Validation of K-indices through comparative analysis for Sonmiani Geomagnetic Observatory, Pakistan

K-indices have been produced and analyzed using two computer based methods for 1-min geomagnetic data from Sonmiani Geomagnetic Observatory (SON), located at 25.203° in latitude and 66.75° in longitude, for the period 2009-2011. The two methods used are Finnish Meteorological Institute (FMI) method and adaptive smoothing (AS) method. Solar quiet daily variation (Sq) and solar regular variation (Sr) curves are produced using FMI method and their comparison is drawn. Various statistical analyses have been carried out by comparing the K-indices obtained through AS method with other geomagnetic observatories having similar time zone and geomagnetic latitude aiming to validate our results. Resulting K-indices obtained from AS method are in a good match with nearby observatories irrespective of the K derivation method used for each of the observatories compared. Further, we have compared the K-indices obtained through AS and FMI methods and found the FMI has a tendency to shift the results to somewhat higher K-values than the AS method.