Geomagnetic storms, the Dst ring-current myth and lognormal distributions
W.H. Campbell
1996, Journal of Atmospheric and Terrestrial Physics (58) 1171-1187
The definition of geomagnetic storms dates back to the turn of the century when researchers recognized the unique shape of the H-component field change upon averaging storms recorded at low latitude observatories. A generally accepted modeling of the storm field sources as a magnetospheric ring current was settled about 30...
A preliminary evaluation of sediment quality assessment values for freshwater ecosystems
Sherri L. Smith, Donald D. MacDonald, Karen A. Keenleyside, Christopher G. Ingersoll, L. Jay Field
1996, Journal of Great Lakes Research (22) 624-638
Sediment quality assessment values were developed using a weight of evidence approach in which matching biological and chemical data from numerous modelling, laboratory, and field studies performed on freshwater sediments were compiled and analyzed. Two assessment values (a threshold effect level (TEL) and a probable effect level(PEL)) were derived for...
Source parameters controlling the generation and propagation of potential local tsunamis along the cascadia margin
Eric L. Geist, Shoichi Yoshioka
1996, Natural Hazards (13) 151-177
The largest uncertainty in assessing hazards from local tsunamis along the Cascadia margin is estimating the possible earthquake source parameters. We investigate which source parameters exert the largest influence on tsunami generation and determine how each parameter affects the amplitude of the local tsunami. The following source parameters were analyzed:...
Source and tectonic implications of tonalite-trondhjemite magmatism in the Klamath Mountains
C. G. Barnes, S. W. Petersen, R. W. Kistler, R. Murray, M. A. Kays
1996, Contributions to Mineralogy and Petrology (123) 40-60
In the Klamath Mountains, voluminous tonalite-trondhjemite magmatism was characteristic of a short period of time from about 144 to 136 Ma (Early Cretaceous). It occurred about 5 to 10 m.y. after the ∼165 to 159 Ma Josephine ophiolite was thrust beneath older parts of the province during the Nevadan orogeny (thrusting from ∼155...
Variability survival of larval fish: disentangling components with a generalized individual-based model
B. H. Letcher, J. A. Rice, L.B. Crowder, K.A. Rose
1996, Canadian Journal of Fisheries and Aquatic Sciences (53) 787-801
Detection and monitoring of H2O and CO2 ice clouds on Mars
J.F. Bell III, W. M. Calvin, M. E. Ockert-Bell, D. Crisp, James B. Pollack, J. Spencer
1996, Journal of Geophysical Research E: Planets (101) 9227-9237
We have developed an observational scheme for the detection and discrimination of Mars atmospheric H2O and CO2 clouds using ground-based instruments in the near infrared. We report the results of our cloud detection and characterization study using Mars near IR images obtained during the 1990 and 1993 oppositions. We focused on...
Region of influence regression for estimating the 50-year flood at ungaged sites
Gary D. Tasker, S.A. Hodge, C. S. Barks
1996, Journal of the American Water Resources Association (32) 163-170
Five methods of developing regional regression models to estimate flood characteristics at ungaged sites in Arkansas are examined. The methods differ in the manner in which the State is divided into subregions. Each successive method (A to E) is computationally more complex than the previous...
A digital system for surface reconstruction
Weiyang Zhou, Robert H. Brock, Paul F. Hopkins
1996, Photogrammetric Engineering and Remote Sensing (62) 719-726
A digital photogrammetric system, STEREO, was developed to determine three dimensional coordinates of points of interest (POIs) defined with a grid on a textureless and smooth-surfaced specimen. Two CCD cameras were set up with unknown orientation and recorded digital images of a reference model and a specimen. Points on the...
Numerical evaluation of static-chamber measurements of soil-atmospheric gas exchange--Identification of physical processes
Richard W. Healy, Robert G. Striegl, Thomas F. Russell, Gordon L. Hutchinson, Gerald P. Livingston
1996, Soil Science Society of America Journal (60) 740-747
The exchange of gases between soil and atmosphere is an important process that affects atmospheric chemistry and therefore climate. The static-chamber method is the most commonly used technique for estimating the rate of that exchange. We examined the method under hypothetical field conditions where diffusion was the only mechanism for...
Seasonal bathymetric distributions of 16 fishes in Lake Superior, 1958-75
James H. Selgeby, Michael H. Hoff
1996, Biological Science Report 7
The bathymetric distributions of fishes in Lake Superior, which is one of the largest and deepest lakes in the world, has not been studied on a lakewide scale. Knowledge about the bathymetric distributions will aid in designing fish sampling programs, estimating absolute abundances, and modeling energy flow in the...
Survival of radiomarked canvasback ducklings in northwestern Minnesota
Carl E. Korschgen, Kevin P. Kenow, William L. Green, Douglas H. Johnson, Michael D. Samuel, Louis Sileo
1996, Journal of Wildlife Management (60) 120-132
Duckling survival, an important factor affecting annual recruitment, has not been determined adequately for canvasbacks (Aythya valisineria). We investigated the magnitude, timing, and causes of mortality of canvasback ducklings from hatch to fledging at the Agassiz National Wildlife Refuge (NWR) in northwestern Minnesota during 1987-90. During the 4 years, 217...
Extension across Tempe Terra, Mars, from measurements of fault scarp widths and deformed craters
M.P. Golombek, K. L. Tanaka, B.J. Franklin
1996, Journal of Geophysical Research E: Planets (101) 26119-26130
Two independent methods, with no common assumptions, have been used to estimate the extension across the heavily deformed Tempe Terra province of the Tharsis region of Mars. One method uses measurements of normal fault scarp width with average scarp slope data for simple grabens and rifts on Mars to estimate...
Mass and body-dimension relationships of polar bears in northern Alaska
George M. Durner, Steven C. Amstrup
1996, Wildlife Society Bulletin (24) 480-484
Models developed from morphometric parameters are useful for estimating body mass (M) of captured wild ursids. The accuracy of those models, however, may depend on sex, season, and geographic location of the population. We tested the suitability of reported models to predict mass of polar bears (Ursus maritimus) captured in...
The 40Ar/39Ar and K/Ar dating of lavas from the Hilo 1-km core hole, Hawaii Scientific Drilling Project
W.D. Sharp, B. D. Turrin, P.R. Renne, M. A. Lanphere
1996, Journal of Geophysical Research B: Solid Earth (101) 11607-11616
Mauna Kea lava flows cored in the Hilo hole range in age from <200 ka to about 400 ka based on 40Ar/39Ar incremental heating and K‐Ar analyses of 16 groundmass samples and one coexisting plagioclase. The lavas, all subaerially deposited, include a lower section consisting only of tholeiitic...
Failure in laboratory fault models in triaxial tests
J.C. Savage, D.A. Lockner, J.D. Byerlee
1996, Journal of Geophysical Research B: Solid Earth (101) 22215-22224
A model of a fault in the Earth is a sand-filled saw cut in a granite cylinder subjected to a triaxial test. The saw cut is inclined at an angle α to the cylinder axis, and the sand filling is intended to represent gouge. The triaxial test subjects the granite...
The initial cooling of pahoehoe flow lobes
L. Keszthelyi, R. Denlinger
1996, Bulletin of Volcanology (58) 5-18
In this paper we describe a new thermal model for the initial cooling of pahoehoe lava flows. The accurate modeling of this initial cooling is important for understanding the formation of the distinctive surface textures on pahoehoe lava flows as well as being the first step in modeling such key...
Geochemistry of aquatic humic substances in the Lake Fryxell basin, Antarctica
G. Aiken, D. McKnight, R. Harnish, R. Wershaw
1996, Biogeochemistry (34) 157-188
Dissolved organic carbon (DOC) in Lake Fryxell, 10 streams flowing into the lake, and the moat surrounding the lake was studied to determine the influence of sources and biogeochemical processes on its distribution and chemical nature. Lake Fryxell is an amictic, permanently ice-covered lake in the McMurdo Dry Valleys which...
Analysis of nitrate in near-surface aquifers in the midcontinental United States: An application of the inverse hyperbolic sine Tobit model
Steven T. Yen, Shiping Liu, Dana W. Kolpin
1996, Water Resources Research (32) 3003-3011
A nonnormal and heteroscedastic Tobit model is used to determine the primary factors that affect nitrate concentrations in near-surface aquifers, using data from the U.S. Geological Survey collected in 1991. Both normality and homoscedasticity of errors are rejected, justifying the use of a nonnormal and heteroscedastic model. The following factors...
Integrating a geographic information system, a scientific visualization system, and a precipitation model
L.E. Hay, L.K. Knapp
1996, Water Resources Bulletin (32) 357-369
Investigating natural, potential, and human-induced impacts on hydrologic systems commonly requires complex modeling with overlapping data requirements, plus massive amounts of one- to four-dimensional data at multiple scales and formats. Given the complexity of most hydrologic studies, the requisite software infrastructure must incorporate many components including simulation modeling and spatial...
Age dating of shallow groundwater with chlorofluorocarbons, tritium/helium: 3, and flow path analysis, southern New Jersey coastal plain
Zoltan Szabo, D.E. Rice, Niel Plummer, E. Busenberg, S. Drenkard, P. Schlosser
1996, Water Resources Research (32) 1023-1038
Groundwater age dating through the combination of transient tracer methods (chlorofluorocarbons (CFCs) and tritium/helium 3 (3H/3He)) and groundwater flow path analysis is useful for investigating groundwater travel times, flow patterns, and recharge rates, as demonstrated by this study of the homogeneous shallow, unconfined Kirkwood-Cohansey aquifer system in the southern New...
A simulation-based approach for designing effective field-sampling programs to evaluate contamination risk of groundwater supplies
R. Nordqvist, C.I. Voss
1996, Hydrogeology Journal (4) 23-39
An approach to model discrimination and network design for evaluation of groundwater contamination risk is proposed and demonstrated by application to a site in a glaciofluvial aquifer in Sweden. The approach consists of first hypothesizing alternative conceptual models of hydrogeology at the site on the basis of both quantitative data...
Potential climatic impacts of vegetation change: A regional modeling study
J.H. Copeland, R.A. Pielke, T.G.F. Kittel
1996, Journal of Geophysical Research D: Atmospheres (101) 7409-7418
The human species has been modifying the landscape long before the development of modern agrarian techniques. Much of the land area of the conterminous United States is currently used for agricultural production. In certain regions this change in vegetative cover from its natural state may have led to local climatic...
The enigma of the New Madrid earthquakes of 1811-1812
A. C. Johnston, E.S. Schweig
1996, Annual Review of Earth and Planetary Sciences (24) 339-384
Continental North America's greatest earthquake sequence struck on the western frontier of the United States. The frontier was not then California but the valley of the continent's greatest river, the Mississippi, and the sequence was the New Madrid earthquakes of the winter of 1811–1812. Their described impacts on the land...
Thermal and mass implications of magmatic evolution in the Lassen volcanic region, California, and minimum constraints on basalt influx to the lower crust
M. Guffanti, M.A. Clynne, L.J.P. Muffler
1996, Journal of Geophysical Research B: Solid Earth (101) 3003-3013
We have analyzed the heat and mass demands of a petrologic model of basalt-driven magmatic evolution in which variously fractionated mafic magmas mix with silicic partial melts of the lower crust. We have formulated steady state heat budgets for two volcanically distinct areas in the Lassen region: the large, late...
NLEAP/GIS approach for identifying and mitigating regional nitrate-nitrogen leaching
M.J. Shaffer, M.D. Hall, B.K. Wylie, D.G. Wagner
D.L. Corwin, K. Loague, editor(s)
1996, Book chapter, Applications of GIS to the modeling of non-point source pollutants in the vadose zone, SSSA Special Publication 48
Improved simulation-based methodology is needed to help identify broad geographical areas where potential NO3-N leaching may be occurring from agriculture and suggest management alternatives that minimize the problem. The Nitrate Leaching and Economic Analysis Package (NLEAP) model was applied to estimate regional NO3-N leaching in eastern Colorado. Results show that...
