Correlation between the sunspot number and tropospheric refractivity in a tropical environment

In this paper, a study of the tropospheric surface refractivity relationship with sunspots number variability on daily scale was carried out in a tropical region in Nigeria. The data was averaged to hourly mean from the initial five minutes update cycle and then to daily mean using spread sheet. The dependence of surface radio refractivity on sunspots number for the period considered in this work was established using linear regression coefficient and the results for Lagos and Anyigba are R2=0.019, R2=0.004, R2=0.010, R2=0.000 and R2=0.000 for 2007, 2008, 2009, 2010 and 2011 and R2=0.089, R2=0.027 and R2=0.007 for 2010, 2011 and 2012 respectively. However, when the spotless days were filtered the regression coefficient was obtained to be R2=0.145, R2=0.01261, R2=0.00001, R2=0.0012 and R2=0.062 for 2007, 2008, 2009, 2010 and 2011 for Lagos and R2=0.1155, R2=0.0261 and R2=0.0071 for 2010, 2011 and 2012 for Anyigba respectively. Meteorological data from 2007 to 2011 was employed for Lagos while meteorological data from 2010 to 2012 was employed for Anyigba. Sunspot data was also obtained from Royal Observatory of Belgium for the period under study. Results obtained show no correlation between Sunspot number and surface refractivity. The sunspot number data was filtered to remove noise due to spotless days. The result obtained after filtering did not show any significant difference. •We examined correlation between sunspot and refractivity in a tropical environment.•There is no correlation between sunspot and surface refractivity observed.•Results show that surface refractivity is driven by the meteorological vagaries.•Results show that surface refractivity does not depends on sunspots variations.•Spotless days gave almost similar correlation result with filtered days.