共查询到20条相似文献，搜索用时 750 毫秒
1.
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. 相似文献
2.
The responses of Earth's and Mars' thermospheres to the quasi-periodic (27-day) variation of solar flux due to solar rotation were measured contemporaneously, revealing that this response is twice as large for Earth as for Mars. Per typical 20-unit change in 10.7-centimeter radio flux (used as a proxy for extreme ultraviolet flux) reaching each planet, we found temperature changes of 42.0 +/- 8.0 kelvin and 19.2 +/- 3.6 kelvin for Earth and Mars, respectively. Existing data for Venus indicate values of 3.6 +/- 0.6 kelvin. Our observational result constrains comparative planetary thermosphere simulations and may help resolve existing uncertainties in thermal balance processes, particularly CO2 cooling. 相似文献
3.
Measurements of the temporal variation in the stratospheric nitric oxide concentration covering a time period from 11:00 to 20:30 local time show the effect of solar ultraviolet sunset. The experimental results strongly support the theorized role of nitric oxide as a catalyst in the destruction of ozone and its importance in the stratospheric ozone balance. 相似文献
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5.
Changes in stratospheric ozone 总被引：2，自引：0，他引：2
Cicerone RJ 《Science (New York, N.Y.)》1987,237(4810):35-42
The ozone layer in the upper atmosphere is a natural feature of the earth's environment. It performs several important functions, including shielding the earth from damaging solar ultraviolet radiation. Far from being static, ozone concentrations rise and fall under the forces of photochemical production, catalytic chemical destruction, and fluid dynamical transport. Human activities are projected to deplete substantially stratospheric ozone through anthropogenic increases in the global concentrations of key atmospheric chemicals. Human-induced perturbations may be occurring already. 相似文献
6.
Large-scale reductions in the ozone content of the middle and upper stratosphere over the polar cap regions were associated with the major solar proton event of 4 August 1972. This reduction, which was determined from measurements with the backscattered ultraviolet experiment on the Nimbus 4 satellite, is interpreted as being due to the catalytic destruction of ozone by odd-nitrogen compounds (NO(x)) produced by the event. 相似文献
7.
Measurements at the Jungfraujoch High Mountain Station (Swiss Alps, 47 degrees N, 3576 meters above sea level) indicate that there has been a slight increase of about 1 percent per year in the flux of solar ultraviolet-B radiation (290 to 330 nanometers) since 1981. A Robertson-Berger detector was used to measure solar erythemal radiation. The increase can be related to a long-term ozone depletion. 相似文献
8.
Ruderman MA 《Science (New York, N.Y.)》1974,184(4141):1079-1081
Hard x-ray pulses or increased cosmic radiation originating in nearby supernova explosions may be capable of temporarily removing most of the earth's atmospheric ozone cover even when direct radiation effects at the earth's surface are negligible. Consequently, terrestrial life may be subject to relatively huge solar ultraviolet fluxes every few hundred million years. 相似文献
9.
Nitrous oxide (N(2)O) and methane (CH(4)) are chemically reactive greenhouse gases with well-documented atmospheric concentration increases that are attributable to anthropogenic activities. We quantified the link between N(2)O and CH(4) emissions through the coupled chemistries of the stratosphere and troposphere. Specifically, we simulated the coupled perturbations of increased N(2)O abundance, leading to stratospheric ozone (O(3)) depletion, altered solar ultraviolet radiation, altered stratosphere-to-troposphere O(3) flux, increased tropospheric hydroxyl radical concentration, and finally lower concentrations of CH(4). The ratio of CH(4) per N(2)O change, -36% by mole fraction, offsets a fraction of the greenhouse effect attributable to N(2)O emissions. These CH(4) decreases are tied to the 108-year chemical mode of N(2)O, which is nine times longer than the residence time of direct CH(4) emissions. 相似文献
10.
Harrison H 《Science (New York, N.Y.)》1970,170(3959):734-736
Simple, steady-state models for ozone photochemistry, radiative heat balance, and eddy-diffusive mass transport can be combined to estimate water-induced changes in the stratospheric ozone concentrations and temperatures, the integrated ozone column, the solar power transmitted to the earth's surface, and the surface temperature. These changes have been computed parametrically for mixing fractions of water vapor between 3 x 10(-6) and 6.5 x 10(-6). With added water from the exhausts of projected fleets of stratospheric aircraft, the ozone column may diminish by 3.8 percent, the transmitted solar power increase by 0.07 percent, and the surface temperature rise by 0.04 degrees K in the Northern Hemisphere. Due to a cancellation of terms, temperatures in the lower stratosphere remain essentially unchanged. These results are sensitive to the form of the water profile and emphasize the potential role of convective transients near 30 kilometers. 相似文献
11.
The potential global atmospheric and climatic consequences of nuclear war are investigated using models previously developed to study the effects of volcanic eruptions. Although the results are necessarily imprecise due to wide range of possible scenaros and uncertainty in physical parameters, the most probable first-order effects are serious. Significant hemispherical attenuation of the solar radiation flux and subfreezing land temperatures may be caused by fine dust raised in high-yield nuclear surface bursts and by smoke from city and forest fires ignited by airbursts of all yields. For many simulated exchanges of several thousand megatons, in which dust and smoke are generated and encircle the earth within 1 to 2 weeks, average light levels can be reduced to a few percent of ambient and land temperatures can reach -15 degrees to -25 degrees C. The yield threshold for major optical and climatic consequences may be very low: only about 100 megatons detonated over major urban centers can create average hemispheric smoke optical depths greater than 2 for weeks and, even in summer, subfreezing land temperatures for months. In a 5000-megaton war, at northern mid-latitude sites remote from targets, radioactive fallout on time scales of days to weeks can lead to chronic mean doses of up to 50 rads from external whole-body gamma-ray exposure, with a likely equal or greater internal dose from biologically active radionuclides. Large horizontal and vertical temperature gradients caused by absorption of sunlight in smoke and dust clouds may greatly accelerate transport of particles and radioactivity from the Northern Hemisphere to the Southern Hemisphere. When combined with the prompt destruction from nuclear blast, fires, and fallout and the later enhancement of solar ultraviolet radiation due to ozone depletion, long-term exposure to cold, dark, and radioactivity could pose a serious threat to human survivors and to other species. 相似文献
12.
不同减菌方式对冰温贮藏草鱼片品质的影响 总被引：2，自引：1，他引：1
分别采用紫外线照射、臭氧杀菌和柠檬酸淋洗3种方式处理草鱼片,然后在冰温(-0.7℃)下贮藏,考察了3种处理方式对草鱼片总菌数、挥发性盐基氮(TVB-N)、硫代巴比妥酸(TBA)值、pH值、总酸度和感官质量的影响。结果表明:与对照组相比,3种处理方式均能抑制细菌生长,延缓蛋白质腐败,其中以臭氧杀菌处理效果最好。由蛋白质腐败指标TVB-N值到达一级鲜度预测草鱼片货架期,臭氧杀菌、柠檬酸淋洗和紫外线照射处理后的货架期分别为15、10和9d。 相似文献
13.
Solar cycle variability, ozone, and climate 总被引：1，自引：0，他引：1
Results from a global climate model including an interactive parameterization of stratospheric chemistry show how upper stratospheric ozone changes may amplify observed, 11-year solar cycle irradiance changes to affect climate. In the model, circulation changes initially induced in the stratosphere subsequently penetrate into the troposphere, demonstrating the importance of the dynamical coupling between the stratosphere and troposphere. The model reproduces many observed 11-year oscillations, including the relatively long record of geopotential height variations; hence, it implies that these oscillations are likely driven, at least in part, by solar variability. 相似文献
14.
基于树干液流技术对杨树冠层吸收臭氧特征的分析1） 总被引：1，自引：0，他引：1
基于树干液流的技术方法,在自然状态下对杨树（ Populus spp．）臭氧吸收特征进行了研究。结果表明：臭氧质量浓度日变化呈单峰型,其变化范围为25．5～175．0μg· m－3;臭氧吸收速率（ FO3）和臭氧吸收导度（ GO3）日变化均为单峰型;FO3均值为（78．22±39．45）nmol· m－2· s－1,GO3均值为（127．60±64．35）mmol· m－2· s－1;环境因子水汽压亏缺（D）、太阳辐射（Rs）和风速对FO3和GO3的响应,导致臭氧吸收通量相对较高,D对更高的GO3和FO3更敏感,随着D增加臭氧吸收减少,Rs在达到50 W· m－2时GO3和FO3也有所降低;臭氧质量浓度抑制树木蒸腾,影响液流密度的变化;臭氧质量浓度超过临界水平引起树木相应的响应,杨树AOT40为72．02 mg· m－3· h－1,远超过对树木危害的臭氧质量浓度的临界水平10．71 mg· m－3· h－1,说明了杨树的高臭氧风险,树干液流技术适用于计算植物的臭氧吸收量。 相似文献
15.
[目的]为超声波、臭氧、光催化协同作用治理环境污染以及复合氧化物体系光催化剂的大规模工业应用提供理论依据。[方法]采用超声法在450℃煅烧合成Ag-Bi2WO6-TiO2复合氧化物体系光催化剂,并研究了在一定条件下超声波、臭氧、Ag-Bi2WO6-TiO2光催化等高级氧化技术的不同组合方法对甲基橙的降解效果。[结果]对于10mg/L甲基橙溶液,反应时间为120min时,超声波、臭氧、可见光和紫外光光催化单独降解率分别为13.45%、40.80%、24.60%和30.50%。超声波与可见光和紫外光光催化组合对甲基橙的降解有一定的协同作用,120min时降解率分别为47.70%、59.00%。同时,臭氧与可见光和紫外光光催化组合对甲基橙的降解也有明显的协同作用,120min时降解率分别为68.80%、82.10%。[结论]超声波、臭氧、可见光和紫外光光催化组合降解甲基橙效果明显。 相似文献
16.
Evans JV 《Science (New York, N.Y.)》1982,216(4545):467-474
The bulk of the sun's radiation is in the visible and infrared. Solar radiation at these wavelengths controls the weather in the lowest levels of the earth's atmosphere. The rate at which this energy is emitted (the so-called solar constant) varies by a few tenths of 1 percent over a time scale of days. Longer period variations may exist, but have yet to be detected. Far more variable are the amounts of energy emitted as ultraviolet, extreme ultraviolet, and x-rays, and in the continuous outflow of ionized solar particles. The latter controls the properties of the space between the earth and the sun as well as those of the earth's magnetosphere. The ultraviolet and particle emissions control the properties of the earth's upper atmosphere, including the global wind circulation and changes therein associated with intense auroral storms. While considerable progress has been made in exploring the solar-terrestrial system since the advent of space research, many problems remain. These include the question of how magnetic energy is converted into ionized particle energy in the sun and in the earth's magnetosphere, the way in which solar and terrestrial magnetic fields join or merge, and how large electric fields are generated and sustained a few thousand kilometers above the earth's poles. Perhaps the most intriguing question concerns the possible relation between solar variability and the earth's weather and climate. 相似文献
17.
日光温室墙体一维导热的MATLAB模拟与热流分析 总被引：1，自引：0，他引：1
为探明日光温室墙体层间温度变化及热量传递动态规律,采用有限差分法建立墙体一维非稳态导热模型,利用MATLAB编制相应的模拟程序,计算出日光温室墙体各点的温度和热流。结果表明:该模型能够比较准确模拟日光温室土墙的温度。墙体内侧存在有效蓄热层,它对日光温室室内热环境有积极的作用。墙体有效蓄热层的热流白天指向墙体外侧,夜间指向墙体内侧,因此它的厚度直接根据热流的方向确定。有效蓄热层与天气、墙体总厚度以及墙体热特性参数有关。2012-12—2013-01期间有效蓄热层厚度为0.26~0.45m不等,最大值出现在连续雪天。同时从理论上验证了3.0m厚的温室土墙内部存在热流相对稳定的"热稳定层"。 相似文献
18.
Calculations have been made to determine the effects of variations in the extreme ultraviolet solar radiation on the upper atmospheres of mars and Venus. The results indicate that the exospheric temperature from 300 degrees K to 600 degrees K during the solar cycle, with a corresponding range on Venus of 450 degrees K to 850 degrees K. At the present time, the temperature of the Martain exosphere should be approximately 500 degrees K. 相似文献
19.
Hydroxyl radicals are often called the "detergent" of the atmosphere because they control the atmosphere's capacity to cleanse itself of pollutants. Here, we show that the reaction of electronically excited nitrogen dioxide with water can be an important source of tropospheric hydroxyl radicals. Using measured rate data, along with available solar flux and atmospheric mixing ratios, we demonstrate that the tropospheric hydroxyl contribution from this source can be a substantial fraction (50%) of that from the traditional O(1D) + H2O reaction in the boundary-layer region for high solar zenith angles. Inclusion of this chemistry is expected to affect modeling of urban air quality, where the interactions of sunlight with emitted NOx species, volatile organic compounds, and hydroxyl radicals are central in determining the rate of ozone formation. 相似文献
20.
采用臭氧工艺,对氨法脱硫的主要副产物亚硫酸铵进行了氧化试验研究,结果表明：在试验范围内,臭氧对高浓度亚硫酸铵具有较好氧化效果,氧化速率随着臭氧质量浓度的升高而增加,随着亚硫酸铵浓度的升高而降低,而循环流量对氧化效果影响不大,温度对氧化效果也有一定影响。在亚硫酸铵初始浓度不超过2 mol/L时,120 min内转化率基本可达到100%,亚硫酸铵完全氧化能耗约为0.5kW.h/kg,显示出良好工业应用前景。 相似文献