Influence of the Storm on the Ionospheric Spread-F in Hainan Region

Using the data observed with DPS-4 ionosonde from February 2002 to December 2007, influence of geomagnetic storm on the ionospheric Spread-F (SF) in Hainan region is statistically studied. The result shows that the occurrence of spread-F as a whole is suppressed by the storm. But for the different type of SF, influences of the storm are different. During storm time, FSF is motivated in 2002 and 2003, and suppressed during 2004---2007; RSF is suppressed during 2002---2005, and motivated in 2006 and 2007; MSF is suppressed in 2002, motivated in 2003 and 2004, and suppressed again during 2005---2007; SSF is suppressed during 2002---2004, motivated in 2005 and 2006, and weakly suppressed in 2007. These results are important to study the mechanism for different type of ionospheric SF during the storm time in the low latitude region.