Observation Of Sporadic Sodium Layer Over Haikou Of China In 2010

Sodium lidar observations of Sporadic Sodium Layers (SSL) in 2010 at a low-latitude location (Haikou, China, 20.0°N, 110.3°E) are reported in this paper. The wavelength of the dye laser is set to 589nm by a sodium fluorescence cell. The energy and divergence of the beam are about 45mJ and 1mrad, respectively. The repetition rate of Nd:YAG laser is 30Hz. The backscattered fluorescence photons from the sodium layer are collected by a telescope with a 1000mm diameter primary mirror. From 38 SSLs events detected in about 458h of observation, an SSL occurrence rate of 1 event every 12h at our location was obtained. This result, combined with previous studies at a mid-latitude location (Wuhan, China, 31°N, 114°E), and compared with the SSLs at a low-latitude location (Brazil, 23°S, 46°W), reveals that the SSL occurrence can be frequent at a low-latitude location of Haikou, China. The profiles of a peak density of the SSL were very spatial symmetry on Dec. 30, 2010. With respect to the correlation with sporadic E, the ionosphere data obtained by an ionosonde operated at Danzhou, China (19.5°N, 109.1°E), about 160km southwest of Haikou lidar station, have been examined. By statistical analysis of 13 events, when simultaneous SSL data and ionograms are available, a considerable correlation was found between sporadic E layers and the SSLs. The sporadic sodium layers have average downward vertical velocities at Haikou, China.