Quantitative guidance for efficient vertical flow measurements at the sediment–water interface using temperature–depth profiles     

Dylan J. Irvine  Barret L. Kurylyk  Martin A. Briggs 《水文研究》2020,34(3):649-661

Upward discharge to surface water bodies can be quantified using analytical models based on temperature–depth (T-z) profiles. The use of sediment T-z profiles is attractive as discharge estimates can be obtained using point-in-time data that are collected inexpensively and rapidly. Previous studies have identified that T-z methods can only be applied at times of the year when there is significant difference between the streambed–water interface and deeper sediment temperatures (e.g., winter and summer). However, surface water temperatures also vary diurnally, and the influence of these variations on discharge estimates from T-z methods is poorly understood. For this study, synthetic T-z profiles were generated numerically using measured streambed interface temperature data to assess the influence of diurnal temperature variations on discharge estimation and provide insight into the suitable application of T-z methods. Results show that the time of day of data collection can have a substantial influence on vertical flux estimates using T-z methods. For low groundwater discharge fluxes (e.g., 0.1 m d⁻¹), daily transience in streambed temperatures led to relatively large errors in estimated flow magnitude and direction. For higher discharge fluxes (1.5 m d⁻¹), the influence of transient streambed temperatures on discharge estimates was strongly reduced. Discharge estimates from point-in-time T-z profiles were most accurate when the uppermost point in the T-z profile was near the bed interface daily mean (two time periods daily). Where temperature time series data are available, daily averaged T-z profiles can produce accurate discharge estimates across a wide range of discharge rates. Seasonality in shallow groundwater temperature generally had a negligible influence on vertical flow estimates. These findings can be used to plan field campaigns and provide guidance on the optimal application of T-z methods to quantify vertical groundwater discharge to surface water bodies.  相似文献   

The HNC/HCN Ratio in Comets     

Irvine  W. M.  Dickens  J. E.  Lovell  A. J.  Schloerb  F. P.  Senay  M.  Bergin  E. A.  Jewitt  D.  Matthews  H. E. 《Earth, Moon, and Planets》1997,78(1-3):29-35

The abundance ratio of the isomers HCN and HNC has been investigated in comet Hale-Bopp (C/1995 O1) through observations of the J = 4−3 rotational transitions of both species for heliocentric distances 0.93 < r < 3 AU, both pre- and post-perihelion. After correcting for the optical depth of the stronger HCN line, we find that the column density ratio of HNC/HCN in our telescope beam increases significantly as the comet approaches the Sun. We compare this behavior to that predicted from an ion-molecule chemical model and conclude that the HNC is produced insignificant measure by chemical processes in the coma; i.e., for comet Hale-Bopp, HNC is not a parent molecule sublimating from the nucleus. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Hco+ in the Coma of Comet Hale–Bopp     

Lovell  A. J.  Schloerb  F. P.  Bergin  E. A.  Dickens  J. E.  Devries  C. H.  Senay  M. C.  Irvine  W. M. 《Earth, Moon, and Planets》1997,77(3):253-258

Maps of comet C/1995 O1 (Hale-Bopp) in the millimeter-wave emission of the ion HCO⁺ revealed a local minimum near the nucleus position, with a maximum about 100,000 km in the antisolar direction. These observed features of the HCO⁺ emission require a low abundance of HCO⁺ due to enhanced destruction in the inner coma of the comet, within a region of low electron temperature (T_e). To set constraints on the formation of HCO⁺ in the coma, as well as the location and magnitude of the transition to higher T_e, the data are compared with the results of ion-molecule chemistry models. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Hydrology of stockpiled industrial coal exposed to rainfall     

K. J. Curran  I. G. Droppo  K. N. Irvine 《水文研究》2002,16(14):2781-2790

The movement of water and particulate matter through a simulated coal pile using a rainfall–coal‐pile simulator is investigated. In conjunction with coal‐pile management practices, this study indicates that coal‐pile systems change their internal and surficial structure with successive rainstorm events. This change in coal‐pile structure alters the proportions, rates and suspended solid concentrations within surface runoff and infiltration during subsequent storm events. Results demonstrate the need to determine the optimal coal‐pile slope that minimizes water contact time, but at the same time minimizes the potential for mass wasting and rill erosion. Promotion of a compacted surface is beneficial for the minimization of solids removal, and a stormwater detention pond with potential flocculant additive is suggested as a viable remedial measure for the containment and treatment of coal‐pile runoff. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Chemistry of the organic-rich hot core G327.3-0.6     

Gibb E  Nummelin A  Irvine WM  Whittet DC  Bergman P 《The Astrophysical journal》2000,545(1):309-326

We present gas-phase abundances of species found in the organic-rich hot core G327.3-0.6. The data were taken with the Swedish-ESO Submillimetre Telescope (SEST). The 1-3 mm spectrum of this source is dominated by emission features of nitrile species and saturated organics, with abundances greater than those found in many other hot cores, including Sgr B2 and OMC-1. Population diagram analysis indicates that many species (CH3CN, C2H3CN, C2H5CN, CH3OH, etc.) have hot components that originate in a compact (~2") region. Gas-phase chemical models cannot reproduce the high abundances of these molecules found in hot cores, and we suggest that they originate from processing and evaporation of icy grain mantle material. In addition, we report the first detection of vibrationally excited ethyl cyanide and the first detection of methyl mercaptan (CH3SH) outside the Galactic center.  相似文献   

Monitoring the Sensible Heat Flux over Urban Areas using Large Aperture Scintillometry: Case Study of Marseille City During the Escompte Experiment     

J. -P. Lagouarde  M. Irvine  J. -M. Bonnefond  C. S. B. Grimmond  N. Long  T. R. Oke  J. A. Salmond  B. Offerle 《Boundary-Layer Meteorology》2006,118(3):449-476

Abtract Sensible heat flux estimated by Large Aperture Scintillometry (LAS) has been tested against the more traditional eddy covariance technique over Marseille city centre, a reasonably homogeneous surface. Over the 3 week test period fluxes were found to be similar, yet less noisy for the LAS due to the spatial integration. No systematic bias between the estimates was found as a function of wind direction, indicating the homogeneity of the site. Sensitivity analysis of the required aerodynamic parameters shows that careful attention must be paid to the displacement height along the measurement path. Spatial variability of surface sensible heat flux is studied via a second LAS measurement path over the city.  相似文献   

Suspension-feeding bivalves and the fate of primary production: An estuarine model applied to Chesapeake Bay   总被引：1，自引：0，他引：1  

Jeroen Gerritsen  A. Frederick Holland  David E. Irvine 《Estuaries and Coasts》1994,17(2):403-416

A probabilistic mathematical model of bivalve suspension-feeding in estuaries is based on bivalve abundance, filtering capacities, and water mixing parameters. We applied the model to five regions of the upper Chesapeake Bay, ranging from shallow tidal fresh habitats to deep mesohaline habitats, for the years 1985 to 1987. Model results indicated that existing suspension-feeding bivalves could consume more than 50% of annual primary production in shallow freshwater and oligohaline reaches of the upper Chesapeake Bay and Potomac River. In deep mesohaline portions of the Chesapeake Bay and Potomac River, suspension-feeding bivalves could consume only 10% of primary production. Independent estimates of benthic carbon demand based on benthic production supported the model predictions. Hydrodynamics of large estuaries restrict the potential of benthic suspension-feeders to crop phytoplankton production because the width and depth of these estuaries limit transport of pelagic waters to the littoral flanks of the estuaries where benthic suspension-feeders can be abundant. Benthic suspension-feeders are dominant consumers in shallow segments of the Chesapeake Bay system, but are suppressed in deeper segments. The suppression is below that set by hydrodynamic limits, and may be due to periodic hypoxia or other factors. Our results suggest that the proposed use of suspension-feeding bivalves to improve water quality of large estuaries will be limited by the depth and width of the estuary, unless the bivalves are suspended in the water column by artificial means.  相似文献   

On the dynamic response of a suspended cable     

H. M. Irvine  J. H. Griffin 《地震工程与结构动力学》1976,4(4):389-402

Linearized equations are derived to account for the additional tensions and deflections induced by dynamically exciting a suspended cable. Wave-type and modal solutions are presented to explore the influence of a fundamental geometric and elastic parameter, λ².  相似文献   

The C3H2 2(20)-2(11) transition: absorption in cold dark clouds     

Matthews HE  Madden SC  Avery LW  Irvine WM 《The Astrophysical journal》1986,307(2):L69-L73

The first observations of the 2(20)-2(11) transition of cyclopropenylidene (C3H2) at 21.6 GHz are described. In all cases where it has been detected, the line appears in absorption, showing that this transition is "refrigerated" (i.e., Tex < 2.7 K) in cold dust clouds. These results are compared with those for the 1(10)-1(01) transition of C3H2, and the consequences for the excitation of C3H2 qualitatively discussed.  相似文献   

New interstellar masers in nonmetastable ammonia     

Madden SC  Irvine WM  Matthews HE  Brown RD  Godfrey PD 《The Astrophysical journal》1986,300(2):L79-L84

We report the astronomical detections of several ammonia inversion transitions involving nonmetastable levels with energies as high s 1090 K above the ground state. The (J, K) = (9, 6) inversion transition shows maser-like emission in the directions of W51, NGC 7538, W49, and DR 21(OH). The NH3 (6, 3) line exhibits similar characteristics in W51 but is seen in absorption in NGC 7538. These are the first definite detections of ammonia masers in space. The intensities and narrow line widths (0.5-1.5 km s-1) for the emission features are in contrast to the previously detected broad, weak, nonmetastable lines attributed to thermal emission in these sources. Temporal variability appears to be evident in the (9, 6) emission in W49 over a 4 month period. The highly excited (J, K) = (9, 6) and (6, 3) ammonia lines are found in regions containing compact H II regions and strong infrared sources with associated H2O and OH masers; i.e., in regions of active star formation.  相似文献