کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1777889 1523672 2009 13 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Spectral observations of polar mesospheric summer echoes at 33 cm (450 MHz) with the Poker Flat Incoherent Scatter Radar
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات فیزیک زمین (ژئو فیزیک)
پیش نمایش صفحه اول مقاله
Spectral observations of polar mesospheric summer echoes at 33 cm (450 MHz) with the Poker Flat Incoherent Scatter Radar
چکیده انگلیسی

In this paper, we report on multi-beam spectral observations of polar mesospheric summer echoes (PMSE) at 450 MHz (Bragg scattering wavelength of ∼33cm) carried out with the Poker Flat Incoherent Scatter Radar (PFISR) located near Fairbanks, Alaska. The observations presented in this paper occurred with auroral particle precipitation, which enhanced the otherwise low nighttime D-region ionization. The observations indicate two classes of spectra associated with PMSE at this frequency: a relatively rare, “broad” class of spectra that seems to be particularly turbulent with spectral widths (root mean square velocity fluctuations) of 6–7 m/s, and the more common “narrow” spectra, with spectral widths close to 1 m/s. The results are discussed in terms of the turbulence scattering theory of PMSE. Using the theories of Rapp and Lübken [2003. On the nature of PMSE: electron diffusion in the vicinity of charged particles revisited. Journal of Geophysical Research 108, 8437, doi:10.1029/2002JD002857], we find that neutral turbulence together with enhancement of the Schmidt number by the presence of charged ice can indeed explain the observations, even at these small scales. The echoes are likely associated with large charged ice particles (a few 10 s of nanometers in radius). The narrowest echoes, while seemingly resulting from relatively modest neutral turbulence, thus acquire long diffusion times which allow them to drift with the background winds for tens of seconds, possibly explaining the predominance of these narrow-width echoes.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Atmospheric and Solar-Terrestrial Physics - Volume 71, Issues 6–7, May 2009, Pages 662–674
نویسندگان
, , , ,