Shock arrival time prediction from CME and flare data by using the SARM model (Núñez et al. 2016)


Flare data (optional):    

Class (e.g. M2.7)


Flare duration:(1)

CME data (optional):    

Initial speed towards the Spacecraft (Vcmex): (2)


Location of the solar event from the spacecraft's point of view:(3)





Distance from the Sun to the target spacecraft: (4)


 Online SARM predictions are available in

(1) Duration should be in hours (e.g. 30 min = 0.5 h). This datum is calculated as the difference between the flare start and end times, consulted in the SWPC's "edited event list" ( ). Historic edited events are located in


(2) Vcmex is calculated depending on the available data:

  • If radial CME speed (Vcme) is available, Vcmex is calculated by using the following formula: Vcmex = Vcme * cos(latitude)*cos(longitude), , where latitude and longitude are the coordinates of the location of the solar event from  the spacecraft's point of view

  • If cone-model speed (e.g. Xie et al. 2004) is available Vcmex = Vc, where Vc is the cone-model-estimated CME speed

  • If the plane-of-sky CME speed Vpos is the only available datum, the following statistical correction should be made Vcmex = 1.26 * Vpos.


(3) For the case of a spacecraft near the Earth, the CME propagation direction is given by the longitude/latitude of the associated flare (if flare data are available) in the SWPC "edited event list". Most of the solar associations of the recent 1-AU shocks are in the list of Richardson & Cane (

For the case of a spacecraft at a different location, the solar event location could be estimated taken the Earth as reference and applying the difference between two locations: the location of the spacecraft relative to Earth, and the location of the solar event relative to Earth.

If flare data are not available, the latitude and longitude are obtained from published studies that estimate these data by analyzing chronograph images or other sources (e.g. NASA's Donki database).


(4) The target distance to calculate the arrival time should be in the range 0.72 to 8.7 AU. The SARM model has been tested with 120 shocks at those distances.


Contact: mnunez AT



Nunez M., Nieves-Chinchilla T., and Pulkkinen A., Empirical prediction of shock arrival times from CME and flare data, Space Weather, 2016.