小尺度重力波引起夜光云反照率变化的统计特征

利用AIM卫星搭载的CIPS云成像探测器获得的云图数据，提取2008-2009年南北半球共6664个小尺度重力波（波长10～150km）个例，通过重力波区域与背景云层反照率变化值的对比分析，研究重力波引起云层反照率的变化特征.结果表明，重力波引起的反照率变化值以正值为主，最大平均值4.48×10-6sr-1出现在南半球降交轨道.反照率变化值与IWC变化值正相关，相关系数均在0.85以上.重力波引起的反照率变化呈现出很强的纬度和时间依赖性，且几乎均为正值.反照率变化值在中期阶段（冬/夏至日之后的50天）的高纬地区（>70°）更大，但在中期以外始末阶段的低纬地区（<70°）逐渐变小，甚至开始出现负值.随着背景云层的增强，反照率平均值呈线性增大，小尺度重力波能够引起背景云层反照率约14.6%～28.8%的变化量.当重力波引起的反照率周期性变化的振幅逐渐增大时，反照率变化值也线性增大，变化率约为0.909%～1.194%.南半球的变化率整体比北半球稍小，这与背景大气条件的差异有关 

Statistical Characteristics of Albedo Variation in Noctilucent Clouds Induced by Small-scale Gravity Waves

The accurate assessment of albedo variations in Noctilucent Clouds (NLC) induced by Gravity Waves (GW) has shown an important significance in evaluating the trend of NLC brightness. This work focuses on the impact of small-scale GW with wavelength of 10~150km on the albedo of Polar Mesospheric Cloud (PMC). Using the Level2 albedo images obtained by the Cloud Imaging and Particle Size (CIPS) experiment onboard Aeronomy of Ice in the Mesosphere mission (AIM) from 2008 to 2009, 6664 small-scale GW are extracted. The wavelength of those GW is from 10 to 150 kilometers. By comparing and analyzing the albedo in GW areas and in mean NLC areas, the characteristics of the albedo variations in NLC induced by small-scale GW are studied. Results show that the albedo variations are primarily positive, and the maximum average value, 4.48×10-6sr-1, is found on the descending portion of South Hemisphere. The albedo and Ice and Water Contents (IWC) variations are positively correlated, and the correlation coefficients are greater than 0.85. The albedo variations largely rely on the location and time of the GW, and the mean albedo variations are almost positive. The albedo variations are larger in higher latitude during the core of the seasons, while they become smaller gradually in lower latitude during the beginning and ending period of the seasons, and even to be negative in some edges of the maps. The albedo average value increases linearly as the background atmosphere increases, and the albedo variations in percentage is from 14.6% to 28.8% induced by small-scale GW. When the albedo amplitude of GW increases, the albedo variations also show a linear increase with the changing rate from 0.909 to 1.194. The whole variation rate of south hemisphere is a little smaller than that of north hemisphere because of the difference of background atmospheric conditions.