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Finer Resolution (finer + resolution)
Selected AbstractsThe relationships between local and regional species richness and spatial turnoverGLOBAL ECOLOGY, Issue 5 2002Patricia Koleff Abstract Aim To determine the empirical relationships between species richness and spatial turnover in species composition across spatial scales. These have remained little explored despite the fact that such relationships are fundamental to understanding spatial diversity patterns. Location South-east Scotland. Methods Defining local species richness simply as the total number of species at a finer resolution than regional species richness and spatial turnover as turnover in species identity between any two or more areas, we determined the empirical relationships between all three, and the influence of spatial scale upon them, using data on breeding bird distributions. We estimated spatial turnover using a measure independent of species richness gradients, a fundamental feature which has been neglected in theoretical studies. Results Local species richness and spatial turnover exhibited a negative relationship, which became stronger as larger neighbourhood sizes were considered in estimating the latter. Spatial turnover and regional species richness did not show any significant relationship, suggesting that spatial species replacement occurs independently of the size of the regional species pool. Local and regional species richness only showed the expected positive relationship when the size of the local scale was relatively large in relation to the regional scale. Conclusions Explanations for the relationships between spatial turnover and local and regional species richness can be found in the spatial patterns of species commonality, gain and loss between areas. [source] Performance analysis of different meteorological data and resolutions using MaScOD hydrological modelHYDROLOGICAL PROCESSES, Issue 16 2004Roshan Shrestha Abstract Distributed meteorological data collected from different sources are rarely identical within the same domain of space and time. Discrepancies of these data in magnitude, pattern, and resolution play an important role in hydrological simulation. Using four different sets of distributed meteorological data (from the HUBEX-Intense Observation Period and GAME experimental products at different resolutions), hydrological simulations are conducted through a distributed hydrological model called MaScOD (macro-scale OHyMoS assisted distributed) hydrological model. The model's performance is measured using 12 different indexes. Based on these indexes, a relative normalized score is calculated to evaluate the overall performance of the result from each data set. Three sub-basins of the Huaihe River basin in China, taking the cases at Bengbu (132 350 km2), Wangjiaba (29 844 km2) and Suiping (2093 km2), are used for numerical experiments. This study shows the competence of coarse-resolution meteorological data, the GAME reanalysis 1·25° data, to apply in hydrological simulations of large catchments. However, that data failed to simulate the hydrograph in smaller catchments. The results are significantly improved by including spatial variability at finer resolution in that data. Copyright © 2004 John Wiley & Sons, Ltd. [source] SENSITIVITY CONSIDERATIONS WHEN MODELING HYDROLOGIC PROCESSES WITH DIGITAL ELEVATION MODEL,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 4 2001Sung-Mm Cho ABSTRACT: The purpose of this paper is to investigate the sensitivity of a hydrologic models to the type of DEM used. This was done while modeling basin water quality with 1:24,000 and 1:250,000 U.S. Geological Survey DEMs as input to model hydrological processes. The manner in which the model results were sensitive to the choice of raster cell size (scale) is investigated in this study. The Broadhead watershed, located in New Jersey, USA, was chosen as a study area. Curve numbers were estimated by a trial and error to match simulated and observed total discharge. Monthly runoff for the watershed was used in the calibration process. Higher runoff volumes were simulated by the model when the 1:24,000 DEM were used as input data, probably due to the finer resolution which simulated increased average slope and hence higher estimated runoff from the watershed. As the simulated slope of the watershed is flatten with the 1:250,000 DEM, the response of stream flow was delayed and simulated less runoff volume. (KEY TERMS: DEM; curve number; sensitivity analysis; runoff volume; water quality; calibration.) [source] Impact of horizontal model resolution and orography on the simulation of a western disturbance and its associated precipitationMETEOROLOGICAL APPLICATIONS, Issue 2 2004A. P. Dimri A nonhydrostatic version of Pennsylvania State University/National Center for Atmospheric Research (PSU/NCAR) Mesoscale Model (MM5) is used to study the effects of the horizontal model resolution and orography while simulating an active western disturbance (WD) that affected northwest India from 21 to 25 January 1999. Two numerical experiments are conducted with six combinations of two factors: horizontal model resolution and topography. National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysed data are used for the initial and boundary conditions. Simulation results indicate that the distribution and the rate of simulated precipitation due to a WD over northwest India is highly sensitive to the horizontal model resolution and topography. The model with finer resolution (30 km) is better able to estimate effects of mesoscale forcing on precipitation over the selected domain. The amount of precipitation simulated over the coarse domain is much less than the observed precipitation owing to the model's unrealistic representation of orographic effects and mesoscale forcing. Simulated terrain, vertical velocity, wind and streamline at different horizontal model resolutions are presented. The detailed structure and distribution of wind speed are simulated in the finer domain. Simulated vertical velocity and precipitation are less in the second experiment when a flat topography is used across the domain, which indicates that topography plays a significant role in modulating the WD. Sensitivity of the horizontal model resolution for precipitation is assessed and it is found that the finer domain of the model simulation gives better results. Copyright © 2004 Royal Meteorological Society. [source] Trend analysis of Indian summer monsoon rainfall at different spatial scalesATMOSPHERIC SCIENCE LETTERS, Issue 4 2009Subimal Ghosh Abstract The results obtained from a conventional trend analysis of the Indian summer monsoon rainfall over a larger region are contradicted when analysis is performed at a finer resolution because of spatial variability and heterogeneity in the rainfall pattern. The present study analyzes the trend of summer monsoon rainfall all over India at a finer spatial resolution (1° latitude × 1° longitude) to identify the places that have a significant trend in terms of both rainfall amount and occurrence. The results obtained from this study are compared with those of a recent study by Goswami et al. (2006), where trend analysis is performed over a larger region [Central India (CI); 10° latitude × 12° longitude; assumed to be homogeneous in that study]. The increasing trend of occurrence of heavy rainfall and decreasing trend of occurrence of moderate rainfall, as concluded from that study, are contradicted by the present results for some places in CI. The present analysis shows spatially varying mixed responses of global warming toward rainfall occurrence and amounts all over India. The perception of increase in daily rainfall amount and occurrence due to climate change is found to be not correct for some of the regions in India. The possible reason may be the spatial variability of local changes such as rapid urbanization, industrialization and deforestation. Copyright © 2009 Royal Meteorological Society [source] | |||||||||||||