Liu, S (reprint author), Chinese Acad Sci, Natl Space Sci Ctr, Beijing, Peoples R China.
; Liu, S (reprint author), Univ Chinese Acad Sci, Sch Astron & Space Sci, Beijing, Peoples R China.
NNSFC [41474164]
; Youth Innovation Promotion Association, Chinese Academy of Sciences
英文摘要:
In this paper, two empirical models are developed for short-term forecast of the Kp index, taking advantage of solar wind-magnetosphere coupling functions proposed by the research community. Both models are based on the data for years 1995 to 2004. Model 1 mainly uses solar wind parameters as the inputs, while model 2 also utilizes the previous measured Kp value. Finally, model 1 predicts Kp with a linear correlation coefficient (r) of 0.91, a prediction efficiency (PE) of 0.81, and a root-mean-square (RMS) error of 0.59. Model 2 gives an r of 0.92, a PE of 0.84, and an RMS error of 0.57. The two models are validated through out-of-sample test for years 2005 to 2013, which also yields high forecast accuracy. Unlike in the other models reported in the literature, we are taking the response time of the magnetosphere to external solar wind at the Earth explicitly in the modeling. Statistically, the time delay in the models turns out to be about 30min. By introducing this term, both the accuracy and lead time of the model forecast are improved. Through verification and validation, the models can be used in operational geomagnetic storm warnings with reliable performance.
