Figure 6- - uploaded by Raj K. Choudhary
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Cartoon illustrating the basic reason why the vertical wind structure of a Kelvin-Helmholtz billow will be detected by an upward looking radar. From St.-Maurice & Choudhary (2006).
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Meter size irregularities are routinely studied with radars in the equatorial and low latitude regions. In both instances echoes from the E-region (90 to 120 km altitude) are a common occurrence. The resulting echoes are labeled as so-called Type I or Type II according to their spectral signature. In this paper we show that the phase velocity of Ty...
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... loose end is left, namely, why should the radar actu- ally see the vertical wind pattern with Type II waves? The car- toon shown in Figure 6 may help answering the question. While complications have to be addressed ( Choudhary et al., 2005), the cartoon gives the basic answer, namely: with the B field lines basically horizontal, a vertical wind with some finite horizontal wavelength and finite vertical extent (such as is expected in KH billows) drags the ions along, but not the electrons. ...
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