电离层赤道异常两日振荡的数值模拟

近20年来,国外学者对电离层赤道异常问题的数值模拟研究未考虑到大气行星波对潮汐发电机电场的调制效应,因而不能解释赤道异常峰值的逐日变化.本文结果表明二日波对F_2区电子浓度的输运有很大影响.这一方法可以推广到赤道异常各种长周期行星波振荡的数值研究. 本文从非定常等离子体连续方程出发,建立包含行星波振荡对E×B漂移的调制效应的方程,并给出数值模拟的方法以及可与实际观测进行比较的结果.文中取二日波漂移振幅为U_p=0 m/s、5m/s、10m/s,而初位相分别为φ=0°、90°共四种情形进行了模拟,结果表明,二日波的调制可使赤道异常的时空分布以及异常峰值产生明显的逐日变化.在所选取的模型中,取U_p=5m/s,φ=0°所得到的f_0F_2t的二日分布特征与观测较吻合.而u_p约5m/s的变化能引起异常峰值f_0F_2约1-2MHz的起伏,而二天之内f_0F_2的二个峰值表现出约2-4MHz的起伏.

NUMERICAL SIMULATION OF 2-DAY OSCILLATION OF EQUATORIAL ANOMALY

For the past two decades, investigators have not considered the modulation effects of planetary waves to tidal dynamo in their numerical studies of equatorial anomaly, hence they could not explain the day-to-day variations of the peak values of the equatorial anomaly. This paper mainly deals with the problem of 2-Day wave modulation to the equatorial anomaly. Results show a significant influence of 2-Day wave to the ionization transport in the F2 region. Methods involved may be developed to the numerical investigations of equatorial anomaly in which planetary waves are taken into account.In this paper an equation in which modulation effect of planetary wave oscillation to the E X B drift is included is developed from the time dependent plasma continuity -equation. Numerical methods and results comparable to the observational facts are also presented. Drift amplitude of diurnal wave is taken to be Us=20m/s. Dxift amplitudes and initial phases of planetary waves are chosen respectively as Up = 0; Up = 5m/s, （?）p = 0°; Up = 5m/s, （?）p = 90° and Up = 10m/s, （?）p = 0° for simulation. Results show an obvious 2-Day fluctuation in temporal and spatial distributions of the equatorial anomaly under the moxlulation of 2-Day waves. In the framework of the chosen models above, the one, Up = 5m/s, （?）p = 0° gives a 2-Day distributions more comparable to observations. Conclusions are also obtained from the results that 5m/s variation in Up make the anomaly peak values of f0F2 1-2 MHz fluctuations while the peak values within two days perform a fluctuations of 2-4MHz.