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1.
The changes of vertical wind structure in equatorial stratosphere in course of Quasi-Biennial Oscillation (QBO) demonstrates
the evident seasonal dependence. The easterly wind regime descending from the middle to lower stratosphere always includes
the stationary period—the stagnation stage. At stagnation stage the bottom boundary of the easterly wind is located in different
QBO-cycles at different altitude in the range from ∼22 to ∼26 km, but in each QBO-cycle this altitude is actually constant
during the whole stagnation period. Stagnation always begins in solstice (in June–July or December–January). Descent of the
easterly wind after stagnation is always resumed near equinox—in March–April or September–October. Consequently, the duration
of stagnation stage varies discretely and can be equal to one, three, or five seasons (three, nine, or fifteen months, respectively)
in different QBO-cycles. The QBO-cycle period determined as an interval between the beginnings of two successive stagnation
stages turns out to be of discrete duration also, and can be equal to 24, 30, or 36 months. The dependence of many atmosphere
phenomena determining the Earth’s climate on QBO-phase suggests the need to forecast the QBO-cycle evolution. The established
seasonal regularity and discrete QBO-cycle period make it possible the forecasting the QBO-cycle evolution, its duration,
and the dates of the QBO-phase changing. 相似文献
2.
B. Kärcher 《Surveys in Geophysics》1999,20(2):113-167
Liquid and solid particles in the plumes of jet aircraft cruising in the upper troposphere and lower stratosphere lead to the formation of ice clouds (contrails), modify the microphysical properties of existing cirrus clouds, and provide sites for heterogeneous chemical reactions. Characterization of aviation-produced particles in terms of physico-chemical properties is an important step in assessing the global impact of aircraft emissions upon atmospheric chemistry and climate parameters. Chemistry and microphysics of the gas-aerosol system in aircraft plumes and its evolution in the atmosphere is a field of intense research. This paper reviews the current knowledge (mid-1998) and outlines possible atmospheric implications. 相似文献
3.
A. A. Cheremisin P. V. Novikov I. S. Shnipov V. V. Bychkov B. M. Shevtsov 《Geomagnetism and Aeronomy》2012,52(5):653-663
Lidar observations during 2007–2008 in Kamchatka revealed aerosol layers in the upper stratosphere at heights of 35–50 km and in the mesosphere at heights of 60–75 km. It is well known that forces of gas-kinetic nature, i.e., photophoretic forces, act on aerosol particles that absorb solar radiation and terrestrial IR radiation; these forces can counteract the gravitational force and even lead to the levitation of these particles at particular heights. The accumulation of particles at these heights may lead to the formation of aerosol layers. We calculated these forces for the conditions of lidar observations in Kamchatka. Aerosol layers were observed at heights where particle levitation can occur. Thus, the stratospheric and mesospheric aerosol layers, detected at heights of 30–50 and 60–75 km, respectively, may be due to the effect of the photophoretic force on aerosol particles. 相似文献
4.
Débora C. Marié Marcos A. E. Chaparro Claudia S. G. Gogorza Ana Navas Ana M. Sinito 《Studia Geophysica et Geodaetica》2010,54(1):135-152
In this work, we carried out a preliminary study of traffic-derived pollutants from primary sources (vehicles), and on roads
(paved area), road borders and surroundings areas. The study is focussed on the identification, distribution and concentration
of pollutants and magnetic carriers. Magnetic parameters and their analyses suggest that the magnetic signal of vehicle-derived
emissions is controlled by a magnetite-like phase. Magnetic grain size estimations reveal the presence of fine particles (0.1–5
μm) that can be inhaled and therefore are dangerous to human health. Magnetic susceptibility results (about 175 × 10−5 SI) show a higher magnetic concentration — magnetic enhancement — in the central area of the tollbooth line that is related
to higher traffic. In addition, magnetic susceptibility was computed on several roadside soils along a length of 120 km and
used to generate a 2-D contour map, which shows higher magnetic values (100–200 10−5 SI) near the edge of the road. The observed distribution of magnetic values indicates that magnetic particles emitted by
vehicles are accumulated and mainly concentrated within a distance of several meters (1–2 m) from the edge of the road. In
consequence, the magnetic susceptibility parameter seems to be a suitable indicator of traffic-related pollution. Non-magnetic
studies show an enrichment of some trace elements, such as Ba, Cr, Cu, Zn and Pb, that are associated with traffic pollution.
Furthermore, statistical correlations between the content of toxic trace metals and magnetic variables support the use of
magnetic parameters as potential proxies for traffic-related pollution in this study area. 相似文献
5.
Dynamical diagnosis of the breakup of the stratospheric polar vortex in the Northern Hemisphere 总被引：3，自引：0，他引：3
The research on climate change in polar regions, especially on the role of polar in the global climate system, has gain unprecedented level of interest. It has been the key scientific issue of the International Polar Year program (IPY, 2007―2008). In this paper, we dealt with the debate upon the breakup time of the stratospheric polar vortex in boreal spring. An observational study of the relation between strato- spheric polar vortex breakup and the extra-tropical circulation was performed. The mean breakup date―when the winter westerly at the core of polar jet turns to summer easterly―is about April 10. The breakup time has large interannual variation with a time span of about 2 months. It also has a long-term trend with the 1990s and 2000s witnessing more and more late breakups of polar vortex. Composite of wind speed at the core of polar jet for the extremely early and late breakup years shows that late years have two periods of westerly weakening while early breakup years have only one. The first weakening in the late years happens in middle January with wind speed dropping sharply from more than 40 m s?1 to about 15 m s?1. This is accompanied with anomalous activities of planetary waves in both strato- sphere and troposphere; while the second weakening in the late breaking years is mainly the results of diabatic heating with very weak wave activities. In early breakup years, the transition from westerly to easterly is rapid with wind speed dropping from more than 30 m s?1 to less than ?10 m s?1 within a month. This evolution is associated with a strong bidirectional dynamical coupling of the stratosphere and troposphere. The circulation anomalies at low troposphere are also analyzed in the extremely early and late breakup years. It shows that there are significant differences between the two kinds of extreme years in the geopotential height and temperature composite analysis, indicating the dynamical cou- pling of stratosphere and troposphere with the evolution of stratospheric polar vortex. 相似文献
6.
The vertical distribution of the methane concentration in the stratosphere is related to its dissociation by two simultaneous daytime reactions with excited oxygen atoms O(1D) and with OH radicals and depends on the stratospheric eddy diffusion coefficient.Dissociation of CH4 in the lower stratosphere leads to the production of CO molecules while in the upper stratosphere thepphotodissociation of CO2 molecules is an additional process to the CO production.In the upper stratosphere (40±10 km) there is an equilibrium between the formation and destruction processes of carbon monoxide which leads to a minimum of its mixing ratio. There is an increase of the CO mixing ratio in the troposphere and mesosphere compared with that of the stratosphere.The vertical distribution of the CO mixing ratio is closely related to the eddy diffusion coefficient in the whole stratosphere but the absolute values of the hydroxyl radical concentration also determine the values of the CO mixing ratio. 相似文献
7.
8.
In order to determine typical sizes of ice-supersaturated regions (ISSRs) in the upper troposphere and lowermost stratosphere we set up the frequency distribution of path lengths flown by MOZAIC aircraft within ISSRs. The mean path length is about 150 km with a standard deviation of 250 km. We analyse the influence of a selection bias (viz. that large ISSRs are more often crossed by aircraft than small ones) on the obtained path length statistics and derive a mathematical equation that relates the path length distribution to the underlying size distribution of ISSRs, assuming that they have circular shape. We solve the equation (by trial and error) and test the result using numerical simulations. Surprisingly, we find that there may be many more very small ISSRs than apparent from the data such that the true mean diameter of the ISSRs may be of the order a few kilometres only. The relevance of the result is discussed and dedicated research flights to measure the true extension of ISSRs are recommended. 相似文献
9.
In this paper, we attempt to use satellite gravity data and a new inversion method to study the lateral density anomaly distribution
in the mantle.
First, density difference Δρ(τ,θ,φ) is expanded in terms of a three—dimensional orthogonal function system, the coefficients of the expansion are to be determined.
Then, a set of observation equations is established from the relationship between density anomaly and disturbing geopotential.
In the equations the unknown vector contains the coefficients of density anomaly expansion, the observational vector is obtained
by computing geopotential perturbations using the potential coefficients of GEM10B, and a filtering process is done for the
observational values by properly selecting the harmonic degrees of geopotentical. Finally, the lateral density variations
in the lower mantle (670 km toCM boundary) are investigated. In this case, the degrees of disturbing geopotential are selected as 2–11, the truncated degrees
of density anomaly expansion are taken asL=6 andK=4, and the damping least squares method is used to solve the observation equations.
The resulting model shows the high level of density perturbations at 670 km discontinuity and core — mantle boundary, a high
— density zone circumscribing the Pacific and a lower—density region under the center of Pacific. These features are in agreement
with the three—dimensional seismic velocity variation features by Dziewonski (1984). In the Antarctic region and some parts
of Atlantic and Indian Ocean, however, the resulting density anomalies are negatively correlated with the seismic velocity
anomalies, the cause resulting in these phenomena is preliminarily analysed in this paper.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 53–65, 1991.
The principle and method represented in this paper can also be suitable to study the lateral density anomaly distribution
in the earth’s crust and the upper mantle. 相似文献
10.
B. V. Borovskii L. M. Bogomolov A. S. Zakupin V. A. Mubassarova 《Izvestiya Physics of the Solid Earth》2011,47(10):926-936
The combined impacts of the electromagnetic fields generated by two independent sources on the process of crack formation
in loaded heterogeneous materials (rocks) are studied. The interest in such experiments lies in the fact that in natural conditions,
the combination of several fields—the potential triggers of seismic activity—is rather the rule than the exception. It is
shown by examples that in the conditions of crossed electric and magnetic fields (CrEMFs) the enhancement in acoustic activity
can be triggered with a lower strength electric field than in case of the electric impact alone. 相似文献
11.
Two methods were used to quantify the flux of volcanic sulphur (as the equivalent mass of SO2) to the stratosphere over different timescales during the Holocene. A combination of satellite-based measurements of sulphur
yields from recent explosive volcanic eruptions with an appropriate rate of explosive volcanism for the past 200 years constrains
the medium-term (∼102 years) flux of volcanic sulphur to the stratosphere to be ∼1 Mt a–1, with lower and upper bounds of 0.3 and 3 Mt a–1. The short-term (∼10- to 20-year) flux due to small magnitude (1010–1012 kg) eruptions is of the order of 0.4 Mt a–1. At any time the instantaneous levels of sulphur in the stratosphere are dominated by the most recent (0–3 years) volcanic
events. The flux calculations do not attempt to address this very short timescale variability. Although there are significant
errors associated with the raw sulphur emission data on which this analysis is based, the approach presented is general and
may be readily modified as the quantity and quality of the data improve. Data from a Greenland ice core support these conclusions.
Integration of the sulphate signals from presumed volcanic sources recorded in the GISP2 core provides a minimum estimate
of the 103–year volcanic SO2 flux to the stratosphere of 0.5–1 Mt a–1 over the past 9000 years. The short-term flux calculations do not account for the impact of rare, large events. The ice-core
record does not fully account for the contribution from small, frequent events.
Received: 27 September 1995 / Accepted: 13 December 1995 相似文献
12.
《Journal of Atmospheric and Solar》2008,70(1):13-40
The solid and liquid particles which constitute polar stratospheric clouds (PSCs) are of manifold importance to the meteorology of the stratosphere. The heterogeneous reactions which take place on and within these particles release halogens from relatively inert reservoir species into forms which can destroy ozone in the polar spring. In addition, solid PSC particles are instrumental in the physical removal of nitrogen oxides (denitrification) and water (dehydration) of regions of the polar stratosphere. Denitrification, in particular, allows extended ozone destruction by slowing the conversion of chlorine radicals back into reservoir species.We review the historical development of PSC studies, with particular emphasis on results from the last decade, encompassing developments in observations, in laboratory experiments, and in theoretical treatments. The technical challenge of measuring sufficient of the parameters describing any given PSC, to allow its microphysics to be understood, has driven forward balloon-borne, aircraft, and satellite instrumentation. The technical challenge of finding suitable laboratory proxies for PSCs, in order to observe the microphysics under controlled conditions, has resulted in a wide variety of experimental designs, some of which maximise the probability of observing phase change, others which mimic the surface–volume ratios of PSCs more closely. The challenge to theory presented by PSCs has resulted in improvements in the thermodynamics of concentrated inorganic solutions of volatile compounds, and a new general theory of freezing of water ice from concentrated aqueous solutions. Of the major processes involving PSCs, heterogeneous reaction probabilities for ternary HNO3/H2SO4/H2O solutions, and heterogeneous freezing to produce nitric-acid hydrates, are the least well understood. 相似文献
13.
Data from three years of MOZAIC measurements made it possible to determine a distribution law for the relative humidity in the upper troposphere and lower stratosphere. Data amounting to 13.5% of the total were obtained in regions with ice supersaturation. Troposphere and stratosphere are distinguished by an ozone concentration of 130 ppbv as threshold. The probability of measuring a certain amount of ice supersaturation in the troposphere decreases exponentially with the degree of ice supersaturation. The probability of measuring a certain relative humidity in the stratosphere (both with respect to water and ice) decreases exponentially with the relative humidity. A stochastic model that naturally leads to the exponential distribution is provided. Mean supersaturation in the troposphere is about 15%, whereas ice nucleation requires 30% supersaturation on the average. This explains the frequency of regions in which aircraft induce persistent contrails but which are otherwise free of clouds. Ice supersaturated regions are 3-4 K colder and contain more than 50% more vapour than other regions in the upper troposphere. The stratospheric air masses sampled are dry, as expected, having mean relative humidity over water of 12% and over ice of 23%, respectively. However, 2% of the stratospheric data indicate ice supersaturation. As the MOZAIC measurements have been obtained on commercial flights mainly between Europe and North America, the data do not provide a complete global picture, but the exponential character of the distribution laws found is probably valid globally. Since water vapour is the most important greenhouse gas and since it might enhance the anthropogenic greenhouse effects via positive feedback mechanisms, it is important to represent its distribution correctly in climate models. The discovery of the distribution law of the relative humidity makes possible simple tests to show whether the hydrological cycle in climate models is represented in an adequate way or not. 相似文献
14.
Vertical profiles of CCl4, CFCl3, and CF2Cl2 mixing ratios in the upper troposphere and lower stratosphere have been measured on four flights with chartered aircraft, type HS 125. The flights were carried out in November and December 1976 over Europe at latitudes between 50 and 60°N. At least eight air samples were taken during each ascent and descent of the aircraft at altitudes between 7 and 12.5 km. The samples were analysed in the laboratory using gaschromatographic procedures. The results indicate a decrease of the CCl4, CFCl3, and CF2Cl2 mixing ratios above the tropopause. The observed average gradients in the stratosphere are 14 pptv/km for CCl4, 12 pptv/km for CFCl3 and 27.8 pptv/km for CF2Cl2. With exception of CFCl3 these gradients are higher than those predicted by model calculations. Apparently, further sink mechanisms for CCl4 and CF2Cl2 exist in the lower stratosphere not yet included in the models. 相似文献
15.
基于Global Positioning System (GPS)掩星数据在平流层具有较高准确性、稳定性的优势,本文尝试用新一代GPS掩星观测——the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC)资料验证不同卫星平台上先进的微波探测仪（AMSU）的平流层观测结果.通过COSMIC大气温度廓线与AMSU辐射传输模式结合,得到模拟亮温,然后与AMSU平流层观测进行匹配比较.分析表明GPS掩星数据能够作为一个相对独立的参量检验NOAA15、16、18卫星平台内部的偏差.通过一年数据的比较验证,初步显示不同卫星平台的AMSU观测亮温在平流层低层都偏低,并且NOAA18平台的亮温偏低程度明显大于NOAA15、16.AMSU亮温偏差在极地冬季较为显著,尤其南极地区NOAA18的偏差幅度达到1.8 K.结合24小时内AMSU观测亮温偏差变化及其样本分布特征,可以看到明显的太阳辐射差异可能是导致AMSU观测亮温在极地偏差显著的主要原因. 相似文献
16.
A. N. Gruzdev 《Geomagnetism and Aeronomy》2014,54(5):633-639
Using spectral, cross-spectral, and regression methods, we analyzed the effect of the 11-year cycle of solar activity on the ozone content in the stratosphere and lower mesosphere via satellite measurement data obtained with the help of SBUV/SBUV2 instruments in 1978–2003. We revealed a high coherence between the ozone content and solar activity level on the solar cycle scale. In much of this area, the ozone content varies approximately in phase with the solar cycle; however, in areas of significant gradients of ozone mixing ratio in the middle stratosphere, the phase shift between ozone and solar oscillations can be considerable, up to π/2. This can be caused by dynamical processes. The altitude maxima of ozone sensitivity to the 11-year solar cycle were found in the upper vicinity of the stratopause (50–55 km), in the middle stratosphere (35–40 km), and the lower stratosphere (below 25 km). Maximal changes in ozone content in the solar cycle (up to 10% and more) were found in winter and spring in polar regions. 相似文献
17.
Simultaneous observations of stratospheric organic and inorganic chlorine were made in September 1993 out of Fort Sumner, New Mexico, using JPL balloon-borne MkIV interferometer. Between 15 and 20 km, a significant fraction (20-60%) of the inorganic chlorine could not be accounted for by the sum of measured HCl, ClONO2, and HOCl. Laboratory measurements of the reaction of ClO radicals on sulfuric acid solutions have indicated that, along with HCl, small amounts of perchloric acid, HClO4, were formed. Very little is known about the fate of HClO4 in the stratosphere and we use a photochemical box model to determine the impact of this new species on the partitioning of inorganic chlorine in the stratosphere. Assuming that HClO4 is photochemically stable, it is shown that in the enhanced aerosol loading conditions resulting from Mt. Pinatubo's eruption, HClO4 could represent a significant reservoir of chlorine in the lower stratosphere, sequestering up to 0.2 ppbv (or 50%) of the total inorganic chlorine at 16 km. The occurrence of this new species could bring to closure the inorganic chlorine budget deficiency made apparent by recent ER-2 aircraft in situ measurements of HCl. 相似文献
18.
J. Röttger 《Pure and Applied Geophysics》1980,118(1):494-527
Powerful VHF radars are capable of almost continuously monitoring the threedimensional velocity vector and the distribution of turbulence in the middle atmosphere, i.e. the stratosphere and mesosphere. Methods of radar investigations of the middle atmosphere are outlined and the basic parameters, mean and fluctuating velocities as well as reflectivity and persistency of atmospheric structures, are defined. Results of radar investigations are described which show that the tropopause level as well as a criterion on the stability of the lower stratosphere can be deduced. Besides mean wind velocities, VHF radars can measure instantaneous velocities due to acoustic gravity waves. The interaction of gravity waves with the background wind is discussed, and it is shown that cumulus convection is an effective source of gravity waves in the lower stratosphere. The vertical microstructure of the stratosphere, manifesting itself in thin stratified sheets in which temperature steps occur, is investigated by applying knowledge from investigations of the oceanic thermocline. Possible origins, like shear generation and lateral convection of the microstructure of the stratosphere, are discussed. Observations of gravity waves in the mesosphere are reviewed and their connection with turbulence structures is pointed out. Finally, some open questions which could be answered by further VHF radar investigations are summarized. 相似文献
19.
Influence of the Precipitating Energetic Particles on Atmospheric Chemistry and Climate 总被引：1，自引：0，他引：1
We evaluate the influence of the galactic cosmic rays (GCR), solar proton events (SPE), and energetic electron precipitation (EEP) on chemical composition of the atmosphere, dynamics, and climate using the chemistry-climate model SOCOL. We have carried out two 46-year long runs. The reference run is driven by a widely employed forcing set and, for the experiment run, we have included additional sources of NO x and HO x caused by all considered energetic particles. The results show that the effects of the GCR, SPE, and EEP fluxes on the chemical composition are most pronounced in the polar mesosphere and upper stratosphere; however, they are also detectable and statistically significant in the lower atmosphere consisting of an ozone increase up to 3?% in the troposphere and ozone depletion up to 8?% in the middle stratosphere. The thermal effect of the ozone depletion in the stratosphere propagates down, leading to a warming by up to 1?K averaged over 46?years over Europe during the winter season. Our results suggest that the energetic particles are able to affect atmospheric chemical composition, dynamics, and climate. 相似文献
20.
利用1992～2005年卤素掩星试验（HALOE）的观测资料分析了中国上空平流层的几种微量气体（NO, NO2, HF, HCl, CH4, H2O 和O3）混合比的垂直分布和变化趋势,以期为研究平流层的辐射和化学过程提供一些有用的数据. 文中除给出我国上空平流层各高度上平均的各种微量气体的含量外,还给出青藏高原上空这些微量气体的含量. 分析结果表明,平流层各种微量气体混合比的垂直分布有其不同的特征,在对流层上层到平流层底部各种微量气体的混合比分布和季节变化与平流层相比有明显的差异;分析结果还表明,这些微量气体的季节变化、准两年周期振荡和长期变化趋势都很明显,并且在平流层的不同高度上它们的变化趋势是不相同的. 在平流层中层,NO, NO2, HCl 和H2O 混合比在1998年以前都是增加而后则是明显下降的,但O3相反,在1998年以前明显减少,1998年后其减少的趋势不明显. 这表明,近年来平流层中层这些微量气体的减少使得它们对臭氧的破坏有所缓解. 但在平流层下层,臭氧的耗损仍然很明显. 相似文献