太阳活动对中山站F2层峰值电子浓度的影响

利用中山站1995-2006年的电离层垂测数据统计分析了当地电离层F2层峰值电子浓度（N_mF2）对太阳活动变化的依赖性，研究发现在中山站N_mF2月中值随修正太阳10.7厘米通量指数F10.7P增大而增大，其饱和或放大趋势不明显。除冬季12-16 UT、20-2 UT与夏季2-11 UT以外的绝大部分时刻，两者具有良好的线性关系。N_mF2月中值随F10.7P变化斜率随季节、地方时而变化。在日变化中，N_mF2随F10.7P变化斜率极大值出现在磁中午附近，明显大于其他时刻，在夜侧变化斜率整体较小，且在分季和冬季的夜侧以及夏季全天，其斜率随地方时变化不大。在年变化中，日侧斜率最大值出现在两分季，冬季次之，夏季最小；而夜侧斜率在夏半年（10月-3月）整体上要大于冬半年（4月-9月）。结合中山站位于极隙区纬度的特殊地理位置，分析了上述N_mF2变化特征的可能原因。

THE EFFECT OF SOLAR ACTIVITY ON THE NmF2 AT ZHONGSHAN STATION

We investigated the solar activity dependence of the ionospheric F2 peak electron density (N_mF2) at Zhongshan Station from 1995 to 2006. We found that N_mF2 increased linearly with solar activity indices. There were also correlations between N_mF2, local time and seasonal changes. Diurnally, N_mF2 was maximal at magnetic noon, larger than other time obviously. There was a weak relationship between N_mF2 and solar activity during the night, with almost no change over time. Annually, the maximum correlation appeared during the equinoxes. There were double peak values in the equinoxes, which were even greater than in the summer of the southern hemisphere. The changes in the slope were relatively smooth in the summer of the southern hemisphere. In the southern hemisphere winter, there was only a change in the slope near the magnetic noon, with almost no changes at other times. At Zhongshan Station, there was usually a strong linear relationship between N_mF2 and P. There was no obvious saturation or amplification effect at Zhongshan compared with middle and low latitudes. We analyzed possible reasons for the N_mF2 variations, linked to the special geographic latitude of the Zhongshan Station.