A trough station (Ouagadougou station) of African Equatorial Ionization Anomaly sector foF2 long term trends are carried out after the elimination of solar cycle long term variation part. For this part, foF2 is expressed as a third degree polynomial function of Rz. We analyzed diurnal, seasonal and annual foF2 long term trends during 30 years covering the period 1966-1996. Diurnal trend variation showed positive hourly trend at the morning (slope maximum value at 0400 LT: + 1.5 x 10-3 per year) and at night (slope maximum value at 2200 LT: + 0.7 x 10-3 per year). During night and morning times well correlation is observed between foF2 and Ap. The absolute maximum trend is observed at 1900 LT (+ 2.5 x 10-3 per year). Seasonal variation at 1900 LT exhibited for each season positive trend except during summer where negative trend was observed (-0.0472 per year). At equinoxes, there is no asymmetry and foF2 trend is + 0.0412 per year. Annual investigation showed that from 1966 to 1981 Ap and foF2 present the same sense variation while from 1981 to 1966 it is the reverse. At 0400 LT, between 1966 and 1981 relative foF2 presents positive trend (+5.4 x 10-3 per year) and between 1981 and 1996, it shows negative trend (- 5.3 x 10-3 per year). At 1900 LT, for the 30 years involved, relative foF2 shows strong negative trend (- 6.5x 10-3 per year).
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机译：在消除了太阳周期长期变化部分之后，开展了非洲赤道电离异常部门foF2长期趋势的低谷站（瓦加杜古站）。对于这部分，foF2表示为Rz的三次多项式函数。我们分析了1966-1996年这30年间的每日，季节性和年度foF2长期趋势。日变化趋势在早晨（0400 LT处的斜率最大值：+ 1.5 x 10-3 /年）和晚上（2200 LT处的斜率最大值：+ 0.7 x 10-3 /年）显示正小时趋势。在夜晚和早晨，foF2和Ap之间存在良好的相关性。在1900 LT（每年+ 2.5 x 10-3）观察到绝对最大趋势。除夏季观察到负趋势（每年-0.0472）外，每个季节的1900 LT的季节变化都呈现出正趋势。在春分点，不存在不对称性，foF2趋势为每年+ 0.0412。年度调查显示，从1966年至1981年，Ap和foF2呈现相同的感官变异，而从1981年至1966年则相反。在0400 LT，1966年至1981年之间的相对foF2呈现正趋势（每年+5.4 x 10-3），而1981年至1996年之间，其foF2呈现负趋势（每年-5.3 x 10-3）。在1900 LT，在涉及的30年中，相对foF2表现出强烈的负趋势（每年6.5倍10-3）。
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