海口上空中高层大气强烈的突发钠层观测

海南激光雷达站（20°N，110°E）2011年11月2日观测到强烈的突发钠层（SSL）.该SSL峰值密度达37087cm-3，半峰全宽仅为0.9km.对该SSL发生前后的钠层峰值密度和高度特性进行分析.统计激光雷达2010年5月至2013年12月共计377天观测到的SSL事件222次，其中仅有1次SSL峰值密度超过30000cm-3.对比距离最近的海南儋州（19.5°N，109.1°E）测高仪和VHF雷达观测到的突发E层（Es）事件，分析事件的相关性.Es最低高度与SSL峰值高度差均在5km以内，约有75%的Es与SSL时间差在±30min之内.实验中使用continuum的Nd:YAG激光器和泵浦染料激光器产生589nm激光，能量为45mJ，使用直径为1000mm的望远镜接收钠层的光子回波. 

Observations of the Prominent Sporadic Sodium Layer over Haikou

The prominent Sporadic Sodium Layer (SSL) were observed by the lidar over Haikou (20°N, 110°E) at 02:47LT on Nov. 2, 2011. The peak density of SSL was 37087cm-3, and its Full Width at Half Maximum (FWHM) was 0.9km. The characters of the peak density and altitude before and after the SSL occurrence were analyzed. 222 SSL events were detected in 377 observation days from 2010 to 2013. The SSL occurrence rate is 12.4h at our location, but only one SSL which peak density was beyond 30000cm-3. By comparing the corresponding data of the nearest ionosonde and VHF radar at Danzhou (19.5°N, 109.1°E), it was found that SSL is closely related to Es. Among the 8 pairs of SSL and Es events checked, all peaks of SSL were accompanied by the lowest Es within 5km in altitude, and 6 pairs of them were correlated within ±0.5h in time. A Nd:YAG laser and pumped dye laser were used to generate the probing beam. The wavelength of the dye laser was set to 589nm by a sodium fluorescence cell. The energy and divergence of the beam were 45mJ and 1mrad, respectively. The backscattered fluorescence photons from the sodium layer were collected by a telescope with a 1000mm diameter primary mirror.