武汉上空Na层季节和夜间变化的观测研究

LIDAR OBSERVATIONS OF THE MESOSPHERICNa LAYER OVER WUHAN: SEASONAL ANDNOCTURNAL VARIATIONS

根据武汉大学激光雷达2001年3月到2002年10月的观测数据,对武汉上空(30.5°N,114.4°E)的背景Na层结构进行了研究,并与其他观测站尤其是Urbana(40°N,88°W)的观测结果进行了比较。发现武汉上空11月的Na层柱密度最大,是4月的2.5倍,质心高度的极小值出现在5月和11月,极大值在4月、9月和12月;全年平均Na层均方根宽度为4.47km.Na层各参数呈现出周期性变化规律,其中Na层均方很宽度呈现出明显的半年周期性变化规律。夜间Na层柱密度呈现总体增加的趋势,质心高度在入夜后立即迅速上升,在2000LT以后上升速度趋缓,凌晨0500LT以后出现下降;Na层均方根宽度在夜间约有1.3km的起伏变化,它入夜后迅速减小,在午夜0035LT时出现一低谷,然后随时间逐渐变宽。

Based on the lidar observations between March 2001 and October 2002, the characteristics of background Na layer over Wuhan (30.5°N, 114.4°E) are presented and compared with other reported lidar measurements, especially with that of Ur-bana (40°N, 88°W). The sodium abundance in Wuhan reaches a maximum value in November which is approximately 2.5 times larger than that in April. In November and May, the layer centroid height reaches its minimum and its maximum in April, September and December. The yearly averaged rms width is 4.47km. There is a variation trend in the parameters of Na layer. Especially, the layer rms width shows a semiannual variation trend. The sodium layer abundance generally increases through the night. After rapidly ascending from sunset, the layer centroid height climbs up slowly between 2000 LT and 0500 LT, then descend swiftly. The sodium layer rms width shows about 1.3km variation during the night. At first the layer rms width diminishes, after arriving at a minimum at 0035 LT, it increases steadily with time.