SDO/AIA 193 image with extracted coronal hole (CH) boundaries derived via histogram-based thresholding methods. The fractional area A of coronal holes is calculated over the outlined meridional slice embracing the central meridian at ±7.5° in longitude (all pixels identified as CH pixels inside this meridional slice are summed up and divided by the total number of pixels in the slice).This fractional CH area, A, is used to forecast the solar wind parameters: speed v and magnetic field strength B at a distance of 1 AU.
For a full description of the method see Rotter, T., Veronig, A.M., Temmer, M. and Vrsnak, B., 2012, Solar Physics.


SDO AIA image & data (UNI Graz) was updated before hour(s) and minute(s) ago.

last model update on 22 April 2013

© Hvar Observatory, 2013