Effect of Trapped Gas on Dissolved Oxygen Transport — Implications for In Situ Bioremediation     

Virginia A. Fry  Jonathan D. Istok  Kirk T. O'Reilly 《Ground water》1996,34(2):200-210

  相似文献   

Calculating climate attractor dimension from δ18O records by the Grassberger-Procaccia algorithm     

Kirk A Maasch 《Climate Dynamics》1989,4(1):45-55

The Grassberger-Procaccia method of calculating dimension from a time series is applied to 14 late Pleistocene ¹⁸O records. The difficulties encountered when using this algorithm on limited data sets are reviewed and the step-by-step procedure actually used to calculate the dimension of each record is explicitly listed. Although the results must be viewed with caution, they do indicate that the dimension cannot be measured accurately enough to determine whether or not it is fractal. However, in spite of inaccuracies in the time scale, the underlying dynamics do not appear to be random and there is a suggestion that a lower bound to the Grassberger-Procaccia dimension is somewhere between 4 and 6.  相似文献   

Constrains on gravity wave induced diffusion in the middle atmosphere     

Darrell F. Strobel 《Pure and Applied Geophysics》1989,130(2-3):533-546

A review of the important constraints on gravity wave induced diffusion of chemical tracers, heat, and momentum is given. Ground-based microwave spectroscopy measurements of H₂O and CO and rocket-based mass spectrometer measurements of Ar constrain the eddy diffusion coefficient for constituent transport (K _zz ) to be (1–3)×10⁵ cm²s^–1 in the upper mesosphere. Atomic oxygen data also limitsK _zz to a comparable value at the mesopause. From the energy balance of the upper mesosphere the eddy diffusion coefficient for heat transport (D _H ) is, at most 6×10⁵ cm²s^–1 at the mesopause and decreasing substantially with decreasing altitude. The available evidence for mean wind deceleration and the corresponding eddy diffusion coefficient for momentum stresses (D _M ) suggests that it is at least 1×10⁶ cm²s^–1, in the upper mesosphere. Consequently the eddy Prandtl number for macroscopic scale lengths is >3.  相似文献   

Geographical Aspects of the “Limits to Growth” Concepts*     

Kirk H. Stone 《The Professional geographer》1976,28(4):336-340

  相似文献   

Municipal initiatives for managing dunes in coastal residential areas: a case study of Avalon, New Jersey, USA     

Karl F. Nordstrom  Nancy L. Jackson  Michael S. Bruno  Harry A. de Butts 《Geomorphology》2002,47(2-4)

The characteristics of foredunes created in a municipal management program on a developed barrier island are evaluated to identify how landforms used as protection structures can be natural in appearance and function yet compatible with human values. Shoreline management zones include a naturally evolving, undeveloped segment; a noneroding, developed segment; eroding and noneroding segments of an “improved beach” where dunes have been built by artificial nourishment; and a privately built, artificially nourished dune on the shoreline of an inlet.A disastrous storm in 1962 resulted in an aggressive program for building dunes using sand fences, vegetation plantings, purchase of undeveloped lots, and sediment backpassing to maintain beach widths and dune elevations. The present nourished and shaped foredune in the improved beach is higher, wider, and closer to the berm crest than the natural dune. Restricted inputs of aeolian sand keep the surface flat and poorly vegetated. A stable section of this engineered shore has a wider beach, and sand fences have created a higher foredune with greater topographic diversity. The cross shore zonation of vegetation here is more typical of natural dunes, but the environmental gradient is much narrower. The privately built dune is low, narrow, and located where it could not be created naturally. Foreshore and aeolian sediments in the undeveloped segment and the improved beach are similar in mean grain size (0.16–0.21 mm) and sorting (0.31–0.39φ), but sediment on the surface of the nourished dune is coarser (28.1% gravel) with a more poorly sorted sand fraction (1.30φ) representing lag elements on the deflation surface.Willingness to enhance beaches and dunes for protection has reduced insurance premiums and allowed the municipality to qualify for funds from the Federal Emergency Management Agency (FEMA) to replace lost sediment, thus placing an economic value on dunes. Success of the management program is attributed to: (i) timing property-purchase and dune-building programs to periods immediately after storms (causing residents to accept high dunes that restrict access or views); (ii) instituting a vigorous education program (reminding residents of hazards during nonstorm periods); (iii) maintaining control over local sediment supplies (to keep pace with erosion and create new shoreline environments); (iv) investing private and municipal economic resources in landforms (qualifying them for external funds for replacement); and (v) maintaining, augmenting, or simply tolerating biodiversity and natural processes (retaining a natural heritage).  相似文献   

Apparent Relative Retardation of Tritium and Bromide in Dolomite   总被引：1，自引：0，他引：1  

Darrell I. Leap 《Ground water》1992,30(4):549-558

  相似文献   

Comparison of USGS and DLR topographic models of Comet Borrelly and photometric applications     

Randolph L Kirk  Elpitha Howington-Kraus  Bernd Giese 《Icarus》2004,167(1):54-69

Stereo analysis of images obtained during the 2001 flyby of Comet Borrelly by NASA's Deep Space 1 (DS1) probe allows us to quantify the shape and photometric behavior of the nucleus. The shape is complex, with planar facets corresponding to the dark, mottled regions of the surface whereas the bright, smooth regions are convexly curved. The photometric as well as textural differences between these regions can be explained in terms of topography (roughness) at and below the image resolution, without invoking significant variations in single-particle properties; the material on Borrelly's surface could be quite uniform. A statistical comparison of the digital elevation models (DEMs) produced from the three highest-resolution images independently at the USGS and DLR shows that their difference standard deviation is 120 m, consistent with a matching error of 0.20 pixel (similar to reported matching accuracies for many other stereo datasets). The DEMs also show some systematic differences attributable to manual versus automatic matching. Disk-resolved photometric modeling of the nucleus using the DEM shows that bright, smooth terrains on Borrelly are similar in roughness (Hapke roughness θ=20°) to C-type asteroid Mathilde but slightly brighter and more backscattering (single-scattering albedo w=0.056, Henyey-Greenstein phase parameter g=−0.32). The dark, mottled terrain is photometrically consistent with the same particles but with roughnesses as large as 60°. Intrinsically darker material is inconsistent with the phase behavior of these regions. Many local radiance variations are clearly related to topography, and others are consistent with a topographic explanation; one need not invoke albedo variations greater than a few tens of percent to explain the appearance of Borrelly.  相似文献   

Spatial patterns of ice storm disturbance on a forested landscape in the Appalachian Mountains, Virginia   总被引：3，自引：0，他引：3  

Kirk M Stueve  Charles W Lafon  Rachel E Isaacs 《Area》2007,39(1):20-30

Ice storms (major freezing rain events) periodically disturb forests in eastern North America. The damage may vary spatially, especially in complex terrain. This study uses satellite imagery to investigate spatial heterogeneity of forest damage caused by ice storms that affected the Appalachian Mountains, Virginia during 1994. The results display a region-scale (southwest-to-northeast) gradient in damage that apparently corresponds to a gradient in the depth of ice that accumulated during the storms. Damage also varied topographically, particularly by aspect. Damage was most extensive on east-, southeast- and south-facing slopes; at middle elevations; and on slopes of moderate steepness.  相似文献   

A solar granulation spectrogram     

J. G. Kirk  W. Livingston 《Solar physics》1968,3(4):510-512

  相似文献   

Natural radionuclides as tracers of coastal biogeochemical processes   总被引：1，自引：0，他引：1  

J. Kirk Cochran  H. Feng  D. Amiel  A. Beck 《Journal of Geochemical Exploration》2006,88(1-3):376

This paper presents an overview of the ways that natural radionuclides have been used as tracers of biogeochemical processes occurring in the coastal ocean. The radionuclides involved include those in the uranium and thorium decay series and those produced in the atmosphere by the interaction of cosmic rays with atmospheric gases (i.e., cosmogenic radionuclides). The property of radioactivity provides a chronometer with which to measure the rates of oceanic processes, and the fundamental biogeochemical behavior of the radionuclide determines which process(es) it may be used to trace. Examples from recent research will be presented in the talk.  相似文献