The Sun's Influence on the Earh's Atmosphere and Interplanetary Space

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.     

Solar Wind Control of the Earth's Electric Field

The sun-weather problem is placed within an electrical framework subject to experimental investigation. An explanation is suggested for how solar variability modulates the earth's electric field. The solar wind velocity is inversely correlated with the electrical potential of the ionosphere, a measure of the overall intensity of the earth's fair-weather atmospheric electric field. In seeking a physical cause of this relationship, galactic cosmic radiation was studied and it was also found to be inversely correlated with solar wind velocity. Thus, the earth's electric field intensity which is maintained by worldwide thunderstorm currents-a meteorological phenomenon-varies in phase with cosmic radiation. Since cosmic radiation is the primary source of atmospheric ionization, these findings support a proposed mechanism in which solar control of ionizing radiation modulates atmospheric electrification and thus possibly cloud physical processes. If the latter occurred, atmospheric energetics would be affected. Sun-weather research need no longer only consist of statistical correlations; an experimental approach is described. Establishment of a proposed geoelectric index would add a new dimension to solar-terrestrial studies.     

Changes in stratospheric ozone

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.     

Biologic effects of supernovae

Estimates of the probability that nearby explosions of supernovae have occurred during the earth's history and the biologic effects of the radiation therefrom are presented. They suggest that cosmic radiation from supernovae could have caused the extinction of many exposed animals without the simultaneous extinction of plant life. This suggests that supernovae should be considered as one possible mechanism by which fauna become extinct.     

Greenhouse Effects due to Man-Mad Perturbations of Trace Gases

Nitrous oxide, methane, ammonia, and a number of other trace constituents in the earth's atmosphere have infrared absorption bands in the spectral region 7 to 14 microm and contribute to the atmospheric greenhouse effect. The concentrations of these trace gases may undergo substantial changes because of man's activities. Extensive use of chemical fertilizers and combustion of fossil fuels may perturb the nitrogen cycle, leading to increases in atmospheric N(2)O, and the same perturbing processes may increase the amounts of atmospheric CH(4) and NH(3). We use a one-dimensional radiative-convective model for the atmospheric thermal structure to compute the change in the surface temperature of the earth for large assumed increases in the trace gas concentrations; doubling the N(2)O, CH(4), and NH(3) concentrations is found to cause additive increases in the surface temperature of 0.7 degrees , 0.3 degrees , and 0.1 degrees K, respectively. These systematic effects on the earth's radiation budget would have substantial climatic significance. It is therefore important that the abundances of these trace gases be accurately monitored to determine the actual trends of their concentrations.     

Power-Line Harmonic Radiation: Can It Significantly Affect the Earth's Radiation Belts?

It has been suggested that harmonic radiation from the earth's 50- and 60-hertz power transmission lines might significantly influence the distribution of electrons in the radiation belts. On the basis of observations presented here, it seems advisable to accept such a hypothesis with caution. New evidence suggests that power-line radiation does not play any major role in the nonadiabatic dynamics of radiation belt electrons.     

Magnetospheric effects of power line radiation

Radiation from electrical power lines leaks into the magnetosphere and stimulates strong very-low-frequency wave activity out to many earth radii. Observations in Antarctica show that wave activity induced by power lines tends to occur during the daytime when power consumption is high in the source region in eastern Canada. The wave frequency ranges from 1 to 8 kilohertz. This man-made wave activity may have significant effects on energetic electrons trapped in the earth's radiation belts.     

植物根际对增强紫外线-B辐射的响应

臭氧层减薄导致地表中波紫外-线B(UV-B,280~320 nm)辐射增强,UV-B辐射能量远高于可见光,并且能被植物体内蛋白质和核酸等生物大分子吸收。当前,植物的UV-B效应研究主要集中在地上部分,对地下部分的研究很少。综述了近年来增强UV-B辐射对植物根际影响的研究进展,主要包括根形态、根系分泌物、根际微生物和根系中矿质营养。并就今后该方面的研究提出建议。     

Ultraviolet radiation levels during the antarctic spring

The decrease in atmospheric ozone over Antarctica during spring implies enhanced levels of ultraviolet (UV) radiation received at the earth's surface. Model calculations show that UV irradiances encountered during the occurrence of an Antarctic "ozone hole" remain less than those typical of a summer solstice at low to middle latitudes. However, the low ozone amounts observed in October 1987 imply biologically effective irradiances for McMurdo Station, Antarctica, that are comparable to or greater than those for the same location at December solstice. Life indigenous to Antarctica thereby experiences a greatly extended period of summerlike UV radiation levels.     

Mercury in a Greenland ice sheet: evidence of recent input by man

The increased mercury content in a Greenland ice sheet over the last several decades suggests the dissemination of this element about the earth's atmosphere through the activities of man. The mercury content in the atmosphere appears to result primarily from the degassing of the earth's crust. Increased flux may come about as a result of the enhancement of this degassing process through the actions of man.     

Bees have magnetic remanence

Honey bees orient to the earth's magnetic field. This ability may be associated with a region of transversely oriented magnetic material in the front of the abdomen. The magnetic moment apparently develops in the pupal state and persists in the adults.     

Motions of the Earth's Core and Mantle, and Variations of the Main Geomagnetic Field

Theoretical work on the magnetohydrodynamics of the earth's liquid core indicates (a) that horizontal variations in the properties of the core-mantle interface that would escape detection by modern seismological methods might nevertheless produce measurable geomagnetic effects; (b) that the rate of drift, relative to the earth's surface, of nonaxisymmetric features of the main geomagnetic field might be much faster than the average zonal speed of hydrodynamic motion of core material relative to the surrounding mantle; and (c) why magnetic astronomical bodies usually rotate. Among the consequences of (a) and (b) are the possibilities that (i) the shortest interval of time that can be resolved in paleomagnetic studies of the geocentric axial dipole component of the earth's magnetic field might be very much longer than the value often assumed by many paleomagnetic workers, (ii) reversals in sign of the geomagnetic dipole might be expected to show some degree of correlation with processes due to motions in the mantle (for example, tectonic activity, polar wandering), and (iii) variations in the length of the day that have hitherto been tentatively attributed to core motions may be due to some other cause.     

Solar neutrino production of long-lived isotopes and secular variations in the sun

Long-lived isotopes produced in the earth's crust by solar neutrinos may provide a method of probing secular variations in the rate of energy production in the sun's core. Only one isotope, calcium-41, appears to be suitable from the dual stand-points of reliable nuclear physics and manageable backgrounds. The proposed measurement also may be interesting in view of recent evidence for neutrino oscillations.     

Paleontological Evidence of Varitions in Length of Synodic Month since Late Cambrian

The values of length of synodic month, obtained from tidally controlled periodical growth patterns in mollusks and stromatolites for several geologic periods, indicate that the deceleration rate of the earth's rotation has not been constant. Two breaks in slope, in the Pennsylvanian and Cretaceous, may be related to changes in distribution of continents, oceans, and adjacent shallow seas.     

Magnetic field reversals, polar wander, and core-mantle coupling

True polar wander, the shifting of the entire mantle relative to the earth's spin axis, has been reanalyzed. Over the last 200 million years, true polar wander has been fast (approximately 5 centimeters per year) most of the time, except for a remarkable standstill from 170 to 110 million years ago. This standstill correlates with a decrease in the reversal frequency of the geomagnetic field and episodes of continental breakup. Conversely, true polar wander is high when reversal frequency increases. It is proposed that intermittent convection modulates the thickness of a thermal boundary layer at the base of the mantle and consequently the core-to-mantle heat flux. Emission of hot thermals from the boundary layer leads to increases in mantle convection and true polar wander. In conjunction, cold thermals released from a boundary layer at the top of the liquid core eventually lead to reversals. Changes in the locations of subduction zones may also affect true polar wander. Exceptional volcanism and mass extinctions at the Cretaceous-Tertiary and Permo-Triassic boundaries may be related to thermals released after two unusually long periods with no magnetic reversals. These environmental catastrophes may therefore be a consequence of thermal and chemical couplings in the earth's multilayer heat engine rather than have an extraterrestrial cause.     

Cracks and pores: a closer look

Most pores and some cracks in several rocks, as directly viewed with a new technique, have a shape that suggests an origin early in the history of these rocks. Thus, behavior in the laboratory may be a reliable indication of behavior in the earth's crust, for electrical resistivity, permeability, or other properties that depend on microporosity.     

Carbon compounds in interplanetary dust: evidence for formation by heterogeneous catalysis

Associations of carbonaceous material with iron-nickel alloy, carbides, and oxides were identified by analytical electron microscopy in ten unmelted chondritic porous micrometeorites from the earth's stratosphere. These associations, which may be interpreted in terms of reactions between a carbon-containing gas and catalytically active dust grains, suggest that some of the carbon in the chondritic porous subset of interplanetary dust was emplaced through heterogeneous catalysis.     

改善阳坡局地小气候与造林成活率

本文是根据1982—1985年在太岳山林区用L_θ(3~4)正交表先后按排的200亩阳坡造林试验资料进行的分析,得到了以早春、水平沟、侧柏组合的阳坡造林最佳方案。水平沟可使太阳辐射比阳坡自然坡减弱22.6％,降低地温2.9—3.6℃,减少地表蒸发耗热量85％,提高土壤湿度4.6％,接近于阴坡小气候生态坏境,从而使造林成活率达到85％以上,保存率93.8％,苗木生长量比常规造林增长57.6％。此外,由于每亩设计造林坑数的蓄水量与当地最大持续降水量一致,在试验区没有水土流失现象,且植被覆盖度由30％增至70％,改善了生态坏境。     

Aerosols, cloud microphysics, and fractional cloudiness

Increases in aerosol concentrations over the oceans may increase the amount of low-level cloudiness through a reduction in drizzle-a process that regulates the liquid-water content and the energetics of shallow marine clouds. The resulting increase in the global albedo would be in addition to the increase due to enhancement in reflectivity associated with a decrease in droplet size and would contribute to a cooling of the earth's surface.     

近地面边界层大气层结稳定度的测定与分析研究

近地面边界层大气层结的稳定度与许多学科有一定的关系，很多科研项目及技术措施都要求在特定的大气层结条件下进行，本文通过测定二种不同下垫面上的温度及风速的垂直分布，经过计算温度梯度和紊流交换系数确定大气层结在不同下垫面上的日变化规律，从而为相关学科提供依据。