共查询到20条相似文献，搜索用时 78 毫秒
1.
Doklady Earth Sciences - Using satellite data and reanalysis data, the characteristics and mechanisms of the formation of an ozone “mini-hole” in the atmosphere over Siberia in the... 相似文献
2.
R. V. Vasil’ev D. S. Kushnarev L. K. Kashapova V. P. Lebedev A. V. Medvedev N. I. Nevedimov K. G. Ratovskii 《Astronomy Reports》2013,57(11):872-881
Using the Irkutsk Incoherent Scattering Radar, it is demonstrated that the high sensitivity of such radars, which are usually used for studies of the Earth’s ionosphere, also enables their use in a passive mode for observations of astronomical radio sources. Observations of solar flares accompanied by coronal mass ejections and of quasi-stationary radio sources on the Sun have been carried out. In addition, scintillations of several of the brightest discrete radio sources (Cygnus A, Cassiopeia A, and the Crab Nebula) have been studied over several months. These data can also be useful for studies of the ionosphere and interplanetary space. 相似文献
3.
Seasonal and solar cycle variations of the various characteristics of night-time anomalous enhancements in total electron content (TEC) of the ionosphere are presented for a low latitude station, Hawaii by considering TEC data for a full solar cycle. All the characteristics of the TEC enhancements have seasonal and solar cycle dependence. TEC enhancement characteristics such as frequency of occurrence, amplitude and duration are positively correlated with solar activity. The possible source mechanisms for the observed enhancements are also discussed. 相似文献
4.
5.
《Comptes Rendus Geoscience》2018,350(7):432-434
NASA has a long and significant history in observations and data analysis research for understanding the short- and long-term changes in ozone in the atmosphere. For nearly 40 years, NASA has overseen satellite observations of stratospheric ozone. These observations have been augmented by ground-based remote sensing, balloon borne, and aircraft observations of ozone and ozone-related species and by continuous observations of ozone depleting substances. Together, they form the evidential basis for understanding ozone changes over these past four decades. Also, NASA has continuously funded laboratory, modeling and data analysis activities to better understand the observations obtained by NASA and other programs. NASA has plans to continue these activities in the future, at a level consistent with available funding, other Earth Science observational priorities, and more importantly, with a goal of ensuring that data exist to understand changes in ozone in the future as the abundances of ozone depleting substances decrease and those of greenhouse gases increase. 相似文献
6.
臭氧变化及其气候效应的研究进展 总被引：10，自引：0，他引：10
综述了近２０年来臭氧变化的规律和机制及其气候效应等领域的研究进展,指出对流层臭氧（主要在北半球）增加、平流层臭氧减少和臭氧总量减少是全球臭氧的变化趋势,原因主要是人类活动导致的ＮＯｘ、ＮＭＨＣ、ＣＯ、ＣＨ４等对流层臭氧前体物的增加和ＮＯｘ、Ｈ２Ｏ、Ｎ２Ｏ、ＣＦＣｓ等平流层臭氧损耗物质的增加。臭氧变化引起的气候效应表现在对流层臭氧的增加将带来地表和低层大气的升温,平流层臭氧的减少则可能导致地表和低层大气的升温或降温。将全球或区域气候模式和大气化学模式进行完全耦合来研究臭氧变化的气候效应是一种十分有效的手段,具有广阔的应用前景。 相似文献
7.
《Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy》2000,25(8):635-638
This paper describes the DUST-2 (Data Utilization software Tools) software, which is a possibility in visualizing and processing ozone and water vapor data of the Earth atmosphere as measured by satellite instruments (TOMS, GOME, MAS) and provided by different data centers. In addition, a new search tool (S4 tool) which allows to search for comparable ozone and water vapor data in four dimensions (location and time) within the DUST-2 data base and a hdf2csv conversion tool are represented. The software package as well as complementary information and data examples are published on CD-ROM (“Data Utilization Software Tools — 2”, DUST-2, Hartmann et al. 2000) under ISBN 3-9804862-3-0 which is available via www.copernicus.org. 相似文献
8.
S. Koshevaya V. Grimalsky A. Kotsarenko R. Prez-Enríquez J. Siquieros-A. E. Gutierrez-D. 《Tectonophysics》2007,431(1-4):241
The simulation of the passage from the lithosphere through the atmosphere to the ionosphere of acoustic waves produced by seismic eruption or explosion shows that there is an acoustic coupling among these layers. This in turn is the cause of change in the transparency of the ionosphere for cosmic radio waves. Underground displacements produce Very Low (VLF) and Extremely Low Frequency (ELF) acoustic waves. In their passage through the lithosphere, the VLF wave is subject to nonlinearity that leads to frequency down-conversion, namely, increasing the ELF acoustic component at the Earth's surface. In turn, the nonlinear propagation of ELF acoustic wave in the atmosphere and the ionosphere leads to the emergence of ultra low frequency (ULF) acoustic waves in the ionosphere. An ultra low frequency acoustic wave (ULF) brings influence into the density of F-layer of the ionosphere and causes the transparency change of the ionosphere for cosmic radio waves. 相似文献
9.
Rumajyoti Hazarika Bitap Raj Kalita Pradip Kumar Bhuyan 《Journal of Earth System Science》2016,125(6):1235-1244
The signature of 11 X-class solar flares that occurred during the ascending half of the present subdued solar cycle 24 from 2009 to 2013 on the ionosphere over the low- and mid-latitude station, Dibrugarh (27.5°N, 95°E; magnetic latitude 17.6°N), are examined. Total electron content (TEC) data derived from Global Positioning System satellite transmissions are used to study the effect of the flares on the ionosphere. A nonlinear significant correlation (R2 = 0.86) has been observed between EUV enhancement (ΔEUV) and corresponding enhancement in TEC (ΔTEC). This nonlinearity is triggered by a rapid increase in ΔTEC beyond the threshold value ～1.5 (×1010 ph cm?2 s?1) in ΔEUV. It is also found that this nonlinear relationship between TEC and EUV flux is driven by a similar nonlinear relationship between flare induced enhancement in X-ray and EUV fluxes. The local time of occurrence of the flares determines the magnitude of enhancement in TEC for flares originating from nearly similar longitudes on the solar disc, and hence proximity to the central meridian alone may not play the dominating role. Further, the X-ray peak flux, when corrected for the earth zenith angle effect, did not improve the correlation between ΔX-ray and ΔTEC. 相似文献
10.
Climatic changes result from variables in planetary orbits which modulate solar energy emission and change seasonal and latitudinal distribution of heat received by the Earth. Small insolation changes are multiplied by the albedo effect of the winter snow fields of the Northern Hemisphere, by ocean-atmosphere feedbacks, and, probably, by the stratospheric ozone layer. The role of volcanic explosions and other aperiodic phenomena is secondary. The immediate climate response to insolation trends permits astronomic dating of Pleistocene events. A new glacial insolation regime, expected to last 8000 years, began just recently. Mean global temperatures may eventually drop about 1o C in the next hundred years. A refinement of the Milankovitch theory in terms of the lunar orbit and more data on solar periodicities are needed for reliable long range predictions. 相似文献
11.
Nandita D. Ganguly 《Journal of Earth System Science》2008,117(1):79-82
The Indian reserve of coking coal is mainly located in the Jharia coal field in Jharkhand. Although air pollution due to oxides
and dioxides of carbon, nitrogen and sulphur is reported to have increased in this area due to large-scale opencast mining
and coal fires, no significant study on the possible impact of coal fires on the stratospheric ozone concentration has been
reported so far. The possible impact of coal fires, which have been burning for more than 90 years on the current stratospheric
ozone concentration has been investigated using satellite based data obtained from Upper Atmospheric Research Satellite (UARS
MLS), Earth Observing System Microwave Limb Sounder (EOS MLS) and Ozone Monitoring Instrument (OMI) in this paper. The stratospheric
ozone values for the years 1992–2007, in the 28–36 km altitude range near Jharia and places to its north are found to be consistently
lower than those of places lying to its south (up to a radius of 1000 km around Jharia) by 4.0–20%. This low stratospheric
ozone level around Jharia is being observed and reported for the first time. However, due to lack of systematic ground-based
measurements of tropospheric ozone and vertical ozone profiles at Jharia and other far off places in different directions,
it is difficult to conclude strongly on the existence of a relationship between pollution from coal fires and stratospheric
ozone depletion. 相似文献
12.
T. Von Clarmann 《Atmósfera》2013,26(3):415-458
This paper reviews the various aspects of chlorine compounds in the stratosphere, both their roles as reactants and as tracers of dynamical processes. In the stratosphere, reactive chlorine is released from chlorofluorocarbons and other chlorine-containing organic source gases. To a large extent reactive chlorine is then sequestered in reservoir species ClONO2 and HCl. Re-activation of chlorine happens predominantly in polar winter vortices by heterogeneous reaction in combination with sunlight. Catalytic cycles involving Cl, ClO, BrO, Cl2O2, ClO2, and others like NO, NO2, OH, and HO2 remove odd oxygen (ozone and atomic oxygen) from the atmosphere. Under an ozone hole condition, the ClO dimer cycle is particularly important, while in mid-latitudes the short-lived reservoir HOC1 has some importance. Solar proton events can also affect stratospheric chlorine chemistry, but whether solar protons effectively activate or deactivate chlorine was shown to depend on illumination conditions. The lifetime of chlorofluorocarbons has an impact on the availability of ozone destructing substances in the stratosphere and depends on the Brewer-Dobson circulation which controls at which altitudes and how long an air parcel is exposed to photochemistry. In turn, the chlorine-containing source gases can be used as tracers to constrain the age of stratospheric air and thus to diagnose the Brewer-Dobson circulation. The use of complementary measurement systems was essential to extend our knowledge on chlorine-containing compounds in the stratosphere. ClO is best measured by remote sensing in its rotational bands in the far infrared and microwave region. For HOC1 the far infrared bands are ideal, but some substantial information was also gained with microwave and mid-infrared measurements. ClONO2 is only measured in the thermal infrared, while HCl has a measurable signal in the microwave, far infrared and mid-infrared regions. The mid-infrared HCl lines, however, are situated at wavelengths where blackbody emission at terrestrial temperatures is so low that infrared measurements of HCl are possible only in solar absorption geometry, but not in thermal emission. Chlorine source gases are most accurately measured by air sampling techniques, while global coverage can only be achieved by satellite-borne thermal infrared measurements. In epistemological terms, research on stratospheric chemistry and particularly the role of chlorine compounds used various scientific concepts from deductive reasoning, falsificationism, abductive reasoning and so-called “puzzle-solving within normal science”. The structuralist theory of science with the concept of non-statement view of theories, however, seems to be best applicable to stratospheric chlorine research of the recent decades. 相似文献
13.
《Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy》2000,25(12):763-768
To account for the annual intensity of wildland fires, a theory has been formerly proposed : it is based on the effect of UV-B radiation on the sensitiveness of plants to fire ignition and propagation. It accounts very satisfactorily for the statistics of annual burned area in the French Mediterranean region. The paper is more particularly devoted to daily variation of the total ozone content of the atmosphere and its possible large daily drop : in the French Mediterranean region, large fires occur in general at the end of such drops, simultaneously in different parts of this region. The UV-B sensitiveness theory based on annual data may predict such large fire occurrence. So, taking into account the daily variation of ozone and solar flux helps to make short-term forecasts of the possibility of large fires in a determined region. 相似文献
14.
《Comptes Rendus Geoscience》2018,350(7):341-346
The comprehensive investigation of polar ozone photochemistry and dynamics has required data obtained from as full a complement of available platforms as possible (ground-based, balloon, aircraft, and satellites). Perhaps the most detailed process studies have been conducted using measurements from aircraft, taking advantage of their targeting capabilities coupled with the potential for enabling measurements at high spatial and temporal resolution. The US National Aeronautics and Space Administration (NASA) conducted the first airborne science investigation of polar ozone in an effort to establish the causes of the recurring seasonal depletion of the Earth's stratospheric ozone layer over Antarctica that was identified in the mid-1980s. Subsequent airborne studies in the polar regions of both hemispheres benefitted from extensive successful collaborations among international scientists and the integration of the aircraft measurements with those obtained using ground-based, balloon-borne, and satellite instruments. This article provides an historical perspective of NASA's utilization of its airborne assets to advance our understanding of the chemical and physical processes that control the abundance of stratospheric ozone in both the Antarctic and Arctic. 相似文献
15.
A mechanism for the acceleration of electrons in the ionosphere of Io due to the moon's motion through the Jovian magnetic field and the presence of Io's ionosphere is considered. Attention is drawn to the important role of the anisotropic conductivity of the ionosphere, which results in the formation of a longitudinal (with respect to the planetary magnetic field) component of the charge-separation electric field. Owing to this anisotropy, the electric field induced by the motion of Io, Ei, produces in Io's ionosphere not only a Pedersen electrical current along Ei but also a Hall current that is approximately perpendicular to the moon's surface in the “upstream” and “downstream” parts of the ionosphere. However, this current cannot be closed through the surface, leading to the formation of a powerful charge-separation field in Io's ionosphere. This field has a component parallel to the magnetic field, with an amplitude comparable to that of the induced electric field. Electron runaway along the magnetic field is also considered, and the occurrence of “active longitudes” and preferred locations for the sources of decametric radio emission in the northern hemisphere of Jupiter are interpreted. The characteristic energies and fluxes of the accelerated electrons injected into Io's flux tube are estimated. The energy of these electron fluxes is sufficient to produce the electromagnetic radiation observed from Io's magnetic tube. 相似文献
16.
Doklady Earth Sciences - Unprecedentedly long and intense depletion in stratospheric ozone over the Arctic observed from January to April 2020 is analyzed. For analysis of the parameters, we... 相似文献
17.
《Comptes Rendus Geoscience》2018,350(7):442-447
The Montreal Protocol has controlled the production and consumption of ozone-depleting substances (ODSs) since its signing in 1987. The levels of most of these ODSs are now declining in the atmosphere, and there are now initial signs that ozone levels are increasing in the stratosphere. Scientific challenges remain for the Montreal Protocol. The science community projected large ozone losses if ODSs continued to increase, and that ozone levels would increase if ODSs were controlled and their levels declined. Scientists remain accountable for these projections, while they continue to refine their scientific basis. The science community remains vigilant for emerging threats to the ozone layer and seeks scientific evidence that demonstrates compliance with Montreal Protocol. As ODSs decrease, the largest impact on stratospheric ozone by the end of the 21st century will be increases in greenhouse gases. The associated climate forcings, and the human responses to these forcings, represent major uncertainties for the future of the stratospheric ozone layer. 相似文献
18.
V. I. Shishov I. V. Chashei V. V. Oreshko S. V. Logvinenko S. A. Tyul’bashev I. A. Subaev P. M. Svidskii V. B. Lapshin R. D. Dagkesamanskii 《Astronomy Reports》2016,60(12):1067-1082
The design properties and technical characteristics of the upgraded Large Phased Array (LPA) are briefly described. The results of an annual cycle of observations of interplanetary scintillations of radio sources on the LPA with the new 96-beam BEAM 3 system are presented. Within a day, about 5000 radio sources displaying second-timescale fluctuations in their flux densities due to interplanetary scintillations were observed. At present, the parameters of many of these radio sources are unknown. Therefore, the number of sources with root-mean-square flux-density fluctuations greater than 0.2 Jy in a 3° × 3° area of sky was used to characterize the scintillation level. The observational data obtained during the period of the maximum of solar cycle 24 can be interpreted using a three-component model for the spatial structure of the solar wind, consisting of a stable global component, propagating disturbances, and corotating structures. The global component corresponds to the spherically symmetric structure of the distribution of the turbulent interplanetary plasma. Disturbances propagating from the Sun are observed against the background of the global structure. Propagating disturbances recorded at heliocentric distances of 0.4–1 AU and at all heliolatitudes reach the Earth’s orbit one to two days after the scintillation enhancement. Enhancements of ionospheric scintillations are observed during night-time. Corotating disturbances have a recurrence period of 27d. Disturbances of the ionosphere are observed as the coronal base of a corotating structure approaches the western edge of the solar limb. 相似文献
19.
In recent years, measurements of total electron content (TEC) have gained importance with increasing demand for the GPS-based
navigation applications in trans-ionospheric communications. To study the variation in ionospheric TEC, we used the data obtained
from GPS Ionospheric Scintillation and TEC monitoring (GISTM) system which is in operation at SVNIT, Surat, India (21.16°N,
72.78°E) located at the northern crest of equatorial anomaly region. The data collected (for the low sunspot activity period
from August 2008–December 2009) were used to study the diurnal, monthly, seasonal semi-annual and annual variations of TEC
at Surat. It was observed that the diurnal variation at the region reaches its maximum value between 13:00 and 16:00 IST.
The monthly average diurnal variations showed that the TEC maximizes during the equinox months followed by the winter months,
and are lowest during the summer months. The ionospheric range delay to TEC for the primary GPS signal is 0.162 m per TECU.
The diurnal variation in TEC shows a minimum to maximum variation of about 5 to 50 TECU (in current low sunspot activity periods).
These TEC values correspond to range delay variations of about 1 to 9 m at Surat. These variations in the range delay will
certainly increase in high sunspot activity periods. Detected TEC variations are also closely related to space weather characterizing
quantities such as solar wind and geomagnetic activity indices. 相似文献
