Sensitivity of crop yields and land resource potential to climatic change in Ontario,Canada     

Barry Smit  Michael Brklacich  Robert B. Stewart  Ray McBride  Murray Brown  Deborah Bond 《Climatic change》1989,14(2):153-174

Increasing concentrations of atmospheric CO₂ and other greenhouse gases are expected to contribute to a global warming. This paper examines the potential implications of a climatic change corresponding to a doubling of atmospheric concentrations of CO₂ on crop production opportunities throughout Ontario, a major food producing region in Canada. The climate is projected to become warmer and drier, but the extent of these shifts are expected to vary from region to region within Ontario. The effect of this altered climate on crop yields and the area of land capable of supporting specific crops varies according to region, soil quality and crop type. Most notable are the enhanced opportunities for grains and oilseeds in the northern regions, and the diminished production prospects for most crops in the most southerly parts of Ontario.  相似文献   

Shape analysis of Pacific seamounts   总被引：2，自引：0，他引：2  

Deborah K. Smith 《Earth and Planetary Science Letters》1988,90(4):457-466

Shape statistics have been compiled from 85 profiles of well-surveyed Pacific seamounts in the height range 140–3800 m. A flat-topped cone was fit to each seamount's cross-sectional profile maintaining the slopes of the sides as closely as possible. On each profile a basal widthd_b, a summit widthd_t, and a maximum heighth, were measured. The height-to-basal-radius ratio isξ_h is estimated by the ratio2hd_b and flatnessf by the ratiod_td_b. Slope angleφ = arctan(ε) is estimated fromε =2h(d_b − d_t). Summit height and basal radius are found to be highly correlated (r = 0.93). The 85-point sample mean of the height-to-basal-radius ratio isξ_h = 0.21 ± 0.08 implying that a seamount's summit height is typically one fifth its basal radius. Despite the high correlation, individual points show some scatter, and there may be groupings into different morphological types. For example, all but one of the seamounts with summit heights above 1000 m have values ofξ_h that are larger than the sample mean. The 85-point sample mean of flatness isf = 0.31 ± 0.18. Data points show a large scatter with values off varying between 0 (a pointy cone) and 0.69 (a flat-topped cone). A histogram representation of flatness, however, indicates that certain values off may be more common than others: the histogram shows a bimodal distribution with maxima occurring at values off in the ranges 0.10–0.20 and 0.35–0.50. Moreover, there is some evidence that the mean flatness decreases with summit height so that the preferred shape of a large-sized seamount may be a pointy cone. Slope angle has an 85-point sample mean ofφ = 18 ± 6°; individual values ofφ vary between 5° and 36°. In addition to having a lower than average mean flatness seamounts with heights above 2600 m also have a lower than average mean slope angle (15°). To determine which variables account for most of the observed variation in the seamount shapes, a multivariate principal component analysis was performed on the data using five shape variables (summit height, basal radius, summit radius, flatness, and slope). The analysis indicates that most of the variation is described by two variables: flatness and summit height.  相似文献   

Distribution of Volatile Organic Compounds in a New Jersey Coastal Plain Aquifer System     

Thomas V. Fusillo  Joseph J. Hochreiter  Jr.  Deborah Grant Lord 《Ground water》1985,23(3):354-360

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Disenchanting democracy     

Deborah Thien 《Area》2007,39(1):134-135

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Economics and Ecological Risk Assessment. Applications to Watershed Management     

Deborah  V Chapman 《The Geographical journal》2007,173(4):395-396

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Soil moisture variability and scale-dependency of nonlinear parameterizations in coupled land–atmosphere models     

Deborah K. Nykanen  Efi Foufoula-Georgiou 《Advances in water resources》2001,24(9-10)

Many of the relationships used in coupled land–atmosphere models to describe interactions between the land surface and the atmosphere have been empirically parameterized and thus are inherently dependent on the observational scale for which they were derived and tested. However, they are often applied at scales quite different than the ones they were intended for due to practical necessity. In this paper, a study is presented on the scale-dependency of parameterizations which are nonlinear functions of variables exhibiting considerable spatial variability across a wide range of scales. For illustration purposes, we focus on parameterizations which are explicit nonlinear functions of soil moisture. We use data from the 1997 Southern Great Plains Hydrology Experiment (SGP97) to quantify the spatial variability of soil moisture as a function of scale. By assuming that a parameterization keeps its general form the same over a range of scales, we quantify how the values of its parameters should change with scale in order to preserve the spatially averaged predicted fluxes at any scale of interest. The findings of this study illustrate that if modifications are not made to nonlinear parameterizations to account for the mismatch of scales between optimization and application, then significant systematic biases may result in model-predicted water and energy fluxes.  相似文献   

Impacts of afforestation on groundwater resources and quality   总被引：4，自引：0，他引：4  

Alistair Allen  Deborah Chapman 《Hydrogeology Journal》2001,9(4):390-400

Plans to double the proportion of land under forest cover in Ireland by the year 2035 have been initiated. The plan, primarily financially driven, ignores potential environmental impacts of forestry, particularly impacts on groundwater resources and quality. Since groundwater supplies almost 25% of Ireland's total potable water, these impacts are important. Field investigations indicate that afforestation leads to a reduction in runoff by as much as 20%, mainly due to interception of rainfall by forest canopies. Clearfelling has the opposite impact. Implications are that uncoordinated forestry practices can potentially exacerbate flooding. Groundwater recharge is affected by forestry, largely due to greater uptake of soil water by trees and to increased water-holding capacity of forest soils, arising from higher organic contents. Recharge rates under forests can be reduced to one tenth that under grass or heathland. Groundwater quality may be affected by enhanced acidification and nitrification under forests, due partly to scavenging of atmospheric pollutants by forest canopies, and partly to greater deposition of highly acid leaf litter. The slower recharge rates of groundwater under forests lead to significant delays in manifestation of deterioration in groundwater quality. Electronic Publication  相似文献   

Ti K-XANES in minerals and ceramics with composition CaZr3-xTixO7     

M. O. Figueiredo  A. Correia dos Santos 《Physics and Chemistry of Minerals》1996,23(4-5):229-229

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Neutron activation analysis of the 1965 taal volcanic ash     

G. P. Santos  R. E. Wainerdi 《Bulletin of Volcanology》1968,32(3):575-578

Neutron activation analysis of the Taal volcanic ash revealed the presence of unusual amount of scandium in the volcanic ash as compared to the standard basalt BCR-1. The BCR-1 value for Fe/Sc is 2760 while that of Taal ash is about 2649. It is suggested that the eruption was probably characterized by the ejection of scandium-rich materials. Scandium may be used as supplementary evidence in evaluating an impending future Taal volcanic activity.  相似文献   

Inflight Calibration of the NEAR Multispectral Imager: II. Results from Eros Approach and Orbit     

Scott MurchieMark Robinson  Deborah DomingueHan Li  Louise ProckterS.Edward Hawkins III  William OwenBeth Clark  Noam Izenberg 《Icarus》2002,155(1):229-243

During the Near-Earth Asteroid Rendezvous (NEAR) spacecraft's investigation of asteroid 433 Eros, inflight calibration measurements from the multispectral imager (MSI) have provided refined knowledge of the camera's radiometric performance, pointing, and light-scattering characteristics. Measurements while at Eros corroborate most earlier calibration results, although there appears to be a small, gradual change in instrument dark current and flat field due to effects of aging in the space environment. The most pronounced change in instrument behavior, however, is a dramatic increase in scattered light due to contaminants accumulated on the optics during unscheduled fuel usage in December 1998. Procedures to accurately quantify and to remediate the scattered light are described in a companion paper (Li et al. 2002, Icarus155, 00-00). Acquisition of Eros measurements has clarified the relative, filter-to-filter, radiometric performance of the MSI. Absolute radiometric calibration appears very well constrained from flight measurements, with an accuracy of ∼5%. Pointing relative to the spacecraft coordinate system can be determined from the temperature of the spacecraft deck with an accuracy of ∼1 pixel.  相似文献