Analysis of small-scale structures in lidar observations of noctilucent clouds using a pattern recognition method
Analysis of small-scale structures in lidar observations of noctilucent clouds using a pattern recognition method
复制标题
使用模式识别方法分析夜光云激光雷达观测中的小尺度结构
DOI：
10.1016/j.jastp.2017.04.005
复制
发表时间：
2017
影响因子：
1.9
通讯作者：
G. Stober
中科院分区：
文献类型：
--
作者：
C. Ridder;G. Baumgarten;J. Fiedler;F. Lübken;G. Stober
自2008年以来，利用时间分辨率为30°S的Alomar Rayleigh/Mie/Raman激光雷达在北纬69°观测到了夜光云。我们提出了一种识别和分析可能由重力波引起的NLC层高度在5-30分钟范围内的局域小尺度波结构的方法。在中层顶区破裂的小尺度重力波对动量通量有显着贡献，但很难观测和表征。该方法基于模板匹配方法，使用要在NLC观测中识别的广义结构。新方法只允许在傅里叶谱或小波谱中出现的时间太短的NLC中存在的结构的识别。该方法不需要连续的时间序列，可以处理多个NLC层和数据间隙。在2008-2015年NLC的2000小时数据中，我们发现了近5000个单波结构，总长度为738小时，这些结构平均位于NLC质心高度以下400米处，其中大量结构的长度下限为5分钟。根据阿洛马附近流星雷达的背景风，根据各个结构的长度估计出水平尺度。水平尺度的分布在15-20公里处与NLC地面相机观测到的水平波长相一致，呈现出一个波动结构的峰值。
Noctilucent clouds (NLC) have been observed with the ALOMAR Rayleigh/Mie/Raman lidar at 69° N using a temporal resolution of 30 s since 2008. We present an approach to identify and analyze the localized small scale wave structures of the varying altitude of the NLC layers in the range of 5–30 min that may be caused by gravity waves. Small scale gravity waves breaking in the mesopause region contribute notably to the momentum flux but are difficult to observe and to characterize. The approach is based on a template matching method using generalized structures to be identified in the NLC observations. The new method permits the identification of structures that are present in NLC only for a time too short to appear in a Fourier or wavelet spectrum. Without the need for a continuous time series the method can handle multiple NLC layers and data gaps. In the 2000 h of NLC data from the years 2008–2015, we find almost 5000 single wave structures with a total length of 738 h. The structures are found on average 400 m below the NLC centroid altitude and a large number of the structures has a length at the lower limit of 5 min. With the background wind from the meteor radar near ALOMAR a horizontal scale is estimated based on the length of the individual structures. The distribution of horizontal scales shows a peak of wave structures at 15–20 km in accordance with the horizontal wavelengths found by ground-based camera observations of NLC.
使用中层温度测绘仪和相关仪器量化重力波动量通量
DOI：
10.1002/2014jd022150
发表时间：
2014
期刊：
Atmospheres
影响因子：
--
作者：
Fritts D
通讯作者：
Fritts D