Analysis of precipitable water vapor from GPS measurements in Chengdu region: Distribution and evolution characteristics in autumn

The rainfall process of Chengdu region in autumn has obvious regional features. Especially, the night-time rain rate of this region in this season is very high in China. Studying the spatial distribution and temporal variation of regional atmospheric precipitable water vapor (PWV) is important for our understanding of water vapor related processes, such as rainfall, evaporation, convective activity, among others in this area. Since GPS detection technology has the unique characteristics, such as all-weather, high accuracy, high spatial and temporal resolution as well as low cost, tracking and monitoring techniques on water vapor has achieved rapid developments in recent years. With GPS–PWV data at 30-min interval gathered from six GPS observational stations in Chengdu region in two autumns (September 2007–December 2007 and September 2008–December 2008), it is revealed that negative correlations exist between seasonally averaged value of GPS–PWV as well as its variation amplitude and local terrain altitude. The variation of PWV in the upper atmosphere of this region results from the water vapor variation from surface to 850 hPa. With the help of Fast Fourier Transform (FFT), it is found that the autumn PWV in Chengdu region has a multi-scale feature, which includes a seasonal cycle, 22.5 days period (quasi-tri-weekly oscillation). The variation of the GPS–PWV is related to periodical change in the transmitting of the water vapor caused by zonal and meridional wind strengths’ change and to the East Asian monsoon system. According to seasonal variation characteristics, we concluded that the middle October is the critical turning point in PWV content. On a shorter time scale, the relationship between autumn PWV and ground meteorological elements was obtained using the composite analysis approach.     

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介绍在AutoCAD2004平台上,利用二次开发系统及其下拉菜单、VLISP语言等控制模块程序而开发轴类零件图绘制系统。软件采用下拉式菜单技术和屏幕图形可视化,使用户方便快捷地进行绘制各种轴类零件图,从而减轻设计人员在绘制轴类零件图的重复性工作,具有交互性好、使用方便及扩展性好等特点。     

某平尾旋转频率降低原因分析及改进

对某型飞机全机共振试验中出现的平尾旋转频率降低的问题进行了详细的分析，并对影响平尾旋转频率降低的部位进行了测试，找出了原因，进行了排除。     

智商、情商与高职高专英语教学——高职高专英语应用能力考试教学方法改革探析

通过对情商及其基本内涵的分析，指出智商是定的，但语言教育工作者可以通过后天的培养，提高学生的情商，最终使情商与写长法、英语学得与习得结合起来服务于英语教学。     

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