Abstract
SPACE WEATHER,
VOL. 7,
S04003,
17 PP., 2009
doi:10.1029/2008SW000407
Real‐time prediction of magnetospheric activity using the Boyle Index
Real‐time prediction of magnetospheric activity using the Boyle Index
Ramkumar Bala
Department of Physics and Astronomy, Rice University, Houston, Texas, USA
P. H. Reiff
Department of Physics and Astronomy, Rice University, Houston, Texas, USA
J. E. Landivar
Department of Physics, University of Texas at Arlington, Arlington, Texas, USA
We present a new algorithm with an improvement in the accuracy and lead time in short‐term space weather predictions by coupling
the Boyle Index, Φ = 10−4 ν 2 + 11.7Bsin3(
$\theta$/2) kV, to artificial neural networks. The algorithm takes inputs from ACE and a handful of ground‐based magnetometers to
predict the next upcoming Kp in real time. The model yields a correlation coefficient of over 86% when predicting Kp with a lead time of 1 hour and over 85% for a 2 hour ahead prediction, significantly larger than the Kp persistence of 0.80. The Boyle Index, available in near‐real time from
http://space.rice.edu/ISTP/wind.html, has been in use for over 5 years now to predict geomagnetic activity. The logarithm of both 3‐hour and 1‐hour averages of
the Boyle Index correlates well with the following Kp: Kp = 8.93 log10 < Boyle Index> –12.55. Using the Boyle Index alone, the algorithm yields a correlation coefficient of 85% when predicting
Kp with a lead time of 1 hour and over 84% for a 3 hour ahead prediction, nearly as good as when using Kp in the history but without any possibility of “persistence contamination.” Although the Boyle Index generally overestimates
the polar cap potential for severe events, it does predict that severe activity will occur. Also, 1‐hour <Boyle Index> value
less than 100 kV is a good indicator that the magnetosphere will be quiet. However, some storm events with Kp > 6 occur when the Boyle Index is relatively low; the new algorithm is successful in predicting those events by capturing
the influence of preconditioning.
Received 28
April
2008;
accepted 3
February
2009;
published 16
April
2009.
Citation: Bala, R., P. H. Reiff, and J. E. Landivar
(2009),
Real‐time prediction of magnetospheric activity using the Boyle Index,
Space Weather,
7,
S04003,
doi:10.1029/2008SW000407.