Geophysical, archaeological and historical evidence support a solar-output model for climate change
C. A. Perry, K.J. Hsu
2000, Conference Paper, Proceedings of the National Academy of Sciences of the United States of America
Although the processes of climate change are not completely understood, an important causal candidate is variation in total solar output. Reported cycles in various climate-proxy data show a tendency to emulate a fundamental harmonic sequence of a basic solar-cycle length (11 years) multiplied by 2(N) (where N equals a positive...
Numerical modelling of geothermal and reflux circulation in Enewetak Atoll: Implications for dolomitization
G. Jones, F. Whitaker, P. Smart, W. Sanford
2000, Conference Paper, Journal of Geochemical Exploration
Two types of regional-scale seawater circulation have been proposed to explain the formation of Enewetak Atoll dolomites: geothermal and reflux circulation. We have used a finite element groundwater flow model to examine the pattern, magnitude and dynamic interaction of these two different circulation mechanisms in Enewetak Atoll. Geothermal circulation is...
Modelling carbon responses of tundra ecosystems to historical and projected climate: Sensitivity of pan-Arctic carbon storage to temporal and spatial variation in climate
A. D. McGuire, Joy S. Clein, J. M. Melillo, D. W. Kicklighter, R.A. Meier, C. J. Vorosmarty, Mark C. Serreze
2000, Global Change Biology (6) 141-159
Historical and projected climate trends for high latitudes show substantial temporal and spatial variability. To identify uncertainties in simulating carbon (C) dynamics for pan-Arctic tundra, we compare the historical and projected responses of tundra C storage from 1921 to 2100 between simulations by the Terrestrial Ecosystem Model (TEM) for the...
Observations of storm and river flood-driven sediment transport on the northern California continental shelf
A.S. Ogston, D.A. Cacchione, R.W. Sternberg, G.C. Kineke
2000, Continental Shelf Research (20) 2141-2162
In the winter of 1996-1997, three bottom-boundary layer tripods were placed in an alongshelf array on the northern California continental shelf off Eureka, CA in 60-65-m water depth. During the observation period, multiple storms and river discharge events occurred, as well as the largest flood on record since 1964. Suspended-sediment...
Reproductive longevity and fecundity associated with nonannual spawning in cui-ui
G.G. Scoppettone, P.H. Rissler, M.E. Buettner
2000, Transactions of the American Fisheries Society (129) 658-669
The cui-ui Chasmistes cujus, a long-lived (40 years or more) and highly fecund catostomid, is often prevented from spawning in drought years. We studied the effect of cui-ui age on egg viability and the effect of nonannual spawning on fecundity in relation to length, age, and growth rate. Egg hatching...
Magma mixing, recharge and eruption histories recorded in plagioclase phenocrysts from El Chichón Volcano, Mexico
F. J. Tepley III, J.P. Davidson, R.I. Tilling, Joseph G. Arth
2000, Journal of Petrology (41) 1397-1411
Consistent core-to-rim decreases of 87Sr/86Sr ratios and coincident increases in Sr concentrations in plagioclase phenocrysts of varying size (∼1 cm to 2 mm) are reported from samples of the 1982 and pre-1982 (∼200 ka) eruptions of El Chichón Volcano. Maximum 87Sr/86Sr ratios of ∼0·7054, significantly higher than the whole-rock isotopic ratios...
Wildlife tradeoffs based on landscape models of habitat
C. Loehle, M.S. Mitchell
2000, Conference Paper, NCASI Proceedings
It is becoming increasingly clear that the spatial structure of landscapes affects the habitat choices and abundance of wildlife. In contrast to wildlife management based on preservation of critical habitat features such as nest sites on a beach or mast trees, it has not been obvious how to incorporate spatial...
Alachlor transformation patterns in aquatic field mesocosms under variable oxygen and nutrient conditions
D.W. Graham, M.K. Miley, F. Denoyelles, Val H. Smith, E.M. Thurman, R. Carter
2000, Water Research (34) 4054-4062
Alachlor is one of the most commonly used herbicides in both Europe and North America. Because of its toxic properties, its fate and attenuation in natural waters is practically important. This paper assesses factors that affect alachlor decay rate in aquatic systems using field-scale experimental units. In particular, we used...
A modified ground-motion attenuation relationship for southern California that accounts for detailed site classification and a basin-depth effect
E. H. Field
2000, Bulletin of the Seismological Society of America (90) S209-S221
The attenuation relationship presented by Boore et al. (1997) has been evaluated and customized with respect to southern California strong-motion data (for peak ground acceleration (PGA) and 0.3-, 1.0-, and 3.0-sec period spectral acceleration). This study was motivated by the recent availability of a new site-classification map by Wills et...
On the modified Mercalli intensities and magnitudes of the 1811-1812 New Madrid earthquakes
S. E. Hough, J.G. Armbruster, L. Seeber, J.F. Hough
2000, Journal of Geophysical Research B: Solid Earth (105) 23839-23864
We reexamine original felt reports from the 1811–1812 New Madrid earthquakes and determine revised isoseismal maps for the three principal mainshocks. In many cases we interpret lower values than those assigned by earlier studies. In some cases the revisions result from an interpretation of original felt reports with an appreciation...
Sampling for mercury at subnanogram per litre concentrations for load estimation in rivers
J.A. Colman, R.F. Breault
2000, Canadian Journal of Fisheries and Aquatic Sciences (57) 1073-1079
Estimation of constituent loads in streams requires collection of stream samples that are representative of constituent concentrations, that is, composites of isokinetic multiple verticals collected along a stream transect. An all-Teflon isokinetic sampler (DH-81) cleaned in 75??C, 4 N HCl was tested using blank, split, and replicate samples to assess...
Pore fluid pressure, apparent friction, and Coulomb failure
N.M. Beeler, R.W. Simpson, S.H. Hickman, D.A. Lockner
2000, Journal of Geophysical Research B: Solid Earth (105) 25533-25542
Many recent studies of stress-triggered seismicity rely on a fault failure model with a single free parameter, the apparent coefficient of friction, presumed to be a material constant with possible values 0 ≤ μ′ ≤ 1. These studies may present a misleading view of fault strength and the role of...
Entrainment of riparian gravel and cobbles in an alluvial reach of a regulated canyon river
John G. Elliott, Lauren A. Hammack
2000, Regulated Rivers: Research & Management (16) 37-50
Many canyon rivers have channels and riparian zones composed of alluvial materials and these reaches, dominated by fluvial processes, are sensitive to alterations in streamflow regime. Prior to reservoir construction in the mid-1960s, banks and bars in alluvial reaches of the Gunnison River in the Black Canyon National Monument, Colorado,...
Chapter 4. Predicting post-fire erosion and sedimentation risk on a landscape scale
L. H. MacDonald, R. Sampson, D. Brady, L. Juarros, Deborah A. Martin
2000, Journal of Sustainable Forestry (11) 57-87
Historic fire suppression efforts have increased the likelihood of large wildfires in much of the western U.S. Post-fire soil erosion and sedimentation risks are important concerns to resource managers. In this paper we develop and apply procedures to predict post-fire erosion and sedimentation risks on a pixel-, catchment-, and landscape-scale...
Synthetic aperture radar interferometry of Okmok volcano, Alaska: radar observations
Zhong Lu, Dorte Mann, Jeffrey T. Freymueller, David Meyer
2000, Journal of Geophysical Research B: Solid Earth (105) 10791-10806
ERS-1/ERS-2 synthetic aperture radar interferometry was used to study the 1997 eruption of Okmok volcano in Alaska. First, we derived an accurate digital elevation model (DEM) using a tandem ERS-1/ERS-2 image pair and the preexisting DEM. Second, by studying changes in interferometric coherence we found that the newly erupted lava...
Dynamics of nutrient cycling and related benthic nutrient and oxygen fluxes during a spring phytoplankton bloom in South San Francisco Bay (USA)
C. Grenz, J. E. Cloern, S.W. Hager, B.E. Cole
2000, Marine Ecology Progress Series (197) 67-80
Benthic oxygen uptake and nutrient releases of N, P and Si were measured weekly at 2 sites in South San Francisco Bay around the 1996 spring bloom. Exchanges across the sediment-water interface were estimated from whole core incubations performed in the laboratory at in situ temperature and in dark. Fluxes changed significantly...
Estimation of potential loss of two pesticides in runoff in Fillmore County, Minnesota using a field-scale process-based model and a geographic information system
Paul D. Capel, Zhang Hua
2000, Conference Paper, Agrochemical fate and movement
In assessing the occurrence, behavior, and effects of agricultural chemicals in surface water, the scales of study (i.e., watershed, county, state, and regional areas) are usually much larger than the scale of agricultural fields, where much of the understanding of processes has been developed. Field-scale areas are characterized by relatively...
Characterization of seismic hazard and structural response by energy flux
E. Afak
2000, Soil Dynamics and Earthquake Engineering (20) 39-43
Seismic safety of structures depends on the structure's ability to absorb the seismic energy that is transmitted from ground to structure. One parameter that can be used to characterize seismic energy is the energy flux. Energy flux is defined as the amount of energy transmitted per unit time through a...
Deep magmatic structures of Hawaiian volcanoes, imaged by three-dimensional gravity models
J. Kauahikaua, T. Hildenbrand, M. Webring
2000, Geology (28) 883-886
A simplified three-dimensional model for the island of Hawai'i, based on 3300 gravity measurements, provides new insights on magma pathways within the basaltic volcanoes. Gravity anomalies define dense cumulates and intrusions beneath the summits and known rift zones of every volcano. Linear gravity anomalies project southeast from Kohala and Mauna...
Application of a modified harness design for attachment of radio transmitters to shorebirds
Peter M. Sanzenbacher, Susan M. Haig, Lewis W. Oring
2000, Wader Study Group Bulletin (91) 16-20
Radio transmitter attachment methodology is important to the design of radio telemetry studies. In 1998, we attached 5 transmitters to a captive population of Western Sandpipers (Calidris mauri) and 7 transmitters to wild Killdeer (Charadriusv ociferus) using a modified version of the Rappole and Tipton (1991) figure-8 leg-loop harness. Captive...
Effect of elevation on distribution of female bats in the Black Hills, South Dakota
P.M. Cryan, M.A. Bogan, J.S. Altenbach
2000, Journal of Mammalogy (81) 719-725
Presumably, reproductive female bats are more constrained by thermoregulatory and energy needs than are males and nonreproductive females. Constraints imposed on reproductive females may limit their geographic distribution relative to other bats. Such constraints likely increase with latitude and elevation. Males of 11 bat species that inhabit the Black Hills...
Combining binary decision tree and geostatistical methods to estimate snow distribution in a mountain watershed
Benjamin Balk, Kelly Elder
2000, Water Resources Research (36) 13-26
We model the spatial distribution of snow across a mountain basin using an approach that combines binary decision tree and geostatistical techniques. In April 1997 and 1998, intensive snow surveys were conducted in the 6.9‐km2 Loch Vale watershed (LVWS), Rocky Mountain National Park, Colorado. Binary decision trees were used to model...
Information technology developments within the national biological information infrastructure
Gladys Cotter, Mike Frame
2000, Mathematics and Computers in Modern Science - Acoustics and Music, Biology and Chemistry, Business and Economics 206-211
Looking out an office window or exploring a community park, one can easily see the tremendous challenges that biological information presents the computer science community. Biological information varies in format and content depending whether or not it is information pertaining to a particular species (i.e. Brown Tree Snake), or a...
Simulations of flooding on Tchoutacabouffa River at State Highways 15 and 67 at D'Iberville, Mississippi
Karl E. Winters
2000, Water-Resources Investigations Report 2001-4007
A two-dimensional finite-element surface-water model was used to simulate the effects of the proposed State Highways 15 and 67 relocation on water-surface elevations and flow distributions for the 100-year flood on the Tchoutacabouffa River at D'Iberville, Mississippi. The Mississippi Department of Transportation plans to relocate State Highways 15 and 67...
The 2000 revision of the joint UK/US geomagnetic field models and an IGRF 2000 candidate model
S. Macmillan, J.M. Quinn
2000, Earth, Planets and Space (52) 1149-1162
The method of derivation of the joint UK/US spherical harmonic geomagnetic main-field and secular-variation models is presented. Early versions of these models, with the main field truncated at degree 10, are the UK/US candidates for the IGRF 2000 model. The main-field model describes the Earth’s magnetic field at the 2000.0...
