Morphology of sporadic E layer retrieved from COSMIC GPS radio occultation measurements: Wind shear theory examination

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Title:	Morphology of sporadic E layer retrieved from COSMIC GPS radio occultation measurements: Wind shear theory examination
Authors:	Chu, Y.H. Wang, C.Y. Wu, K.H. Chen, K.T. Tzeng, K.J. Su, C.L. Feng, W. Plane, J.M.C.
Contributors:	物理學系
Keywords:	E-REGION IRREGULARITIES UPPER-ATMOSPHERE IONOSPHERIC IRREGULARITIES ELECTRON-DENSITY PLASMA-WAVES GPS/MET RADAR SCINTILLATIONS IONOSONDE CHEMISTRY
Date:	2014-03
Issue Date:	2015-01-27 11:45:55 (UTC+8)
Abstract:	On the basis of the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC)-measured fluctuations in the signal-to-noise ratio and excess phase of the GPS signal piercing through ionospheric sporadic E (Es) layers, the general morphologies of these layers are presented for the period from July 2006 to May 2011. It is found that the latitudinal variation in the Es layer occurrence is substantially geomagnetically controlled, most frequent in the summer hemisphere within the geomagnetic latitude region between 10 degrees and 70 degrees and very rare in the geomagnetic equatorial zone. Model simulations show that the summer maximum (winter minimum) in the Es layer occurrence is very likely attributed to the convergence of the Fe+ concentration flux driven by the neutral wind. In addition to seasonal and spatial distributions, the height-time variations in the Es layer occurrence in the midlatitude (>30 degrees) region in summer and spring are primarily dominated by the semidiurnal tides, which start to appear at local time around 6 and 18 h in the height range 110-120 km and gradually descend at a rate of about 0.9-1.6 km/h. In the low-latitude (<30 degrees) region, the diurnal tide dominates. The Horizontal Wind Model (HWM07) indicates that the height-time distribution of Es layers atmiddle latitude (30 degrees-60 degrees) is highly coincident with the zonal neutral wind shear. However, Es layer occurrences in low-latitude and equatorial regions do not correlate well with the zonal wind shear.
Relation:	JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 卷: 119 期: 3 頁碼: 2117-2136
Appears in Collections:	[Department of Physics ] journal articles

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