Long-term variation of solar UVB (290–330 nm) observed at the earth's surface

During solar cycle 21 (1976–86), the primary solar irradiance at 300 nm was steady during 1980–82 and thereafter decreased until 1986 by only 2–3%. The stratospheric ozone in middle latitudes had a QBO of 3–4% in this interval but the long-term ozone trend was less than 3% per decade, which could result in a UVB increase of only 5–6% per decade. Thus, the combined effect of changes in primary solar irradiance and ozone changes could be an increase of 5–6% in UVB, observed at ground during 1977–81 and a steady level during 1981–86. During 1976–86, the average cloudiness changed by less than 5% indicating UVB changes of 5% or less on this count. The aerosol level was almost constant during 1976–82 and increased abruptly in 1982 due to the E1 Chichon eruption and decayed slowly unitl 1986. Thus, due to aerosols only, the UVB was expected to be constant during 1976–82, to decrease sharply in 1982 and to recoup slowly thereafter.Measurements of clear-sky solar UVB at ground made at Jungfraujoch (Swiss Alps, 47°N, 8°E) during 1981–89 and at Rockville, USA (39°N, 77°W) were not comparable between themselves and did not follow the above expected patterns. Neither did the all-day R-B meter UVB measurements at Philadelphia, USA (40°N, 75°W) and Minneapolis, USA (45°N, 93°W). We suspect that some of these measurements are erroneous. This needs further detailed scrutiny.     

太湖水面太阳辐射中的光合有效成份

本文利用睛空大气辐射传输分光参数化模式,讨论了到达太湖水面太阳总辐射中光合有效成分所占比例的日变化状况。辐射传输计算所涉及的气象参数采用无锡地区气象站资料;水体反射仅考虑有风浪状况下的水平Fresnel反射。两次湖面实测太阳总辐射日变化曲线与计算值对比分析表明,计算结果基本上能反映晴空条件下太湖水面辐射状况。本文结果对利用总辐射值估算水体生态研究中感兴趣的光合有效成份有一定参考价值。     

Exchange flux of total gaseous mercury between air and natural water surfaces in summer season

The exchanges of mercury between surface and air are of significance in the biogeochemical cycling of Hg in the environment, but there are still few reliable data on air/surface exchange in aquatic systems. Field measurement campaigns over seawater surface at Kristineberg Marine Research Station (KMRS) and over Hovg?rds?n River surface at Knobesholm in southwestern Sweden were conducted to measure mercury flux using a dynamic flux chamber technique coupled with automatic mercury vapor-phase analyzers. Both sites show net emissions during summer time. Mercury fluxes measured over both river and seawater surfaces exhibit a consistently diurnal pattern with maximum fluxes during the daytime period and minimum fluxes during the nighttime period. At freshwater site, mercury flux is strongly correlated with the intensity of net solar radiation, and negatively correlated with relative humidity. A typical exponential relationship between mercury flux and water temperature was observed at freshwater measurement site. At seawater site, a strong correlation between mercury flux and intensity of solar radiation was obtained. The driving force of mercury emission from water surface to air is the super-saturation of dissolved gaseous mercury in aqueous phase.     

Near‐surface temperatures and heat balance of bare outcrops exposed to solar radiation

Subsurface temperatures in rocks naturally fluctuate under the influence of local meteorological conditions. These fluctuations play a role in mechanical weathering, thus creating the environmental conditions conducive to natural hazards such as rockfalls and providing important sediment source terms for landscape evolution. However, the physics that control heat penetration into rocks are not fully understood, which makes the underground thermal state difficult to interpret when temperature measurements are available and even more difficult to estimate for unmonitored sites. This is an important lacuna given possible impacts of future climate change on mechanical weathering processes. The natural daily variations of subsurface temperatures were investigated on a bare gneiss outcrop exposed to solar radiation, where temperatures at various depths (up to 50 cm), as well as the solar radiation reaching a pyranometer, were monitored hourly for several months. This detailed times series of thermal data was used to gain insight into the heat balance at the inclined free surface of the rock mass. Attention was focused on two major contributors to the heat balance; the heat flux entering the rock mass through conduction and the incoming shortwave (solar) radiation. A Fourier decomposition of the temperature measurements provided an estimate of the in situ thermal conductivity of the rock and was used to calculate the conductive term. The shortwave radiation term was determined on the basis of the pyranometer measurements adjusted to account for the angle of incidence of the sun. It is shown that, throughout clear‐sky periods, heat exchanges at the surface are mainly controlled by direct solar radiation during the day, and by a roughly constant outgoing heat flux during the night. Subsurface temperatures can be reliably estimated with a semi‐infinite medium model whose boundary condition is derived from an analytical insolation model that takes atmospheric attenuation into account. Copyright © 2011 John Wiley & Sons, Ltd.     

Total Atmospheric Transmittance in the UV and VIS Spectra in Athens,Greece

This work investigates the seasonal and diurnal variation of total spectral transmittance of solar radiation. Such a study dealing with ultraviolet and visible wavelengths (310–575 nm) is carried out in Athens for the first time. The spectral values presented are averages over a number of records in a period of 42 days and have been calculated using ground-based spectral measurements of direct-beam irradiance. The data were recorded on selected days throughout a year by a simple pyrheliometer capable of performing spectral measurements. All data were recorded under clear-sky conditions in the city center of Athens and the total spectral atmospheric transmittance was estimated in the direction of local zenith to become independent of any optical mass effects. The comparison between seasons reveals that the atmospheric transmittance is higher in the cold period of the year than in the warm, simply because the photochemical pollution in the summer is more severe. Various features of seasonal and diurnal variation are also discussed with respect to emission sources, topographic peculiarities and wind regime.     

近50年中国东南地区地面太阳辐射变化对气温变化的影响

太阳是地球表层的最终能量来源,地面太阳辐射的变化会深刻影响地球的气候变化.本文利用中国东南地区14个气象台站1961～2008年总辐射和气温的同步观测资料,分析了近50年该地区地面太阳辐射的变化对气温变化的可能影响.结果表明,1961～1989年期间,该地区的地面太阳辐射显著减弱,所引起的气温下降超过了其他因素的增温效...     

An improved hemispherical photography model for stream surface shortwave radiation estimations in a central U.S. hardwood forest

Hemispherical photographs of forest canopies can be used to develop sophisticated models that predict incident below canopy shortwave radiation on the surface of interest (i.e. soil and water). Hemispherical photographs were collected on eight dates over the course of a growing season to estimate leaf area index and to quantify solar radiation incident on the surface of two stream reaches based on output from Gap Light Analyser and Hemisfer software. Stream reaches were shaded by a mixed‐deciduous Ozark border forested riparian canopy. Hemispherical photo model results were compared to observed solar radiation sensed at climate stations adjacent to each stream reach for the entire 2010 water year. Modeled stream‐incident shortwave radiation was validated with above‐stream pyranometers for the month of September. On average, the best hemispherical photo models underestimated daily averages of solar radiation by approximately 14% and 12% for E–W and N–S flowing stream reaches, respectively (44.7 W/m² measured vs 38.4 W/m² modeled E–W, 46.8 W/m² vs. 41.1 W/m²N–S). The best hemispherical photo models overestimated solar radiation relative to in–Stream pyranometers placed in the center of each stream reach by approximately 7% and 17% for E–W and N–S stream reaches respectively (31.3 W/m² measured vs 33.5 W/m² modeled E–W, 31.5 W/m² vs. 37.1 W/m²N–S). The model provides a geographically transferable means for quantifying changes in the solar radiation regime at a stream surface due to changes in canopy density through a growing season, thus providing a relatively simple method for estimating surface and water heating in canopy altered environments (e.g. forest harvest). Copyright © 2012 John Wiley & Sons, Ltd.     

起伏地形下黄河流域太阳散射辐射分布式模拟研究

针对天文、大气、宏观地理与局地地形等因子对起伏地形下太阳散射辐射的复杂作用,将影响起伏地形下太阳散射辐射的天空因素与地面因素分开处理.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;依据各向异性散射机理,建立了起伏地形下太阳散射辐射分布式计算模型,探索出一条利用DEM数据和常规气象观测资料实现山区太阳散射辐射定量模拟的技术路线.以1 km×1 km分辨率的DEM数据作为地形的综合反映,实现了起伏地形下黄河流域1 km×1 km分辨率的太阳散射辐射分布式模拟.     

Solar ultraviolet irradiance and its temporal variation

Solar radiation at wavelengths below 300 nm is almost completely absorbed by the Earth’s atmosphere, becoming the dominant direct energy source and playing a major role in the chemistry and dynamics. Even small changes in this incoming radiation field will have both direct and indirect influences on atmospheric processes, and perhaps will affect the Earth’s climate as well. Some of the very earliest space missions included devices to measure solar ultraviolet irradiance, but for the most part they lacked the necessary precision and accuracy to record true solar variability over long time periods. The technology has continued to improve, and today reliable measurements over time scales up to, and including, the 11-year solar cycle, are being obtained. This review provides a summary of measurements made during the most recent solar cycle (number 22 extending from 1986 1996), with emphasis on the spectral range 120-300 nm. Comparisons and validations of recent data sets are considered, together with an assessment of the present understanding of the solar variations. There is now general agreement that for solar cycle 22 the variation is as large as a factor of two at the shortest wavelengths, decreasing to roughly 10% near 200 nm. Proceeding to wavelengths above 200 nm the solar variability continues to decrease, and at about 300 nm it becomes smaller than the present measurement capability of about 1%.     

Solar EUV Flux Variations in 11–Year Solar Activity Cycle According to Measurements On-Board PROGNOZ Satellite Series, INTERBALL-1 and ELECTRO Satellites during 1978–1997 Period

The paper presents data on flux variations of ionizing EUV radiation for wavelengths shorter than 130 nm and in L-alpha hydrogen line on the basis of measurements performed on-board a Russian Earth-orbiting and interplanetary spacecrafts in the period since 1978 to 1997. These data were received by using common heritage instrumentation installed on four PROGNOZ satellites, INTERBALL-1, PHOBOS, and the geosynchronous meteorological satellite ELECTRO. Though the time series of observations is not continuous, it gives a possibility to estimate flux variations in certain periods of time and during 11–year cycle. During quiet periods of solar activity (except for flares) a level of diurnal variations is rather low, it being equal to about 3%. Radiation changes in L-alpha line from maximum to minimum in an 11–year cycle of solar activity achieves 200% and increases in the range of short waves. Data measured onboard the Russian satellites are compared with data obtained by Solar Mesospheric Explorer.     

基于流体动力学的探空仪GTS1湿度测量误差修正研究

准确的湿度垂直廓线对短期数值天气预报和中长期气候研究分析均具有重要参考价值,但太阳辐射与高空云雨等因素导致探空湿度测量精度较低.针对探空仪GTS1白天进行湿度测量时存在明显偏干误差的现象,本文建立了GTS1湿度测量结构模型,采用计算流体动力学方法重点研究了太阳辐射对GTS1湿度测量的影响,同时探讨了其防雨/防辐射罩的防雨效果.结合改进的太阳辐射计算模型,利用Fluent模拟分析了防雨/防辐射罩云雨滴轨迹和内部温度场分布,数值仿真结果表明:在垂直气流下防雨/防辐射罩基本保护湿度传感器免受高空云雨的影响,对太阳辐射也起到一定防护作用.但太阳辐射对GTS1湿度测量的偏干影响仍较显著,海拔30km左右相对误差甚至高达70%.通过与RS92及GTS1探空湿度测量中的太阳辐射偏干误差相对比,发现基于流体动力学数值计算的湿度相对误差随海拔高度的变化趋势与之基本吻合.本文也给出了理论计算与实验测量存在一定差异的原因,进而以南京探空站2014年不同季节的温度、气压、气球的上升速度等探空数据为计算参数,获取了太阳辐射误差与海拔及环境温度的关系,并对四组探空湿度廓线进行太阳辐射误差修正,提升了GTS1探空仪高空湿度测量的精度.本文研究结果为探空湿度测量太阳辐射偏干误差的有效修正提供了一定的参考.     

Model data selection using gamma test for daily solar radiation estimation

Hydrological modelling is a complicated procedure and there are many tough questions facing all modellers: what input data should be used? how much data is required? and what model should be used? In this paper, the gamma test (GT) has been used for the first time in modelling one of the key hydrological components: solar radiation. The study aimed to resolve the questions about the relative importance of input variables and to determine the optimum number of data points required to construct a reliable smooth model. The proposed methodology has been studied through the estimation of daily solar radiation in the Brue Catchment, the UK. The relationship between input and output in the meteorological data sets was achieved through error variance estimation before the modelling using the GT. This work has demonstrated how the GT helps model development in nonlinear modelling techniques such as local linear regression (LLR) and artificial neural networks (ANN). It was found that the GT provided very useful information for input data selection and subsequent model development. The study has wider implications for various hydrological modelling practices and suggests further exploration of this technique for improving informed data and model selection, which has been a difficult field in hydrology in past decades. Copyright © 2008 John Wiley & Sons, Ltd.     

Determining the amplitude and timing of streamflow discontinuities: A cross wavelet analysis approach

Records of natural processes, such as gradual streamflow fluctuations, are commonly interrupted by long or short disruptions from natural non‐linear responses to gradual changes, such as from river‐ice break‐ups, freezing as a result of annual solar cycles, or human causes, such as flow blocking by dams and other means, instrument calibrations and failure. The resulting abrupt or gradual shifts and missing data are considered to be discontinuities with respect to the normal signal. They differ from random noise as they do not follow any fixed distribution over time and, hence, cannot be eliminated by filtering. The multi‐scale resolution features of continuous wavelet analysis and cross wavelet analysis were used in this study to determine the amplitude and timing of such streamflow discontinuities for specific wavebands. The cross wavelet based method was able to detect the strength and timing of abrupt shifts to new streamflow levels, gaps in data records longer than the waveband of interest and a sinusoidal discontinuity curve following an underlying modeled annual signal at ±0.5 year uncertainty. Parameter testing of the time‐frequency resolution demonstrated that high temporal resolution using narrow analysis windows is favorable to high‐frequency resolution for detection of waveband‐related discontinuities. Discontinuity analysis on observed daily streamflow records from Canadian rivers showed the following: (i) that there is at least one discontinuity/year related to the annual spring flood in each record studied, and (ii) neighboring streamflows have similar discontinuity patterns. In addition, the discontinuity density of the Canadian streamflows studied in this paper exhibit 11‐year cycles that are inversely correlated with the solar intensity cycle. This suggests that more streamflow discontinuities, such as through fast freezing, snowmelt, or ice break‐up, may occur during years with slightly lowered solar insolation. Copyright © 2013 John Wiley & Sons, Ltd.     

Numerical modelling of spectral sky radiance during a total solar eclipse

Ground-based observations of the spectral sky radiance within the totality region during a total solar eclipse are of significant interest because the contribution from direct and single scattered light from the solar disk is eliminated. In the present paper, we develop a numerical model of the spectral sky radiance during totality, evaluate the contribution of double scattered sunlight to the sky radiance at totality and compare it to solar corona emissions. The results show that the single scattered coronal light is the major contaminant in ground-based observations of the corona, opposite to what was believed before. For observation directions outside the corona the double scattered sun radiation dominates over the single scattered coronal light.     

月表有效太阳辐照度实时模型

月表太阳辐射是深入研究月表温度分布的关键问题之一. 本文根据月表有效太阳辐照度与太阳常数、太阳辐射入射角以及日月距离之间的关系,建立月表有效太阳辐照度的实时模型. 该模型在1950～2050年的100年内的理论误差百分比小于0.28％, 相对前人提出的模型在精度上有了很大程度的提高,能较为真实地反映月表有效太阳辐照度随时间的变化规律. 计算结果表明2007年月表太阳辐照度的年变化范围在1321.5～1416.6 W·m^-2之间,平均为1368.0 W·m^-2. 通过对月表太阳辐射入射角计算结果的分析,证实了月球的两极可能存在极昼极夜.     

极移的成因及其移动特征

作者发现：太阳辐射，地球自转与公转，黄、赤交角的存在，陆地和海洋在地球表面南、北半球的不规则、不对称地理分布，及地球内部因〖ZZ(〗核外液体〖ZZ)〗形成的分层结构，构成了一套天然的能使地球产生自由章动的日、地间动量（能量）相耦合的物理机制.经研究，由该机制产生的极移具有以下主要特征：（1）极移轨迹的运动周期为13个月（0.92周/年），该周期由二个主要分量组成，一个为12个月（1周/年），另一个是14.1个月（0.85周/年，即钱德勒周期）.（2）极移运动轨迹是是椭圆，短半轴（b）与长半轴(a)之比为0.86；扁率（a\|b/a）为1：7.1.（3）瞬时极移振幅|m|的变化：对1周/年项，|m|随太阳回归运动而变化，在二至点时最大，在二分点时最小，具有对称性；对0.85周/年项，|m|随太阳回归运动而变化，在夏至点最大，每年12月5日左右最小.（4）瞬时极移存在反向运动（由东向西）.在1周/年项极移运动中，自转极的正、反方向运动振幅的贡献各占50%；在0.85周/年项的极移运动中，反向运动的时间仅有33天，约占正向运动时间的1/10，正向运动振幅的贡献占96%，反向运动振幅的贡献大约占4%.（5）若以国际极点（CIO）为原点，自转极相对CIO的位移运动轨迹必然落在偏向于CIO的西侧.（6）极移振幅将长期保持下去而不会衰减，原因是太阳辐射为自转轴受迫摆动提供了长期、稳定的激发能源.     

The possible influence of solar activity on Indian summer monsoon rainfall

The Indian summer monsoon rainfall （ISMR） plays an important role in the climate system of South Asia. Recently, studies about ISMR variations have been going into more depth. In this present paper, we mainly use the Scargle periodogram and wavelet transform methods to study the periodicity of ISMR changes between 1871 and 2004 and review the possible influence of solar activity on the rainfall. Analysis results show complicated ISMR variations have periodicities with remarkable time-variable characteristics. Investigating a possible connection between the rainfall and solar variations, we believe that solar activity affects the ISMR variations to some extent.     

Influence of turbidity and aeration on the albedo of mountain streams

Stream surface albedo plays a key role in the energy balance of rivers and streams that are exposed to direct solar radiation. Most physically based analyses and models have incorporated a constant stream albedo between 0.03 and 0.10, based primarily on measurements from low‐gradient streams with low suspended sediment concentrations. However, albedo should vary with solar elevation angle, suspended sediment concentration, aeration, and fraction of direct versus diffuse radiation. The objective of this study was to quantify the dependence of albedo of mountain streams on the controlling factors and to develop a predictive model for use in physically based analysis and modelling of stream temperature, especially for future climate and land‐use scenarios. Stream surface albedo was measured at nine sites with a variety of gradients and suspended sediment characteristics in the southern Coast Mountains of British Columbia, Canada. As expected, albedo of low‐gradient, non‐white water (flatwater) streams increased with solar elevation angle, suspended sediment concentration, and proportion of diffuse to direct solar radiation, ranging between 0.025 during cloudy periods over clear water to 0.25 for turbid water at elevation angles of less than 20°. Albedo was enhanced in steep reaches or at channel steps and cascades where flow was visibly aerated, with a range of 0.09 to 0.33. In clear weather, albedo exhibited notable diurnal variability at flatwater sampling sites. For example, during late summer, surface albedo typically fluctuated between 0.08 and 0.15 on a daily basis at a flatwater site on the highly turbid, glacier‐fed Lillooet River. Multiple regression models explained approximately 60% and 40% of the variance under cross validation for flatwater and white water data subsets, respectively, with corresponding root mean square errors of approximately 0.02 and 0.06.     

太阳活动对印度夏季风降水的可能影响

印度夏季风降水在南亚气候系统中是一个非常重要的内容,近年来对它的研究日益受到人们的重视.本文主要结合Scargle周期图和小波分析的方法研究了1871-2004年间该降水变化的周期性.结果表明,该降水变化非常复杂,其周期性波动具有明显的时变特征.进一步考察了印度夏季风降水与太阳活动的可能关联后,作者认为太阳活动在一定程度上影响印度的夏季风降水.