Prescribing the Kp, AE and Dst Response Using the Magnetospheric State Technique

Abstract:

The magnetosphere exhibits a variety of geomagnetic activities in response to different solar wind and interplanetary magnetic field (IMF) input. Global-scale geomagnetic activities, such as those due to substorms and storms, are reflected in the K_p, AE and D_st indices, which are constructed from ground-based magnetometer observations. Understanding how and the conditions under which a geomagnetic storm or substorm occurs are outstanding questions in heliophysics and space weather predication. While it is generally accepted that Earth-directed coronal mass ejections from the sun can cause geomagnetic storms and substorms in the magnetosphere, the specific necessary and sufficient conditions, in terms of both the solar wind drivers and pre-existing magnetospheric conditions, for triggering different types of geomagnetic activities are yet to be delineated. For example, while it is generally thought that geomagnetic storms can be triggered by extended intervals of southward IMF Bz, it is still not clear how and at what point during the southward-IMF Bz interval a storm will arise, and how the storm-triggering process may be affected by the pre-existing state of the magnetosphere. To address these specific questions, we have applied the magnetospheric state prescription technique developed by Fung and Shao [2008]. We have used solar wind and geomagnetic indices data taken in 1970-2009 to constructed a magnetospheric state lookup table and applied the table to perform out-of-sample predictions or prescriptions of the K_p, AE and D_st indices during different geomagnetic storm intervals (with minimum D_st ≤ -100 nT) that occurred after 2009. Our presentation will discuss the validity of the magnetospheric state prescription technique and the role of different magnetopsheric state parameters in prescribing geomagnetic storm development.

Fung, S. F. and X. Shao, Specification of multiple geomagnetic responses to variable solar wind and IMF input, Ann. Geophys., 26, 639–652, 2008