西藏地区近地晴天大气电场气象效应和时间变化研究

基于西藏羊八井宇宙线观测站在2006年3月至2011年6月期间记录的近地大气电场数据, 分析研究了该地区近地晴天大气电场气象效应和时间变化特征. 气象效应分析结果显示, 该地区近地晴天大气电场与三个气象参量(大气压强、温度和相对湿度)的长时间变化趋势基本一致, 并有明显的季节效应. 冬春季, 大气电场强度整体水平相对较低, 约为0.14 kV/m; 夏秋季, 电场强度水平相对较高, 为0.18 kV/m左右. 近地晴天大气电场强度与大气温度间的线性相关性最强, 拟合相关系数达到0.89; 与大气压强和相对湿度间的线性相关性相对较弱, 拟合相关系数依次为0.43和0.53. 傅里叶分析结果表明: 晴天大气电场时间变化受太阳日周期、半太阳日周期及其三、四次谐波分量调制作用, 调制强度依次减弱. 西藏地区近地晴天大气电场日变化特征呈大陆简单型, 即双峰双谷. 主、次峰谷分别出现在白天和夜间, 主峰谷出现的早晚因季节不同略有差异, 次峰谷出现的早晚因季节不同差异相对较大.

The study of meteorological effects and time variations of the fair weather atmospheric electric field near ground in YBJ, Tibet

Based on the fair weather atmospheric electric field recorded by YBJ Cosmic Ray Station located at the YBJ High Altitude Cosmic Ray Laboratory (90° 31'50" E, 30° 06'38" N, 4300 m a.s.l., 606 g/cm2), Tibet, China, its meteorological effects and time variations are studied. The analysis in this paper is to look into how the factors like atmospheric pressure, temperature and relative humidity in the presence of the meteorological factors in four seasons govern the fair weather atmospheric electric field at the site of measurement. The results of meteorological effects show that there is a strong positive correlation between the fair weather atmospheric electric field and temperature, while a moderate positive correlation is seen between the fair weather atmospheric electric field and the atmospheric pressure, also the relative humidity. The long-term variations of the fair weather atmospheric electric field are affected by seasons. The mean value is higher in summer and fall, but lower in winter and spring. The daily variation of the fair weather atmospheric electric field is modulated by solar diurnal, semi-solar diurnal, and its third and fourth harmonic component. The higher the harmonic frequency, the lower the modulate amplitude is. The daily variation curves show bimodal variation with evening peak and sunrise peak. Two minima can also be seen in early morning and evening. Sunrise peak value is highest during summer and fall, but lowest in spring and winter morning. Sunrise peak occurs at around noon, and evening peak is modulated by the season effects.