Sporadic E tidal variabilities and characteristics observed with the Cyprus Digisonde
Sporadic E tidal variabilities and characteristics observed with the Cyprus Digisonde
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塞浦路斯数字探空仪观测到的零星潮汐变化和特征
DOI：
10.1016/j.jastp.2014.07.014
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发表时间：
2014
影响因子：
1.9
通讯作者：
Chris Meek
中科院分区：
文献类型：
--
作者：
C. Oikonomou;H. Haralambous;C. Haldoupis;Chris Meek
在这项研究中，使用塞浦路斯数字探空仪(35°N；33°E)进行的电离图观测采用了电离仪高度-时间-强度(HTI)方法进行了分析。研究太阳热层潮汐通过风切变层形成机制影响的零星E(ES)和中间下降层(IDL)的发生和高度输送的优势周期和日变化规律。结果表明，零星E的日发生和高度下降以半日潮汐周期为主，但各季节都有一定的差异。白天层在日出前约125公里处开始，黑夜层在下午晚些时候约130公里处出现，两层都以2~3公里/小时的速度下降，并在10~12小时内达到100公里水平。此外，数据显示，快速下降层起源于日出和日落附近的F区高度，这受半日周期的影响。尽管这些层大部分时间在180公里以下很少被数字探空仪看到，而且从不在夜间出现，但数据提示它们与下面零星的E层相连，因此，IDL和ES在低电离层形成了一个完整的潮汐离子层系统。一个例外的结果是，在3月分点的白天发现了强烈的中间下降层，从F区开始，以大约10公里/小时的速度向下下降。尽管人们试图解释这种平分IDL特征，但对它的理解还需要更多的工作。
In this study, ionogram observations made with the Cyprus digisonde (35°N; 33°E) are analyzed by applying an ionosonde height–time–intensity (HTI) methodology. The aim is to study dominant periodicities and diurnal patterns in occurrence and altitude transport of sporadic E (Es) and intermediate descending layers (IDL), which are impacted upon by solar thermospheric tides via the windshear layer formation mechanism in the E and lower F region ionosphere. The results show the diurnal occurrence and altitude descent of sporadic E to be dominated by a semidiurnal tide-like periodicity, which prevails, with some differences, in all seasons. It is characterized by a daytime layer starting near sunrise at ~125 km, followed by a nighttime layer appearing first in late afternoon at ~130 km; both layers descend in altitude with speeds between about 2 and 3 km/h, therefore reaching the 100 km level in ~10–12 h. Also, a terdiurnal tide-like periodicity is present in daily Es occurrence and altitude descent but only in summer solstice. In addition, the data show fast-descending layers to originate at F region altitudes near sunrise and sunset, which are subject to a semidiurnal periodicity. Although these layers are rarely seen by the digisonde below about 180 km for most times and never during the night, the data hint that they connect with sporadic E layers below, therefore, both IDLs and Es form an integral tidal ion layer system in the lower ionosphere. An exceptional result is the detection during daytime of strong intermediate descending layers in March equinox, starting at F region and descending downwards with speeds of ~10 km/h. Although an effort is made to interpret this equinoctial IDL signature, more work is needed for its understanding.