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Wind Data (wind + data)
Selected AbstractsDetermination of Weibull parameters for wind energy analysis of ,zmir, TurkeyINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 6 2002K. Ulgen Abstract In this study, the two Weibull parameters of the wind speed distribution function, the shape parameter k (dimensionless) and the scale parameter c (ms,1), were computed from the wind speed data for ,zmir. Wind data, consisting of hourly wind speed records over a 5-year period, 1995,1999, were measured in the Solar/Wind-Meteorological Station of the Solar Energy Institute at Ege University. Based on the experimental data, it was found that the numerical values of both Weibull parameters (k and c) for ,zmir vary over a wide range. The yearly values of k range from 1.378 to 1.634 with a mean value of 1.552, while those of c are in the range of 2.956,3.444 with a mean value of 3.222. The average seasonal Weibull distributions for ,zmir are also given. The wind speed distributions are represented by Weibull distribution and also by Rayleigh distribution, with a special case of the Weibull distribution for k=2. As a result, the Weibull distribution is found to be suitable to represent the actual probability of wind speed data for ,zmir (at annual average wind speeds up to 3 ms,1). Copyright © 2002 John Wiley & Sons, Ltd. [source] Using wind to power a groundwater circulation well,preliminary resultsREMEDIATION, Issue 4 2004Andrew Curtis Elmore In areas of the country where the U.S. Department of Energy has classified the available wind resources as Class 3 or greater, the use of wind turbines to provide power to relatively small remediation systems such as groundwater circulation wells may be technically and economically feasible. Groundwater circulation wells are a good candidate technology to couple with renewable energy, because the remediation system removes contamination from the subject aquifer with no net loss of the groundwater resource, while the wind turbine does not create potentially harmful air emissions. Wind data collected in the vicinity of the former Nebraska Ordnance Plant Superfund site were used to select a wind turbine system to provide a portion of the energy necessary to power a groundwater circulation well located in an area of high trichloroethylene groundwater contamination. Because utility power was already installed at the remediation system, a 10 kW grid inter-tie wind turbine system supplements the utility system without requiring batteries for energy storage. The historical data from the site indicate that the quantity of energy purchased correlates poorly with the quantity of groundwater treated. Preliminary data from the wind turbine system indicate that the wind turbine provides more energy than the remediation system treatment components and the well submersible pump require on a monthly average. The preliminary results indicate that the coupling of wind turbines and groundwater circulation wells may be an attractive alternative in terms of the system operation time, cost savings, and contaminant mass removal. © 2004 Wiley Periodicals, Inc. [source] Backshore coarsening processes triggered by wave-induced sand transport: the critical role of storm events,EARTH SURFACE PROCESSES AND LANDFORMS, Issue 11 2010Keiko Udo Abstract Spatial backshore processes were investigated through field observations of topography and median sand grain size at a sandy beach facing the Pacific Ocean in Japan. A comparison of the backshore profile and cross-shore distribution of the median sand grain size in 1999 and 2004 revealed an unusual sedimentary process in which sand was coarsened in a depositional area in the 5-year period, although sediment is generally coarsened in erosional areas. In support of these observations, monthly spatial field analyses carried out in 2004 demonstrated a remarkable backshore coarsening process triggered by sedimentation in the seaward part of the backshore during a storm event. In order to elucidate mechanisms involved in the backshore coarsening process, thresholds of movable sand grain size under wave and wind actions (a uniform parameter for both these cases) in the onshore and offshore directions were estimated using wave, tide, and wind data. The cross-shore distributions of the estimated thresholds provided reasonable values and demonstrated a coarsening mechanism involving the intermediate zone around the shoreline under alternating wave and wind actions as a result of which coarse sand was transported toward the seaward part of the backshore by large waves during storms and then toward the landward part by strong onshore winds. The 5-year backshore coarsening is most certainly explained by repetition of short-term coarsening mechanisms caused by wave-induced sand transport occurring from the nearshore to the intermediate zone. Copyright © 2010 John Wiley & Sons, Ltd [source] Aeolian fetch distance and secondary airflow effects: the influence of micro-scale variables on meso-scale foredune developmentEARTH SURFACE PROCESSES AND LANDFORMS, Issue 7 2008Kevin Lynch Abstract Unsuccessful attempts to use process-scale models to predict long-term aeolian sediment transport patterns have long been a feature of aeolian research. It has been proposed that one approach to overcome these problems is to identify micro-scale variables that are important at longer timescales. This paper assesses the contribution of two system variables (secondary airflow patterns and fetch distance) to medium-term (months to years) dune development. The micro-scale importance of these variables had been established during previous work at the site (Magilligan Strand, Northern Ireland). Three methods were employed. First, sand drift potentials were calculated using 2 years of regional wind data and a sediment transport model. Second, wind data and large trench traps (2 m length × 1 m width × 1·5 m depth) were used to assess the actual sediment transport patterns over a 2-month period. Third, a remote-sensing technique for the identification of fetch distance, a saltation impact sensor (Safire) and wind data were utilized to gauge, qualitatively, sediment transport patterns over a 1-month period. Secondary airflow effects were found to play a major role in the sediment flux patterns at these timescales, with measured and predicted rates matching closely during the trench trap study. The results suggest that fetch distance is an unimportant variable at this site. Copyright © 2007 John Wiley & Sons, Ltd. [source] Variability of the recent climate of eastern AfricaINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 6 2004Carl J. Schreck III Abstract The primary objective of this study is to investigate the recent variability of the eastern African climate. The region of interest is also known as the Greater Horn of Africa (GHA), and comprises the countries of Burundi, Djibouti, Eritrea, Ethiopia, Kenya, Rwanda, Somalia, Sudan, Uganda, and Tanzania. The analysis was based primarily on the construction of empirical orthogonal functions (EOFs) of gauge rainfall data and on CPC Merged Analysis of Precipitation (CMAP) data, derived from a combination of rain-gauge observations and satellite estimates. The investigation is based on the period 1961,2001 for the ,short rains' season of eastern Africa of October through to December. The EOF analysis was supplemented by projection of National Centers for Environmental Prediction wind data onto the rainfall eigenmodes to understand the rainfall,circulation relationships. Furthermore, correlation and composite analyses have been performed with the Climatic Research Unit globally averaged surface-temperature time series to explore the potential relationship between the climate of eastern Africa and global warming. The most dominant mode of variability (EOF1) based on CMAP data over eastern Africa corresponds to El Niño,southern oscillation (ENSO) climate variability. It is associated with above-normal rainfall amounts during the short rains throughout the entire region, except for Sudan. The corresponding anomalous low-level circulation is dominated by easterly inflow from the Indian Ocean, and to a lesser extent the Congo tropical rain forest, into the positive rainfall anomaly region that extends across most of eastern Africa. The easterly inflow into eastern Africa is part of diffluent outflow from the maritime continent during the warm ENSO events. The second eastern African EOF (trend mode) is associated with decadal variability. In distinct contrast from the ENSO mode pattern, the trend mode is characterized by positive rainfall anomalies over the northern sector of eastern Africa and opposite conditions over the southern sector. This rainfall trend mode eluded detection in previous studies that did not include recent decades of data, because the signal was still relatively weak. The wind projection onto this mode indicates that the primary flow that feeds the positive anomaly region over the northern part of eastern Africa emanates primarily from the rainfall-deficient southern region of eastern Africa and Sudan. Although we do not assign attribution of the trend mode to global warming (in part because of the relatively short period of analysis), the evidence, based on our results and previous studies, strongly suggests a potential connection. Copyright © 2004 Royal Meteorological Society. [source] Climatology of near-surface wind patterns over SwitzerlandINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 7 2001Rudolf O. Weber Abstract Over complex, mountainous terrain the near-surface winds can form intricate patterns as large-scale winds and locally forced wind systems interplay. Switzerland, with its mountainous topography and dense meteorological network of 115 automated surface stations, ideally serves as a study area for such wind system interactions. Applying an automated classification scheme to the wind data of one single year (1995), 16 distinct near-surface flow patterns were found. These patterns also show characteristic distributions in magnitude and areal extent of temperature, global radiation and precipitation. An 18-year climatology of flow patterns was created with an identification method for fewer stations. This allowed the determination of annual and diurnal variations in the frequencies of occurrence of the different flow patterns, revealing pronounced daytime and night-time classes characterized by thermally forced winds. Transition probabilities between the flow patterns were computed as well. The relationship between the near-surface wind patterns and the synoptic flow situation was investigated with a comparison with synoptic weather types defined for the Alpine region. The results show clear but not unequivocal interdependencies between the synoptic weather type and the near-surface flow pattern. Copyright © 2001 Royal Meteorological Society [source] Characteristics of wind variations on Jeju Island, KoreaINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 1 2010Kyungnam Ko Abstract In order to clarify the long-term variability of the wind in complex terrain, an investigation was conducted on Jeju Island, Korea. The four coastal areas and the three mountainous areas were selected and wind data for 8,11 years from meteorological observatories were collected for this work. Inter-annual variations, monthly variations and diurnal variations in wind characteristics were calculated from the long-term wind data. As a result, it was found that wind speed is higher in the winter season while it is lower in the summer season. Wind at all sites blew strongly in the daytime and weakly at night. Also, wind energy and the range of variation in wind energy varied significantly from region to region on Jeju Island. Inter-annual variations in wind energy on Jeju Island occurred a little greater than seen in the results of earlier works conducted in other place. Copyright © 2009 John Wiley & Sons, Ltd. [source] Implications of seasonal and diurnal variations of wind velocity for power output estimation of a turbine: a case study of GrenadaINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2003D. Weisser Abstract This case study highlights the importance of taking into consideration diurnal variations of wind velocity for wind energy resources assessment. Previous studies of wind energy distribution that are based on the two-parameter Weibull density function have so far neglected to consider time of day fluctuations in wind speed, instead concentrating primarily on seasonal deviations. However, this has serious implications where such a wind energy model is the underpinning of calculations for the potential power production from a wind turbine and in particular where the timing of the energy output is essential to meet electricity loads. In the case of Grenada the energy output from a wind turbine during the day is approximately two times the output at night thereby fluctuating enormously around the seasonal mean distribution. When this is not taken into account the economic and technological viability of a wind turbine project may be overestimated or not even be identified. This work shows how a wind energy resources assessment based on the Weibull distribution model can be done and how the power output of a horizontal axis turbine is calculated. An analysis of the recorded wind data confirms the application of the Weibull density function as a suitable tool for modelling wind regimes. Copyright © 2003 John Wiley & Sons, Ltd. [source] Loop migration in adult marsh harriers Circus aeruginosus, as revealed by satellite telemetryJOURNAL OF AVIAN BIOLOGY, Issue 2 2010Raymond H. G. Klaassen Loop migration among birds is characterized by the spring route lying consistently west or east of the autumn route. The existence of loops has been explained by general wind conditions or seasonal differences in habitat distribution. Loop migration has predominantly been studied at the population level, for example by analysing ring recoveries. Here we study loop migration of individual marsh harriers Circus aeruginosus tracked by satellite telemetry. We show that despite a generally narrow migration corridor the harriers travelled in a distinct clockwise loop through Africa and southern Europe, following more westerly routes in spring than in autumn. We used the Normalized Difference Vegetation Index (NDVI) to identify potential feeding habitat in Africa. Suitable habitat seemed always more abundant along the western route, both in spring and autumn, and no important stopover site was found along the eastern route. Observed routes did thus not coincide with seasonal variation in habitat availability. However, favourable habitat might be more important during spring migration, when the crossing of the Sahara seems more challenging, and thus habitat availability might play an indirect role in the harriers' route choice. Grid-based wind data were used to reconstruct general wind patterns, and in qualitative agreement with the observed loop marsh harriers predominantly encountered westerly winds in Europe and easterly winds in Africa, both in autumn and in spring. By correlating tail- and crosswinds with forward and perpendicular movement rates, respectively, we show that marsh harriers are partially drifted by wind. Thus, we tentatively conclude that wind rather than habitat seems to have an overriding effect on the shape of the migration routes of marsh harriers. General wind conditions seem to play an important role also in the evolution of narrow migratory loops as demonstrated for individual marsh harriers. [source] Numerical simulation of particle trajectory and atmospheric dispersion of airborne releasesMETEOROLOGICAL APPLICATIONS, Issue 3 2009S. Shoaib Raza Abstract Numerical simulation of particle trajectory and atmospheric dispersion has been performed for an airborne accidental release from a nuclear power plant site. A Long-range Particle transport and Dispersion Model (LPDM) based on a Lagrangian approach is developed and tested in this work. The Lagrangian transport/dispersion model is directly coupled with an atmospheric prediction model, RAMS (Regional Atmospheric Modeling System), to provide necessary meteorological fields in a three-dimensional domain. An advantage of this direct coupling is that the meteorological data generated by RAMS can be used directly for trajectory calculations without storage, thus reducing the CPU time consumed in the data storage and retrieval. This effort was done to be able to use this directly coupled modelling system for real-time predictions in case of an accidental release from a potential site. The simulated Lagrangian trajectories were compared with those obtained using observed hourly weather data obtained from an on-site meteorological tower. The results indicated that this one-way coupling between LPDM-RAMS provided almost identical trajectories when compared with those obtained using LPDM alone driven by hourly observed wind data. The comparison demonstrated the reliability of the RAMS meteorological predictions for the site under consideration. The comparison also indicated that LPDM (run in a stand alone mode), with hourly-observed wind data, could also be used for trajectory calculations over flat terrain. The model was developed on a parallel processing computer (SGI workstation, ORIGIN 2000 computer with eight processors) for use in real-time forecast mode. The computational time was about one-third of the simulation time, while using four processors. The model options need to be explored to reduce the computational time further and test its performance for real-time atmospheric dispersion applications. Copyright © 2009 Royal Meteorological Society [source] Quasi-periodic bora gusts related to the structure of the troposphereTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 598 2004Danijel Belu Abstract This study provides a new insight into the behaviour of the bora wind gusts. Wind speed and direction measured with a 1 s sampling interval between 1 December 2001 and 31 January 2002 at Senj (east Adriatic) provided a sufficiently large database for a study of the gusts behaviour. The performed spectral analysis confirmed the occurrence of pulsations in the bora flow. Moreover, a new type of dynamics, involving the onset, cessation and reappearance of the pulsations within a single episode, has been observed in several cases. Suggested mechanisms responsible for generating these phenomena have been determined from comparisons of surface wind data with the upstream tropospheric thermodynamical structure derived from Zagreb radiosonde data. In particular, it has been shown that the appearance of an upper-tropospheric jet stream results in cessation of the pulsations, and the decrease in the jet stream supports quasi-periodic gust behaviour. As the pulsations are generated by wave breaking, the jet stream appearance has been related to the disappearance of the wave-breaking region in the lee of the mountain, which is in accordance with previous studies of downslope windstorms. Copyright © 2004 Royal Meteorological Society. [source] | ||||||||||