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11.

Glacial lake outburst floods (GLOFs) are among the most serious cryospheric hazards for mountain communities. Multiple studies have predicted the potential risks posed by rapidly expanding glacial lakes in the Sagarmatha (Mt. Everest) National Park and Buffer Zone of Nepal. People’s perceptions of such cryospheric hazards can influence their actions, beliefs, and responses to those hazards and associated risks. This study provides a systematic approach that combines household survey data with ethnography to analyze people’s perceptions of GLOF risks and the socioeconomic and cultural factors influencing their perceptions. A statistical logit model of household data showed a significant positive correlation between the perceptions of GLOF risks and livelihood sources, mainly tourism. Risk perceptions are also influenced by spatial proximity to glacial lakes and whether a village is in potential flood zones. The 2016 emergency remediation work implemented in the Imja Tsho (glacial lake) has served as a cognitive fix, especially in the low-lying settlements. Much of uncertainty and confusions related GLOF risks among locals can be attributed to a disconnect between how scientific information is communicated to the local communities and how government climate change policies have been limited to awareness campaigns and emergency remediation efforts. A sustainable partnership of scientists, policymakers, and local communities is urgently needed to build a science-driven, community-based initiative that focuses not just in addressing a single GLOF threat but develops on a comprehensive cryospheric risk management plan and considers opportunities and challenges of tourism in the local climate adaptation policies.

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12.
Ecosystem Modeling Adds Value to a South African Climate Forecast   总被引:2,自引:0,他引:2  
Livestock production in South Africa is limited by frequent droughts. The South African Weather Service produces climate forecasts estimating the probability of low rainfall three and six months into the future. We used the ecosystem model SAVANNA applied to five commercial farms in the Vryburg region of the North-West Province, and five communal areas within the Province, to assess the utility of a climate forecast in refining drought coping strategies. Rainfall data from 1970 to 1994 were modified to represent a drought (225 mm of rainfall) in 1977/1978, and used in simulations. In a simulation on an example commercial farm we assumed a forecast was available in 1977 portending an upcoming drought, and that the owner sold 490 cattle and 70 sheep prior to the drought. Over the simulation period, the owner sold 31% more cattle when the forecast was used,versus when the forecast was ignored. Populations of livestock on both commercial and communal farms recovered more quickly following the drought when owners sold animals in response to the forecast. The economic benefit from sales is being explored using optimization techniques. Results and responses from South African livestock producers suggest that a real-time farm model linked with climate forecasting would be a valuable management tool.  相似文献   
13.
The energy components of sixteen Soil-Vegetation Atmospheric Transfer (SVAT) schemes were analyzed and intercompared using 10 years of surface meteorological and radiative forcing data from the Red-Arkansas River basin in the Southern Great Plains of the United States. Comparisons of simulated surface energy fluxes among models showed that the net radiation and surface temperature generally had the best agreement among the schemes. On an average (annual and monthly) basis, the estimated latent heat fluxes agreed (to within approximate estimation errors) with the latent heat fluxes derived from a radiosonde-based atmospheric budget method for slightly more than half of the schemes. The sensible heat fluxes had larger differences among the schemes than did the latent heat fluxes, and the model-simulated ground heat fluxes had large variations among the schemes. The spatial patterns of the model-computed net radiation and surface temperature were generally similar among the schemes, and appear reasonable and consistent with observations of related variables, such as surface air temperature. The spatial mean patterns of latent and sensible heat fluxes were less similar than for net radiation, and the spatial patterns of the ground heat flux vary greatly among the 16 schemes. Generally, there is less similarity among the models in the temporal (interannual) variability of surface fluxes and temperature than there is in the mean fields, even for schemes with similar mean fields.  相似文献   
14.
Fragmentation of the ecosystems of the earth into spatially isolated units has emerged as a primary component of global change. Often, fragmentation results from actions that are intended to enhance human livelihoods and well-being; however, there are often costs to ecosystems and human economies that are not considered. We describe the three general categories of processes causing fragmentation of rangelands worldwide: dissection, decoupling, and compression. We show that access to heterogeneity of landscapes is an important attribute of grazing ecosystems worldwide, and that fragmentation of these systems, even when it proceeds in the absence of habitat loss, can limit options of people and animals, options that are particularly important in temporally heterogeneous environments. We discuss the consequences of fragmentation for people, livestock, wildlife, and landscapes and describe potential adaptations that can mitigate its harmful outcomes. We close by reviewing policy options that promote re-aggregation of landscapes and adaptation to fragmentation.  相似文献   
15.
 Using atmospheric forcing data generated from a general circulation climate model, sixteen land surface schemes participating in the Project for the Intercomparison of Land-surface Parametrization Schemes (PILPS) were run off-line to equilibrium using forcing data from a GCM representative of a tropical forest and a mid-latitude grassland grid point. The values for each land surface parameter (roughness length, minimum stomatal resistance, soil depth etc.) were provided. Results were quality controlled and analyzed, focusing on the scatter simulated amongst the models. There were large differences in how the models’ partitioned available energy between sensible and latent heat. Annually averaged, simulations for the tropical forest ranged by 79 1 3;W m-2 for the sensible heat flux and 80 W m-2 for the latent heat flux. For the grassland, simulations ranged by 34 W m-2 for the sensible heat flux and 27 W m-2 for the latent heat flux. Similarly large differences were found for simulated runoff and soil moisture and at the monthly time scale. The models’ simulation of annually averaged effective radiative temperature varied with a range, between all the models, of 1.4 K for tropical forest and 2.2 K for the grassland. The simulation of latent and sensible heat fluxes by a standard ‘bucket’ models was anomalous although this could be corrected by an additional resistance term. These results imply that the current land surface models do not agree on the land surface climate when the atmospheric forcing and surface parameters are prescribed. The nature of the experimental design, it being offline and with artificial forcing, generally precludes judgements concerning the relative quality of any specific model. Although these results were produced de-coupled from a host model, they do cast doubt on the reliability of land surface schemes. It is therefore a priority to resolve the disparity in the simulations, understand the reasons behind the scatter and to determine whether this lack of agreement in de-coupled tests is reproduced in coupled experiments. Received: 15 October 1997 / Accepted: 22 April 1999  相似文献   
16.
Permafrost and fire are important regulators of hydrochemistry and landscape structure in the discontinuous permafrost region of interior Alaska. We examined the influence of permafrost and a prescribed burn on concentrations of dissolved organic carbon (DOC), dissolved organic nitrogen (DON) and other solutes ( , Ca2+, K+, Mg2+, Na+) in streams of an experimentally burned watershed and two reference watersheds with varying extents of permafrost in the Caribou–Poker Creeks Research Watershed in interior Alaska. The low‐permafrost watershed has limited permafrost (3%), the high‐permafrost watershed has extensive permafrost (53%), and the burn watershed has intermediate permafrost coverage (18%). A three end‐member mixing model revealed fundamental hydrologic and chemical differences between watersheds due to the presence of permafrost. Stormflow in the low‐permafrost watershed was dominated by precipitation and overland flow, whereas the high‐permafrost watershed was dominated by flow through the active layer. In all watersheds, organic and groundwater flow paths controlled stream chemistry: DOC and DON increased with discharge (organic source) and base cations and (from weathering processes) decreased. Thawing of the active layer increased soil water storage in the high‐permafrost watershed from July to September, and attenuated the hydrologic response and solute flux to the stream. The FROSTFIRE prescribed burn, initiated on 8 July 1999, elevated nitrate concentrations for a short period after the first post‐fire storm on 25 July, but there was no increase after a second storm in September. During the July storm, nitrate export lagged behind the storm discharge peak, indicating a flushing of soluble nitrate that likely originated from burned soils. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
17.
Rapid urbanization of the Phoenix Metropolitan Area exemplifies the dominant US Southwest urban growth pattern of the past six decades. Using a combination of multitemporal land cover data, gradient analysis, and landscape metrics, we quantify and characterize spatiotemporal patterns of land fragmentation observed in Phoenix. We analyze historical, qualitative data to identify five major socio-ecological drivers critical to understanding the urbanization processes and fragmentation patterns: population dynamics, water provisioning, technology and transportation, institutional factors, and topography. A second objective is to assess the applicability and accuracy of National Land cover Database (NLCD)-—a widely used land cover dataset—-to detect and measure urban growth and land fragmentation patterns in the relatively treeless desert biome of the US Southwest. In contrast to studies in the temperate eastern USA where NLCD has proved inaccurate for detection of exurban development, our study demonstrates that NLCD is a reliable data source for measuring land use in the southwest, even in low-density environments. By combining qualitative analyses of social-ecological drivers with fragmentation analyses, we move toward an improved understanding of urbanization and insights on the human modification framework used widely in land change science.  相似文献   
18.
ABSTRACT

The communication of data uncertainty is a crucial problem in data science, information visualization, and geographic information science (GIScience). Effective ways to communicate the uncertainty of data enables data consumers to interpret the data as intended by the producer, reducing the possibilities of misinterpretation. In this article, we report on an empirical investigation of how sound can be used to convey information about data uncertainty in an intuitive way. To answer the research question How intuitive are sound dimensions to communicate uncertainty? we carry out a cognitive experiment, where participants were asked to interpret the certainty/uncertainty level in two sounds A and B (= 33). We produce sound stimuli by varying sound dimensions, including loudness, duration, location, pitch, register, attack, decay, rate of change, noise, timbre, clarity, order, and harmony. In the stimuli, both synthetic and natural sounds are used to allow comparison. The experiment results identify three sound dimensions (loudness, order, and clarity) as significantly more intuitive to communicate uncertainty, providing guidelines for sonification and information visualization practitioners.  相似文献   
19.

Background

A large proportion of the world’s tropical peatlands occur in Indonesia where rapid conversion and associated losses of carbon, biodiversity and ecosystem services have brought peatland management to the forefront of Indonesia’s climate mitigation efforts. We evaluated peat volume from two commonly referenced maps of peat distribution and depth published by Wetlands International (WI) and the Indonesian Ministry of Agriculture (MoA), and used regionally specific values of carbon density to calculate carbon stocks.

Results

Peatland extent and volume published in the MoA maps are lower than those in the WI maps, resulting in lower estimates of carbon storage. We estimate Indonesia’s total peat carbon store to be within 13.6 GtC (the low MoA map estimate) and 40.5 GtC (the high WI map estimate) with a best estimate of 28.1 GtC: the midpoint of medium carbon stock estimates derived from WI (30.8 GtC) and MoA (25.3 GtC) maps. This estimate is about half of previous assessments which used an assumed average value of peat thickness for all Indonesian peatlands, and revises the current global tropical peat carbon pool to 75 GtC. Yet, these results do not diminish the significance of Indonesia’s peatlands, which store an estimated 30% more carbon than the biomass of all Indonesian forests. The largest discrepancy between maps is for the Papua province, which accounts for 62–71% of the overall differences in peat area, volume and carbon storage. According to the MoA map, 80% of Indonesian peatlands are <300 cm thick and thus vulnerable to conversion outside of protected areas according to environmental regulations. The carbon contained in these shallower peatlands is conservatively estimated to be 10.6 GtC, equivalent to 42% of Indonesia’s total peat carbon and about 12 years of global emissions from land use change at current rates.

Conclusions

Considering the high uncertainties in peatland extent, volume and carbon storage revealed in this assessment of current maps, a systematic revision of Indonesia’s peat maps to produce a single geospatial reference that is universally accepted would improve national peat carbon storage estimates and greatly benefit carbon cycle research, land use management and spatial planning.
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20.
—We analyze source parameters of microseismic events (M < ? 1) associated with high flow-rate water injections in a shale formation at a depth of 220 m. Two types of events were observed several hundred impulsive events with clear P- and S-wave arrivals, and continuous emissions with peaked spectra detected well into the experiment. For a representative collection of impulsive events, an ?2 model provided satisfactory fits to displacement spectra corrected for attenuation, and average quality factors of 34 and 15 were obtained for P and S waves. P-wave first motion analysis and E S ?/E P ratios indicated the existence of a non-double-couple component in some events, particularly early in the experiment. A clear difference was observed for estimates of stress release parameters as non-double-couple events had smaller stress drops and apparent stresses. The seismic efficiency of double-couple and non-double-couple events was limited to 0.9% and 0.05% respectively, with average values being 0.25% and 0.02%. A comparison of our results with those reported for a similar magnitude range in a hard-rock formation indicates considerably smaller estimates of stress drop and apparent stress in our case while seismic efficiencies are comparable.  相似文献   
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