High-Time Resolution Dayside Convection Monitoring By Incoherent Scatter Radar and a Sample Application


Convection and its changes, driven by the solar wind, are related to geomagnetic disturbances such as substorms, dynamic pressure disturbances and convection bays. Furthermore, convection is theoretically related to the evolution of the Harang electric field reversal (or “discontinuity”), which has been related observationally and theoretically to these disturbances. Interplanetary measurements generally used for studying and making associations of convection with disturbances are acceptable for statistical studies, but spatial structure and propagation timing errors due to the highly variable orientation of interplanetary structures create significant ambiguity for case studies and have prevented definitive understanding. Moreover, small but geoeffective structure in the solar wind may be missed by even multispacecraft observations. Direct observation of dayside convection with high time resolution offers a potential solution to this problem. In this paper, we demonstrate that Sondrestrom incoherent scatter radar (ISR) observations have the ability to accurately monitor the dayside convection with ∼2.5 min temporal resolution. The observations clearly show the dayside convection responses to IMF Bz, By and solar wind dynamic pressure variations and thus shed new light on how the magnetosphere and ionosphere respond to different external driving. Then, we illustrate an application of this technique by showing how it can be applied to study substorm triggering. We plan to use this technique in the future to study the relationships between convection, other geomagnetic disturbances, and the Harang reversal, as well as to evaluate the preceding convection strength and duration and the convection changes that lead to substorm onset.

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