The occurrence and morphology of ionospheric Es-s
over Wuchang,China,are examined and statistically analysed.The Es-s
over this area is possessed of high occurrence and clear trace.We consider that Es-s
is neither an intrinsic companion of magnetic disturbances,nor a phenomenon existing exclusively in the auroral zones and in the geomagnetic equatorial region. Over this area,Es-s
occurred mostly in magnetic quiet days,and the maximum of occurrence rate is arround 09h
LMT diurnally and in summer months seasonally.No effect on this feature due to variations of geomagnetic field or solar activity has so far been detected.