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61.
The possibility of H3+ playing a role as a sink for noble gases has been investigated in the case of Argon. Elaborate quantum methods (ab initio Coupled Cluster and density functional BH&HLYP levels of theory) have been shown to reproduce the rotational constants within 0.3% together with the only known IR frequency on the test case of Ar…D3+. Dissociation energies of (Ar)n…H3+ as a function of cluster size, i.e. 7.2 (n=1), 3.7 (n=2), 3.6 (n=3), 1.6 (n=4), 1.7 (n=5) kcal/mol, follow the pattern established experimentally for (Ar)n…H3+ and (H2)n…H3+ series. Rotational constants and harmonic frequencies of (Ar)n…H3+ (n=1-3) are presented. 相似文献
62.
63.
Reliable land cover land use (LCLU) information, and change over time, is important for Green House Gas (GHG) reporting for climate change documentation. Four different organizations have independently created LCLU maps from 2010 satellite imagery for Malawi for GHG reporting. This analysis compares the procedures and results for those four activities. Four different classification methods were employed; traditional visual interpretation, segmentation and visual labelling, digital clustering with visual identification and supervised signature extraction with application of a decision rule followed by analyst editing. One effort did not report classification accuracy and the other three had very similar and excellent overall thematic accuracies ranging from 85 to 89%. However, despite these high thematic accuracies there were very significant differences in results. National percentages for forest ranged from 18.2 to 28.7% and cropland from 40.5 to 53.7%. These significant differences are concerns for both remote-sensing scientists and decision-makers in Malawi. 相似文献
64.
Observational analyses have demonstrated that the Hadley circulation has expanded poleward in recent decades. Important issues are what caused the widening of the Hadley circulation and whether the observed widening is related to anthropogenic forcing. In the present study, we use currently available simulations of the Coupled Model Intercomparison Project Phase-5 (CMIP5) to analyze changes in the width of the Hadley circulation. It is found that CMIP5 historical simulations with greenhouse gas (GHG) forcing generate a total widening of ~0.15o0.06o in latitude (10 yr)-1 for the period 1979--2005, and the widening in CMIP5 historical simulations with all forcings is ~0.17o0.06o per decade. Similar to that in CMIP3, the simulated poleward expansion in CMIP5 is much weaker than the observational reanalyses. In CMIP5 projection simulations for the 21st century, magnitudes of widening of the Hadley circulation increase with radiative forcing. For the extreme projected radiative forcing of RCP8.5, the total annual-mean widening of the Hadley circulation is ~0.27o0.04o(10 yr)-1 in the 21st century. Although CMIP5 underestimates observed poleward expansion of the Hadley circulation, the results of this study suggest that the observed trends in the width of the Hadley circulation are caused by anthropogenic forcing and that increasing GHGs play an important role in the observed poleward expansion of the Hadley circulation, in addition to other forcings emphasized in previous studies. 相似文献
65.
The aerosol number spectrum and gas pollutants were measured and the new particle formation (NPF) events were discussed in Nanjing. The results showed that the size distributions of aerosol number concen- trations exhibited distinct seasonal variations, implying the relations of particle sizes and their sources and sinks. The number concentrations of particles in the nuclei mode (10-30 nm), Aitken mode (30-100 nm), accumulation mode (100 -1000 nm) and coarse mode (〉1μm) varied in the order of summer 〉 spring 〉 autumn, summer 〉 autumn 〉 spring, autumn 〉 summer 〉 spring, and spring 〉 autumn 〉summer, re- spectively. The diurnal variation of total aerosol number concentrations showed three peaks in all observed periods, which corresponded to two rush hours and the photochemistry period at noon. In general, the NPF in summer occurred under the conditions of east winds and dominant air masses originating from marine areas with high relative humidity (50%-70%) and strong solar radiations (400 -700 W m-2). In spring, the NPF were generally accompanied by low relative humidity (14%-30%) and strong solar radiations (400-600 W m-2). The new particle growth rates (GR) were higher in the summertime in the range of 10- 16 nm h-1. In spring, the GR were 6.8-8.3 nm h-1. Under polluted air conditions, NPF events were seldom captured in autumn in Nanjing. During NPF periods, positive correlations between 10- 30 nm particles and 03 were detected, particularly in spring, indicating that NPF can be attributed to photochemical reactions. 相似文献
66.
W. Thomas T. Ruppert M. Van Roozendael J. Verdebout D. Balis C. Meleti C. Zerefos 《Journal of Atmospheric Chemistry》2005,50(3):295-320
We focus on the retrieval of volcanic sulfur dioxide (SO2) emissions from an analysis of atmospheric UV backscatter spectra obtained by the Global Ozone Monitoring Experiment (GOME) spectrometer on board the ESA European Remote Sensing Satellite (ERS-2). Here, the last major eruptions of Mt. Etna on Sicily (Italy) in July/August 2001 and October/November 2002 provided an excellent opportunity to study the retrieval of SO2 columnar amounts from ground-based, LIDAR and satellite measurements. Our study shows that the bulk of emitted SO2 was confined in the troposphere, mainly between 700 hPa and 400 hPa which is confirmed by trajectory analysis, by LIDAR observations and AVHRR observations. The area of influence of Mt. Etna eruptions ranges from the Western Saharan Desert to Greece and the near east states and even down to the basin of Tschad, Africa. Our analysis revealed that information about the plume height of volcanic eruptions and aerosol parameters is necessary for a reliable quantitative retrieval of SO2 from space-borne sensor data at periods perturbed by volcanic eruptions. 相似文献
67.
Diffuse CO<Subscript>2</Subscript> degassing at Vesuvio,Italy 总被引:1,自引:0,他引:1
Francesco?FrondiniEmail author Giovanni?Chiodini Stefano?Caliro Carlo?Cardellini Domenico?Granieri Guido?Ventura 《Bulletin of Volcanology》2004,66(7):642-651
At Vesuvio, a significant fraction of the rising hydrothermal–volcanic fluids is subjected to a condensation and separation process producing a CO2–rich gas phase, mainly expulsed through soil diffuse degassing from well defined areas called diffuse degassing structures (DDS), and a liquid phase that flows towards the outer part of the volcanic cone. A large amount of thermal energy is associated with the steam condensation process and subsequent cooling of the liquid phase. The total amount of volcanic–hydrothermal CO2 discharged through diffuse degassing has been computed through a sequential Gaussian simulation (sGs) approach based on several hundred accumulation chamber measurements and, at the time of the survey, amounted to 151 t d–1. The steam associated with the CO2 output, computed assuming that the original H2O/CO2 ratio of hydrothermal fluids is preserved in fumarolic effluents, is 553 t d–1, and the energy produced by the steam condensation and cooling of the liquid phase is 1.47×1012 J d–1 (17 MW). The location of the CO2 and temperature anomalies show that most of the gas is discharged from the inner part of the crater and suggests that crater morphology and local stratigraphy exert strong control on CO2 degassing and subsurface steam condensation. The amounts of gas and energy released by Vesuvio are comparable to those released by other volcanic degassing areas of the world and their estimates, through periodic surveys of soil CO2 flux, can constitute a useful tool to monitor volcanic activity.Editorial responsibility: H. Shinohara 相似文献
68.
北京地区大气主要温室气体的季节变化 总被引:7,自引:0,他引:7
摘 要:报道了北京主要温室气体浓度最新变化情况,采用1993—2002年北京主要温室气体周平均浓度的数据,用时间序列分解的方法对其季节变化进行了分析研究,并对造成北京主要温室气体季节变化的原因进行了初步探讨。分析发现北京大气CH4的季节变化范围在-49.2×10- 9~ 55.7×10- 9(V/V)之间,并呈现出双峰模态;北京大气CO2浓度的季节变化范围在-26.4×10- 6~ 34.0×10- 6(V/V)之间;北京大气 N 2 O浓度变化没有明显的季节变化特点。 相似文献
69.
The potential resources on the ion-stimulated syntheses effects of aerosol particles of lower troposphere in test sites in the arctic, mountain, arid and forest areas as the function of irradiation time and gas-precursor concentration were experimentally and theoretically evaluated. The dust-free outdoor air was irradiated with an ionization current of 10− 6 A by α-rays from isotope 239Pu. The total output of radiolytic aerosols (RA) with a diameter of 3–1000 nm was found to be 0.05–0.1 molecules per 1 eV of absorbed radiation, while the physical upper limit is 0.25–0.4 molecules/eV. In an interval of exposition time from 6 to 800 s (adsorbed energy is 3 · 1012–1014 eV/cm3) the RA mass concentration at different sites was increased from 1–10 to 50–500 μg/m3. According to the liquid chromatography data the major RA material is the H2O/HNO3 solution with acid concentration 25%. The used physical model presents new aerosols as a product from small and intermediate ion association through formation of neutral clusters and describes adequately some of the peculiarities in field experiment data. Introducing SO2, NH3, and also hydrochloric, nitric and sulphuric acid vapours with concentration 0.1–1 mg/m3 in the irradiated air stimulated an increase of mass aerosol concentration by a factor of 8–30. The mean size also decreased by a factor of 3–5. These facts allowed us to expect that the chemical composition of radiolytic aerosols generated in outdoor air would noticeably differ after addition of the gas-precursors. 相似文献
70.
Detlef P. van Vuuren Bert de Vries Arthur Beusen Peter S.C. Heuberger 《Global Environmental Change》2008,18(4):635
The conditional probabilistic scenario analysis combines statistical methods of uncertainty analysis at parameter level with storylines which recognize the deep uncertainty that exists for several underlying trends. The model calculations indicate that cumulative 21st century emissions could range from 800 to 2500 GtC in the absence of climate policy. This range originates partly from the underlying storylines, and partly from the probabilistic analysis. Among the most important parameters contributing to the uncertainty range are uncertainty in income growth, population growth, parameters determining energy demand, oil resources and fuel preferences. The contribution of these factors is also scenario-dependent. 相似文献