Making local futures tangible—Synthesizing, downscaling, and visualizing climate change scenarios for participatory capacity building   总被引：1，自引：0，他引：1  

Alison Shaw  Stephen Sheppard  Sarah Burch  David Flanders  Arnim Wiek  Jeff Carmichael  John Robinson  Stewart Cohen 《Global Environmental Change》2009,19(4):447-463

Local in its causes and global in its impacts, climate change still poses an unresolved challenge for scientists, politicians, entrepreneurs, and citizens. Climate change research is largely global in focus, aims at enhanced understanding, and is driven by experts, all of which seem to be insufficient to anchor climate change action in regional and local contexts. We present results from a participatory scenario study conducted in collaboration with the municipality of Delta in SW British Columbia, Canada. This study applies a participatory capacity building approach for climate change action at the local level where the sources of emissions and the mechanisms of adaptation reside and where climate change is meaningful to decision-makers and stakeholders alike. The multi-scale scenario approach consists of synthesizing global climate change scenarios, downscaling them to the regional and local level, and finally visualizing alternative climate scenarios out to 2100 in 3D views of familiar, local places. We critically discuss the scenarios produced and the strengths and weaknesses of the approach applied.  相似文献   

The Combined Atmospheric Photochemistry and Ion Tracing code: Reproducing the Viking Lander results and initial outflow results     

L. Andersson  R.E. Ergun  A.I.F. Stewart 《Icarus》2010,206(1):120-129

A Combined Atmospheric Photochemistry and Ion Tracing code (CAPIT) has been developed to explore ion loss into space at Mars. The CAPIT code includes the major photochemical reactions of Mars’ ionosphere, ion tracing in the presence of magnetic fields, and plasma wave heating of ions. In particular, we examine whether O⁺ escape from the day-side ionosphere is limited by ion production (UV input) or by external energy input to the ions. To verify the code, it is demonstrated that the CAPIT solutions reproduce the Viking 1 Lander’s ion density and temperature profiles. Using Viking 1 Lander conditions as a baseline, ion outflow rates are examined as function of solar wind energy input via plasma waves and UV ionization rates. The O⁺ outflow rates predicted by the simulation are comparable to the outflow rates estimated by observation. The results indicate that plasma waves are a viable source of energy to O⁺ ions and suggest that present-day O⁺ outflow rates at Mars are source limited by photochemical production (UV input) during periods of strong energy input (plasma wave activity), but otherwise regulated by both UV input and energy input. These results imply that ion heating by plasma waves can influence the present-day loss of O⁺.  相似文献   

A comprehensive numerical simulation of Io’s sublimation-driven atmosphere     

Andrew C. Walker  Sergey L. Gratiy  Chris H. Moore  Laurence M. Trafton  Bénédicte Stewart 《Icarus》2010,207(1):409-432

Io’s sublimation-driven atmosphere is modeled using the direct simulation Monte Carlo (DSMC) method. These rarefied gas dynamics simulations improve upon earlier models by using a three-dimensional domain encompassing the entire planet computed in parallel. The effects of plasma heating, planetary rotation, inhomogeneous surface frost, molecular residence time of SO₂ on the exposed (non-volatile) rocky surface, and surface temperature distribution are investigated. Circumplanetary flow is predicted to develop from the warm dayside toward the cooler nightside. Io’s rotation leads to a highly asymmetric frost surface temperature distribution (due to the frost’s high thermal inertia) which results in circumplanetary flow that is not axi-symmetric about the subsolar point. The non-equilibrium thermal structure of the atmosphere, specifically vibrational and rotational temperatures, is also examined. Plasma heating is found to significantly inflate the atmosphere on both the dayside and nightside. The plasma energy flux causes high temperatures at high altitudes but plasma energy depletion through the dense gas column above the warmest frost permits gas temperatures cooler than the surface at low altitudes. A frost map (Douté, S., Schmitt, B., Lopes-Gautier, R., Carlson, R., Soderblom, L., Shirley, J., and the Galileo NIMS Team [2001]. Icarus 149, 107-132) is used to control the sublimated flux of SO₂ which can result in inhomogeneous column densities that vary by nearly a factor of four for the same surface temperature. A short residence time for SO₂ molecules on the “rock” component is found to smooth lateral atmospheric inhomogeneities caused by variations in the surface frost distribution, creating an atmosphere that looks nearly identical to one with uniform frost coverage. A longer residence time is found to agree better with mid-infrared observations (Spencer, J.R., Lellouch, E., Richter, M.J., López-Valverde, M.A., Jessup, K.L, Greathouse, T.K., Flaud, J. [2005]. Icarus 176, 283-304) and reproduce the observed anti-jovian/sub-jovian column density asymmetry. The computed peak dayside column density for Io assuming a surface frost temperature of 115 K agrees with those suggested by Lyman-α observations (Feaga, L.M., McGrath, M., Feldman, P.D. [2009]. Icarus 201, 570-584). On the other hand, the peak dayside column density at 120 K is a factor of five larger and is higher than the upper range of observations (Jessup, K.L., Spencer, J.R., Ballester, G.E., Howell, R.R., Roesler, F., Vigel, M., Yelle, R. [2004]. Icarus 169, 197-215; Spencer et al., 2005).  相似文献   

UVIS observations of the FUV OI and CO 4P Venus dayglow during the Cassini flyby     

B. Hubert  J.C. Gérard  V.I. Shematovich  A.I. Stewart 《Icarus》2010,207(2):549-557

We analyze FUV spatially-resolved dayglow spectra obtained at 0.37 nm resolution by the UVIS instrument during the Cassini flyby of Venus. We use a least-squares fit method to determine the brightness of the OI emissions at 130.4 and OI 135.6 nm, and of the bands of the CO fourth positive system which are dominated by fluorescence scattering. We compare the brightness observed along the UVIS foot track of the two OI multiplets with that deduced from a model of the excitation of these emissions by photoelectron impact on O atoms and resonance scattering of the solar 130.4 nm emission. The large optical thickness 130.4 nm emission is accounted for using a radiative transfer model. The airglow intensities are calculated along the foot track and found to agree with the observed 130.4 nm brightness within ∼10%. The modeled OI 135.6 nm brightness is also well reproduced by the model. The oxygen density profile of the VTS3 model is found to be consistent with the observations. We find that self-absorption of the (0, v″) bands of the fourth positive emission of CO is important and we derive a CO vertical column of about 6.4 × 10¹⁵ cm⁻² in close agreement with the value provided by the VTS3 empirical atmospheric model.  相似文献   

Andesites as Magmatic Liquids or Liquid-crystal Mixtures; Insights from Egmont and Ruapehu Volcanoes, New Zealand Research Article     

Robert B. Stewart 《Central European Journal of Geosciences》2010,2(3):329-338

Late Quaternary andesitic magmas in New Zealand contain complexly zoned antecrysts and glomerocrysts that are not in equilibrium with either the host whole rock compositions or siliceous groundmass glass and glass inclusions. Glass inclusions represent partial melts of mafic to gabbroic cumulates in the lower crust that mix with restite crystals, or cumulates from earlier magma batches. Assimilation of partial melts of mid-crustal rocks, represented by glass in crustal xenoliths, contributes a crustal component to the andesites. Magmas at Egmont are stored at about the brittle/ductile transition at about 10 km depth and variability in the composition of erupted material is a function of the composition of the recharging magma, and which parts of the storage system are tapped during the eruption. At Taranaki recharge occurs on a c. 1400 year cycle while interactions within the storage give rise to shorter period events. A similar process on a less well constrained timescale operates at Ruapehu. Andesites are therefore complex mixtures of fractionated mantle basalts, siliceous partial melts of both the lower crust and underplated cumulates, restite and cumulate crystals. Further modification occurs by interaction with partial melts of lower to middle crustal basement as geotherms increase with time.  相似文献   

Ore-body imaging by crosswell seismic waveform inversion: A case study from Kambalda,Western Australia     

Kun Xu  Stewart Greenhalgh 《Journal of Applied Geophysics》2010,70(1):38-45

Seismic P waveforms from a hardrock crosswell experiment were inverted for the velocity distribution between boreholes. The inversion was carried out by an iterative source estimation scheme in the frequency domain. Six frequencies in the range 900–2000 Hz were employed to yield a tomogram which closely matches the known geology, and clearly discloses the nickel sulphide mineralization. The waveform inversion is superior to traveltime tomography, which was used to obtain the starting model. Pre-processing, to isolate the direct P arrivals, is critical to the success of the method, because noise in the form of tube wave-to-body-wave conversions in the source hole, and body wave-to-tube wave conversions in the receiver hole complicate the seismograms and cannot be satisfactorily accommodated in the wavefield modelling. Such noise also precludes a successful migration. Even though the very fine detailed velocity structure cannot be fully recovered using just the first arrival full waveform, it remains a viable and useful approach.  相似文献   

Shrinkage and desiccation cracking in bentonite–sand landfill liners     

Y. Y. Tay  D. I. Stewart  T. W. Cousens 《Engineering Geology》2001,60(1-4):263-274

Data are reported on the shrinkage and desiccation cracking exhibited by bentonite-enhanced sand mixtures (BES) upon air-drying. Mixtures containing 10 and 20% bentonite by dry weight, compacted at moisture contents ranging from 8 to 32%, were investigated. Hydraulic conductivity data for BES specimens saturated and tested immediately after compaction, and for similar specimens that had no visible damage after air-drying, are also presented.

All the mixtures exhibited volumetric shrinkage upon air-drying with the amount of shrinkage increasing with increasing moisture content during compaction. At any initial moisture content mixtures containing 20% bentonite shrink more than those containing 10% bentonite, but the shrinkage is insensitive to the compactive effort. Compacted beds of BES containing 10 and 20% bentonite exhibit no visible desiccation cracking as the top surface is dried when compacted at 15 and 14% moisture content, respectively, and only minor cracking when compacted at initial moisture contents of 20 and 15%, respectively. For the range of mixtures tested, it appears that cracking only occurs when BES undergoes more than about 4% volumetric shrinkage when air-dried. The saturated hydraulic conductivity of intact BES specimens is unaffected by a drying episode prior to testing.  相似文献   

New Tricks with Old Maps: Urban Landscape Change,GIS, and Historic Preservation in the Less Developed World     

Dona J. Stewart 《The Professional geographer》2001,53(3):361-373

This article presents a methodology for a more detailed investigation of urban landscape change in rapidly growing cities of the less developed world beyond typical macrolevel approaches. This research is an attempt to bridge the gap between traditional landscape analysis and geographic information science (GIS). The article presents the preliminary results from a pilot project in Zamalek, Egypt, highlighting the benefits and drawbacks of the two techniques. Rarely used to study the less developed world, these techniques are utilized to assess change within a portion of Cairo's urban landscape. Large‐scale historic maps and high‐resolution satellite imagery, combined with field attribute collection, are the major data sources in this applied landscape analysis. A motivating factor in the desire to examine landscape change at such a large scale is the need to create monitoring systems for historic preservation in cities of the less developed world.  相似文献   

Magma mingling in an andesite pyroclastic flow of the Pourahu Member, Ruapehu volcano, New Zealand     

S.L. Donoghue  J.A. Gamble  A.S. Palmer  R.B. Stewart 《Journal of Volcanology and Geothermal Research》1995,68(1-3)

We describe a magma mingling episode from Ruapehu volcano between two andesite magmas, one very much minor in volume relative to the other. The event acted to trigger eruption of the andesitic Pourahu pyroclastic flow which is preserved in a thick sequence of tephras and laharic deposits in the southeastern ring plain of the volcano. The predominant andesite is pale brown coloured and porphyritic containing phenocrysts of plagioclase-clinopyroxene-orthopyroxene-Fe-Ti oxides. Rare clasts of a darker andesite are different texturally, less vesicular, and contain distinctive microphenocrysts of plagioclase and quench olivine. Equally rare clasts, of streaky pumice consisting of interbanded ‘dark’ and ‘light’ andesite attest to mingling between these two andesite components.Chemical analyses of discrete clasts demonstrate that the Pourahu pyroclastic flow andesites span much of the compositional spectrum of Ruapehu andesites. This observation demonstrates heterogeneity in the products of a relatively small eruption. The darker clast analyses and those from associated distal fall deposits lie within the fields defined by the dominant light coloured clasts. Phenocryst and microphenocryst geothermometry suggest slightly higher temperatures in the dark component. However, glasses from groundmass and phenocryst inclusions in the same specimen may differ considerably, leading us to conclude that many phenocrysts are in fact xenocrystic and were incorporated in the melts as they migrated towards the surface.We prefer a model in which a small volume of hot andesite magma injects a vent-feeding magma chamber, triggering vesiculation and eruption. We infer that the process of magma withdrawal extended downward into the magma body causing the dark component to intermingle with the lighter (dominant) component, ‘sucking’ more dark magma into the chamber. Our observations are entirely consistent with the existence of a plexus of small, possibly interlinked magma chambers beneath Ruapehu.  相似文献   

A comparison of turbulence measurements by different instruments; Tsimlyansk field experiment 1970     

L. R. Tsvang  B. M. Koprov  S. L. Zubkovskii  A. J. Dyer  B. Hicks  M. Miyake  R. W. Stewart  J. W. McDonald 《Boundary-Layer Meteorology》1973,3(4):499-521

In the summer of 1970 an international intercomparison of turbulence measurement sensors was carried out at the Tsimlyansk field station of the Institute of Atmospheric Physics (IFA) Academy of Sciences of the U.S.S.R. Improved sonic anemometer sensors of the IFA were compared with the Kaijo sonic used by the Canadian group and with the fluxatron from CSIRO, Australia.Results from the experiment indicate that spectral and cospectral shapes are basically similar between the sonic anemometers. The spectra and cospectra of the fluxatron in the high-frequency region showed an attenuation which can be explained in terms of the response characteristics of the fluxatron. The maintenance of absolute calibration of the sensors in the field was found to be difficult, but when properly corrected for this variation, the measurements were found to agree within 13%, with a standard error of 0.2. A single point observation of turbulent fluxes at a few meters above the surface and averaged over a period of the order of one hour was shown to be representative of turbulent fluxes at the site.  相似文献