Observations of colocated optical and radar aurora

[1] This article presents case studies of common volume observations of the E region radar aurora obtained with a 30 MHz imaging radar and the optical aurora (green line emissions) recorded by an all sky camera. In addition, in situ rocket electric field measurements in the vicinity of an auroral arc are presented in a separate case study. As inferred from the measurements, the radar aurora in the vicinity of a stable evening auroral arc arises because of the arc's polarization electric fields, which excite the two stream instability and generate electron density irregularities at meter scales. The radar aurora is the backscattering of radar waves from these irregularities.

[1]  A. Otto,et al.  Fluid Plasma Simulation of Coupled Systems: Ionosphere and Magnetosphere , 2003 .

[2]  D. T. Farley,et al.  Plasma irregularities associated with a morning discrete auroral arc: Radar interferometer observations and theory , 1985 .

[3]  D. T. Farley,et al.  Vertical structure of the VHF backscattering region in the equatorial electrojet and the gradient drift instability , 1975 .

[4]  Y. Kamide,et al.  Relationship of radar aurora, visual aurora, and auroral electrojets in the evening sector , 1976 .

[5]  H. U. Frey,et al.  E-region echo characteristics governed by auroral arc electrodynamics , 2003 .

[6]  G. Sofko,et al.  On the origin of narrow non‐ion‐acoustic coherent radar spectra in the high‐latitude E region , 1994 .

[7]  L. Cogger,et al.  Statistical analysis of the spatial relationship between the radio and optical aurora: Further evidence for refraction , 1992 .

[8]  David L. Hysell,et al.  Optimal aperture synthesis radar imaging , 2006 .

[9]  A. Otto,et al.  Ionosphere‐magnetosphere simulation of small‐scale structure and dynamics , 2001 .

[10]  D. Hysell.  Radar imaging of equatorial F region irregularities with maximum entropy interferometry , 1996 .

[11]  I. McCrea,et al.  Ohmic heating as evidence for strong field‐aligned currents in filamentary aurora , 2001 .

[12]  David L. Hysell,et al.  The 30 MHz imaging radar observations of auroral irregularities during the JOULE campaign , 2005 .

[13]  P. J. Williams,et al.  Electric fields and currents of stable drifting auroral arcs in the evening sector , 2002 .

[14]  J. Watermann.  Refraction of 50‐MHz radar waves in a realistic ionospheric model , 1990 .

[15]  R. Greenwald,et al.  Auroral currents, irregularities, and luminosity , 1973 .

[16]  K. Kauristie,et al.  Characteristics of a stable are based on FAST and MIRACLE observations , 2000 .

[17]  Warner L. Ecklund,et al.  VHF Doppler spectra of radar echoes associated with a visual auroral form: observations and implications , 1973 .

[18]  I. McCrea,et al.  Relationship between large horizontal electric fields and auroral arc elements , 1996 .

[19]  Mark Lester,et al.  On the altitude dependence of the spectral characteristics of decametre-wavelength E region backscatter and the relationship with optical auroral forms , 2001 .

[20]  S. Chakrabarti,et al.  Simultaneous ground based observations of an auroral arc in daytime/twilighttime O I 630.0 nm emission and by incoherent scatter radar , 2001 .

[21]  T. B. Jones,et al.  DARN/SuperDARN , 1995 .