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Literatura académica sobre el tema "Wind profilers"

Autor: Grafiati

Publicado: 25 de mayo de 2024

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Artículos de revistas sobre el tema "Wind profilers"

Hartten, Leslie M., Paul E. Johnston, Valerie M. Rodríguez Castro, and Paola S. Esteban Pérez. "Postdeployment Calibration of a Tropical UHF Profiling Radar via Surface- and Satellite-Based Methods." Journal of Atmospheric and Oceanic Technology 36, no. 9 (2019): 1729–51. http://dx.doi.org/10.1175/jtech-d-18-0020.1.

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Wind profiling radars are usually not calibrated with respect to reflectivity because such calibrations are both unnecessary for good wind measurements and costly. However, reflectivity from calibrated profilers can reveal many atmospheric attributes beyond winds. Establishing ways to calibrate these radars even after they have been taken out of service would expand the utility of archived profiler data. We have calibrated one operating mode of a 915-MHz profiler deployed at Manus, Papua New Guinea (1992–2001), using two methods. The first method adjusts a radar parameter until the profiler’s estimate of rainfall during stratiform events closely matches surface observations. The second adjusts the parameter so that mean brightband heights observed by the profiler (July 1992–August 1994) match the mean brightband reflectivities over the profiler as observed by the TRMM Precipitation Radar (January 1998–July 2001). The results differ by about 5% and yield very similar precipitation errors during tested stratiform events. One or both of these methods could be used on many other wind profilers, whether they have been decommissioned or are currently operational. Data from such calibrated profilers will enable research employing the equivalent reflectivity factor observed by profilers to be compared with that from other radars, and will also enable turbulent studies with C n2.

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Monna, W. A. A. "On the use of wind profilers in meteorology." Annales Geophysicae 12, no. 6 (1994): 482–86. http://dx.doi.org/10.1007/s00585-994-0482-9.

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Abstract. As an introduction to this special issue of Annales Geophysicae a review is given of the applicability and performance of wind profilers. In meteorology, wind profilers play an increasingly important role. They can provide upper-wind measurements with an accuracy comparable to radiosonde data, but with a significantly higher temporal resolution. Height coverage and vertical resolution depend on the operating frequency, which, depending on the application, is usually chosen to be around 50, 400 or 1000 MHz. Measurements from stand-alone profilers in sparse data areas as well as data from wind profiler networks - which have increased the spatial resolution of an existing radiosonde network - have shown a positive impact on numerical weather forecasting. Information from nearby profilers can help the individual meterologist to optimize local short-term weather forecasts. In atmospheric research, wind profilers have been used for various boundary layer studies. In several mesoscale monitoring experiments wind profilers have played an important role. In Europe the development and implementation of wind profiler networks have been supported since 1987 by the CEC-sponsored COST-74 project. A follow-up project will probably start in 1994. Several topics deserve attention. A further assessment of the quality of wind profiler measurements is important. Automatic quality control procedures should be refined. Improved data assimilation techniques in numerical models will enable a better use of the high temporal resolution of wind profiler data. For a cost-effective development and use of wind profilers, the realization of frequency allocations, as globally harmonized as possible, is essential. Finally, the integration of wind profilers with other complementary measuring techniques is important.

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Barth, M. F., R. B. Chadwick, and D. W. van de Kamp. "Data processing algorithms used by NOAA's wind profiler demonstration network." Annales Geophysicae 12, no. 6 (1994): 518–28. http://dx.doi.org/10.1007/s00585-994-0518-1.

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Abstract. The National Oceanic and Atmospheric Administration's (NOAA) Wind Profiler Demonstration Network consists of 32 wind profiling radars, based primarily in the central United States. The network is being used to determine the operational feasibility and characteristics of a possible future nationwide profiler network. Data processing is performed both at the individual profiler sites and at a central hub processing system. This paper documents the algorithms used at the profilers to produce profiles of the moments of the velocity spectrum every 6 minutes, as well as those used on the hub to produce quality-controlled hourly winds.

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Chen, Zhao-Yu, Yen-Hsyang Chu, and Ching-Lun Su. "Intercomparisons of Tropospheric Wind Velocities Measured by Multi-Frequency Wind Profilers and Rawinsonde." Atmosphere 12, no. 10 (2021): 1284. http://dx.doi.org/10.3390/atmos12101284.

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Concurrent measurements of three-dimensional wind velocities made with three co-located wind profilers operated at frequencies of 52 MHz, 449 MHz, and 1.29 GHz for the period 12–16 September 2017 are compared for the first time in this study. The velocity–azimuth display (VAD) method is employed to estimate the wind velocities. The result shows that, in the absence of precipitation, the root mean square difference (RMSD) in the horizontal wind speed velocities U and wind directions D between different pairs of wind profilers are, respectively, in the range of 0.94–0.99 ms−1 and 7.7–8.3°, and those of zonal wind component u and meridional wind component v are in the respective ranges of 0.91–1.02 ms−1 and 1.1–1.24 ms−1. However, the RMSDs between wind profilers and rawinsonde are in the range of 2.89–3.26 ms−1 for horizontal wind speed velocity and 11.17–14.48° for the wind direction, which are around 2–3 factors greater than those between the wind profilers on average. In addition to the RMSDs, MDs between wind profilers and radiosonde are around one order of magnitude larger than those between wind profilers. These results show that the RMSDs, MDs, and Stdds between radars are highly consistent with each other, and they are much smaller than those between radar and rawinsonde. This therefore suggests that the wind profiler-measured horizontal wind velocities are much more reliable, precise, and accurate than the rawinsonde measurement.

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Schafer, Robert, Susan K. Avery, Kenneth S. Gage, and George N. Kiladis. "Wind Profiler Observations over the Central Equatorial Pacific: Optimizing Processing to Improve Quality and Height Coverage." Journal of Atmospheric and Oceanic Technology 24, no. 10 (2007): 1710–25. http://dx.doi.org/10.1175/jtech2072.1.

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Abstract UHF (boundary layer) and VHF (troposphere–stratosphere) wind profilers have operated at Christmas Island (2°N, 157°W) in the central equatorial Pacific from 1986 to 2002. Observed profiles of winds are sparse over the tropical oceans, but these are critical for understanding convective organization and the interaction of convection and waves. While the zonal winds below about 10 km have previously shown good agreement with the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis (RI), significant differences were found above a height of 10 km that were attributed to the low detectability of the wind signal in the profiler observations. Meridional winds at all levels show less agreement, with differences attributed to errors of representativeness and the sparseness of observations in the region. This paper builds on previous work using the Christmas Island wind profilers and presents the results of reprocessing the 17-yr profiler record with techniques that enhance the detectability of the signal at upper heights. The results are compared with nearby rawinsonde soundings obtained during a special campaign at Christmas Island and the RI, NCEP–Department of Energy (DOE) reanalysis (RII), and the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40). The newly processed profiler zonal and meridional wind observations show good agreement with rawinsonde observations from 0.5 to 19 km above sea level, with difference statistics similar to other studies. There is also significant improvement in the agreement of RI and RII reanalysis and profiler upper-level zonal and meridional winds from previous studies. A comparison of RII and ERA-40 reanalysis shows that difference statistics between the reanalyses are similar in magnitude to differences between the profiler and the individual reanalyses.

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Wang, Cheng, Min Chen, and Yaodeng Chen. "Impact of Combined Assimilation of Wind Profiler and Doppler Radar Data on a Convective-Scale Cycling Forecasting System." Monthly Weather Review 150, no. 2 (2022): 431–50. http://dx.doi.org/10.1175/mwr-d-20-0383.1.

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Abstract The two types of wind observations, profiler and radar radial velocity, have been successfully assimilated into numerical weather prediction (NWP) systems. However, the added value of profiler data, especially from a densely deployed profiler network, is unknown when assimilated together with Doppler radar radial velocity. In this article, two combined assimilation strategies of profilers along with radar radial winds are compared within a convective-scale data assimilation (DA) framework. In strategy I, the profiler data are assimilated with conventional observations to generate an intermediate analysis that acts as a prior for radar data assimilation. In strategy II, both profiler and radar data are considered as storm-scale and assimilated within the same pass. Single- and dual-observation assimilation experiments indicate that for strategy I, the profiler DA improvement can be partly canceled by the potentially negative impact of the assimilation of single-radar radial velocity afterward, particularly when the radial wind is nearly orthogonal to the prevailing wind. For strategy II, important complements are provided when profilers are assimilated within the same pass along with radial winds. The diagnostics for a low-level jet case demonstrate that both strategies facilitate improved analyses and forecasts. But strategy II may bring more moderate analysis increments, which indicate mutual constraints of the profiler and radial winds when assimilated within the same pass. The results obtained in 1-month, retrospective cycling experiments also show that the strategy II outperforms the strategy I with slightly better wind and precipitation forecasts. Significance Statement Due to the high spatial–temporal wind information provided by profiler and radar radial velocity measurements, their combined assimilation would be expected to improve wind analysis. To fully utilize dense profiler data and radar radial wind in future operational applications, this study proposes a suitable assimilation strategy. If the profilers are defined as synoptic-scale observations, the profiler and Doppler radar data must be assimilated in different passes to adopt different length and variance scales. Whereas it is more reasonable to use a small background correlation length consistent with the radial velocity and, therefore, assimilate in the same pass if the profiler data are considered to better sample storm-scale features. Single- and dual-observation experiments indicate that profiler data provide important complements, while the assimilation of single-radar radial wind may yield analyzed wind results that do not depict the ground truth. A low-level jet case and a 1-month impact study further show that the combined assimilation strategy of assimilating both profiler and Doppler radar using smaller background correlation lengths enhances the analysis and forecasting of wind, resulting in more accurate accumulated precipitation forecasts.

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Adachi, Ahoro, Takahisa Kobayashi, Kenneth S. Gage, et al. "Evaluation of Three-Beam and Four-Beam Profiler Wind Measurement Techniques Using a Five-Beam Wind Profiler and Collocated Meteorological Tower." Journal of Atmospheric and Oceanic Technology 22, no. 8 (2005): 1167–80. http://dx.doi.org/10.1175/jtech1777.1.

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Abstract In this paper a five-beam wind profiler and a collocated meteorological tower are used to estimate the accuracy of four-beam and three-beam wind profiler techniques in measuring horizontal components of the wind. In the traditional three-beam technique, the horizontal components of wind are derived from two orthogonal oblique beams and the vertical beam. In the less used four-beam method, the horizontal winds are found from the radial velocities measured with two orthogonal sets of opposing coplanar beams. In this paper the observations derived from the two wind profiler techniques are compared with the tower measurements using data averaged over 30 min. Results show that, while the winds measured using both methods are in overall agreement with the tower measurements, some of the horizontal components of the three-beam-derived winds are clearly spurious when compared with the tower-measured winds or the winds derived from the four oblique beams. These outliers are partially responsible for a larger 30-min, three-beam standard deviation of the profiler/tower wind speed differences (2.2 m s−1), as opposed to that from the four-beam method (1.2 m s−1). It was also found that many of these outliers were associated with periods of transition between clear air and rain, suggesting that the three-beam technique is more sensitive to small-scale variability in the vertical Doppler velocity because of its reliance on the point measurement from the vertical beam, while the four-beam method is surprisingly robust. Even after the removal of the rain data, the standard deviation of the wind speed error from the three-beam method (1.5 m s−1) is still much larger than that from the four-beam method. Taken together, these results suggest that the spatial variability of the vertical airflow in nonrainy periods or hydrometeor fall velocities in rainy periods makes the vertical beam velocities significantly less representative over the area across the three beams, and decreases the precision of the three-beam method. It is concluded that profilers utilizing the four-beam wind profiler technique have better reliability than wind profilers that rely on the three-beam wind profiler technique.

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St-James, Judy S., and Stéphane Laroche. "Assimilation of Wind Profiler Data in the Canadian Meteorological Centre’s Analysis Systems." Journal of Atmospheric and Oceanic Technology 22, no. 8 (2005): 1181–94. http://dx.doi.org/10.1175/jtech1765.1.

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Abstract Real-time horizontal wind observations from the National Oceanic and Atmospheric Administration’s (NOAA’s) Profiler Network (NPN) are assessed in preparation for their assimilation in the Canadian Meteorological Centre (CMC) analysis systems. As a first step, radiosonde winds from 20 stations were compared to the central U.S. profiler stations over the 2001/02 winter season. It was found that profilers are at least as good as conventional radiosonde data. The 2001/02 winter season data were also used to examine the vertical correlation structure of the observation error for profilers. Using a statistical analysis of innovations, the observation error standard deviation of the wind components is estimated as 2.2 m s−1 and the vertical correlation length is approximately 500 m. These results suggest that the data are vertically correlated because they are available every 250 m. Therefore, a thinning process is proposed in which one out of three data are selected in the vertical for each station. Since January 2004, a close monitoring of NPN profiler data revealed significant errors at some stations in the lower and upper troposphere. Consequently, a monthly blacklist of NPN profilers is built based on data from the previous month. A data impact study with both the three-dimensional variational data assimilation (3DVAR) and four-dimensional variational data assimilation (4DVAR) analysis systems was conducted using data from the 2003/04 winter season in which the vertical thinning was tested. It was found that the vertical thinning improves slightly the 6-h forecast error, especially in the 4DVAR over the central United States in which 6 times more profilers are assimilated. The impact of the vertical thinning is found to be neutral in the 3DVAR. Also, the impact of profiler data is significant over the central U.S. domain compared to a control run with the only difference being the addition of profiler data. These results were sufficiently good to implement NPN profilers in both the CMC global and regional analysis systems with the thinning process in fall of 2004.

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Goodrich, Robert K., Corrinne S. Morse, Larry B. Cornman, and Stephen A. Cohn. "A Horizontal Wind and Wind Confidence Algorithm for Doppler Wind Profilers." Journal of Atmospheric and Oceanic Technology 19, no. 3 (2002): 257–73. http://dx.doi.org/10.1175/1520-0426-19.3.257.

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Abstract Boundary layer wind profilers are increasingly being used in applications that require high-quality, rapidly updated winds. An example of this type of application is an airport wind hazard warning system. Wind shear can be a hazard to flight operations and is also associated with the production of turbulence. A method for calculating wind and wind shear using a linear wind field assumption is presented. This method, applied to four- or five-beam profilers, allows for the explicit accounting of the measurable shear terms. An error analysis demonstrates why some shears are more readily estimated than others, and the expected magnitudes of the variance for the wind and wind shear estimates are given. A method for computing a quality control index, or confidence, for the calculated wind is also presented. This confidence calculation is based on an assessment of the validity of the assumptions made in the calculations. Confidence values can be used as a quality control metric for the calculated wind and can also be used in generating a confidence-weighted average wind value from the rapid update values. Results are presented that show that errors in the wind estimates are reduced after removing values with low confidence. The wind and confidence methods are implemented in the NCAR Wind and Confidence Algorithm (NWCA), and have been used with the NCAR Improved Moments Algorithm (NIMA) method for calculating moments and associated moment confidence from Doppler spectra. However, NWCA may be used with any moment algorithm that also computes a first moment confidence. For example, a very simple confidence algorithm can be defined in terms of the signal-to-noise ratio.

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Baray, Jean-Luc, Yves Pointin, Joël Van Baelen, et al. "Case Study and Climatological Analysis of Upper-Tropospheric Jet Stream and Stratosphere–Troposphere Exchanges Using VHF Profilers and Radionuclide Measurements in France." Journal of Applied Meteorology and Climatology 56, no. 11 (2017): 3081–97. http://dx.doi.org/10.1175/jamc-d-16-0353.1.

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AbstractThe authors present a climatological analysis of tropospheric horizontal wind profiles and jet stream events using long series of wind profiles from two VHF profilers located in France: Lannemezan (2001–14) and Opme (1999–2014). A case study of jet stream and stratospheric intrusion of air into the troposphere that occurred in January 2013 is first described and demonstrates the capability of the VHF profilers to detect jet stream events. The climatology study over the two sites reveals the strongest values of seasonal wind during winter (21.4 m s−1 at 8.7-km height at Opme; 25.1 m s−1 at 9.6-km height at Lannemezan). A methodology based on the automatic detection of maximum winds on a decadal series of hourly wind profiles allows the detection of jet stream events and establishes its climatology for each site. A frequency analysis of jet stream events of westerly winds over 50 m s−1 presents a clear seasonality at the two sites, with a maximum in winter (3.5%–9.7% of hourly profiles) and a minimum in summer (near 1%). Cosmogenic radionuclides sampled at Opme also exhibit a clear seasonal variation with maximum in spring and minimum in the cold seasons; the 7Be/22Na activity ratio confirms stratosphere-to-troposphere exchanges for the studied cases. The mean interannual variability of the frequency of jet stream events is 1.5% in Opme and 2.9% in Lannemezan. Positive decadal trends are observed for the two sites: +1.6 ± 1.2% decade−1 for Opme and +2.4 ± 2.2% decade−1 for Lannemezan.

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Tesis sobre el tema "Wind profilers"

Lee, Christopher Francis. "Use of wind profilers to quantify atmospheric turbulence." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/use-of-wind-profilers-to-quantify-atmospheric-turbulence(d6a12ed2-533a-4dae-9f0d-747bc0b4c725).html.

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Doppler radar wind profilers are already widely used to measure atmospheric winds throughout the free troposphere and stratosphere. Several methods have been developed to quantify atmospheric turbulence with such radars, but to date they have remained largely un-tested; this thesis presents the first comprehensive validation of one such method. Conventional in-situ measurements of turbulence have been concentrated in the surface layer, with some aircraft and balloon platforms measuring at higher altitudes on a case study basis. Radars offer the opportunity to measure turbulence near continuously, and at a range of altitudes, to provide the first long term observations of atmospheric turbulence above the surface layer. Two radars were used in this study, a Mesosphere-Stratosphere-Troposphere (MST) radar, at Capel Dewi, West Wales, and the Facility for Ground Based Atmospheric Measurements (FGAM) mobile boundary layer profiler. In-situ measurements were made using aircraft and tethered-balloon borne turbulence probes. The spectral width method was chosen for detailed testing, which uses the width of a radar's Doppler spectrum as a measure of atmospheric velocity variance. Broader Doppler spectra indicate stronger turbulence. To obtain Gaussian Doppler spectra (a requirement of the spectral width method), combination of between five and seven consecutive spectra was required. Individual MST spectra were particularly non-Gaussian, because of the sparse nature of turbulence at its observation altitudes. The width of Gaussian fits to the Doppler spectrum were compared to those from the `raw' spectrum, to ensure that non-atmospheric signals were not measured. Corrections for non-turbulent broadening, such as beam broadening, and signal processing, were investigated. Shear broadening was found to be small, and the errors in its calculation large, so no corrections for wind shear were applied. Beam broadening was found to be the dominant broadening contribution, and also contributed the largest uncertainty to spectral widths. Corrected spectral widths were found to correlate with aircraft measurements for both radars. Observing spectral widths over time periods of 40 and 60 minutes for the boundary layer profiler and MST radar respectively, gave the best measure of turbulence intensity and variability. Median spectral widths gave the best average over that period, with two-sigma limits (where sigma is the standard deviation of spectral widths) giving the best representation of the variability in turbulence. Turbulent kinetic energies were derived from spectral widths; typical boundary layer values were 0.13 m 2.s (-2) with a two-sigma range of 0.04-0.25 m 2.s (-2), and peaked at 0.21 m 2.s (-2) with a two-sigma range of 0.08-0.61 m 2.s (-2). Turbulent kinetic energy dissipation rates were also calculated from spectral widths, requiring radiosonde measurements of atmospheric stability. Dissipation rates compared well width aircraft measurements, reaching peaks of 1x10 (-3) m 2.s (-3) within 200 m of the ground, and decreasing to 1-2x10 (-5) m 2.s (-3) near the boundary layer capping inversion. Typical boundary layer values were between 1-3x10 (-4) m 2.s (-3). Those values are in close agreement with dissipation rates from previous studies.

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Adachi, Ahoro. "An observational study of mesoscale phenomena with UHF wind profilers." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/136957.

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Renggono, Findy. "Study on precipitating clouds over Kototabang, west Sumatra observed by wind profilers." 京都大学 (Kyoto University), 2006. http://hdl.handle.net/2433/144127.

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Leblanc, Sylvain G. "Studies of turbulence with a wind profiler." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22755.

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In Doppler radar analysis of the atmosphere the spectrum width is rarely used but it contains information about turbulence. Turbulence is not the only effect that contributes to the broadening of the spectrum. Another effect is the cross-beam wind, which can be dominant in broad-beam radars such as wind profilers. Once this effect is removed, the so-called residual width then serves as an indication of turbulence. A large snowstorm is used in this study for the computation of the residual width. Strong wind and wind shear were observed during the storm. The time-height pattern of residual width bears a close resemblance to that of wind shear. This supports the interpretation of the residual width as being an indication of turbulence induced by wind shear. Energy dissipation rates are also estimated for the snowstorm. In some regions values as large as 800 cm$ rm sp2 s sp{-3}$ are observed. These are large, but within the range of what has been reported by others. The same techniques were applied to the study of clear-air turbulence to relate radar reflectivity with turbulence.

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Domps, Baptiste. "Identification et détection de phénomènes transitoires contenus dans des mesures radar à faible rapport signal à bruit : Applications conjointes aux problématiques océanographique et atmosphérique." Electronic Thesis or Diss., Toulon, 2021. http://www.theses.fr/2021TOUL0001.

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L'observation de la dynamique de l'atmosphère et de la surface de l'océan peut être réalisée par télédétection radar. L'approche habituelle consiste, dans les deux cas, à calculer numériquement le spectre Doppler des échos temporels reçus à l'aide d'une transformée de Fourier discrète. Bien que satisfaisante pour la plupart des applications, cette méthode ne convient pas pour l'observation de phénomènes transitoires, plus courts que le temps d'intégration nécessaire à l'observation radar. Nous utilisons une technique alternative, basée sur une représentation autorégressive des séries temporelles radar et associée à la méthode dite à entropie maximale. Cette approche est appliquée à la mesure de courants de surface par radar côtier dans la bande des hautes fréquences, puis à celle de vent dans la basse atmosphère par radar en bande L. Dans les deux situations, nous montrons à l'aide de simulations numériques, de comparaisons avec d'autres instruments et d'études de cas que l'approche proposée conduit à des estimations fiables des grandeurs géophysiques (courants marins et vitesses de vent) pour des temps d'intégration brefs, là où la méthode conventionnelle échoue<br>Observations of atmospheric and ocean surface dynamics can be performed via radar remote sensing. The usual approach consists, in both cases, in numerically calculating the Doppler spectrum of the received temporal echoes using a discrete Fourier transform. Although satisfactory for most applications, this method is not suitable for observations of transient phenomena due to being shorter than the integration time required for radar observations. We use an alternative technique based on an autoregressive representation of the radar time series combined with the maximum entropy method. This approach is applied to coastal radar measurements of surface currents in the high frequency band as well as to L-band radar measurements of wind in the lower atmosphere. For both cases, through numerical simulations and case studies, we compare our approach with others that use different instruments. We show that for short integration times, where conventional methods fail, our proposed approach leads to reliable estimates of geophysical quantities (ocean currents and wind speeds)

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Soler-Bientz, Rolando. "Evaluation of the wind patterns over the Yucatán Peninsula in México." Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/5988.

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Wind power is seen as one of the most effective means available to combat the twin crises of global climate change and energy security. The annual market growth has established wind power as the leading renewable energy technology. Due to the availability of sparsely populated and flat open terrain, the Yucatán Peninsula located in eastern México is a promising region from the perspective of wind energy development but no comprehensive assessment of wind resource has been previously published. A basic requirement when developing wind power projects is to study the main characteristic parameters of wind in relation to its geographical and temporal distribution. The analysis of diurnal and seasonal wind patterns are an important stage in the move towards commercial exploitation of wind power. The research developed during the PhD has comprehensively assessed the wind behaviour over the Yucatán Peninsula region covering long term patterns at three sites, a spatial study using short term data for nine sites, a vertical profile study on one inland site and an offshore study made on a pier at 6.65km from the North shore. Monthly trends, directional behaviours and frequency distributions were identified and discussed. The characteristics of the wind speed variation reflected their proximity to the coast and whether they were influenced by wind coming predominantly from over the land or predominantly from over the sea. The atmospheric stability over the eastern seas was also analysed to assess thermal effects for different wind directions. Diurnal wind speed variations are shown to be affected in particular by the differing wind conditions associated with fetches over two distinct offshore regions. Seasonal behaviour suggests some departure from the oscillations expected from temperature variation. The offshore wind is thermally driven suggesting largely unstable conditions and the potential development of a shallow Stable Internal Boundary Layer.

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Ritlop, Robert. "Toward the aerodynamic shape optimization of wind turbine profiles." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66672.

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This research presents automatic aerodynamic shape optimization results for the NREL S809 wind turbine profile. The objective of this re-design was to improve the total lift to drag ratio for steady low-Mach number flows. This research sets the groundwork for the development of a multidisciplinary optimization framework for complete wind turbine rotors. To develop the aerodynamic design framework for the wind turbine applications, low-Mach preconditioning and Menter's k-omega SST turbulence model have been implemented into the flow solver. A preconditioned discrete viscous adjoint-based automatic aerodynamic optimization method has been developed and validated. Various design case studies of the NREL Phase VI blade, at different free-stream Mach numbers, have been conducted.<br>Ce projet de recherche présente les résultats d'une méthode d'optimisation automatique de formes aérodynamiques, appliquée aux profils de l'éolienne NREL S809. L'objectif de cette reconception est d'améliorer le rapport portance sur traîné e dans le cas d'écoulements stationnaires à faible nombre de Mach. Ce projet de recherche définit les bases de travail pour le développement de méthodes et d'outils d'optimisation multidisciplinaire de rotors d'éolienne. Dans ce cadre de conception aérodynamique appliquée aux éoliennes, un préconditionneur pour faible nombre de Mach ainsi que le modèle de turbulence k-omega SST de Menter ont été implémentés dans le modèle numérique de simulation de mécanique des fluides. Une méthode adjointe discrète préconditionnée automatique d'optimisation aérodynamique pour les fluides visqueux a été développée et validée. Plusieurs études de cas de conception de la pale NREL Phase VI ont été effectuées pour différents Mach infini-amonts.

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Ignace, Richard, R. Bessey, and C. Price. "Modeling Forbidden Line Emission Profiles from Colliding Wind Binaries." Digital Commons @ East Tennessee State University, 2009. https://dc.etsu.edu/etsu-works/6266.

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This paper presents calculations for forbidden emission-line profile shapes arising from colliding wind binaries. The main application is for systems involving a Wolf–Rayet (WR) star and an OB star companion. The WR wind is assumed to dominate the forbidden line emission. The colliding wind interaction is treated as an Archimedean spiral with an inner boundary. Under the assumptions of the model, the major findings are as follows. (i) The redistribution of the WR wind as a result of the wind collision is not flux conservative but typically produces an excess of line emission; however, this excess is modest at around the 10 per cent level. (ii) Deviations from a flat-toped profile shape for a spherical wind are greatest for viewing inclinations that are more nearly face-on to the orbital plane. At intermediate viewing inclinations, profiles display only mild deviations from a flat-toped shape. (iii) The profile shape can be used to constrain the colliding wind bow shock opening angle. (iv) Structure in the line profile tends to be suppressed in binaries of shorter periods. (v) Obtaining data for multiple forbidden lines is important since different lines probe different characteristic radial scales. Our models are discussed in relation to Infrared Space Observatory data for WR 147 and γ Vel (WR 11). The lines for WR 147 are probably not accurate enough to draw firm conclusions. For γ Vel, individual line morphologies are broadly reproducible but not simultaneously so for the claimed wind and orbital parameters. Overall, the effort demonstrates how lines that are sensitive to the large-scale wind can help to deduce binary system properties and provide new tests of numerical simulations.

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Stec, Jeffrey D. "Wind profiler study of the central California sea/land breeze /\." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA317994.

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Thesis (M.S. in Meteorology and Physical Oceanography) Naval Postgraduate School, September. 1996.<br>Thesis advisor(s): Carlyle H. Wash. "September 1996." Includes bibliographical references (p. 97-100). Also available online.

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Low, David J. "Studies of the lower atmosphere with a VHF wind profiler /." Title page, abstract and contents only, 1996. http://web4.library.adelaide.edu.au/theses/09PH/09phl9121.pdf.

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Libros sobre el tema "Wind profilers"

B, Chadwick Russell, and Forecast Systems Laboratory (U.S.), eds. Coherent interference tests for wind profilers. U.S. Dept. of Commerce, National Oceanic and Atmospheric Administration, Environmental Research Laboratories, Forecast Systems Laboratory, 1992.

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Strauch, R. G. Radar wind profilers in the Colorado network. U.S. Dept. of Commerce, National Oceanic and Atmospheric Administration, Environmental Research Laboratories, Wave Propagation Laboratory, 1985.

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Gossard, Earl E. Automated editing of spectra from wind profilers. U.S. Dept. of Commerce, National Oceanic and Atmospheric Administration, Environmental Research Laboratories, Environmental Technology Laboratory, 1997.

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E, Gaines Steven, Hipskind R. Stephen, United States. National Aeronautics and Space Administration., and San Jose State University. Meteorology Dept., eds. An atlas of objectively analyzed atmospheric cross sections 1973-1980. National Aeronautics and Space Administration, 1985.

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Wuertz, David B. Editing wind profiler measurements. U.S. Dept. of Commerce, National Oceanic and Atmospheric Administration, Environmental Research Laboratories, Wave Propagation Laboratory, 1989.

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Wuertz, David B. Editing wind profiler measurements. U.S. Dept. of Commerce, National Oceanic and Atmospheric Administration, Environmental Research Laboratories, Wave Propagation Laboratory, 1989.

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Wuertz, David B. Editing wind profiler measurements. U.S. Dept. of Commerce, National Oceanic and Atmospheric Administration, Environmental Research Laboratories, Wave Propagation Laboratory, 1989.

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Baillie, S. W. An investigation of lateral tracking techniques, flight directors and automatic control coupling on decelerating IFR approaches for rotorcraft. National Aeronautical Establishment, 1988.

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J, Murphy Patrick, FWG Associates, and George C. Marshall Space Flight Center., eds. Analysis of wind profile measurements from an instrumented aircraft: Interim final report. FWG Associates, Inc., 1991.

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Graham, R. Electrical demand profiles at six wind monitoring sites. Scottish Agricultural College, Engineering Dept., 1999.

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Capítulos de libros sobre el tema "Wind profilers"

Gu, Taofeng, Jiamin Wang, Feng Shen, et al. "3D Wind Field Construction with Multiple Wind Profilers." In Lecture Notes in Electrical Engineering. Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-7505-1_47.

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Emeis, Stefan, and Matthias Turk. "Comparison of Logarithmic Wind Profiles and Power Law Wind Profiles and their Applicability for Offshore Wind Profiles." In Wind Energy. Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-33866-6_11.

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Lehmann, Volker, and William Brown. "Radar Wind Profiler." In Springer Handbook of Atmospheric Measurements. Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-52171-4_31.

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Tambke, J., J. A. T. Bye, Bernhard Lange, and J. O. Wolff. "Wind Speed Profiles above the North Sea." In Wind Energy. Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-33866-6_5.

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Emeis, Stefan. "Vertical Profiles Over Flat Terrain." In Wind Energy Meteorology. Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-72859-9_3.

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Emeis, Stefan. "Vertical Profiles Over Flat Terrain." In Wind Energy Meteorology. Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-30523-8_3.

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Bedka, Kristopher, John Marketon, Sammy Henderson, and Michael Kavaya. "AWP: NASA’s Aerosol Wind Profiler Coherent Doppler Wind Lidar." In Space-based Lidar Remote Sensing Techniques and Emerging Technologies. Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-53618-2_3.

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Bourguet, Rémi, Guillaume Martinat, Gilles Harran, and Marianna Braza. "Aerodynamic Multi-Criteria Shape Optimization of VAWT Blade Profile by Viscous Approach." In Wind Energy. Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-33866-6_39.

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Sepe, Vincenzo, Alberto M. Avossa, Fabio Rizzo, and Francesco Ricciardelli. "Can Wind Lidars Be Used to Calibrate Mean Wind Profiles?" In Lecture Notes in Civil Engineering. Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-53059-3_19.

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Barreal Pernas, Jesús, and Gil Jannes. "Comparison of international tourist profiles in the Spanish wine and olive oil PDOs." In Tourism marketing in Western Europe. CABI, 2021. http://dx.doi.org/10.1079/9781789248753.0005.

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Abstract This chapter, by Jesús Barreal Pernas and Gil Jannes, deals with gastro-tourism in Spain and studies the international tourist profile in the Spanish wine and olive oil Protected Destinations of Origin (PDOs). Specifically, the study focuses on regions that have such PDOs and examines the differences and similarities among the profiles of international tourists that visit them. The study concludes with a classification of four clusters according to demographic, travel and motivational characteristics of tourists in the particular area.

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Actas de conferencias sobre el tema "Wind profilers"

STRAUCH, R., D. MERRITT, K. MORAN, P. MAY, and B. WEBER. "Doppler radar wind profilers for support of flight operations." In 27th Aerospace Sciences Meeting. American Institute of Aeronautics and Astronautics, 1989. http://dx.doi.org/10.2514/6.1989-713.

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Lei Wu, Xuhui Zhou, and Furan Wang. "Primary analysis of the comparison test of wind profilers Made in China." In 2011 International Conference on Information Science and Technology (ICIST). IEEE, 2011. http://dx.doi.org/10.1109/icist.2011.5765324.

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Flowers, Wayne, Elaine Santantonio, Glenn Hoidale, et al. "Wind measurements from Doppler radar profilers and rawinsondes - A comparison of 50-MHz and 404-MHz profilers and rawinsonde data at White Sands Missile Range." In Aerospace Sensing, edited by Anton Kohnle and Walter B. Miller. SPIE, 1992. http://dx.doi.org/10.1117/12.137899.

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Westwater, E. R., and B. B. Stankov. "Recent Results in Combined Ground-based and Satellite Remote Sensing." In Optical Remote Sensing of the Atmosphere. Optica Publishing Group, 1993. http://dx.doi.org/10.1364/orsa.1993.mc.2.

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The implementation of the Wind Profiler Demonstration Network [1] is an indication of the increased reliance of the operational community on remote sensors. The Wind Profilers themselves can measure winds to about 16 km with a spatial resolution of 300-900 m on an hourly basis; their horizontal spacings vary from about 200 to 300 km. If the same spatial and temporal coverage of temperature, water vapor and clouds could be achieved many of the needs of forecasters and researchers could be met. However, even if the ambitious goal of measuring both dynamic and thermodynamic variables from a network of surface-based stations could be met, station deployment on a 25 to 50 km grid would be prohibitively expensive. Observations from both polar-orbiting and geostationary satellites, when combined with data from a limited grid of surface-based remote sensors, may provide the necessary horizontal coverage as well as improve upper altitude accuracy. In this paper, we present new results and discuss several possibilities of combining surface-based and satellite data.

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Zarate, Luz, Shejun Fan, Pak Leung, et al. "Hurricane Ida Passage Over Gulf of Mexico Oil and Gas Offshore Facilities." In Offshore Technology Conference. OTC, 2022. http://dx.doi.org/10.4043/31757-ms.

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Abstract Hurricane Ida made landfall in Port Fourchon, Louisiana, as a Category 4 hurricane on August 29th, 2021, traveling over some offshore oil and gas facilities on its path. Shell Exploration and Production's offshore oil and gas installations in the Gulf of Mexico (GoM) have the most comprehensive suite of metocean instrumentation in the region, including wave and wind systems that captured the passage of hurricane Ida. This paper analyzes the wind and wave conditions measured by some Shell facilities located along the path of hurricane Ida. The number of LiDAR wind profilers and their spatial distribution with respect to Ida makes Shell the only operator in the Gulf of Mexico able to provide a detailed vertical wind profile at multiple locations throughout the extreme wind event. These observations, combined with satellite products such as Sea Surface Height (SSH) and Sea Surface Temperature (SST), help understand the hurricane track and intensity. Three Shell Tension Leg Platforms (TLPs) and one Semi-Submersible offshore Louisiana, measured wave data, with an overall maximum wave height of 21 m and a maximum significant wave height of 13 m. Two Shell TLPs and one Semi-Submersible measured wind profiles with maximum wind speeds of 46.82 ms−1 (91 knots, 104 mph), 43.52 ms−1 (84 knots, 97 mph), and 39.95 ms−1 (77 knots, 89 mph). Out of those three Platforms, the two sites that captured the strongest wind speeds were located right on Ida's path, where it was possible to record the wind direction shift as Hurricane Ida passed over the, and the third site was east of the track.

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Johnson, Steven C. "Space Shuttle Wind Profiler." In Coherent Laser Radar. Optica Publishing Group, 1991. http://dx.doi.org/10.1364/clr.1991.tud3.

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Knowledge of winds is required to reduce aerodynamic loads on the Space Shuttle during launch. Knowledge of winds is also required to safely land the unpowered orbiter. Balloons are currently used in both instances to produce the necessary wind profiles. The balloons require an hour to rise through the altitude range, sometimes drifting far from the area where the wind measurement is desired. As a result, the correlation between the actual winds encountered by the vehicle and those measured is reduced. NASA is investigating the potential of alternate wind sensors to produce more local wind measurement in less time to increase this correlation. Lidar is one technique under investigation.

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Sinsabvarodom, Chana, Bernt J. Leira, Knut V. Høyland, Wei Chai, Arvid Naess, and Gowtham Radhakrishnan. "On the Relationship Between Spectral Models of Ice Drift and Wind Turbulence." In ASME 2023 42nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/omae2023-104751.

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Abstract At present, there is quite limited research activity related to mathematical models of the ice drift spectrum. The intention of this work is to propose a novel mathematical model of a generalized ice drift speed spectrum to describe the ice drift behavior in the frequency domain. The drift of sea ice is naturally influenced by external forces such as wind stress at the air-ice interface, water stress at the water-ice interface, the Coriolis force, pressure gradients due to sea surface tilting, and internal stress within the sea ice itself. Typically, wind dominates the ice drift at higher frequencies, while current is likely to play an important role in the lower frequency range. This is due to the slow rate of change for the ocean current. Typically, sea ice will drift at approximately 2–3% of the wind speed as referred to a height of 10-meter above the ocean surface in the Arctic region. The magnitude of the ice drift speed can approximately be predicted by the Nansen number corresponding to the drift speed magnitude as a percentage of the wind speed. The physical connection between the wind speed and the ice drift speed is presently utilized in order to generate a generalized ice drift spectrum. The ice drift data is collected from local subsurface measurements by means of acoustic Doppler current profilers (ADCP) in the Beaufort Sea. The frequency spectra of the wind speed and ice drift speed are calculated by application of the Fourier transform (as implemented in the WAFO software) based on the measured time series. It is found that the sea ice drifts at around 2.5% of the wind speed in the winter season (which corresponds to non-free drift conditions). However, during the summer season the sea ice tends to drift faster than 2.5% of the wind speed (which corresponds to free drift conditions). According to the scaling relationship between the ice drift speed and the wind speed, the Kaimal turbulence spectra are adopted to describe the ice drift behavior. This provides a good match for the winter season. However, the empirical ice drift spectrum contains higher energy levels than the Kaimal turbulence spectra in the high frequency range during the summer season. Accordingly, a generalized ice drift spectrum is proposed in the present paper, which is developed based on expressions for the general turbulence spectrum. The corresponding expression is more flexible in order to capture the ice drift behavior in the high frequency range for both the winter and the summer seasons. The generalized ice drift spectrum is found to provide a better match to the empirical spectra from ADCP measurements than the Kaimal turbulence spectrum.

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Colidiuc, Alexandra, Bogdan Suatean, Stelian Galetuse, et al. "Aerodynamic Characteristics of Wing Profiles for Wind Generators." In NUMERICAL ANALYSIS AND APPLIED MATHEMATICS ICNAAM 2011: International Conference on Numerical Analysis and Applied Mathematics. AIP, 2011. http://dx.doi.org/10.1063/1.3637908.

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Jeans, Gus, Dave Quantrell, Andrew Watson, Laure Grignon, and Gil Lizcano. "A New Assessment of Offshore Wind Profile Relationships." In ASME 2018 1st International Offshore Wind Technical Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/iowtc2018-1052.

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Engineering design codes specify a variety of different relationships to quantify vertical variations in wind speed, gust factor and turbulence intensity. These are required to support applications including assessment of wind resource, operability and engineering design. Differences between the available relationships lead to undesirable uncertainty in all stages of an offshore wind project. Reducing these uncertainties will become increasingly important as wind energy is harnessed in deeper waters and at lower costs. Installation of a traditional met mast is not an option in deep water. Reliable measurement of the local wind, gust and turbulence profiles from floating LiDAR can be challenging. Fortunately, alternative data sources can provide improved characterisation of winds at offshore locations. Numerical modelling of wind in the lower few hundred metres of the atmosphere is generally much simpler at remote deepwater locations than over complex onshore terrain. The sophistication, resolution and reliability of such models is advancing rapidly. Mesoscale models can now allow nesting of large scale conditions to horizontal scales less than one kilometre. Models can also provide many decades of wind data, a major advantage over the site specific measurements gathered to support a wind energy development. Model data are also immediately available at the start of a project at relatively low cost. At offshore locations these models can be validated and calibrated, just above the sea surface, using well established satellite wind products. Reliable long term statistics of near surface wind can be used to quantify winds at the higher elevations applicable to wind turbines using the wide range of existing standard profile relationships. Reduced uncertainty in these profile relationships will be of considerable benefit to the wider use of satellite and model data sources in the wind energy industry. This paper describes a new assessment of various industry standard wind profile relationships, using a range of available met mast datasets and numerical models.

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Informes sobre el tema "Wind profilers"

Coulter, R. L., B. M. Lesht, M. L. Wesely, D. R. Cook, D. J. Holdridge, and T. J. Martin. Performance of radar wind profilers, radiosondes, and surface flux stations at the SGP CART site. Office of Scientific and Technical Information (OSTI), 1995. http://dx.doi.org/10.2172/81006.

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Boss, Emmanuel. Shelf-Slope Physical/Biological Response to Monsoonal Wind Forcing and Riverine Inflow - 4D Sampling with Towed Profilers and Autonomous Gliders Off Vietnam. Defense Technical Information Center, 2012. http://dx.doi.org/10.21236/ada572165.

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Jones, Burton H. Shelf-Slope Physical/Biological Response to Monsoonal Wind Forcing and Riverine Inflo - 4D Sampling with Towed Profilers and Autonomous Gliders Off Vietnam. Defense Technical Information Center, 2012. http://dx.doi.org/10.21236/ada572175.

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Boss, Emmanuel, and Burton H. Jones. Shelf-Slope Physical/Biological Response to Monsoonal Wind Forcing and Riverine Inflow - 4D Sampling with Towed Profilers and Autonomous Gliders off Vietnam. Defense Technical Information Center, 2013. http://dx.doi.org/10.21236/ada601223.

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Ziegler, Nancy, Nicholas Webb, Adrian Chappell, and Sandra LeGrand. Scale invariance of albedo-based wind friction velocity. Engineer Research and Development Center (U.S.), 2021. http://dx.doi.org/10.21079/11681/40499.

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Obtaining reliable estimates of aerodynamic roughness is necessary to interpret and accurately predict aeolian sediment transport dynamics. However, inherent uncertainties in field measurements and models of surface aerodynamic properties continue to undermine aeolian research, monitoring, and dust modeling. A new relation between aerodynamic shelter and land surface shadow has been established at the wind tunnel scale, enabling the potential for estimates of wind erosion and dust emission to be obtained across scales from albedo data. Here, we compare estimates of wind friction velocity (u*) derived from traditional methods (wind speed profiles) with those derived from the albedo model at two separate scales using bare soil patch (via net radiometers) and landscape (via MODIS 500 m) datasets. Results show that profile-derived estimates of u* are highly variable in anisotropic surface roughness due to changes in wind direction and fetch. Wind speed profiles poorly estimate soil surface (bed) wind friction velocities necessary for aeolian sediment transport research and modeling. Albedo-based estimates of u* at both scales have small variability because the estimate is integrated over a defined, fixed area and resolves the partition of wind momentum be-tween roughness elements and the soil surface. We demonstrate that the wind tunnel-based calibration of albedo for predicting wind friction velocities at the soil surface (us*) is applicable across scales. The albedo-based approach enables consistent and reliable drag partition correction across scales for model and field estimates of us* necessary for wind erosion and dust emission modeling.

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Helmus, Jonathan, and Virendra P. Ghate. Improved Estimates of Moments and Winds from Radar Wind Profiler. Office of Scientific and Technical Information (OSTI), 2017. http://dx.doi.org/10.2172/1343609.

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Nahmer, Thomas. Die Investition in Fine Wine unter Diversifikations- und Kostengesichtspunkten. Sonderforschungsgruppe Institutionenanalyse, 2018. http://dx.doi.org/10.46850/sofia.9783941627710.

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Dieses Papier untersucht die Sinnhaftigkeit von Fine Wine als Alternatives Investment unter besonderer Berücksichtigung der Kosten eines Fine Wine Investments. Ist Fine Wine zur weiteren Diversifizierung und damit zur Verbesserung des Risikio-Return-Profils von global in Aktien und Anleihen investierenden Portfolios geeignet? Die Analyse erfolgt in einem ersten Schritt auf Indexbasis und in einem zweiten Schritt auf Basis von realen Investitions-möglichkeiten. Die Referenzwährungen sind der US-Dollar und der Euro. Für die Indexbetrachtung werden auf der Aktienseite der MSCI-World-Index und für die Anleihen der JPM-World-Government-Bond-Index verwendet. Bei den Daten für die Investition in Fine Wine liegt der Fokus auf dem Liv-ex-50-Index der im Jahre 1999 gegründeten Londoner Weinbörse Liv-ex. Bei der realen Investition werden für die Datenanalyse bei Aktien und Anleihen Indexfonds verwendet. Da es für die Investition in Fine Wine keinen Indexfonds gibt, wird der Liv-ex-50-Index inklusive aller Kosten einer realen Investition berechnet. Es werden verschiedene Portfoliozusammensetzungen verglichen. Zum einen wird ein Portfolio aus 50% Aktien und 50% Anleihen einem Portfolio aus 45% Aktien, 45% Anleihen und 10% Fine Wine gegenübergestellt. Zum an-deren wird ein Portfolio aus 25% Aktien und 75% Anleihen gegen ein Portfolio aus 20% Aktien, 70% Anleihen und 10% Fine Wine gemessen. Als Vergleichsmaßstab werden die annualisierte Rendite, die Standardabweichung sowie das Sharpe-Ratio der jeweiligen Portfolios berechnet. Die Ergebnisse für die genannten Zeiträume sind ernüchternd. Die Beimischung von Fine Wine führt auf Indexebene lediglich zu einer leichten Verbesserung der annualisierten Rendite aber zu einer markanten Erhöhung des Risi-kos. Bei der Betrachtung der realen Investition kommen die hohen Kosten eines Investments in Fine Wine zum Tragen. Die annualisierte Rendite ist im Vergleich zu den Portfolios ohne Beimischung von Fine Wine niedriger bei gleichzeitig höheren Risikowerten. Lediglich bei der Betrachtung auf Indexbasis in Euro kann bei einem Portfolio eine leichte Verbesserung der Sharpe-Ratio verzeichnet werden. Bei der Betrachtung nach Kosten führt in allen Fällen die Beimischung von Fine Wine zu einer Verschlechterung der Sharpe-Ratios.

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Coulter, R. 915-MHz Radar Wind Profiler (915RWP) Handbook. Office of Scientific and Technical Information (OSTI), 2005. http://dx.doi.org/10.2172/1020560.

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Newsom, Rob, and Gabriel Gibler. Doppler Lidar Motion-Correction Wind Profiles (DLMCPROF-WIND) Value-Added Product Report. Office of Scientific and Technical Information (OSTI), 2024. http://dx.doi.org/10.2172/2301604.

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