非迁移潮作用下的电离层赤道异常区单峰现象及其经度分布

当喷泉效应较弱而双峰结构发展不充分的时候，可能在赤道异常区仅能够观测到一个电子密度的峰值，称之为单峰现象.本文利用CHAllenging Minisatellite Payload卫星在2001-2010年的电子密度数据给出了单峰的发生规律，单峰在地方时早上08：00-10：00和下午16：00-19：00发生率高，发生位置在经度上呈现多波数分布，尤其在10：00-18：00明显：在分季时多呈现四波，而在冬至季时以三波为主.单峰发生多的经度，正好对应着双峰的结构特征较弱之处.究其原因，是非迁移潮的DE2和DE3分量调制了背景风场和大气发电机电场，在电场和喷泉效应减弱的经度，双峰结构难以形成时，就会表现为单峰结构.本文扩展了对单峰现象的地方时、季节和经度分布等规律的了解，明确了非迁移潮在其中施加的影响，由此，单峰同双峰现象一样可以用于研究非迁移潮对热层-电离层的作用.

Single crest phenomenon in the equatorial ionospheric anomaly region and its longitudinal distribution caused by nonmigrating tides

When the fountain effect is weak so the double crest structure is not fully developed in the equatorial ionospheric anomaly region, only one peak of electron density is probably observed, which is called single crest phenomenon. In this study, we statistically present the occurrence of the single crest phenomenon during year 2001-2010, based on the electron density data measured by the CHAllenging Minisatellite Payload. The single crest appears more frequently at 08:00-10:00 and 16:00-19:00 local time, showing longitudinal dependence that is more obvious at 10:00-18:00. Around equinox, wave number 4 longitudinal structure is observed, and around winter solstice, wave number 3 is the predominant component. The longitude where the single crest frequently occurs in general corresponds to the place where the double crests structure is weak. We suggest that, the occurrence of the single crest phenomenon is affected by the DE2 and DE3 components of nonmigrating tides that modulate the wind field and thus the atmospheric dynamo electric field. At the longitude where the dynamo zonal electric field is weak, the resultant fountain effect is not strong enough to produce the double crest structure, then the ionosphere will have only one crest in response to the direct solar ionization. The single crest phenomenon can therefore be used to study the nonmigrating tides and related electrodynamics in the equatorial ionospheric anomaly region.