A first-order global model of late Cenozoic climatic change II. Further analysis based on a simplification of CO2 dynamics     

Barry Saltzman  Kirk A Maasch 《Climate Dynamics》1991,5(4):201-210

A model developed recently for the long-term variations of global ice mass, carbon dioxide, and mean ocean temperature through the late Cenozoic is simplified by hypothesizing a new equation for the CO₂ variations containing one less adjustable parameter, but retaining the essential physical content of the previous equation (including nonlinearity and the potential for instability). By assuming plausible time constants for the glacial ice mass and global mean ocean temperature, and setting the values of six adjustable parameters (rate constants), a solution for the last 5 My is obtained displaying many of the features observed over this period, including the transition to the near-100 ky major ice-age oscillations of the late Pleistocene. In obtaining this solution it is also assumed that variations in tectonic forcing lead to a reduction of the equilibrium CO₂ concentration (perhaps due to increased weathering of rapidly uplifted mountain ranges over this period). As a consequence of this CO₂ reduction, the model dynamical system can bifurcate to a free oscillatory ice-age regime that is under the pacemaker influence of earthorbital (Milankovitch) forcing. Expanded discussions are given of the surface temperature variations accompanying the evolution of ice, CO₂, and ocean temperature, and of the bifurcation properties of the model from both mathematical and physical viewpoints.This paper was presented at the International Conference on Modelling of Global Climate Change and Variability, held in Hamburg 11–15 September 1989 under the auspices of the Meteorological Institute of the University of Hamburg and the Max Planck Institute for Meteorology. Guest Editor for these papers is Dr. L. Dumenil  相似文献   

Trophic structure and pathways of biogenic carbon flow in the eastern North Water Polynya   总被引：1，自引：0，他引：1  

Jean-ric Tremblay  Hiroshi Hattori  Christine Michel  Marc Ringuette  Zhi-Ping Mei  Connie Lovejoy  Louis Fortier  Keith A. Hobson  David Amiel  Kirk Cochran 《Progress in Oceanography》2006,71(2-4):402

In the eastern North Water, most of the estimated annual new and net production of carbon (C) occurred during the main diatom bloom in 1998. During the bloom, at least 30% of total and new phytoplankton production occurred as dissolved organic carbon (DOC) and was unavailable for short-term assimilation into the herbivorous food web or sinking export. Based on particle interceptor traps and ²³⁴Th deficits, 27% of the particulate primary production (PP) sank out of the upper 50 m, with only 7% and 1% of PP reaching the benthos at shallow (≈200 m) and deep (≈500 m) sites, respectively. Mass balance calculations and grazing estimates agree that ≈79% of PP was ingested by pelagic consumers between April and July. During this period, the vertical flux of biogenic silica (BioSi) at 50 m was equivalent to the total BioSi produced, indicating that all of the diatom production was removed from the euphotic zone as intact cells (direct sinking) or empty frustules (grazing or lysis). The estimated flux of empty frustules was consistent with rates of herbivory by the large, dominant copepods and appendicularians during incubations. Since the carbon demand of the dominant planktivorous bird, Alle alle, amounted to ≈2% of the biomass synthesized by its main prey, the large copepod Calanus hyperboreus, most of the secondary carbon production was available to pelagic carnivores. Stable isotopes indicated that the biomass of predatory amphipods, polar cod and marine mammals was derived from these herbivores, but corresponding carbon fluxes were not quantified. Our analysis shows that a large fraction of PP in the eastern North Water was ingested by consumers in the upper 50 m, leading to substantial carbon respiration and DOC accumulation in surface waters. An increasingly early and prolonged opening of the Artic Ocean is likely to promote the productivity of the herbivorous food web, but not the short-term efficiency of the particulate, biological CO₂ pump.  相似文献   

A three-component ocean bottom seismograph for controlled source and earthquake seismology     

R. E. Kirk  R. B. Whitmarsh  J. J. Langford 《Marine Geophysical Researches》1982,5(3):327-341

A three-component pop-up ocean-bottom seismograph was built at the Institute of Oceanographic Sciences in 1978. It is constructed around a buoyant 71 cm diam aluminium alloy forged sphere which contains three 4.5 Hz orthogonal geophones and an external hydrophone. The instrument will record continuously in analogue mode for over eight days using a modified reel-to-reel tape-recorder running at 1.5 mm s^-1. The geophones have a bandwidth of 2–25 Hz and the hydrophone bandwidth is 5–40 Hz. Ballast release is by pre-set clock or by acoustic command.Fifty-four deployments have been carried out in five cruises for the loss of only one instrument. Good recordings of dropped weights, airguns, explosions and earthquakes have been obtained.  相似文献   

The inferential basis of species hypotheses: the solution to defining the term 'species'   总被引：2，自引：0，他引：2  

Kirk Fitzhugh 《Marine Ecology》2005,26(3-4):155-165

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Dynamic and static analysis of a marine riser   总被引：1，自引：0，他引：1  

C. L. Kirk  E. U. Etok 《Applied Ocean Research》1979,1(3):125-135

A frequency domain normal mode solution is presented for the dynamic response of an unbuoyed marine riser subjected to periodic excitation from a surface vessel in the direction of wave propagation. The variable tension beam-column equation is solved in terms of normal modes of free vibration of the riser and the rigid body displacement. Drag forces on the riser are represented by Morison's formula taking account of the velocity of the riser and wave-induced fluid velocity. A periodic solution for the flexural motion of the riser and the bending stress is then obtained by means of an iterative solution of the frequency response function. The drag force induced stresses arising from a linearly varying current are also determined. The results presented compare favourably with those obtained by other methods.  相似文献   

An analytic study of impact ejecta trajectories in the atmospheres of Venus,Mars, and Earth     

Michael E. Tauber  Donn B. Kirk  Donald E. Gault 《Icarus》1978,33(3):529-536

Calculations have been made to determine the effects of atmospheric drag and gravity on impact ejecta trajectories on Venus, Mars, and the Earth. The equations of motion were numerically integrated for a broad range of body sizes, initial velocities, and initial elevation angles. A dimensionless parameter was found from approximate analytic solutions which correlated the ejecta range, final impact angle, and final impact velocity for all three planets.  相似文献   

Variable effects of cinder-cone eruptions on prehistoric agrarian human populations in the American southwest     

Michael H. Ort  Mark D. Elson  Kirk C. Anderson  Wendell A. Duffield  Terry L. Samples 《Journal of Volcanology and Geothermal Research》2008

Two ∼ 900 BP cinder-cone eruptions in the American Southwest affected prehistoric human populations in different ways, mostly because of differences in the eruption styles and area affected. Primary pre-eruption cultural factors that may have led to successful adaptation to the eruptions include decision-making at the family or household level, low investment in site structures, dispersion of agricultural sites in varied environments, and settlement spread over a large area so that those who were less affected could shelter and feed evacuees.  相似文献   

Modeling Sediment Transport Dynamics in Thompson Island Pool,Upper Hudson River     

Ziegler  C. Kirk  Israelsson  Peter H.  Connolly  John P. 《Water Quality and Ecosystems Modeling》2000,1(1-4):193-222

Two-dimensional, vertically-averaged hydrodynamic and sediment transport models were developed and applied as part of a PCB fate and transport modeling study of Thompson Island Pool (TIP), Upper Hudson River. Mechanistic formulations were used to simulate cohesive and non-cohesive suspended load transport; site-specific data were extensively used to determine model inputs. This modeling approach is compared and contrasted to non-mechanistic solids transport sub-models used in other contaminant fate studies. A minimum number of model parameters were adjusted to calibrate the sediment transport model using data collected during the 1994 spring flood. The model was validated during the 1997 spring flood and for a 22-year (1977–1998) period. Successful calibration and validation of the model showed that: (1) deposition and resuspension processes were realistically and accurately formulated in the model; (2) the model is an effective diagnostic tool for quantitatively evaluating net deposition and erosion from various areas of TIP; and (3) sediment transport results can be coupled with a PCB fate model with a high degree of confidence.  相似文献   

On the Basis for the 0.1 mg/L Water Quality Objective for “Taste and Odor” for Diesel in Groundwater          下载免费PDF全文

Dawn A. Zemo  Kirk T. O'Reilly 《Ground Water Monitoring & Remediation》2016,36(3):88-90

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The Origin of Sequential Chromospheric Brightenings     

M. S. Kirk  K. S. Balasubramaniam  J. Jackiewicz  H. R. Gilbert 《Solar physics》2017,292(6):72

Sequential chromospheric brightenings (SCBs) are often observed in the immediate vicinity of erupting flares and are associated with coronal mass ejections. Since their initial discovery in 2005, there have been several subsequent investigations of SCBs. These studies have used differing detection and analysis techniques, making it difficult to compare results between studies. This work employs the automated detection algorithm of Kirk et al. (Solar Phys. 283, 97, 2013) to extract the physical characteristics of SCBs in 11 flares of varying size and intensity. We demonstrate that the magnetic substructure within the SCB appears to have a significantly smaller area than the corresponding \(\mbox{H}\upalpha\) emission. We conclude that SCBs originate in the lower corona around \(0.1~R_{\odot}\) above the photosphere, propagate away from the flare center at speeds of \(35\,\mbox{--}\,85~\mbox{km}\,\mbox{s}^{-1}\), and have peak photosphere magnetic intensities of \(148\pm2.9~\mbox{G}\). In light of these measurements, we infer SCBs to be distinctive chromospheric signatures of erupting coronal mass ejections.  相似文献