A numerical diffusion model for continuous releases     

C. J. P. Van Buijtenen  J. Holland  D. Van Leeuwen 《Boundary-Layer Meteorology》1973,5(3):275-283

The purpose of this study was to develop a diffusion model for a continuous point source which takes into account the increase of wind speed with height, and to compare this model with short-range diffusion experiments. The main problem was to find a good expression for the vertical diffusion coefficient. It turned out that good agreement between theory and experiment could only be obtained by introducing a settling speed W for the tracer combined with a conventional expression for the vertical diffusion (K(Z) = K ₀Z^1−p). An empirical relation was found between K ₀ and τ _vU and between W and bar σ _vU².  相似文献   

Detection of station coordinate discontinuities within the Italian GPS Fiducial Network     

Nicola Perfetti 《Journal of Geodesy》2006,80(7):381-396

The Detection Identification Adaptation (DIA) procedure was applied to the coordinate time-series of some permanent GPS stations belonging to the Italian GPS Fiducial Network (IGFN), of the Italian Space Agency (ASI), to detect discontinuities and to reject outliers. The daily solutions of the stations of Cagliari, Genoa, Medicina, Noto, Turin, Perugia and Venice were computed for the period 1997.0–2003.0 using Bernese GPS software v.4.2. The data were interpolated using a model with a linear term and an annual periodic term. The parameters were estimated by least squares. The DIA procedure was organized to automatically detect discontinuities and outliers. Approximately, 70% of the discontinuities present in the coordinate time-series were identified and their magnitudes were estimated. The identified discontinuities are basically caused by equipment replacement and reference frame changes, but in a few cases the reason is still unknown. With regard to the outliers, roughly 6% of the data were rejected. These data were considered outliers on the base of the level of significance and of the power of the test adopted in this work. Except for the stations of Perugia and Venice, the estimated coordinates agree with ITRF2000 values at the 10 mm level, and the estimated velocities are within a few mm/year of the ITRF2000 values.  相似文献   

Product study of the reaction of OH radicals with isoprene in the atmosphere simulation chamber SAPHIR     

M. Karl  H.-P. Dorn  F. Holland  R. Koppmann  D. Poppe  L. Rupp  A. Schaub  A. Wahner 《Journal of Atmospheric Chemistry》2006,55(2):167-187

Atmospheric oxidation of isoprene and its oxidation products methacrolein (MACR) and methyl vinyl ketone (MVK) have an important impact on the photochemical activity in the boundary layer, in particular in forested areas. The oxidation of isoprene by OH radicals was investigated in chamber experiments conducted under tropospheric conditions in the atmosphere simulation chamber SAPHIR at the Research Center Jülich. The aim was to determine the product yield of MVK and MACR in the OH-induced isoprene oxidation and the rate constant of their reaction with OH under real atmospheric conditions. The recently published updated degradation scheme for isoprene from Geiger et al. (2003) was used to determine rate constants and product yields. The fractional yields in the isoprene peroxy radical reaction with NO were found to be 0.41±0.03 for MVK and 0.27±0.03 for MACR. The rate coefficient for MACR with OH was found to be in very good agreement with the recommended value of IUPAC Atkinson (Atkinson et al., 2005). while the rate coefficient for MVK with OH was 27% lower.  相似文献   

Some economics of ‘dangerous’ climate change: Reflections on the Stern Review     

Simon Dietz  Chris Hope  Nicola Patmore 《Global Environmental Change》2007,17(3-4):311-325

The Stern Review on the Economics of Climate Change concluded that there can be “no doubt” the economic risks of business-as-usual (BAU) climate change are “very severe” [Stern, 2006. The Economics of Climate Change. HM Treasury, London, p. 188]. The total cost of climate change was estimated to be equivalent to a one-off, permanent 5–20% loss in global mean per-capita consumption today. And the marginal damage cost of a tonne of carbon emitted today was estimated to be around $312 [p. 344]. Both of these estimates are higher than most reported in the previous literature. Subsequently, a number of critiques have appeared, arguing that discounting is the principal explanation for this discrepancy. Discounting is important, but in this paper we emphasise that how one approaches the economics of risk and uncertainty, and how one attempts to model the very closely related issue of low-probability/high-damage scenarios (which we connect to the recent discussion of ‘dangerous’ climate change), can matter just as much. We demonstrate these arguments empirically, using the same models applied in the Stern Review. Together, the issues of risk and uncertainty on the one hand, and ‘dangerous’ climate change on the other, raise very strongly questions about the limits of a welfare-economic approach, where the loss of natural capital might be irreversible and impossible to compensate. Thus we also critically reflect on the state-of-the-art in integrated assessment modelling. There will always be an imperative to carry out integrated assessment modelling, bringing together scientific ‘fact’ and value judgement systematically. But we agree with those cautioning against a literal interpretation of current estimates. Ironically, the Stern Review is one of those voices. A fixation with cost-benefit analysis misses the point that arguments for stabilisation should, and are, built on broader foundations.  相似文献   

Discussion of “Thermodynamic parameters of CaMgSi2O6-Mg2Si2O6 pyroxenes based on regular solution and cooperative disordering models” by Holland,Navrotsky, and Newton     

Donald H. Lindsley  Paula M. Davidson  T. J. B. Holland  A. Navrotsky  R. C. Newton 《Contributions to Mineralogy and Petrology》1981,75(3):301-306

  相似文献   

Identification and description of macrobenthic communities in the calvert cliffs region of the Chesapeake Bay     

Nancy K. Mountford  A. F. Holland  J. A. Mihursky 《Estuaries and Coasts》1978,1(2):139-139

  相似文献   

Amphibole zonation in metabasites as a guide to the evolution of metamorphic conditions   总被引：2，自引：0，他引：2  

Timothy J. B. Holland  Stephen W. Richardson 《Contributions to Mineralogy and Petrology》1979,70(2):143-148

In low grade metabasites the amphibole components tremolite, glaucophane, edenite and tschermakite have their activities controlled by interactions with the excess components albite, clinozoisite, chlorite, quartz and H₂O vapor. Three types of reaction are involved, (i) Those in which only components of condensed phases take part: isopleths of equilibrium constant are straight lines in the P-T plane. (ii) Dehydration reactions in which entropy change due to change in Al coordination is of the same sign as that due to dehydration: isopleths of constant K are positive at low pressure and negative at high pressure. (iii) Dehydration reactions in which entropy change due to Al coordination change is opposite in sign to that of dehydration: isopleths of constant K loop in the P-T plane with positive slopes at low and at high pressure. Zonation in naturally occurring amphiboles records the evolution of metamorphic conditions in particular rocks. In an example from the eastern Alps (Austria) early conditions calculated as 15 kb, 200 ° C evolve upgrade to 6 kb, 525 ° C implying concurrent heating and erosion. The record of evolving conditions may span some 30 Ma of geological history.  相似文献   

Archimedes and the Tauern eclogites: the role of buoyancy in the preservation of exotic eclogite blocks     

P.C. England  T.J.B. Holland 《Earth and Planetary Science Letters》1979,44(2):287-294

The eclogite fragments of the Tauern Window formed at pressures around 20 kbar and temperatures in the region 600–650°C; these pressures are higher by 10–12 kbar than those experienced by the units now surrounding the eclogite-bearing zone. The eclogites probably formed in a subduction zone prior to the main Austroalpine collision: downward shearing forces dominated over buoyancy forces in the subduction zone mélange, permitting the subduction of relatively light material to great depth. At the cessation of subduction this buoyant material returned to the surface, carrying eclogite blocks that were too small to sink rapidly through it. A similar mechanism could account for the emplacement of certain Alpine-type garnet peridotites.  相似文献   

Intercomparison of Tropospheric OH Measurements by Different Laser Techniques during the POPCORN Campaign 1994     

A. Hofzumahaus  U. Aschmutat  U. Brandenburger  T. Brauers  H.-P. Dorn  M. Hausmann  M. Heßling  F. Holland  C. Plass-Dülmer  D. H. Ehhalt 《Journal of Atmospheric Chemistry》1998,31(1-2):227-246

In-situ OH measurements by laser-induced fluorescence (LIF) spectroscopy and folded long-path differential optical absorption spectroscopy (DOAS) were carried out in a rural environment in North-East Germany as part of the field experiment POPCORN in August 1994. The large set of OH data obtained allowed an intercomparison of both techniques based on relative diurnal profiles and simultaneously measured absolute concentrations. Most of the time the two OH instruments encountered the same air and agreed well in the measured relative diurnal variations. Only on a few occasions the measurements significantly disagreed due to a perturbation of the DOAS measurements by a local OH source in the north-western wind sector. Excluding data from this wind direction, the statistical analysis of 137 data pairs yields a correlation coefficient of r = 0.90 and a weighted linear fit with a slope of 1.09 ± 0.12. The correlations are carefully analyzed. The comparison of both instruments is discussed in the light of newly published effective absorption cross-sections for H2O and O2 that affect the calibration of LIF.  相似文献   

Petrology and geochemistry of Easter Island     

P. E. Baker  F. Buckley  J. G. Holland 《Contributions to Mineralogy and Petrology》1974,44(2):85-100

Easter Island has developed around three volcanoes—Poike, an older (3 m.y.) strato-volcano, Rano Kau, a caldera, and the fissure complex of Terevaka and its associated cones. The lavas show a wide compositional spread from tholeiites and olivine tholeiites to hawaiites, mugearites, benmoreites, trachytes and rhyolites (comendites). Hawaiite is by far the most abundant rock type and trachytes and rhyolites are relatively rare. Intermediate and acid rocks are concentrated in the southwestern part of the island on or around Rano Kau.The basaltic rocks, which are plagioclase-phyric or aphyric, are transitional hypersthenenormative types characterized by high contents of Fe, Ti and Zr but low K and Mg. The Poike basalts are marginally lower in Zr, Nb, Y and Zn compared with those of the younger volcanoes, but the trachytes from this centre show anomalously high concentrations of Rb, Zr and Nb.The island's youngest flow, the Roiho basalt, is an olivine tholeiite with distinctly more alkaline affinities: it is olivine-microphyric with relatively high contents of Mg, Ni and K.The study was initiated whilst this author was at Department of Geology and Mineralogy, University of Oxford.  相似文献