Bz Predictions and Forecasts for the Background Solar Wind and CMEs Using UCSD Analysis Techniques

Abstract:

Since the middle of the last decade, UCSD has incorporated magnetic field data in its Institute for Space-Earth Science (ISEE), Japan interplanetary scintillation (IPS) tomographic analysis. These data are extrapolated upward from the solar surface using the Current Sheet Source Surface (CSSS) model (Zhao & Hoeksema, 1995) to provide predictions of the interplanetary field in RTN coordinates. When extrapolated to Earth, these fields can be displayed in a variety of ways, including GSM fields in Bx, By, and Bz coordinates. UCSD currently operates a website that forecasts these GSM Bz field component variations several days in advance of the present. The Bz GSM field component gives a fair correlation with in-situ derived fields near Earth of a few nano-Tesla variation, but more significantly its daily variation is shown to be correlated with geomagnetic Kp and Dst indices, and can forecast minor to moderate geomagnetic storms within a few-day window with about a 50% accuracy; progress to provide even finer resolutions is ongoing. More challenging to predict are large, short-lived magnetic field components that can be north-south near the times of CMEs, and whose southward GSM Bz can help produce the most extreme geomagnetic effects. Here, the record for success is not as clear, but we have made inroads into these predictions from this analysis that will be discussed.