Regional and Monthly Assessment of Extraterrestrial Solar Radiations in Pakistan

The monthly extraterrestrial solar radiations (ESR) have been simulated separately for all the months of the year. The subtropical location and distribution of mountains and their height determine the spatial distribution and amount of ESR in Pakistan. The mountains, piedmonts, enclosed valleys and plains show distinct diversity of ESR values. The assessment acknowledged that countries like Pakistan with ever increasing demand of energy receive sufficient amount of ESR that could be linked with solar irradiance where development of solar energy has great potential. The simulation was done with the help of ArcGIS based on distributed modeling.

Trends in Global Solar Radiation and Sunshine Duration in Past Two Decades in Japan

Global solar radiation (GSR) is an essential physical quantity for agricultural management and designing infrastructures. Because GSR has often been modeled as a function of sunshine duration (SD) and day length for a given set of locations and calendar days, analyzing interannual trends in GSR and SD is important to evaluate, predict or regulate the cycles of energy and water between geosphere and atmosphere. This study aimed to exemplify interannual trends in GSR and SD, which had been recorded from 2001 to 2022 in 40 meteorological stations in Japan, and validate the applicability of an SD-based model to the evaluation of GSR. Both the measured GSR and SD had increased in many of the stations in the study period with averaged rates of 0.252 [W·m−2·y−1] and 0.015 [h·d−1·y−1], respectively. The offset and the slope of the SD-based model were estimated by fitting the model to the measured data sets and were found to have been almost constant with the averages of 0.201[-] and 0.566[-], respectively, indicating that characteristics of the SD-GSR relation had not varied for the 22-year period and that the model and its parameter set can be stationarily applicable to the analyses and predictions of GSR in recent years. The stable trends in both parameters also implied that the upward trend in SD can be a main explanatory factor for that in the measured GSR. The upward trend in SD had coincided with the increase in the frequency of heavy-shortened rains, suggesting that the time period of each rainfall event had gradually decreased, which may be attributable to the obtained upward trend in SD. Further studies are required to clarify if there is some cause-effect relation between the changes in rainfall patterns and the standard level of solar radiation reaching the land surface.

Deriving the slope-mean shielded astronomical solar radiation spectrum and slope-mean possible sunshine duration spectrum over the Loess Plateau

Solar radiation is often shielded by terrain relief, especially in mountainous areas, before reaching the surface of the Earth. The objective of this paper is to study the spatial structures of the shielded astronomical solar radiation(SASR) and the possible sunshine duration(PSD) over the Loess Plateau. To this end, we chose six test areas representing different landforms over the Loess Plateau and the software package of Matlab was used as the main computing platform. In each test area, 5-m-resolution digital elevation model established from 1:10,000 scale topographic maps was used to compute the corresponding slope, SASR and PSD. Then, we defined the concepts of the slope-mean SASR spectrum and the slope-mean PSD spectrum, and proposed a method to extract them from the computed slope, SASR and PSD over rectangular analysis windows. Using this method, we found both spectrums in a year or in a season for each of the four seasons in the six test areas. Each spectrum was found only when the area of the corresponding rectangular analysis window was greater than the corresponding stable area of the spectrum. The values of the two spectrums decreased when the slope increased.Furthermore, the values of the stable areas of the spectrums in a year or in a season were positively correlated with the variable coefficients of the slope or the profile curvature. The values of the stable areas of the two spectrums in a year or in a season may represent the minimum value of test areas for corresponding future research on the spatial structures of the SASR or PSD. All the findings herein suggest that the spatial structures of the PSD and the SASR are caused by the interactions between solar radiation and terrain relief and that the method for extracting either spectrum is effective for detecting their spatial structures. This study may deepen our understanding of the spatial structure of solar radiation and help us further explore the distribution of solar energy in mountainous regions.

Studying Air Pollution with Kitt Peak Solar Flux Atlas—Analysis Method and Results of Observation

For the measurement of atmospheric NO2 vertical column density (VCD), Kitt Peak Solar Flux Atlas can be substituted as an extraterrestrial solar radiation. Compared with differential analysis method, the Taylor expansion of integrated transfer equation underestimates the VCD. This underestimation is as large as 35% when the amount of NO2 is 1 × 1017 cm?2 and observation is conducted with an air mass factor of 10. Even when the VCD is 2 × 1016 cm?2 and the air mass factor is 4, the relative error of the retrieved VCD is still no less than 3%. If the observation is restricted under the small air mass factor condition (≤ 4), with Kitt Peak Solar spectrum as an extraterrestrial solar radiation, only an atmospheric layer of 2 km thick from ground can be studied, which will make the absorption too weak to be detected by normal instruments. The VCD in winter Tokyo area was observed and analyzed by differential method, which shows a good precision even when the absorption is as low as 3%. The largest average VCD was about 1.3 × 1017 cm-2, and the lowest was about 1.3 × 1016 cm?2. The trend of its variation was almost the same as the ground level observation by Saltzman reagent method. Key words Vertical column density (VCD) - Extraterrestrial solar radiation - NO2 - Atmospheric contamination

Solar Radiation Climatology Calculation in China

The Angstrom-Prescott formula is commonly used in climatological calculation methods of solar radiation simulation. Fitting the coefficients is carried out using linear regression and in recent years it has been found that these coefifcients have obvious spatial variability. A common solution is to divide the study area into several subregions and ift the coefifcients one by one. Here, we use ground observation data for sunshine hours and solar radiation from 1961 to 2010. Adopting extraterrestrial radiation as the initial value, Angstrom-Prescott coefifcients are obtained by Geographically Weighted Regression at a national scale. The surfaces of solar radiation are obtained on the basis of the surfaces of sunshine hours interpolated by high accuracy surface modeling and astronomical radiation;results from spatial y nonstationary and error comparison tests show that Angstrom-Prescott coefifcients have signiifcant spatial nonstationarity. Compared to existing research methods, the method presented here achieves a better simulation effect.

起伏地形下天文辐射分布式估算模型

基于数字高程模型(DEM),建立了起伏地形下天文辐射分布式估算模型.模型全面考虑了地形因子对天文辐射的影响,只需DEM数据作为输入项,适用于遥感图像处理、地理信息系统等数据处理平台.以1km×1km分辨率的DEM数据作为地形的综合反映,计算了我国全年各月天文辐射的空间分布.结果表明:我国年天文辐射总量有明显的纬向分布特点,随着纬度的降低,年天文辐射总量由北向南增加;由于受坡向、坡度和地形遮蔽因子影响,山区天文辐射表现出非地带性分布特征.本文所提供的我国天文辐射数据产品,可作为基础地理数据供相关研究应用.

近40a来青藏高原地区总辐射变化特征分析

利用青藏高原及周边22个日射站近40a的总辐射及日照百分率资料确定了Angstrom-Prescott模型(APM)系数,结合高原及毗邻地区116个地面站的资料估算了高原地区近40a的总辐射.结果表明:高原主体光照充沛,年均日照时数可达3000h以上,有较好的利用前景;总辐射40a平均年总量在高原西部为高值区,此高值带向东北和东南延伸,其中北支可抵达内蒙古高原.年代际变化在高原及周边地区不一致,但从整体上看,总辐射距平值60、70年代为正值,表明这一时期高原总辐射增大;80、90年代总辐射距平为负,这一时期总辐射减小.火山活动是该时段总辐射减小的一个重要原因;总辐射随着纬度的增大而减小,随着海拔、日照百分率的增大而增大.纬度、海拔、日照3个因子中,日照是总辐射的一个主要影响因子,纬度对总辐射影响较大,海拔对总辐射影响较小;高原地区总辐射变差系数大值区在高原西部.就平均状况而言,高原地区总辐射变差系数仅为0.031,表明高原地区总辐射波动相对较小,总辐射较稳定.

中国三种太阳辐射起始数据分布式模拟

天文辐射、干洁大气总辐射和湿洁大气总辐射是太阳辐射模拟的3种重要起始数据。依托Iqbal Model C和起伏地形下干/湿洁大气总辐射模型,实现了水平面和起伏地形下干/湿洁大气总辐射分布式模拟。以DEM数据作为地形的综合反映,结合常规气象资料,计算了水平面和起伏地形下中国1 km×1 km分辨率日天文辐射量、干洁大气总辐射量、湿洁大气总辐射量的空间分布,并对3种太阳辐射起始数据的时空分布特征做了对比分析。结果表明:3种辐射量均遵循随纬向变化的宏观分布规律;水平面干/湿洁大气总辐射量的分布体现了海拔的影响,水平面湿洁大气总辐射量的分布还体现了水汽分布的影响;起伏地形下的3种辐射量能很好的体现坡度、坡向和地形之间相互遮蔽等局部地形特征对辐射量的影响;以干/湿洁大气总辐射作为起始数据,将有助于提高太阳总辐射的模拟精度。

坡面天文辐射总量的椭圆积分模式

本文讨论了坡面天文辐射总量的计算方法。在坡面日出日没时角配置关系及其变化规律的基础上建立了椭圆积分模式。该模式可计算全球范围内任意坡向、坡度在任意时段内的坡面天文辐射总量。

水平面上太阳辐射空间模拟对比研究

面域的太阳辐射数据是进行其他各项有关辐射研究的基础。由辐射台站的点数据来模拟太阳辐射的空间分布时,传统的模拟方式都会产生精度与效率之间的矛盾。直接以辐射观测值与其影响因子建立非线性回归模型,以各因子的面域数据来模拟水平面上太阳辐射的空间分布,与引入了辐射基数值的模式相比,模型的误差更小,复相关系数大于0．96,运算效率提高29-286倍。当采用模拟的天文辐射经验公式来计算辐射基数时效率仍可提高2- 11倍。用两种方式的回归模型模拟中国1km栅格的水平面太阳辐射,平均差值仅2．41％,而本文模式模拟结果与实测值更为接近。

福建省散射辐射的计算方法及其分布特征

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＝Ｓ１Ｑ０ｅａ＋ｂｎ，式中Ｄ为散射辐射；Ｓ１为日照百分率；Ｑ０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、县的散射辐射月、年平均辐照度并分析其分布特征。

我国散射辐射的气候计算方法及其分布特征

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。

宁夏区域太阳日辐射通量计算方法的研究

利用银川站过去5 a的太阳日辐射观测资料（1981-1985）与大气外太阳辐射、日照时数、日照长度间的相关关系,确定了区域系数as。通过对bs的取值进行敏感测试,可得到一组最佳推算太阳辐射通量的区域系数：as=0.3,bs=0.5。用此系数和太阳日辐射通量计算公式,推算了银川站1986、1987年太阳日辐射通量并用观测值进行验证,结果表明：两者之间有很好的线性相关,R^2=0.94,验证了区域系数的可信度。通过对银川站2 a（1986,1987）资料的平均误差、平均偏差、平均绝对偏差和均方根偏差的计算表明,结果与国内相关报道基本一致。对宁夏永宁站1989-2000年的太阳日辐射通量用区域系数进行估算,并与银川站的实际观测资料比较,结果显示永宁站太阳日辐射通量估算值和银川站实测值间有很好的线性关系,12 a间的方差最小值R^2=0.88。

太阳光照射产生的牙釉质电子自旋共振信号的稳定性研究

对不同的牙釉质样品分别进行60Coγ射线和太阳光的照射,放置不同时间后,使用电子自旋共振(ESR)谱仪测量ESR信号的强度,研究不同种类辐射照射后牙釉质所产生的ESR信号强度随时间的变化。结果表明,60Coγ射线照射后产生的牙釉质ESR信号,其剂量学峰的信号很稳定。太阳光照射与γ射线照射具有相同的剂量学峰的信号,最后一次照射后2年半,其强度衰减约20%;紧邻本底和另一较弱信号衰减约30%;信号相对稳定,对剂量学信号和本底水平可能会有一定的影响。所以用牙釉质ESR信号的剂量学峰进行剂量重建时,尤其是在低剂量区域内,应该认真考虑并去除其他种类辐射引起的影响。

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。

我国太阳总辐射气候学计算方法研究

目前太阳辐射主要通过计算获得，因此建立太阳辐射的气候学计算方法十分必要。论文利用中国54个站1961--2000年的逐日太阳总辐射和日照百分率资料，分别以天文辐射、晴天太阳辐射和理想大气太阳辐射作为三种起始值建立了各站的太阳辐射回归方程，并对其经验系数进行聚类分析，分为东部和西部两个地区。然后利用54个站1961--1990年的资料建立了3种起始值情况下，东部、西部地区和全国统一的太阳总辐射计算公式。最后利用这些站1991-2000年的观测资料对所建立的公式进行了检验。结果表明：无论是利用分区还是全国统一公式都是以天文辐射为起始值时计算结果好，其中分区公式比全国统一公式的计算结果精度略高，但差别不大。全国54个站以天文辐射为起始值的分区公式相对误差变化于2．67％-19．30％，平均为7．79％。全国统一公式的相对误差变化于3．33％-18．75％，平均为8．39％。从模拟结果的地区差异看，无论采用何种起始值，都是西部地区模拟误差小于东部地区，这与西部地区干燥、空气湿度小有密切关系。与其他研究结果相比，论文所建立的各种公式模拟结果较好，这是由于采用的资料序列长、站点多。考虑到计算天文辐射所需参数容易获得，因此建议实际应用时，采用以天文辐射为起始值的全国统一公式。

起伏地形下朝鲜半岛天文辐射的时空分布

本文应用数字高程模型(DEM)数据和地理信息系统(GIS),建立了起伏地形下天文辐射分布式计算模型,计算了朝鲜半岛起伏地形下全年各月的100m×100m分辨率天文辐射精细空间分布结果,并详细分析了朝鲜半岛天文辐射的空间分布特征。计算结果表明:①在朝鲜半岛天文辐射同时受到南北方向纬度带的影响和山地条件的影响,其中山地影响大于纬度带影响;②朝鲜半岛天文辐射具有明显的季节特征;③朝鲜半岛地形对天文辐射的影响存在季节差异,夏季6月最小,冬季12月最大。

天文辐射空间分布与尺度效应研究

天文辐射是地表实际入射太阳辐射的基础背景,也是辐射计算、太阳能资源评估和农业生产潜力估算等方面的重要天文参量。本文基于分辨率为30 m的福建省数字高程模型,使用MATLAB软件提供的并行计算框架模拟了起伏地形下福建省天文辐射空间分布,定量地分析了坡度坡向对天文辐射分布的影响规律,同时探讨数字高程模型对天文辐射产生的空间尺度效应。结果表明:福建省年天文辐射量大部分处于10 000~13 000 MJ/m^2,呈现东南沿海向中西部递减的分布特征;不同季节的天文辐射分布受纬度和坡度坡向的影响具有明显的差异性,呈现季节分布的不对称性;不同坡度和坡向对天文辐射的影响与福建省总体上西北高东南低地势特征相吻合,天文辐射量随坡度增大而减小,东、东南和南坡向是天文辐射分布较集中的区域,总体上呈现山脊多、山谷少、阳坡多、阴坡少的地域差异性;数字高程模型的空间尺度效应在起伏较大的福建中西部丘陵地貌表现更加明显,该区域的天文辐射对分辨率的变化更加敏感。