An upper limit to the acetylene abundance toward BN in the Orion molecular cloud     

Knacke RF  Kim YH  Irvine WM 《The Astrophysical journal》1989,345(1):265-267

We report a search for the acetylene (C2H2) nu 3 infrared vibration-rotation absorption near 3 micrometers toward the Becklin-Neugebauer source in the Orion molecular cloud. The relative abundance of C2H2/CO in the quiescent gas (9 km s-1 component) is less than 3 x 10(-3) (5 sigma).  相似文献   

IAU Symposium 65 “exploration of the planetary system”     

William M. Irvine 《Icarus》1974,21(2):202-207

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When Can Inverted Water Tables Occur Beneath Streams?     

Yueqing Xie  Peter G. Cook  Philip Brunner  Dylan J. Irvine  Craig T. Simmons 《Ground water》2014,52(5):769-774

Decline in regional water tables (RWT) can cause losing streams to disconnect from underlying aquifers. When this occurs, an inverted water table (IWT) will develop beneath the stream, and an unsaturated zone will be present between the IWT and the RWT. The IWT marks the base of the saturated zone beneath the stream. Although a few prior studies have suggested the likelihood of an IWT without a clogging layer, most of them have assumed that a low‐permeability streambed is required to reduce infiltration from surface water to groundwater, and that the IWT only occurs at the bottom of the low‐permeability layer. In this study, we use numerical simulations to show that the development of an IWT beneath an unclogged stream is theoretically possible under steady‐state conditions. For a stream width of 1 m above a homogeneous and isotropic sand aquifer with a 47 m deep RWT (measured in an observation point 20 m away from the center of the stream), an IWT will occur provided that the stream depth is less than a critical value of 4.1 m. This critical stream depth is the maximum water depth in the stream to maintain the occurrence of an IWT. The critical stream depth decreases with stream width. For a stream width of 6 m, the critical stream depth is only 1 mm. Thus while theoretically possible, an IWT is unlikely to occur at steady state without a clogging layer, unless a stream is very narrow or shallow and the RWT is very deep.  相似文献   

Quantitative particle size,microtextural and outline shape analyses of glacigenic sediment reworked by paraglacial debris flows     

A. M. Curry  P. R. Porter  T. D. L. Irvine‐Fynn  G. Rees  T. B. Sands  J. Puttick 《地球表面变化过程与地形》2009,34(1):48-62

Particle size analysis and scanning electron microscopy have been used with some success to differentiate sediments sampled from varying geomorphological environments. In the paraglacial environment, however, discrimination of paraglacially reworked deposits from in situ glacigenic deposits has proven to be problematic. We consider till sediments that have been reworked by paraglacial debris flows and in situ, unreworked parent material, and apply a series of quantitative techniques in an attempt to discriminate samples from each environment. Initial analysis of particle size suggests some eluviation of fines from the debris‐flow‐reworked deposits but is of insufficient significance to allow reliable differentiation of geomorphological environment. Similarly, although slight differences are identified in terms of quartz grain surface microtextures and quartz grain outline shape, subsequent PCA, cluster and Fourier analyses fail to reliably differentiate quartz grains from each geomorphological environment, owing to high levels of intra‐sample heterogeneity. This lack of apparent difference may arise from a lack of paraglacial process operation of significant magnitude or duration for a characteristic process imprint to emerge at this scale of observation. Accordingly, further assessment of particle‐size and microtextural characteristics of glacial and paraglacial sediments may be most fruitful where sediments have been reworked over long distances. Moreover, differentiating glacial from paraglacial deposits is likely to yield the most reliable results where rigorous statistical analyses are combined with a wide range of sedimentological and geomorphological techniques. Copyright © 2008 John Wiley and Sons, Ltd.  相似文献   

Land use,sediment loads and dispersal pathways from two catchments at the southern end of Lake Tanganyika,Africa: implications for lake management   总被引：1，自引：0，他引：1  

Ian?DonohueEmail author  Robert?W.?Duck  Kenneth?Irvine 《Environmental Geology》2003,44(4):448-455

Increasing sediment loads entering the Lake Tanganyika ecosystem are hastening the need for improved understanding of the linkages between catchment characteristics and influent sediment transport and loading. Sediment loads of two catchments at the southern end of the lake were estimated for October 1998–December 1999, and catchment characteristics determined using GIS. It was found that both sediment yields and loads were higher from the catchment of the Lunzua River (19.8 t km^?2 and 20,114 t, respectively) compared with that of the Kalambo (4.1 t km^?2 and 12,197 t) in 1999. These differences were both attributed to the smaller size and higher road density of the Lunzua catchment, and suggest that previous recommendations regarding the positioning of underwater lake reserves fail to take into account the low sediment retention capacity of small mountainous rivers. Differences between the study rivers in the transport of suspended sediments, organic matter, and bedload sediments into the lake were also found, the latter determined by the novel application of the 'McLaren Model'.  相似文献   

Upper limits for the ethyl-cyanide abundances in TMC-1 and L134N: Chemical implications     

Y. C. Minh  W. M. Irvine 《Astrophysics and Space Science》1991,175(1):165-169

We have sought interstellar ethyl-cyanide via its 2₀₂–1₀₁ transition towards two cold, dark clouds and report upper limits of the total column densities of 3×10¹²cm^–2 and 2×10¹²cm^–2 for TMC-1 and L134N, respectively. We also observed the 2₀₂–1₀₁ transition of vinyl cyanide previously identified in TMC-1 by Matthews and Sears (1983b). The detection of vinyl cyanide and the non-detection of ethyl cyanide in TMC-1 are consistent with gas phase ion-molecule chemical models, and there is thus no necessity of invoking grain surface synthesis for vinyl cyanide in cold clouds.  相似文献   

Radioastronomical observations of comets IRAS-Araki-Alcock (1983d) and Sugano-Saigusa-Fujikawa (1983e)     

W.M. Irvine  Z. Abraham  M. A&#x;Hearn  W. Altenhoff  Ch. Andersson  J. Bally  W. Batrla  A. Baudry  D. Bockelée-Morvan  G. Chin  J. Crovisier  I. de Pater  D. Despois  L. Ekelund  E. Gerard  T. Hasegawa  C. Heiles  J.M. Hollis  A. Wootten 《Icarus》1984,60(1):215-220

Detections and upper limits to the continuum emission (1 ≤ λ ≤6 cm) and spectral line emission (OH, CO, CS, HCN, HCO⁺, CN, CH₃CN, CH₃C₂H, NH₃, H₂O, HC₃N, CH₃CH₂CN) are reported from radio observations of Comets 1983d and 1983e. Comparison is made with observations of CN at optical wavelengths. These results may be useful in planning future cometary observations.  相似文献   

Comets and the origin of life: C. Ponnamperuma,Editor. D. Reidel Publ. Co., Dordrecht, 1981. vii + 282 pp, $39.50     

William M. Irvine 《Icarus》1982,51(1):164-165

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The urban boundary-layer field campaign in marseille (ubl/clu-escompte): set-up and first results     

P. G. Mestayer  P. Durand  P. Augustin  S. Bastin  J. -M. Bonnefond  B. Bénech  B. Campistron  A. Coppalle  H. Delbarre  B. Dousset  P. Drobinski  A. Druilhet  E. Fréjafon  C. S. B. Grimmond  D. Groleau  M. Irvine  C. Kergomard  S. Kermadi  J. -P. Lagouarde  A. Lemonsu  F. Lohou  N. Long  V. Masson  C. Moppert  J. Noilhan  B. Offerle  T. R. Oke  G. Pigeon  V. Puygrenier  S. Roberts  J. -M. Rosant  F. Sanïd  J. Salmond  M. Talbaut  J. Voogt 《Boundary-Layer Meteorology》2005,114(2):315-365

The UBL/CLU (urban boundary layer/couche limite urbaine) observation and modelling campaign is a side-project of the regional photochemistry campaign ESCOMPTE. UBL/CLU focuses on the dynamics and thermodynamics of the urban boundary layer of Marseille, on the Mediterranean coast of France. The objective of UBL/CLU is to document the four-dimensional structure of the urban boundary layer and its relation to the heat and moisture exchanges between the urban canopy and the atmosphere during periods of low wind conditions, from June 4 to July 16, 2001. The project took advantage of the comprehensive observational set-up of the ESCOMPTE campaign over the Berre–Marseille area, especially the ground-based remote sensing, airborne measurements, and the intensive documentation of the regional meteorology. Additional instrumentation was installed as part of UBL/CLU. Analysis objectives focus on (i) validation of several energy balance computational schemes such as LUMPS, TEB and SM2-U, (ii) ground truth and urban canopy signatures suitable for the estimation of urban albedos and aerodynamic surface temperatures from satellite data, (iii) high resolution mapping of urban land cover, land-use and aerodynamic parameters used in UBL models, and (iv) testing the ability of high resolution atmospheric models to simulate the structure of the UBL during land and sea breezes, and the related transport and diffusion of pollutants over different districts of the city. This paper presents initial results from such analyses and details of the overall experimental set-up.  相似文献