| There are tons of charged particles in the ionosphere,which has the function of reflection,refraction and absorption for radio waves.the rapid rise and fall and jitter of radio signal phase and amplitude,caused by irregularities in the ionosphere,has important influence on human radio communications,satellite launch,GPS position-ing and human space activities.With the development of science and technology of China,the space exploration activities is more,developing high vertical resolution of the ionosphere observation method,accumulating the ionosphere irregular data,has become the urgent needs of the atmospheric science research,the safe operation of the aircraft,improving the defense capability of the military and the national science and technology level,etc.Over the decades,the research of low latitude region ionosphere irregularities had made great progress,but the ionospheric irregularities of physical mechanism and changing law hasn't been good to know,especially,the relationship between the spread F(SF)and planetary wave is not lucubrate enough.Therefore researching on ionosphere observation and the irregularities has important application value.In this paper,using the digital ionosonde as a platform,using 2012 sanya regional characteristic parameters of the ionosphere,using wavelet analysis method to study the characteristics of planetary wave disturbances in the ionosphere,and adopting the method of planetary wave disturbances are used to refer to oscillation of the true height combined with global geomagnetic parameters,analyzes the relation between the planetary wave and SF.Firstly,this paper systematically introduces the ionosphere,irregularities structure,the ionosphere characteristic parameters and the basic structure and working principle of the ionosphere digital ionosonde,which is the latest development,and the signal source are described in detail sheet design idea and implementation method,and the control program is used to simulation.Finally combined with hardware circuit for the signal source work on the test,and the result shows: the signal source work stability,the output signal is reliable,and satisfy the system requirements.Secondly,this paper,by using the 34080 ionogram data,which observed by Digital Portable Sounder 4d(DPS-4D)ionosonde at sanya in 2012,based on the characteristics of planetary wave,we list the virtual height change at three different times(12 LT,LT,19,21 LT)of sanya in 2012,its day-to-day variability is analyzed by the method of Morlet wavelet analysis,at the same time also to the ionosphere characteristic parameters Fof2,h'f,dNe/dt and dh'f/dt,Finally the results of the analysis are discussed.Results show that: the Morlet wavelet analysis can clearly obtain the disturbance characteristics of long period wave on different heights in F layer.Study large-scale irregularities could analysis the virtual high in different frequency,minimum virtual high and the critical frequency in different time;In the present results,the presence of 3-day related to quasi 2-day oscillations,periods of 27 ~ 31 days are related to solar rotation(27.3 days),periods of 7 ~ 10 days and 13 ~ 15 days are related to planetary wave type oscillations due tropospheric sources with possible influence of the half solar rotation period.Finally,In this paper,the basic principle of the uplifting of the F layer is introduced,the modulation mechanism of traveling planetary wave ionospheric disturbances(TPWIDs)on F layer is analysised,and given several effects without SF,finally the characteristics of planetary wave disturbance is analyzed during the high SF season in china's low latitude region,and the influence of TPWIDs phase on the formation and development of SF is investigated by the method that TPWIDs are used to refer to oscillation of the true height,which is the day-to-day variability,with the Dst.The occurrence situation of different types of SF in different seasons is also researched.The results show that TPWIDs-type oscillations controlling the strength of the electric field during PRE,therefore,slowly push the F layer height up and down according to the TPWIDs phase in the geomagnetic quiet period.the occurrence of SF is strongly controlled by the change of post-sunset F layer height and the altitude of 250 km may be a threshold at sanya,so when the the electric PRE causes the F layer bottom side to reach heights above 250 km,it is conducive to generate SF.Also during equinox(March,April,September and October)the onset time of SF is modulated by the TPWIDs phase in such way that,when the phase greater,SF occurs earlier and when the phase smaller,SF occurs later or no SF. |
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