Empirical relation between foE over Tanjungsari and sunspot number

Hunsucker and Hargreaves (2002) expresse the correlation between the critical frequency of ionospheric E layer foE and solar activity as f.E = a [(1 + BR) cos xJ025, where a = 3.3 and ß - 0.008. Calculation by using foE data taken from Tanjungsari station on January and December 2001, March and July 2000 when maximum solar activity and foE data on January and December 2007-2009, March 2007-2008 and July 2008 when minimum solar activity was obtained a = 3.35 and B = 0.011. It is compared between deviation of foE reference to foE data (AfoE ref) and foE calculation to foE data (AfoE cal), where foE reference is foE obtained based on a = 3.3; B 0.008 and foE calculation is obtained based on foE a = 3.35 ; ß - 0.011 and foE data is foE observed from Tanjungsari ionosonde on 2010. It seems that AfoE ref is higher than AfoE cal and it is found that 76.1 % foE results by using a = 3.35 and B = 0.011 are more close to foE real data than foE calculation by using the formula of Hunsucker and Hargreaves.