度、坡向、地形遮蔽等对太阳总辐射影响显著,地形对复杂地形下太阳总辐射的影响是不容忽视的。(2)在缺乏复杂地形下坡面考察资料的情况下,建立以常规气象站观测资料为主的物理经验统计模型是实现细网格辐射资源计算的可行途径。

日总辐射推算模型在中国的适用性研究

归纳了经验模型的类型并基于中国数据状况提出3大类8种模型形式用于比较和分析。选择覆盖中国5个建筑气候区的7个典型台站2000-2013年的数据，引入相关系数R^2和均方根误差（RMSE）作为衡量标准完成模型适用性研究。研究发现在晴空指数较高的地区可以选择基于日照时数的模型（模型2），随着晴空指数的降低，二参数（模型6）及三参数（模型8）模型的推算结果优于单参数模型（模型2）。研究为在不同地域选择适当的日总辐射推算模型提供依据。