This study investigates both the characteristics of the vertical wind profile at the Bobo Dioulasso site located in the Sudanian climate zone in Burkina Faso during a day and night convective wind cycle and the estima...This study investigates both the characteristics of the vertical wind profile at the Bobo Dioulasso site located in the Sudanian climate zone in Burkina Faso during a day and night convective wind cycle and the estimation and variability of the wind resource. Wind data at 10 m above ground level and satellite data at 50 m altitude in the atmospheric boundary layer were used for the period going from January 2006 to December 2016. Based on Monin-Obukhov theory, the logarithmic law and the power law made it possible to characterize the wind profile. On the study site, the atmosphere is generally unstable from 10:00 to 18:00 and stable during the other periods of the day. Wind extrapolation models were tested on our study site. Fitting equations proposed are always in agreement with the data, contrary to other models assessed. Based on these equations, the profile of a day and night cycle wind cycle was established by extrapolation of wind data measured at 10 m above the ground. Lastly, the model of the power law based on the stability was used to generate data on wind speed from 20 m to 50 m based on data from 10 m above the ground. Weibull function was used to characterize wind speed rate distribution and to calculate wind energy potential. The average annual power density on the site is estimated at 53.13 W/m2 at 20 m and at 84.05 W/m2 at 50 m, or 36.78% increase. Considering these results, the Bobo-Dioulasso site could be appropriate to build small and medium-size turbines to supply the rural communities of the Bobo Dioulasso region with electricity.展开更多
During summer Monex-79, a variety of observing systems viz. research ships, research aircrafts, constant pressure balloons and geostationary satellite etc. were deployed, besides the regular conventional observations....During summer Monex-79, a variety of observing systems viz. research ships, research aircrafts, constant pressure balloons and geostationary satellite etc. were deployed, besides the regular conventional observations. The purpose of these additional systems was to make the best possible data for the studies on various aspects of monsoon circulation. The present study is aimed at the construction of vertical wind profile using cloud motion vectors obtained from GOES (I-O) satellite and to examine whether the constructed wind profiles improves the representation of the monsoon system, flow pattern etc. in the objective analysis. For this purpose, climatological normals of the wind field are considered as the initial guess and the objective analyses of the wind field are made with, first using only data from conventional observations over land areas, subsequently including the constructed winds from cloud motion vectors. These analyses are then compared with the standard analyses of wind field obtained from Quick Look Atlas by T. N. Krishnamurti et al. (1979).It is inferred that satellite estimated mean wind profiles show good agreement with the mean wind profiles of the research ships with RMS errors less than 5 mps below 500 hPa and less than 8 mps above 500 hPa. It is further inferred that the inclusion of constructed winds shows a positive impact on the objective analysis and improvement is seen to be more marked in the data-sparse region of the Arabian sea. Analyses which include the constructed winds show better agreement with the standard analysis, than the analyses obtained using only conventional winds. Thus, results of our study suggest that the wind profiles constructed using cloud motion vectors are of potential use in objective analysis to depict the major circulation features over the Indian region.展开更多
Tropical cyclones and cyclogenesis are active areas of research. Chute-operated dropsondes are capable of acquiring high resolution vertical wind profile of tropical cyclones. This work proposes a chute-free vertical ...Tropical cyclones and cyclogenesis are active areas of research. Chute-operated dropsondes are capable of acquiring high resolution vertical wind profile of tropical cyclones. This work proposes a chute-free vertical retardation technique (termed as spinsonde) that can accurately measure vertical wind speed profile. Unlike the expendable dropsondes, the spinsonde allows multi-cycle measurement to be performed within a single flight. Proof of principle is demonstrated via simulation and results indicate that the ground speed correlates with the wind speeds to within ±5 km·h-1. This technique reduces flying weight and increases payload capacity by eliminating bulky chutes. Maximum cruising speed (VH) achieved by the spinsonde UAV is 368 km·h-1.展开更多
Reliable estimation of the mass-flux profiles of aeolian sediment is essential for predicting sediment transport rates accurately and designing measures to cope with wind-erosion. Vertical mass-flux profiles from seve...Reliable estimation of the mass-flux profiles of aeolian sediment is essential for predicting sediment transport rates accurately and designing measures to cope with wind-erosion. Vertical mass-flux profiles from seventeen wind-erosion events were re-evaluated using five typical models based on observed data obtained from a smooth bare field at the southern fringe of the Taklimakan Desert, China. The results showed that the exponential-function model and the logarithmic-function model exhibited the poorest fit between observed and predicted mass-flux profiles. The power-function model and the modified power-function model improved the fit to field data to an equivalent extent, while the five-parameter combined-function model with a scale constant（σ） of 0.00001 m（different from the σ value proposed by Fryear, which represented the height above which 50% of the total mass flux occurred） was verified as the best for describing the vertical aeolian sediment mass-flux profiles using goodness of fit（R2） and the Akaike Information Criterion（AIC） values to evaluate model performance. According to relationships among model parameters, the modified power model played a prominent explanatory role in describing the vertical profiles of the observed data, whereas the exponential model played a coordinating role. In addition, it was found that the vertical profiles could not be extrapolated using the five selected models or easily estimated using an efficient model without field observations by a near-surface sampler at 0 to 0.05 m.展开更多
To improve the level of meteorological service for the Oilfield region in the Taklimakan Desert, the Urumqi Institute of Desert Meteorology of the China Meteorological Administration （CMA） conducted a detection expe...To improve the level of meteorological service for the Oilfield region in the Taklimakan Desert, the Urumqi Institute of Desert Meteorology of the China Meteorological Administration （CMA） conducted a detection experiment by means of wind profiling radar （WPR） in Tazhong Oilfield region of Xinjiang, China in July 2010. By using the wind profiler data obtained during the rainfall process on 27 July, this paper analyzed the wind field fea- tures and some related scientific issues of this weather event. The results indicated that： （1） wind profiler data had high temporal resolution and vertical spatial resolution, and could be used to analyze detailed vertical structures of rainfall processes and the characteristics of meso-scale systems. Before and after the rain event on 27 July, the wind field showed multi-layer vertical structures, having an obvious meso-scale wind shear line and three airflows from different directions, speeding up the motion of updraft convergence in the lower atmosphere. Besides, the wind directions before and after the rainfall changed inversely with increasing height. Before the rain, the winds blew clockwise, but after the onset of the rain, the wind directions became counterclockwise mainly; （2） the temperature advection derived from wind profiler data can reproduce the characteristics of low-level thermodynamic evolution in the process of rainfall, which is capable to reflect the variation trend of hydrostatic stability in the atmosphere. In the early stage of the precipitation on 27 July, the lower atmosphere was mainly affected by warm advection which had accumulated unstable energy for the rainfall event and was beneficial for the occurrence of updraft motion and precipitation; （3） the ＂large-value zone＂ of the radar reflectivity factor Z was virtually consistent with the onset and end of the rainfall, the height for the formation of rain cloud particles, and precipitation intensity. The reflectivity factor Z during this event varied approximately in the range of 18-38 dBZ and the rain droplets formed mainly at the layer of 3,800-4,500 m.展开更多
台风风场径向廓线模型对台风灾害的评估以及台风尺度的研究具有重要的价值.利用西北太平洋2001-2020年的台风最佳路径观测数据,评估了目前国际上应用比较广泛的六个分别基于经验参数和物理过程的台风风场径向廓线模型对台风尺度(台风大...台风风场径向廓线模型对台风灾害的评估以及台风尺度的研究具有重要的价值.利用西北太平洋2001-2020年的台风最佳路径观测数据,评估了目前国际上应用比较广泛的六个分别基于经验参数和物理过程的台风风场径向廓线模型对台风尺度(台风大风半径,R17)的估计精度,并探讨了台风结构、强度等内部因素以及垂直风切变和移动速度等环境因子对模型精度的影响.评估发现,所有模型均高估了R17较小的台风而低估了R17较大的台风,且R17越小,高估越明显,R17越大,低估越严重.总体而言,Willoughby et al发展的基于参数的模型具有最小的估计偏差且与观测记录之间最高的相关性.研究还发现,台风内核尺度(最大风速半径,RMW)和强度(最大地面风速,V_(max))对不同模型的影响具有显著的差异性.此外,在高环境风切变和高移速条件下,模型的估计偏差的量级会显著增加.以上研究为进一步完善适用于不同环境条件下,不同结构与强度台风的风场模型提供参考.展开更多
文摘This study investigates both the characteristics of the vertical wind profile at the Bobo Dioulasso site located in the Sudanian climate zone in Burkina Faso during a day and night convective wind cycle and the estimation and variability of the wind resource. Wind data at 10 m above ground level and satellite data at 50 m altitude in the atmospheric boundary layer were used for the period going from January 2006 to December 2016. Based on Monin-Obukhov theory, the logarithmic law and the power law made it possible to characterize the wind profile. On the study site, the atmosphere is generally unstable from 10:00 to 18:00 and stable during the other periods of the day. Wind extrapolation models were tested on our study site. Fitting equations proposed are always in agreement with the data, contrary to other models assessed. Based on these equations, the profile of a day and night cycle wind cycle was established by extrapolation of wind data measured at 10 m above the ground. Lastly, the model of the power law based on the stability was used to generate data on wind speed from 20 m to 50 m based on data from 10 m above the ground. Weibull function was used to characterize wind speed rate distribution and to calculate wind energy potential. The average annual power density on the site is estimated at 53.13 W/m2 at 20 m and at 84.05 W/m2 at 50 m, or 36.78% increase. Considering these results, the Bobo-Dioulasso site could be appropriate to build small and medium-size turbines to supply the rural communities of the Bobo Dioulasso region with electricity.
文摘During summer Monex-79, a variety of observing systems viz. research ships, research aircrafts, constant pressure balloons and geostationary satellite etc. were deployed, besides the regular conventional observations. The purpose of these additional systems was to make the best possible data for the studies on various aspects of monsoon circulation. The present study is aimed at the construction of vertical wind profile using cloud motion vectors obtained from GOES (I-O) satellite and to examine whether the constructed wind profiles improves the representation of the monsoon system, flow pattern etc. in the objective analysis. For this purpose, climatological normals of the wind field are considered as the initial guess and the objective analyses of the wind field are made with, first using only data from conventional observations over land areas, subsequently including the constructed winds from cloud motion vectors. These analyses are then compared with the standard analyses of wind field obtained from Quick Look Atlas by T. N. Krishnamurti et al. (1979).It is inferred that satellite estimated mean wind profiles show good agreement with the mean wind profiles of the research ships with RMS errors less than 5 mps below 500 hPa and less than 8 mps above 500 hPa. It is further inferred that the inclusion of constructed winds shows a positive impact on the objective analysis and improvement is seen to be more marked in the data-sparse region of the Arabian sea. Analyses which include the constructed winds show better agreement with the standard analysis, than the analyses obtained using only conventional winds. Thus, results of our study suggest that the wind profiles constructed using cloud motion vectors are of potential use in objective analysis to depict the major circulation features over the Indian region.
文摘Tropical cyclones and cyclogenesis are active areas of research. Chute-operated dropsondes are capable of acquiring high resolution vertical wind profile of tropical cyclones. This work proposes a chute-free vertical retardation technique (termed as spinsonde) that can accurately measure vertical wind speed profile. Unlike the expendable dropsondes, the spinsonde allows multi-cycle measurement to be performed within a single flight. Proof of principle is demonstrated via simulation and results indicate that the ground speed correlates with the wind speeds to within ±5 km·h-1. This technique reduces flying weight and increases payload capacity by eliminating bulky chutes. Maximum cruising speed (VH) achieved by the spinsonde UAV is 368 km·h-1.
基金financially supported by the Special Scientific Research Fund of Meteorological Public Welfare Profession of China (GYHY201106025)the National Natural Science Foundation of China (41471031)
文摘Reliable estimation of the mass-flux profiles of aeolian sediment is essential for predicting sediment transport rates accurately and designing measures to cope with wind-erosion. Vertical mass-flux profiles from seventeen wind-erosion events were re-evaluated using five typical models based on observed data obtained from a smooth bare field at the southern fringe of the Taklimakan Desert, China. The results showed that the exponential-function model and the logarithmic-function model exhibited the poorest fit between observed and predicted mass-flux profiles. The power-function model and the modified power-function model improved the fit to field data to an equivalent extent, while the five-parameter combined-function model with a scale constant（σ） of 0.00001 m（different from the σ value proposed by Fryear, which represented the height above which 50% of the total mass flux occurred） was verified as the best for describing the vertical aeolian sediment mass-flux profiles using goodness of fit（R2） and the Akaike Information Criterion（AIC） values to evaluate model performance. According to relationships among model parameters, the modified power model played a prominent explanatory role in describing the vertical profiles of the observed data, whereas the exponential model played a coordinating role. In addition, it was found that the vertical profiles could not be extrapolated using the five selected models or easily estimated using an efficient model without field observations by a near-surface sampler at 0 to 0.05 m.
基金co-funded by the National Basic Research Program of China(2010CB951001)the Research Subject with the Support of National Science and Technology(2012BA C23B01)the Central Scientific Research and Operational Project(IDM201002)
文摘To improve the level of meteorological service for the Oilfield region in the Taklimakan Desert, the Urumqi Institute of Desert Meteorology of the China Meteorological Administration （CMA） conducted a detection experiment by means of wind profiling radar （WPR） in Tazhong Oilfield region of Xinjiang, China in July 2010. By using the wind profiler data obtained during the rainfall process on 27 July, this paper analyzed the wind field fea- tures and some related scientific issues of this weather event. The results indicated that： （1） wind profiler data had high temporal resolution and vertical spatial resolution, and could be used to analyze detailed vertical structures of rainfall processes and the characteristics of meso-scale systems. Before and after the rain event on 27 July, the wind field showed multi-layer vertical structures, having an obvious meso-scale wind shear line and three airflows from different directions, speeding up the motion of updraft convergence in the lower atmosphere. Besides, the wind directions before and after the rainfall changed inversely with increasing height. Before the rain, the winds blew clockwise, but after the onset of the rain, the wind directions became counterclockwise mainly; （2） the temperature advection derived from wind profiler data can reproduce the characteristics of low-level thermodynamic evolution in the process of rainfall, which is capable to reflect the variation trend of hydrostatic stability in the atmosphere. In the early stage of the precipitation on 27 July, the lower atmosphere was mainly affected by warm advection which had accumulated unstable energy for the rainfall event and was beneficial for the occurrence of updraft motion and precipitation; （3） the ＂large-value zone＂ of the radar reflectivity factor Z was virtually consistent with the onset and end of the rainfall, the height for the formation of rain cloud particles, and precipitation intensity. The reflectivity factor Z during this event varied approximately in the range of 18-38 dBZ and the rain droplets formed mainly at the layer of 3,800-4,500 m.
文摘台风风场径向廓线模型对台风灾害的评估以及台风尺度的研究具有重要的价值.利用西北太平洋2001-2020年的台风最佳路径观测数据,评估了目前国际上应用比较广泛的六个分别基于经验参数和物理过程的台风风场径向廓线模型对台风尺度(台风大风半径,R17)的估计精度,并探讨了台风结构、强度等内部因素以及垂直风切变和移动速度等环境因子对模型精度的影响.评估发现,所有模型均高估了R17较小的台风而低估了R17较大的台风,且R17越小,高估越明显,R17越大,低估越严重.总体而言,Willoughby et al发展的基于参数的模型具有最小的估计偏差且与观测记录之间最高的相关性.研究还发现,台风内核尺度(最大风速半径,RMW)和强度(最大地面风速,V_(max))对不同模型的影响具有显著的差异性.此外,在高环境风切变和高移速条件下,模型的估计偏差的量级会显著增加.以上研究为进一步完善适用于不同环境条件下,不同结构与强度台风的风场模型提供参考.
