In this study, kinetic energy budget equations of rotational and divergent flow in pressure coordinates are derived on terrain-following coordinates. The new formulation explicitly shows the terrain effects and can be...In this study, kinetic energy budget equations of rotational and divergent flow in pressure coordinates are derived on terrain-following coordinates. The new formulation explicitly shows the terrain effects and can be applied directly to model-simulated dynamic and thermodynamic fields on the model's original vertical grid. Such application eliminates interpolation error and avoids errors in virtual weather systems in mountainous areas. These advantages and their significance are demonstrated by a numerical study in terrain-following coordinates of a developing vortex after it moves over the Tibetan Plateau in China.展开更多
Using Time History of Events and Macroscale Interactions during Substorms （THEMIS） observations from 2007 to 2011 tail seasons, we study the plasma properties of high speed flows （HSFs） and background plasma sheet...Using Time History of Events and Macroscale Interactions during Substorms （THEMIS） observations from 2007 to 2011 tail seasons, we study the plasma properties of high speed flows （HSFs） and background plasma sheet events （BPSs） in Earth＇s magnetotail （｜YGsM｜〈13RE, ｜ZGsM｜〈5RE, -30RE〈XrsM〈-6RE）, and their correlations with solar wind parameters. Statistical results show that the closer the HSFs and BPSs are to the Earth, the hotter they become, and the temperature increase of HSFs is larger than that of BPSs. The density and temperature ratios between HSFs and BPSs are also larger when events are closer to Earth. We also find that the best correlations between the HSFs （BPSs） density and the solar wind density occur when the solar wind density is averaged 2 （3.5） hours prior to the onset of HSFs （BPSs）. The normalized densities of both HSFs and BPSs are correlated with the interplanetary magnetic field （IMF） 0 angles （ 0 = arctan（Bz √Bx^2＋y^2 ） which are averaged 3 hours before the observation time. Further analysis indicates that both HSFs and BPSs become denser during the northward IMF period.展开更多
The interaction of bodies like spheres and disks in rotating fluids leads to novel flow structures. The primary swirling flow in circumferential direction is superimposed by a secondary motion in the meridional plane....The interaction of bodies like spheres and disks in rotating fluids leads to novel flow structures. The primary swirling flow in circumferential direction is superimposed by a secondary motion in the meridional plane. The flow is visualized by introducing ink through a hole in the center of the axes and distributed radially in the central plane between the interacting bodies. The flow structure depends on the shape of the bodies, their geometrical arrangement and the Reynolds number given by the rotational speed. The observed flow structures gave rise to further investigations with PIV-measurcments and numerical simulations.展开更多
基金supported by the Key Program of the Chinese Academy of Sciences(No.KZZD-EW-05-01)the Supporting Program for Science and Technological Research of China(No.2008BAC37B01)+1 种基金the National Basic Research Program of China(Nos.2012CB417201 and 2009CB421505)the National Natural Sciences Foundation of China(Nos.41205033 and 41175056)
文摘In this study, kinetic energy budget equations of rotational and divergent flow in pressure coordinates are derived on terrain-following coordinates. The new formulation explicitly shows the terrain effects and can be applied directly to model-simulated dynamic and thermodynamic fields on the model's original vertical grid. Such application eliminates interpolation error and avoids errors in virtual weather systems in mountainous areas. These advantages and their significance are demonstrated by a numerical study in terrain-following coordinates of a developing vortex after it moves over the Tibetan Plateau in China.
基金National Natural Science Foundation of China (Grant Nos. 41322031, 41031065 & 41574157)the Shandong Province Outstanding Young Scientist Award (Grant No. 2013BSE27132)+2 种基金the Research Fund for the Doctoral Program of Higher Education (Grant No. 20130131120073)the program for New Century Excellent Talents in University (Grant No. NCET-12-0332)State Key Laboratories of Space Weather
文摘Using Time History of Events and Macroscale Interactions during Substorms （THEMIS） observations from 2007 to 2011 tail seasons, we study the plasma properties of high speed flows （HSFs） and background plasma sheet events （BPSs） in Earth＇s magnetotail （｜YGsM｜〈13RE, ｜ZGsM｜〈5RE, -30RE〈XrsM〈-6RE）, and their correlations with solar wind parameters. Statistical results show that the closer the HSFs and BPSs are to the Earth, the hotter they become, and the temperature increase of HSFs is larger than that of BPSs. The density and temperature ratios between HSFs and BPSs are also larger when events are closer to Earth. We also find that the best correlations between the HSFs （BPSs） density and the solar wind density occur when the solar wind density is averaged 2 （3.5） hours prior to the onset of HSFs （BPSs）. The normalized densities of both HSFs and BPSs are correlated with the interplanetary magnetic field （IMF） 0 angles （ 0 = arctan（Bz √Bx^2＋y^2 ） which are averaged 3 hours before the observation time. Further analysis indicates that both HSFs and BPSs become denser during the northward IMF period.
文摘The interaction of bodies like spheres and disks in rotating fluids leads to novel flow structures. The primary swirling flow in circumferential direction is superimposed by a secondary motion in the meridional plane. The flow is visualized by introducing ink through a hole in the center of the axes and distributed radially in the central plane between the interacting bodies. The flow structure depends on the shape of the bodies, their geometrical arrangement and the Reynolds number given by the rotational speed. The observed flow structures gave rise to further investigations with PIV-measurcments and numerical simulations.
