Structure and dynamics of ionization and auroral luminosity during the auroral events of March 16, 1972, near Chatanika, Alaska

Abstract

During the period 1000–1030 UT on March 16, 1972, a very dynamic auroral event occurred in the latitudinal region from College to Fort Yukon, Alaska. Simultaneous observations of this auroral event were made with an all‐sky camera, a geomagnetic meridian scanning photometer, an incoherent scatter radar, a three‐component magnetometer, a 30‐MHz riometer, and two VHF/UHF auroral radars. The basic purpose of this report is to illustrate the advantages of such coordinated measurements and the possibilities for future experiments. These preliminary results point out many relationships which, although not hitherto unknown, are important to the understanding of the auroral ionosphere. Paramount among these are (1) intense discrete auroral forms (> 25 kR in 4278 Å) are associated with enhanced E‐layer electron densities near 106 electrons/cm3; (2( the riometer data and the height of maximum Ne from the incoherent scatter radar suggest that few energetic (> 40 kev) particles were precipitating during this event; (3) enhanced regions of VHF backscatter seem to be associated with eastward and westward electrojet current systems but do not spatially correspond to the regions of high Ne or bright auroral forms; and (4) the collective data yield a description which indicates that this period is associated with the Harang discontinuity region of the auroral current systems.

Investigation of the relationship between optical auroral forms and HF radar E region backscatter

“…Greenwald et al, 1973) and optical aurora (e.g. Balsley et al, 1973;Greenwald et al, 1975;Romick et al, 1974;Hunsucker et al, 1975). These studies suggested that while a relationship did exist, the radar and discrete optical aurora were located adjacent to each other, but were not co-located.…”

Atmospheric gravity waves generated in the high‐latitude ionosphere: A review

“…Its signature on a magnetometer is the region between a positive and a negative bay. In another paper, Hunsucker et al [1975] presented Chatanika radar, auroral radar, all-sky camera, and magnetometer data to illustrate that the Harang discontinuity can at times be, indeed, a very dynamic region. The rapid change in magnitude and direction of the auroral electrojet could at these times, possibly through a Lorentz force, initiate AGW's Brekke [ 1977] also presented a correlative study using ATS 5 satellite and Chatanika radar data illustrating the relationship between the Harang discontinuity and the substorm injection boundary and related to strong particle precipitation which could also generate AGW's.…”

The spectral characteristics of E-region radar echoes co-located with and adjacent to visual auroral arcs

“…Considerable work was conducted in the 1970s concerning the relationship between optical auroral arcs and VHF coherent radar backscatter echoes from the E-region Greenwald et al, 1973Greenwald et al, , 1975Romick et al, 1974;Tsunoda et al, 1974Tsunoda et al, , 1976Hunsucker et al, 1975;Tsunoda and Fremouw, 1976a, b). In general, it was found that backscatter was observed adjacent to auroral arcs as opposed Correspondence to: S. E. Milan (steve.milan@ion.le.ac.uk) to the two phenomena being co-located.…”