Ecosystem response to solar ultraviolet-B radiation: influence of trophic-level interactions

Solar ultraviolet radiation (UVR) can reduce the photosynthesis and growth of benthic diatom communities in shallow freshwater. Nevertheless, greater amounts of algae accumulate in UVR-exposed habitats than in UVR-protected environments. Near-ultraviolet (UVA wavelengths of 320 to 400 nanometers) and mid-ultraviolet (UVB, wavelengths of 280 to 320 nanometers) radiation also inhibit algal consumers (Diptera: Chironomidae). Larval chironomids are more sensitive to UVB than sympatric algae. Differential sensitivity to UVB between algae and herbivores contributes to counterintuitive increases in algae in habitats exposed to UVB. These mesocosm experiments illustrate that predictions of the response of entire ecosystems to elevated UVB cannot be made on single trophic-level assessments.     

日光温室番茄群体太阳总辐射量的分布规律及其与光合作用的关系

【目的】研究日光温室番茄群体的太阳总辐射量分布规律,为优化日光温室结构、控制日光温室环境提供理论依据。【方法】将日光温室番茄冠层按高度均匀分为4层,观测不同冠层的太阳总辐射量、叶面积指数、净光合速率和太阳总辐射透光率,探讨群体太阳总辐射量的变化规律及其与光合作用的关系。【结果】在番茄盛果期,日光温室内的太阳总辐射量南部明显高于北部,平均高出200 W/m2以上;中部略高于东、西部。太阳总辐射量在植株群体内垂直方向上随冠层高度的下降而减少,1.2,0.9,0.6和0.3 m冠层的太阳总辐射量日平均值分别为507,398,289和76 W/m2;越靠近冠层底部太阳总辐射量衰减的日变化越不明显。随着冠层高度的降低,累积叶面积指数增大,太阳总辐射量减小。净光合速率由冠层顶部向底部表现为随累积叶面积指数的增加而降低,随着太阳总辐射透光率的减少而减小,冠层顶部净光合速率最大,为22.59μmol/(m2.s),冠层底部最小,为8.00μmol/(m2.s)。【结论】日光温室中番茄群体太阳总辐射量的分布规律为:南部高于北部,中部略高于东、西部;太阳总辐射量分布与冠层高度、累积叶面积指数和净光合速率均有一定的相关性。     

Evidence for large upward trends of ultraviolet-B radiation linked to ozone depletion

Spectral measurements of ultraviolet-B radiation made at Toronto since 1989 indicate that the intensity of light at wavelengths near 300 nanometers has increased by 35 percent per year in winter and 7 percent per year in summer. The wavelength dependence of these trends indicates that the increase is caused by the downward trend in total ozone that was measured at Toronto during the same period. The trend at wavelengths between 320 and 325 nanometers is essentially zero.     

Measurement of solar radiation exergy

Methods of estimating the energy of solar radiation during it conversion into other forms of energy-thermal, photoelectric, and chemical-during photosynthesis of plants are examined. Analytical expressions are given for estimating the conversion of the energy of solar radiation into thermal, photoelectric, and photosynthetic exergy for the purpose of realizing it in the software and hardware parts of the measuring instrument.     

日光温室内各表面太阳辐射照度的模拟计算

建立了温室内各表面太阳辐照度计算模型,并对沈阳地区跨度为12 m的日光温室进行模拟,分析了温室建筑参数改变对温室内各表面太阳辐射照度的影响。结果表明:冬季最冷月(2003 12至2004 02)温室内后坡单位面积太阳辐射照度分别为土壤表面及后墙面的1.45和1.49倍;温室地面太阳辐射照度模拟结果与实际测试结果差值不超过5%。改变温室跨度和高度分别对地面及北墙面太阳辐射照度有较大影响,且呈线性关系;改变温室后坡仰角对温室内各表面太阳辐射照度的影响不显著。     

Detection of emerging sunspot regions in the solar interior

Sunspots are regions where strong magnetic fields emerge from the solar interior and where major eruptive events occur. These energetic events can cause power outages, interrupt telecommunication and navigation services, and pose hazards to astronauts. We detected subsurface signatures of emerging sunspot regions before they appeared on the solar disc. Strong acoustic travel-time anomalies of an order of 12 to 16 seconds were detected as deep as 65,000 kilometers. These anomalies were associated with magnetic structures that emerged with an average speed of 0.3 to 0.6 kilometer per second and caused high peaks in the photospheric magnetic flux rate 1 to 2 days after the detection of the anomalies. Thus, synoptic imaging of subsurface magnetic activity may allow anticipation of large sunspot regions before they become visible, improving space weather forecast.     

高寒地区日光温室芦笋栽培技术

<正>芦笋又名石刁柏、龙须菜,属百合科天门冬属多年生宿根草本植物,其嫩茎质地细腻、纤维柔软,含有多种人体必需的氨基酸、蛋白质和维生素,是一种营养价值极高的药食兼用高档保健蔬菜。在国际市场上享有"蔬菜之王"的美称。栽培芦笋以夏季温暖,     

Sea-level solar radiation in the biologically active spectrum

Calculations show a significant depletion of ultraviolet and visible radiation due to absorption and scattering by particulates and cloud drops for a fixed amount of ozone.     

Observed ozone response to variations in solar ultraviolet radiation

During the winter of 1979, the solar ultraviolet irradiance varied with a period of 13.5 days and an amplitude of 1 percent. The zonal mean ozone values in the tropics varied with the solar irradiance, with an amplitude of 0.25 to 0.60 percent. This observation agrees with earlier calculations, although the response may be overestimated. These results imply changes in ozone at an altitude of 48 kilometers of up to 12 percent over an 11-year solar cycle. Interpretation of ozone changes in the upper stratosphere will require measurements of solar ultraviolet radiation at wavelengths near 200 nanometers.     

太阳辐射减弱对浮游与底栖藻类竞争的影响

为了解辐射减弱对浮游藻类和底栖藻类竞争的影响,构建了浅水生态系统,设置遮光组和不遮光的对照组两种处理,通过测定水中氮、磷营养盐、浮游藻类生物量及底栖藻类生物量等指标,分析遮光时浮游藻类和底栖藻类生长变化,研究辐射减弱对浮游与底栖藻类竞争的影响。结果表明,遮光条件下,水体浮游藻类Chl a降低15%,DO浓度平均增加9%,TN、TP浓度分别增加30%和24%时,底栖藻类Chl a增加48%。说明辐射减弱虽可显著降低水体光照强度和浮游藻类生物量,但可提高水体中氮、磷营养盐浓度,促进底栖藻类生物量增加。因此,在辐射减弱背景下,不利于浮游藻类生长,而有利于底栖藻类竞争。     

太阳辐射作用下冻结期衬砌渠道温度场分析

【目的】对季节性冻土区衬砌渠道在太阳辐射作用下的温度场进行数值模拟,分析太阳辐射对渠道温度分布的影响。【方法】利用Hottel太阳辐射模型,结合热传导理论和有限元分析方法,考虑渠道自身的遮蔽作用,对太阳辐射作用下的梯形衬砌渠道的温度场进行计算。【结果】提出了梯形渠道太阳辐射的计算方法;衬砌渠道表面太阳辐射的日变化表现为早晚最小、中午最大;渠道阴、阳坡接受到的太阳辐射差异明显,阴坡太阳总辐射约为阳坡的20%;渠道表面温度的日变化趋势与大气温度相同,近似为正弦分布,其温度变幅小于大气温度变幅,变化滞后于太阳辐射约2.5h,阴、阳坡温度最大相差4℃左右,阳坡温度值与日间温度增加速率均大于阴坡。【结论】渠道温度变化与太阳辐射有密切关系,阴、阳坡接受到的太阳辐射量不同是渠道温度存在较大差异的原因,太阳辐射是渠道冻融循环的动力,在渠道冻胀研究中必须考虑太阳辐射的影响。     

Photolysis of sulfuric acid vapor by visible solar radiation

Atmospheric field measurements and models of the stratospheric sulfate aerosol layer led to the suggestion that sulfuric acid (H2SO4) must photolyze at high altitudes. We propose that excitation of vibrational overtones of H2SO4 and its hydrate in the near-infrared and visible leads to photolysis, forming sulfur trioxide (SO3) and water. On the basis of absorption cross sections calculated with ab initio methods calibrated to experimental measurements, we estimated J values that are sufficient to explain stratospheric and mesospheric sulfur dioxide (SO2) concentrations and the observation of the sulfate layer.     

Strategies for increasing the capture,storage, and utilization of precipitation in semiarid regions

Crop production in semiarid regions is always challenging because of the high variability of amount and distribution of precipitation.These regions become more important each year, however, because the rapidly increasing and more prosperous world population seeks greater consumption of animal products(meat, milk and eggs) that requires additional grain to that consumed directly.The dry areas of the developing world where approximately 40% of the world population lives comprise about 40% of the earth's land area.Crop production, particularly cereal grains, must increase in these areas to meet these growing demands.Grain yield of cereal crops is a function of the amount of water used for evapotranspiration(ET), the portion of ET used for transpiration(T), the units of water as T to produce 1 unit of biomass, and the harvest index(HI).The most important factor is the amount of evapotranspiration not only because it is closely proportional to grain yield, but because it tends to also make the other factors more favorable.Therefore, even small increases in ET can be significant.Strategies for manipulating soil and plant conditions for increasing ET, and how additional ET affects the other factors, are discussed for water deficient areas.The use of crop residues as mulch is highly beneficial but often insufficient in dryland regions or is required for animal feed and fuel.Plastic mulch, mainly restricted to China, has significantly increased grain yields in dryland areas by decreasing evaporation from the soil surface.     

Comment on "Detection of emerging sunspot regions in the solar interior"

Ilonidis et al. (Reports, 19 August 2011, p. 993) report acoustic travel-time decreases associated with emerging sunspot regions before their appearance on the solar surface. An independent analysis using helioseismic holography does not confirm these travel-time anomalies for the four regions illustrated by Ilonidis et al. This negative finding is consistent with expectations based on current emerging flux models.     

南亚热带针阔混交林辐射通量特征

该文分析了南亚热带针阔混交林各辐射分量:下行短波辐射(RSd)、 上行短波辐射(RSu)、下行长波辐射(RLd)和上行长波辐射(RLu)在不同时间尺度上的分布特征和相互关系.结果表明:在日尺度上,各辐射分量日总量的大小顺序为:RLu(36.34 MJ/(m2·d)) RLd(32.43 MJ/(m2·d))RSd(12.46 MJ/(m2·d)) RSu(0.98 MJ/(m2·d)),长波辐射的变异系数（CV）远小于短波辐射,而波长相同时上行辐射的 CV小于下行辐射.除RLd外,其余3种辐射的月均通量呈单峰形变化.RSd与RSu在不同季节的日变化均呈规则的单峰曲线,而RLd和RLu的日均变化则大致呈波浪形.全年系统辐射支出中RLu为80.7％,RSu仅占2.2％,RLu在辐射平衡中的作用远超过以往强调最多的RSu.日尺度上,2003年反射率η的平均值为8.3％.在不同时间尺度上影响η的主要因素是不同的.与旱季相比,雨季两种长波辐射的相关性高,数值也更接近.在较大时间尺度(1个月)上,净辐射(Rn）与RLu相关性最好,而在较小的时间尺度(≤1 d)上,Rn与RSd相关性最好,故在考察辐射通量间相互关系时,应充分注意尺度效应的影响.      

赤水、习水沟谷地区的日照和太阳辐射状况

通过地形遮蔽图法对赤水、习水沟谷地区的日照和太阳辐射进行了测算，结果表明，该区年太阳总辐射为2466.3-2999.2Mj/m^2，较当地开阔地形站减少21%-35%，年实照时间为451.2-786.9h，较当地开阔地形站减少39%-65%，年日照百分率为10.2%-17.8%。7、8月晴朗天气多，太阳高度角大，地形遮蔽作用小，实照时间较当地开阔地形站减少35%-63%；12月阴雨天气多，太阳高度角小，地形遮蔽作用大，实照时间减少53%-84%。沟谷地区阴蔽，阳光和煦，冬暖夏凉，湿润风和，形成了喜阴湿耐阴蔽植被繁茂的小生境和旅游观光的适宜气候。     

Absorption of solar radiation by clouds: observations versus models

There has been a long history of unexplained anomalous absorption of solar radiation by clouds. Collocated satellite and surface measurements of solar radiation at five geographically diverse locations showed significant solar absorption by clouds, resulting in about 25 watts per square meter more global-mean absorption by the cloudy atmosphere than predicted by theoretical models. It has often been suggested that tropospheric aerosols could increase cloud absorption. But these aerosols are temporally and spatially heterogeneous, whereas the observed cloud absorption is remarkably invariant with respect to season and location. Although its physical cause is unknown, enhanced cloud absorption substantially alters our understanding of the atmosphere's energy budget.     

北温带干旱地区土壤剖面CO_2通量的变化特征

采用开放式样杆方法,对干旱土纲的4种土壤类型(栗钙土、灰钙土、粗骨土、山地灰褐土)进行土壤剖面CO2通量的观测研究,结果表明:1)在0～60cm深度范围内土壤剖面CO2通量随土壤深度的增加而增加,60cm为转折点,之后,随土壤深度的增加而减小。2)土壤剖面CO2通量平均值为660μmol/(m2·h),在-9076～16988μmol/(m2·h)范围内变化,如果土地利用/土地覆盖发生改变(0～70cm深度),将可能有254.6t/(km2·a)CO2从土壤向大气释放。3)土壤种类不同,CO2通量明显不同,森林土壤释放量大于草原土壤。4)在通量-深度曲线中,各土壤类型均出现1～2个拐点,变化原因与土壤剖面结构和根系分布有关,钙积层的有无、厚度起决定作用。5)存在季节变化,植物生长季节的CO2通量远大于其他季节,其他季节可能存在土壤吸收CO2现象。因此,应避免在植物生长季节施工动土,以减少土壤CO2向大气中释放。     

Preliminary results of the solar flux radiometer experiment aboard the pioneer venus multiprobe mission

The solar flux radiometer aboard the Pioneer Venus large probe operated successfully during its descent through the atmosphere of Venus. Upward, downward, and net fluxes from 0.4 to 1.0 micrometers were obtained at more than 390 levels between 185 millibars (at an altitude of approximately 61 kilometers) and the surface. Fluxes from 0.4 to 1.8 micrometers were also obtained between 185 millibars and about the level at which the pressure was 2 atmospheres. Data from 80 to 185 millibars should be available after additional decoding by the Deep Space Network. Upward and downward intensities in a narrower band from 0.59 to 0.66 micrometers were also obtained throughout the descent in order to constrain cloud properties. The measurements indicate three cloud regions above the 1.3-atmosphere level (at an altitude of approximately 49 kilometers) and a clear atmosphere beneath that level. At the 67 degrees solar zenith of the probe entry site, some 15 watts per square meter are absorbed at the surface by a dark ground, which implies that about 2 percent of the solar energy incident on the planet is absorbed at the ground.     

Deflection of the local interstellar dust flow by solar radiation pressure

Interstellar dust grains intercepted by the dust detectors on the Ulysses and Galileo spacecrafts at heliocentric distances from 2 to 4 astronomical units show a deficit of grains with masses from 1 x 10(-17) to 3 x 10(-16) kilograms relative to grains intercepted outside 4 astronomical units. To divert grains out of the 2- to 4-astronomical unit region, the solar radiation pressure must be 1.4 to 1.8 times the force of solar gravity. These figures are consistent with the optical properties of spherical or elongated grains that consist of astronomical silicates or organic refractory material. Pure graphite grains with diameters of 0.2 to 0.4 micrometer experience a solar radiation pressure force as much as twice the force of solar gravity.